The International Journal of Prosthodontics, Pre-Print

Purpose: To investigate the effect of irradiation time and zirconia thickness using low power Er,Cr:YSGG laser irradiation (for debonding purposes) on the thermal changes and shear bond strength of resin-bonded 3% mol yttrium oxide stabilized tetragonal zirconia polycrystal (3Y-TZP) specimens. Materials and Methods: 3Y-TZP slices of 0.5, 2, and 3 mm thick were used. The temperature during laser irradiation using single spot irradiation at different times (30, 60, 90, and 120 s) and line scanning irradiation from one spot tanother at three different distances (2-, 4-, and 6- mm) were recorded. Single spot and line scanning irradiation data were analyzed using three-way ANOVA (α: 0.05) and generalized linear mixed model, respectively. Non-irradiated (control) and irradiated resin-bonded 3Y-TZP  specimens were shear tested, and the data were analyzed using two-way ANOVA (α: 0.05). Results: Under single spot irradiation, the laser-induced temperature was higher through thin 3Y-TZP at any time compared to thick 3Y-TZP. For the line scanning method, short distances (2 and 4 mm) resulted in a significant increase in temperature in 0.5 mm thick specimens.  Laser irradiation significantly decreased the shear bond strength of the 0.5 mm group compared to the non-irradiated group. After irradiation, the bond strength of the 2- and 3-mm thick 3Y-TZP was similar to the non-irradiated group. Conclusion: The temperature and bond strength of low-power laser irradiated 3Y-TZP specimens was affected by the specimen thickness but not by the irradiation time tested. Low-power laser irradiation is an effective debonding method for thin Y-TZP restorations. 

This article reports a case of maxillary rehabilitation with an implant-supported fixed partial denture on six zirconia implants. A female patient with impacted maxillary canines attended our dental clinic seeking a metal-free maxillary restoration. After the extraction of both impacted maxillary canines and the placement of autogenous bone graft, six one-piece zirconia implants with conical abutments were placed in the anterior maxillary region. Two zirconia fixed dental prosthesis with porcelain veneering, separated at the mid-line, were placed on these zirconia implants. The ten-year follow-up monitored the adequate evolution of both implants and restorations with no signs of peri-implant disease.

Purpose: The aim of this study was to evaluate the effect of toothbrushing on the surface roughness (Sa), roughness profile (Rv), gloss units (GU) and surface morphology of three glazed ceramics. Materials and Methods: Specimens (n=7) from different CAD/CAM materials 1- Lithium disilicate-based glass ceramic (IPS e.max CAD); 2- Zirconia-reinforced lithium silicate glass ceramic (Celtra Duo) and 3- 6 mol% yttria partially-stabilized zirconia (InCoris) were evaluated. IPS e.max CAD and InCoris specimens were sintered and all the groups were pre-polished and glazed according to the manufacturer's recommendations: IPS Ivocolor Glaze Paste (Ivoclar Vivadent) or Universal Overglaze High Flu (Dentsply/Sirona). Sa, Rv, GU and morphology were analyzed before and after brushing at 30.000, 120.000 and 180.000 cycles. The data of Sa and GU were analyzed by ANOVA two-way and post-hoc Tukey’s test (α=0.05). Rv was analyzed by Kruskal-Wallis and Student-Newman-Keuls. The surface morphology was analyzed qualitatively. Results: The Sa decreased significantly after 180.000 toothbrushing cycles for all materials tested. CE showed higher Rv than EM and IN, and IN showed the highest GU after 180.000 toothbrushing cycles, which promoted a polishing effect for all materials. Conclusion: Long-term toothbrushing was not able to jeopardize the glazed-surface of all tested materials compared to unbrushed.

Purpose: To evaluate the fabrication trueness, intaglio surface adaptation, and marginal integrity of additively- or subtractively manufactured resin-based onlay restorations. Materials and methods: An onlay restoration was designed (Exocad Dental CAD Galway 3.0) and saved as standard tessellation language (STL) file to generate design STL file (DO-STL). By using this design, a total of 45 onlays were fabricated either with additive (3D-printed resin for definitive (Tera Harz TC-80DP, AM-D) and interim (Freeprint temp, AM-I) restorations) or subtractive manufacturing (composite resin, Tetric CAD (SM)) technologies. Onlays were scanned with an intraoral scanner (CEREC Primescan SW 5.2, Dentsply Sirona) and the scans were saved as test STL files (TO-STLs). For trueness evaluation, TO-STLs were superimposed over DO-STL, and root mean square (RMS) values of overall and intaglio surfaces were measured (Geomagic Control X). For the intaglio surface adaptation and marginal integrity, triple scan protocol was performed. Kolmogorov-Smirnov, one-way analysis of variance, and a post-hoc Tukey honestly significant difference test were used to analyze data(α=.05). Results: RMS values of intaglio and overall surfaces, intaglio adaptation, and marginal integrity varied among test groups (P<0.001). AM-D had the greatest overall surface RMS (P <0.001), while SM had the greatest intaglio surface RMS (P<0.001). SM had the highest average distance deviations for intaglio surface adaptation and marginal integrity, whereas AM-D had the lowest (P <0.001). Conclusion: Additively manufactured definitive onlays showed lower overall trueness than additively manufactured interim onlays and subtractively manufactured definitive onlays. However, additively manufactured definitive onlays presented high intaglio surface trueness, intaglio surface adaptation, and marginal integrity. 

Purpose: To evaluate the effect of material thickness and coffee thermocycling on the optical properties of additively (AM) and subtractively manufactured (SM) definitive resin-based materials. Materials and Methods: Specimens in 3 thicknesses (1 mm, 1.5 mm, and 2 mm) were prepared from 3 AM (3D-CB, 3D-TH, and 3D-CT) and 2 SM (G-CAM and VE) resin-based materials (n=15). Color coordinates of each specimen were measured after polishing and after 10000 cycles of coffee thermocycling. Color differences (ΔE00) and relative translucency parameter (RTP) values were calculated. After logarithmic transformation, ΔE00 values were analyzed with 2-way analysis of variance, while RTP values were analyzed with generalized linear model test (α=.05).  Results: 3D-TH had the highest and G-CAM had the lowest pooled ΔE00 (P≤.004). 3D-CB had higher pooled ΔE00 than VE and 3D-CT (P≤.002). SM specimens, 1.5 mm- and 2 mm-thick 3D-CT, and 1 mm-thick 3D-TH had lower ΔE00 than 1.5 mm- and 2 mm-thick 3D-TH (P≤.036). Most of the AM specimens and 1 mm-thick VE had higher ΔE00 than 2 mm-thick G-CAM (P≤.029). Most of the AM specimens had higher ΔE00 than 1.5 mm-thick G-CAM (P≤.006). RTP values of specimens were 3D-CT, G-CAM, VE, 3D-CB, and 3D-TH in an increasing order (P<.001). Increased thickness and coffee thermocycling mostly reduced RTP (P<.001). Conclusion: 3D-TH mostly had higher color change than subtractively manufactured specimens, while G-CAM mostly had lower color change than additively manufactured specimens. Only 1.5 mm- and 2 mm-thick 3D-TH had unacceptable color changes. Thickness and coffee thermocycling mostly reduced the translucency. 

Purpose: This study aimed to evaluate the effects of an ergonomic dentist stool design on muscle activity and fatigue in dentists. Materials and methods: Fourteen dentists were recruited, and electrodes were attached to the arm, neck, and shoulder muscles of these dentists according to the Surface ElectroMyoGraphy for the Non-Invasive Assessment of Muscles protocol. After measuring the maximal voluntary contraction, eight-channel surface electromyography was performed during simulations of two dental procedures (intraoral scanning and tooth preparation) while the dentists were using two types of dentist stools. Furthermore, muscle activity and fatigue were determined based on the eight-channel surface electromyography data, and ergonomic risk levels were evaluated according to the muscle activity. The Shapiro–Wilk test was used to confirm that all data were normally distributed, and the Mann–Whitney U test was used to compare the two types of dentist stools (α = 0.05). Results: There was a significant difference between the conventional and ergonomically designed dentist stools in terms of the activity of trapezius descendens muscle (p < 0.05). Notably, the activity of the trapezius descendens muscle was lesser when the dentists used ergonomically designed dentist stools than when they used a conventional dentist stool. The activity of all muscles, except for the sternocleidomastoid, indicated moderate ergonomic risk. Conclusion: A dentist stool that enables dentists to maintain ergonomic posture should be used to prevent musculoskeletal disorders. 

Purpose. The purpose of this prospective study was to investigate the long term predictability of simplifying mandibular overdenture treatment using single-stage surgery and immediate prosthetic loading of a single implant to provide a more affordable treatment option. Material and methods. Twenty-nine patients with a mean age of 68 years with problematic mandibular dentures were treated. A single implant (Brånemark TiUnite Mk lll) was placed into the mandibular midline, achieving primary stability. A ball attachment was placed, and the retentive cap incorporated into the existing denture. The patients were recalled at 3 and 12 months and at 3, 5, 10 and 15 years. Clinical assessments, radiographs and resonance frequency analysis were recorded. All complications, failures, maintenance, and reasons for failure to follow-up were noted. Visual analogue scale questionnaires were used to record patient satisfaction (analysis of variance P<.05). Results. One implant did not achieve sufficient primary stability to be immediately loaded and was, therefore treated with a two-stage delayed loading protocol. Of the 28 patients receiving immediately loaded implants, 14 patients were available for follow-up at 15 years. Implant survival remained at 100% throughout the study. Patient satisfaction was high, with a significant increase in all comfort and functional parameters (P values ranged from <.001 to .07) throughout the 15 year period. Conclusions. These 15-year results indicate that immediate loading of a single oxidized surface implant used to retain a mucosa-borne overdenture is a safe, reliable, and cost-effective treatment with high levels of patient satisfaction long term. 

Purpose: To evaluate changes in color and translucency of stained and glazed monolithic lithium disilicates and zirconia under toothbrushing with conventional or whitening dentifrices followed by thermocycling. Materials and Methods: Samples (n=20/material) from CAD/CAM (IPS e.max CAD[EC]) and pressable (IPS e.max Press[EP]) lithium disilicates and 4Y-TZP zirconia (Prettau 4 Anterior[PA]) were prepared and received staining and glazing procedures. Aging was performed by toothbrushing with conventional (n=10) or whitening (n=10) dentifrices, followed by thermocycling, simulating 5, 10, and 15-years. Color coordinates L*, a*, b*, C*, and hº values were assessed with a spectrophotometer at baseline and after each aging period to calculate changes in color (ΔE00), lightness (ΔL*), and translucency (T.P.). Data were analyzed by 3-way repeated measures ANOVAs followed by Sidak’s post-hoc tests (α=.05). Results: Comparing the dentifrices, EC and EP produced the greatest ΔE00 after 15-years with the whitening dentifrice (P<.05). Regardless of the dentifrice, PA showed higher ΔE00 than EC after 10-years (P<.05). Comparing the aging periods, EC and PA did not show differences in ΔE00 for both dentifrices (P≥.05). EC and EP produced an increased ΔL* after 15-years in the whitening group (P<.05). In the whitening groups, the ΔL* values of PA differ (P<.005) from those of lithium disilicates. Regardless of the experimental group, the T.P. values followed the inequality PA〈EC〈EP (P<.05). Conclusions: Overall, the color of stained/glazed monolithic lithium disilicates and zirconia changed under aging with greater effects for whitening dentifrice. The aging did not influence translucency.

Immediate non-functional loading of an implant in the anterior region is a documented treatment modality with high success rates. This therapeutic approach is frequently used to overcome esthetic and functional problems during the provisionalization period, but also because it provides better support of the peri-implant soft tissues. For that purpose, an implant-supported resin restoration, either traditionally or digitally made, is used. This clinical report describes the modification of patient's natural tooth, that was previously fractured, used as an implant-supported provisional restoration to obtain better esthetics and preservation of the soft tissues in their original, pre-extraction, position. 

Purpose: To investigate the influence of milling parameters on the durability during in-vitro aging-simulation, and fracture force of resin-based composite crowns. Materials and Methods: Identical molar crowns (n=8 per group) were milled from resin-based composite crowns (Grandio, VOCO, Germany) with different processing speed (soft, normal, fast) or level of details (very high, high, low) form 98mm discs. To investigate the influence of cooling, one group was milled wet. The influence of polishing was tested in two groups. All crowns were adhesively bonded on standardized resin-based composite molars. Aging was performed with thermal cycling and mechanical loading (2x3000x5°C/55°C, 2min, H20 dist., 1.2x106 force 50N). Fracture forces were determined (v=1mm/min, Z010, Zwick, Germany). Statistics: Pearson-correlation, one-way ANOVA, Bonferroni post-hoc-tests (α=0.05). Results: All crowns survived TCML without any failures. The fracture values varied between 1237.3 +/- 326.7N and 3308.6 +/- 655.8N. Significant (p<0.001) differences between the individual manufacturing approaches were detected. Failure was categorized as a fracture of the crown and partial loosening of the crown. No different failure pattern was observed between the tested systems. Conclusion: A medium level of detail seems to be ideal to achieve highest fracture forces. No relationship existed between machining speed and fracture force. Fracture force was not affected by wet grinding. In individual cases, polishing reduced crown fracture values, due to reduced wall thickness. 

Peri-implant diseases define bacterial-plaque-induced inflammatory conditions affecting implant-surrounding tissues, classified as peri-implant mucositis and peri-implantitis. Peri-implant mucositis characterizes an inflammatory lesion that resides in the soft-tissue compartment, whereas at peri-implantitis sites, the lesions also feature progressive loss of implant-supporting bone. Inflammation resolution of and disease progression arrestment are the main therapeutic endpoints of peri-implant diseases treatment. The present position paper presents the current evidence and clinical recommendations of the European Association for Osseointegration for the treatment of peri-implant diseases. Mechanical biofilm removal along with the reinforcement of patient-administered oral hygiene is considered the standard treatment for managing peri-implant mucositis. It is recommended to assess the outcomes of peri-implant mucositis treatment 2 to 3 months after therapy, and in the absence of treatment success, a repeated intervention should be considered. Peri-implantitis treatment should follow a stepwise treatment approach, starting with a non-surgical treatment, and if not sufficient, followed by the surgical intervention. Surgical peri-implantitis therapies encompass non-reconstructive, reconstructive, and combined treatment modalities. Implantoplasty may be advocated for the treatment of supracrestal peri-implant defects, whereas reconstructive therapy is indicated at peri-implantitis sites featuring intra-osseous defects with a depth of ≥ 3 mm. Adjunctive reconstructive measures may be beneficial in enhancing radiographic defect fill and maintaining postoperative soft-tissue levels, which may have a great impact in aesthetic cases. The adjunctive use of systemic antibiotics during surgical therapy does not seem to improve the clinical outcomes. Regular supportive peri-implant therapy with biofilm removal should be an integral part of the treatment protocol of peri-implant diseases. In the presence of advanced bone loss at implants that do not play a strategic role in masticatory function, implant removal may be immediately considered.  

Purpose: Evaluating the facial esthetics of complete denture (CD) treatment using a 3D analysis of the lower third of the face before (T1) and after (T2) treatment by comparing and correlating measurements. Material and Methods: Thirty-one edentulous patients were enrolled, and three-dimensional (3D) images were captured before (T1) and after (T2) CD delivery. Twelve landmarks were established in the face. Linear, angular, surface, and perimeter measurements were evaluated and compared with the paired t test. The delta (Δ) values (T2-T1) were assessed by the Spearman correlation to verify the associations between all measurements according to the facial parameters (α=.05). Results: Statistical differences were identified in the lower third of the face in the linear measurement Sn-Gn (P = 0.006), the angular measure Tright-Pg-Tleft (P = 0.004), and at the surface of the lower third of the face (P = 0.001). All measurements were statistically different in the labial protrusion area: the nasolabial angle (Prn-Sn-Ls), the surface, and the perimeter (P = 0.001). In the lip evaluation, statistical differences were observed in the linear (Ls-Li), surface, and perimeter measurements (P = 0.001). Conclusion: The facial esthetic proportions of the linear and perimeter measurements increased, and the angles of sealed lips and nasolabial and lower facial convexity decreased after CD delivery. The present study showed a clinical important correlation between linear and angular measurements that should help restore facial esthetics, providing metrics that can aid the clinician in facial composition. 

Purpose: To describe a digital workflow for the management of the emergence profile and restoration’s finishing line on vertical prepared teeth, utilizing a digital data set. Material & methods: The scan of the prepared teeth the day of the preparation, the scan of the provisional restoration placed on the preparation after soft tissue maturation and the scan of the provisional restoration outside of the oral cavity, are combined under a common data set, that can provide all the necessary information in order to design the final restoration. Results: The presented digital technique can facilitate the implementation of the vertical preparation, as the desired finish line can be defined by the clinician and be transferred predictable to the dental lab. Current approach provides also, an alternative gingival management method, taken advantage of the displacement of soft tissue in the appointment of vertical preparation. Conclusions: The positioning of the final finishing line on vertical prepared teeth, the management of the soft tissue and the fabrication of the final restoration, can be facilitated combining digital data sets, that have been obtained during a distinct phase of the treatment. 

Purpose: To investigate the psychosocial and behavioural impact of oligodontia across three presentation types and determine if presentation type can infer impact. Materials/Methods: Thirty patients, diagnosed and treated for oligodontia between 2006 and 2021, identified from hospital records. Patients received two questionnaires; the first was a modified version of a condition-specific questionnaire, the Cleft Research Questionnaire (CRQ),used to investigate demographic, life and treatment details and impacts, and the second, the Oral Health Impact Profile (OHIP-14) used to investigate the oral health related quality of life. Patients were assigned to three presentations (Types 1 to 3) of oligodontia identified according to the edentulous space present and complexity of prosthodontic treatment required. Hypothesis test to determine if there is a relationship between oligodontia type and study variables. Results: Twenty-two questionnaires were completed and returned. There were 9 females. The age range was from 16 to 32 years. Eighteen patients had nonsyndromic and 4 oligodontia associated with anhidrotic ectodermal dysplasia. The main areas of impact were patient reported life less satisfying (64.5%, n=14)(pre-treatment), making friends (45%, N=10), school participation (45%, n=10), and public speaking (45%, n=10). No relationship was discovered between the degree of physical effect of the presentation type and study variables including the degree of psychosocial impact or life satisfaction. Conclusion: Oligodontia can have a negative functional and social impact on a patient prior to prosthodontic treatment. Prosthodontic treatment improved the life satisfaction for most patients. Psychosocial outcomes could not be inferred by the presentation type of oligodontia. 

Purpose: This study aimed to evaluate the prevalence of biological and technical/mechanical complications in edentate elders rehabilitated with complete removable dental prostheses (CDs) and overdentures [tooth-retained (ODs), implant-retained (IODs)]. Materials and Methods: Patient records of adults (>60y) rehabilitated with CDs, ODs, and IODs were included. Demographic information (age, sex), information on the prostheses type, number/type of biological/prosthetic complications, along with the number/time of the complications, were extracted.Kaplan-Meier model was used for the statistical analyses. Results: 162 patients (mean age: 74.5±9.45y; prostheses: n=224, CD=172; OD=21; IOD=31) were included. The average period of function in situ was 19.70±27.66, 32.72±27.84, and 31.73±32.67 months, for the CDs, ODs, and IODs, respectively. 5 prostheses failed. Survival analysis revealed an overall survival rate (SR) of 97.8%, with individual five-year cumulative survival probability of 96.1% for CDs, 94.1% for ODs, and 100.0% for IODs. There were no significant survival differences between maxillary and mandibular prostheses within each type of rehabilitation. In the maxilla, no significant differences were found in maintenance visit times due to prosthodontic complications among the different types of prostheses. Patients with mandibular CDs required maintenance visits earlier compared to mandibular ODs (p<0.001) and IODs (p<0.001). Patients with mandibular ODs also required maintenance visits earlier than those with mandibular IODs (p=0.005). Conclusions: Rehabilitation of the edentate jaws, whether with CDs, ODs, or IODs, is a predictable treatment modality with high survival rates. Differences in maintenance visit times were observed, with CDs and ODs in the mandible requiring earlier visits compared to IODs.

Aim: The aim of this study was to validate the effectiveness of a simplified ultrasonic cleaning protocol to clean customized abutments. The second purpose was to investigate the percentage of pollutants on customized abutments delivered by the implants company and the additional effect of dental laboratory manipulations.  Materials and methods: Twenty-four customized abutments were divided in two groups, 12 returning from the implant company and 12 others returning from the dental laboratory. In each group, there were 6 zirconia (Zr02) abutments and 6 titanium (Ti) abutments. For each conditions, half of the samples were clean with the experimental protocol and the other were left as delivered by the company. The two steps cleaning protocol consisted of mechanical treatment with a sterile compress soaked in a detergent over the transgingival part of the abutment followed by 3 successive ultrasound baths for 2 min/bath. The presence of pollutants was quantified by scanning electron microscopy. Results: The suggested cleaning method allowed to significantly decrease the quantity of pollutants (p=0.0006). The abutments returning from the dental laboratory were significantly more polluted than those coming directly from the implant company (p=0.0043). The cleaning effect was highly significant in both groups (p<0.0001). The quantity of pollutants before cleaning were similar in the titanium and in the zirconia groups and the cleaning effect was highly significant in both groups (p=0.0009). Conclusion: The tested cleaning protocol was successful on the customized abutments from each group.

Purpose. To compare the fit and fracture load of temporary fixed partial prostheses, fabricated by means of a conventional direct technique, milling or 3D printing. Material and methods. Upper right first premolar and molar were prepared on a frasaco cast, which was then duplicated 40 times. Ten provisional 3-unit fixed prosthesis (Protemp 4, 3M Espe, Neuss Germany) were made using the conventional technique with a putty mould. The thirty remaining casts were scanned to design a provisional restoration using CAD-software. Ten designs were milled (Cerec MC X5 / shaded PMMA Disk, Dentsply), while the other 20 were 3D printed by one of the two 3D printers (Asiga UV MAX or Nextdent 5100, PMMA Liquid, C&B, Nextdent). Internal and marginal fit were examined using the replica technique. Next, the restorations were cemented on their respective cast and loaded upon fracture using a universal testing machine. The location and propagation of the fracture were also evaluated. Results. 3D printing demonstrated the best internal fit. Nextdent (median internal fit: 132µm) was significantly better compared to the milled (median internal fit: 185µm) (p=0.006) and conventional restorations (median internal fit 215µm) (p<0.001), while the fit of Asiga (median internal fit 152µm) was only significantly better than the conventional restorations (p<0.012). The lowest marginal marginal discrepancy was found for the milled restorations (Median marginal fit 96µm), but this was only significant when compared to the conventional group (median internal fit 163µm) (p<0.001). The conventional restorations demonstrated the lowest fracture load (median fracture load 536N), which was only significant when compared to Asiga (median fracture load 892N) (p=0.003). Conclusion. Within the limitations of the present in vitro study, CADCAM demonstrated superior fit and strength compared to the conventional technique. Clinical implication. A poor temporary restoration will result in marginal leakage, loosening and fracture of the restoration. This results in pain and frustration for both the patient and clinician. The technique with the best properties should be selected for clinical use. 

Glass-ceramic restorations often require adjustments using coarse diamond burs (D) which have the potential to introduce critical defects at the surface from which a crack can initiate and propagate until fracture. Surface finishing using fine and ultra-fine burs (F), polishing (P), or glazing (G) have the potential to reduce or eliminate these defects. Purpose. This study investigated the influence of finishing, polishing, and glazing on the roughness, flexural strength, and microstructure of a lithium disilicate glass-ceramic (LD). Materials and Methods. LD CAD-CAM blocks were cut into 96 discs (1.2 mm x 12 mm). After crystallization, a layer of glaze was applied to the discs surface. The specimens were randomly divided into eight groups (n=12) for different surface treatments: G- glaze (control), GD, GDG, GDP, GF GFG, GFP, and GDFP. Mean roughness (Ra), mean square height (Rq) and maximum roughness (Rz) were measured. The biaxial flexural strength test was performed in a universal testing machine at 0.5 mm/min. Microstructural analysis was performed using X-ray diffraction patterns (XRD). Differences on the roughness obtained in distinct groups was analyzed by Kruskal-Wallis and Bonferroni tests (α = 0.05). The flexural strength tests were compared by one-way ANOVA. Results. Glazed groups (G, GDG and GFG) presented the lowest surface roughness, lower crystallinity, and higher flexural strength than the other groups. Although polishing and glaze presented similar surface roughness, polishing protocol decreased the flexural strength compared to the control group G. Conclusion. clinically adjusted LD glass-ceramic restorations should be reglazed whenever possible to improve strength. 

Purpose: To evaluate the effect of simulated gastric acid solution (SGAS) and resin cement composition on the shear bond strength (SBS) of zirconia-based materials with different levels of translucency to composite resin. Materials and Methods: A total of 40 medium-opacity (MO; 3Y-TZP) and 40 medium-translucency (MT; 4Y-PSZ) zirconia slabs were distributed into four groups according to the composition of the resin luting system (MDP free or with MDP [primer + Panavia V5]) and storage method (distilled water or SGAS [5% hydrochloric acid]). Composite resin cylinders were cemented on the zirconia surface and stored for 91 hours. SBS, failure mode, and surface characterization analyses via scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were performed. SBS data were analyzed using three-way ANOVA and Tukey test, and failure mode was assessed using one-way ANOVA (P < .05). Results: Storage media (P = .180), resin cement (P = .110), zirconia (P = .404), and their interactions did not affect SBS values. Bond strength ranged from 21.41 to 26.11 MPa. SEM images showed that SGAS modified the surface topography of zirconia and resin cement. The presence of chlorine and silicon (wt%) were higher after SGAS storage than after water storage in both cements used, while barium was higher only for the MDP cement. There was a prevalence of mixed failures for most of the groups. Conclusion: The SBS between both types of zirconia and resin cement was not affected by SGAS, although changes in zirconia topography were observed after SGAS exposure. The presence of MDP in the cement layer had no effect on the SBS challenged by SGAS.

Purpose. This study aims to evaluate the effect of different finishing protocols on the wear behavior of a lithium disilicate glass-ceramic. Material and methods. Specimens were produced from lithium disilicate glass-ceramic prefabricated CAD/CAM blocks and divided into three groups, according to the surface treatment (n = 8): control; polishing; glaze. Ceramic specimens were subjected to wear test using a dual-axis chewing simulator. A 49 N load was applied in the axial direction combined with a lateral movement (1 mm path) using a lithium disilicate glass-ceramic spherical piston for a total of 10⁶ cycles. Qualitative analysis of the wear surface was performed using an optical microscope. Quantitative analysis of surface roughness and volume loss was performed using a confocal microscope and a 3D-image editing software, respectively. Surface roughness and volume loss data were analyzed using Friedman's non-parametric statistical test for repeated measures and the Student-Newman-Keuls test (α = 0.050). Results. There were statistical differences for surface roughness and volume loss of lithium disilicate glass-ceramic specimens in the different experimental conditions (P˂0.001). Control and polishing groups showed similar surface roughness and volume loss values for all testing times. Glaze group had greater wear volume after 10³, 10⁴ and 10⁵ cycles. After 10⁶ cycles, surface roughness and volume loss were similar among groups. For the piston, surface roughness was similar over time and among groups. Conclusions. A distinct wear behavior was found for glazed glass-ceramic specimens in comparison to control and polished specimens. The end of the simulation, the surface roughness and volume loss was similar for the groups.

Purpose: To investigate the microscopic structure and fracture toughness of two pressable glass-ceramics comprising GC Initial LiSi Press (LiSi) and IPS e.max Press (e.max) with different levels of translucency.  Materials and methods: Four groups of LiSi and e.max with medium opacity and high translucency levels were examined. The crystal morphology of acid-etched specimens was observed under a scanning electron microscope (SEM). Six specimens in each group were fabricated in square shape (12 mm ´12 mm ´ 1.5 mm) to measure translucency parameters (TP) using a spectrophotometer. Ten bar-shaped specimens each group with dimension of 23 mm ´ 2 mm ´ 4 mm were determined the fracture toughness (K_Ic) by a surface crack in flexure (SCF) using a universal testing machine. One-way ANOVA and Scheffe post-hoc tests were used for statistical analysis. Results: LiSi showed fine dense crystals 1 – 1.5 µm in size, while e.max showed long rod-shaped crystals 3 – 4 µm in size. The TP values of all specimens were coincided with their translucency levels.There was no statistical difference in the K_Ic between different translucency for both ceramics (p<0.05). However, the K_Ic of e.max was significantly higher than that of LiSi at both translucency levels. As a result of larger and longer crystals in e.max, it could provide better crack deviation mechanism to resist the fracture. Conclusion: Within the limitations of this study, the translucency levels of both lithium disilicate ceramics did not affect the fracture toughness of the materials. The fracture toughness of e.max was statistically higher than LiSi.

Objective: To identify pressure areas using an impression technique and to evaluate whether adjustment of dentures prior to installation can decrease ulcer frequency, number of adjustments, and improve satisfaction with treatment. Materials and Methods: Fifty complete denture users were selected and randomly divided into two groups. Pressure areas were identified in 25 subjects using the impression technique with fluid silicone, and the denture base in these areas was adjusted before installation. A total of 25 subjects received new complete dentures without adjustments before installation. The number of ulcers observed was registered at 1, 7, 15, and 30 days after installation. Patient satisfaction was collected before and 1 month after the installation. The number of necessary post-installation adjustments was considered. Comparisons between the groups with respect to the number of ulcers, adjustments, and patient satisfaction were performed using the Mann-Whitney test. Results: Identification of pressure areas reduced the number of ulcers after installation of the new prostheses. These results were observed in the 1- (p = 0.004) and 7-day (p = 0.002) adjustments for the maxilla and in all the adjustments for the mandible. The technique improved patient satisfaction (p = 0.031) and reduced the number of post-installation adjustments (p ≤ 0.001). Conclusion: A reduction in the incidence of ulcers, number of adjustments and improvement in patient satisfaction could be observed with the use of the technique.

Purpose: To investigate the resistance of an implant crown telescopically engaged to a geometrically defined hexagonal abutment with and without cement under compressive dynamic cyclic fatigue loading. Materials and Methods: 40 crowns, 9 mm in height, were cast from prefabricated plastic copings each telescopically engaged to a 3 mm high machined hexagonal abutment. 20 crowns were retained with zinc phosphate cement and 20 crowns were retained with a screw. A vertical load of 15 kg was applied to all samples under oscillation. A Periotest was used to measure the mobility of the implant crown in Periotest values (PTV). Test endpoints were defined by; fatigue cycles ≥ 20 million; crown PTV > 10; or if samples became visibly loose or component fracture. Results: Cement-retained crowns failed on average at 2.60 x 10⁶ cycles ± 2.27, while screw-retained crown samples failed at 2.17 x 10⁶ cycles ± 1.27 with no significant difference (p > 0.05). Implant and abutment screw fractures were the most prevalent mode of failure in the cement-retained group, while in the screw-retained group failures were caused by the loosening of one or both screw joints. The rate of increase in PTV was higher in the screw-retained group than in the cement-retained group. Conclusions: Under the experimental conditions, an implant crown telescopically engaged vertically to a 3 mm tall hexagonal abutment, under compressive dynamic cyclic fatigue loading with or without cement demonstrated no differences in resistance or failure outcomes. A cement-retained implant crown with telescopic engagement to the abutment is more rigid, resulting in more implant and abutment screw fractures than loosening. Keywords: Screw vs Cement Retention, Telescopic Engagement, Set Screw, Dynamic Cyclic Fatigue Loading, Implant Crown, Emergence Profile

Purpose: To evaluate the masticatory efficiency in various facial forms of dentate and rehabilitated complete denture patients. Materials and methods: A total of 60 subjects were selected for the study based on the inclusion criteria. Out of which 30 subjects belong to the dentate group (D) and 30 subjects belong to the completely edentulous group rehabilitated with conventional complete denture (CECD). They were sub-grouped as brachyfacial, mesofacial, and dolichofacial facial form using facial index measurement and cephalometric analysis. After which they had undergone masticatory efficiency test using spectrophotometric analysis using diluted expectorate of chewed natural test food beetroot (10, 15 and 20 strokes). Mean of absorbance value obtained was considered as mean masticatory efficiency. From which average masticatory efficiency percentage was determined using masticatory efficiency percentage equation and considered as the masticatory efficiency of that particular subject. Results: Statistical analysis reveals that among dentate subject (D) group, brachyfacial subjects exhibited highest masticatory efficiency (70.9 ± 12.64 %) followed by mesofacial (60.6 ± 10.66 %) and dolichofacial (34.3 ± 10.81%) subjects. Similarly in completely edentulous subjects rehabilitated with conventional complete denture (CECD), brachyfacial (52.7 ± 8.11%) subgroups, mesofacial (42.3 ± 6.52%) and dolichofacial (29.3 ± 7.76 %). Conclusion: Along with other determinant factors, facial form also plays an influential role on masticatory efficiency. Brachyfacial subjects exhibited highest masticatory efficiency followed by mesofacial and dolichofacial subjects among both the study groups.

Traditionally, metal-ceramics, metal-reinforced acrylics, and more recently full-contour or layered zirconia have been the materials of choice for definitive fixed implant-supported rehabilitations. Polymethyl Methacrylate (PMMA) is commonly used in implant dentistry for the fabrication of implant-supported interim prostheses and as milled or 3D printed prototypes. This article describes a novel protocol to prosthetically restore a completely edentulous patient following a digital workflow, with fixed, screw-retained, implant-supported prostheses fabricated from CAD/CAM milled polymethyl methacrylate (PMMA), with no metal substructure. After two years follow up in terms of esthetics, phonetics, function and biological tissue response, the outcome remains functional and free of mechanical, biomechanical or biological complications. The aim of this article is to illustrate the feasibility of using milled PMMA as viable definitive prosthetic material for the fixed implant rehabilitation of edentulous patients. Keywords: milled-PMMA, Implant-supported prostheses, long-term implant-retained restorations, CAD-CAM milled restoration

Statement of problem: 5Y-PSZ-based zirconia dental restorations exhibit high translucency and good esthetics but have a higher fracture risk compared to 3Y-TZP. Objectives: To investigate the effect of BruxZir SteelTM treatment on the fracture resistance of zirconia three-unit bridges prepared using 5Y-PSZ-based zirconia blanks. Methods: Three-unit zirconia bridges were milled using CAD/CAM from homogeneous bisque zirconia blanks (5Y-PSZ-based) supplied by various manufacturers and sintered. Their fracture resistance was analyzed by dynamic loading. For each zirconia blank, the fracture resistance of the sintered test restoration (cementation surface treated with BruxZir SteelTM) was compared with the sintered control restoration (untreated cementation surface). Finite Element Analysis (FEA) was used to analyze the stress distribution on the three—unit bridge under an axial load. Results: The fracture resistance of the test restorations was significantly higher than that of the control restorations for all the manufacturers considered in this study (P < 0.05). Furthermore, the restoration made of BruxZirⓇ Esthetic treated with BruxZir SteelTM had the highest fracture resistance compared to the other restorations. In addition, the three-unit bridge restorations prepared from 5Y-PSZ-based zirconia blocks exhibited differences in grain size and fracture toughness depending on the presence or absence of BruxZir SteelTM treatment. The locations of high stresses under FEA correlated well with the fracture locations in the corresponding experimental test. FEA also demonstrated the improved performance of BruxZir Steel-treated sample compared to the control. Significance: The fracture resistance of 5Y-PSZ-based BruxZir SteelTM-treated three-unit bridges was significantly higher (min. 30%, max. 198%) than control. Keywords: Fracture Resistance, Three-unit Bridge, 5Y-PSZ, Fracture Toughness, grain size, critical loads

Disconnection and reconnection of abutments multiple times have known to affect the mucosal barrier around implants leading to marginal bone loss. This clinical report describes a novel technique that amalgamates the benefits of digital technologies encompassing the fabrication of surgical guides for implant placement, customized hybrid zirconia abutments and all ceramic lithium disilicate crowns prior to implant placement. A correct 3-dimensional implant positioning along with immediate placement of the definitive hybrid customized abutment and a lithium disilicate crown has the potential to reduce treatment time, visits and costs while delivering optimal esthetic outcomes.

Purpose: This scoping review mapped the literature on CAD/CAM (computer-aided design and manufacturing) removable complete and partial dentures regarding patient and clinician-reported outcomes. Materials and Methods: We performed an electronic search of the Cochrane Central Register of controlled trials (CENTRAL), MEDLINE (Ovid), EMBASE, SCOPUS, and Web of Science databases (last update: March 2023). All clinical trials or observational studies investigating CAD/CAM removable dentures (conventional or implant-retained) were included. Results: The search yielded 4035 records and led to 58 included studies. Results suggest that CAD/CAM complete and partial dentures, when compared to the conventional ones, can save time and resources while being rated either non-inferior or superior by patients and clinicians in most studies. However, consensus on which workflow offers fewer adjustments and postoperative sessions is still pending. Conclusion: The literature suggests that CAD/CAM complete and partial dentures can combine substantial time and cost savings with patient and clinician experiences at least comparable to the conventional prostheses. Given the low evidence level of existing studies, future well-designed randomized trials with large sample size are required to confirm those advantages. Keywords: Removable denture, CAD/CAM, Patient-reported outcomes, Clinical outcome

Purpose. The purpose of this in vitro study is to evaluate the effect of tea tree oil into denture liners on Candida albicans and bond strength to the acrylic denture base. Material and methods. Disc-shaped specimens were fabricated from silicone based resilient liner (Tokuyama, Molloplast), acrylic based hard liner (GC Reline) and acrylic based soft liner (Visco-gel) and tea tree oil was incorporated into liners at varying concentrations (0%-control, 2%, 5%, 8%). Candida albicans were counted by viable colony count and optical density (OD) was measured by spectrophotometer. The tensile strength to heat polymerized acrylic denture base was measured in a universal testing machine. The compliance of the data to the distribution of normality was evaluated using the Shapiro Wilk test. Two-way ANOVA, Bonferroni correction, paired sample t-test were performed (α=.05). Results. Tea tree oil addition into liners provided a significant decrease in the OD values (p <.001). The control groups of liners presented the highest colony counts, whereas increasing tea tree oil decreased the results (p <.01). According to tensile bond strength test, 8% tea tree oil addition resulted significant decrease for Tokuyama (p <,01) and Molloplast liners (p <.05), while 2% TTO resulted significance for GC Reline (p <.001). Conclusions. Denture liners containing tea tree oil presented lower Candida albicans colonies by the increasing amount, besides decreased the bond strength to denture bases. While using the antifungal activity of the oil, the amount of addition should be carefully selected as the tensile bond strength may be affected.

Purpose: The aim of the current study is to evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intra-coronal preparation designs. Materials and Methods: An examination of the marginal adaption of two materials, lithium disilicate (IPS e.max CAD) (EX) and polymer infiltrated ceramic network material (PICN; Vita Enamic) (EN), and two preparation designs where D1 represents MOD inlay preparation with no cusp reduction and D2 in addition of the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. 4 sub-groups (EX-D1), (EX-D2), (EN-D1), (EN-D2) were conducted. Forty (n=40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, standard deviation (Sd), minimum, maximum, and 95% confidence interval. Pair-wise comparisons using Tukey's Post-Hoc test were performed following a significant analysis of variance (ANOVA) P ≤ 0.05. Results: The results revealed that lithium disilicate (IPS e.max CAD) showed statistically significantly higher mean gap distance than polymer infiltrated ceramic network material (PICN; Vita Enamic) (61μm to 99μm). Pair-wise comparisons showed that D2 design has statistically significant higher mean gap values than D1. Conclusions: Both lithium disilicate (IPS e.max CAD) or polymer infiltrated ceramic network material (PICN; Vita Enamic) provided marginal adaptation within clinical accepted range. Polymer infiltrated ceramic network material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional Preparation. Keywords: Glass Ceramic; Hybrid Ceramic; Marginal gap; Partial coverage.

Objective: to identify the prevalence of and factors associated with total edentulism in the elderly Brazilian population. In addition, we sought to verify whether edentulism influences the self-perception of oral health and difficulty in eating. Materials and Methods: This cross-sectional, population-based study used the database of the National Health Survey conducted in Brazil. The chi-square test was initially used for data analysis. Subsequently, a multivariate analysis of the Poisson multiple regression type was performed to verify the adjusted prevalence ratios. Results: A total of 43,554 elderly people participated in the study, of whom 32% had completely lost their teeth. This total edentulism, based on the multivariate analysis, was associated with female gender (p < 0.001), advances age (p < 0.001), illiterate (p < 0.001), smokers (p < 0.001), and those who did not have health insurance (p < 0.001) or dental insurance (p < 0.001). Total edentulism had an impact on better self-perception of oral health (p < 0.001) and greater difficulties in eating (p = 0.001). Conclusion: It was concluded that total edentulism in the elderly is associated with worse socioeconomic conditions and a worse lifestyle. This condition has a negative impact on diet and positively affects self-perception of oral health. Keywords: Edentulism; seniors; prevalence.

Purpose: Digitally planned and manufactured PMMA for full arch implant supported immediate loading interim prosthesis are becoming popular comparing with conventional acrylic prosthesis. Studies on prosthodontic performance and patient related outcomes are scarce but needed. The purpose of this study was to evaluate the clinical survival and impact on oral health related quality of life of immediate loading implant supported full arch CAD-CAM milled PMMA interim rehabilitations. Methods: This was a practice based prospective cohort study performed in a Portuguese dental clinic. Eleven patients received a total of seventeen CAD CAM full implant-supported, screw-retained, full arch rehabilitation with milled PMMA and were followed up for 1 year. Primary outcome was Prosthesis survival determined with a modification of the California Dental Association score and a Kaplan Meyer survival function analysis. Secondary outcome was patient’s quality of life as defined by application of the OHIP 14 PT questionnaire and standardized effect size variation between two visits. Significance was set at 5%. Results: Survival probability at 12 months was 76%, complete fracture of the prosthesis occurred in 17,6 % of the cases and small fractures without lab involvement in 5,9%. There was a significant improvement in oral health related quality of life between visit 1 and 4. Mean difference and effect size for total OHIP-14 PT score were -32.91 (+- 3.68 SD) and 3.66 (95% CI -1.83 to -5.80) P < 0.001* Wilcoxon matched paired rank test. Conclusions: Full arch implant supported CAD-CAM milled PMMA interim prosthesis seems a viable approach with good survival rate and great impact on patient’s oral health related quality of life.

Treatment of acute cases of amelogenesis imperfecta is challenging in children due to the absence of a consensus statement on therapy recommendations. This article presents the effectiveness of an interdisciplinary approach, including orthodontics, orthognathic surgery, and prosthodontics using digital technology, in a child with amelogenesis imperfecta and skeletal deformities. The early management over a 6-year period had a very positive impact on the quality of life related to oral health. The full-mouth rehabilitation in adulthood with all-ceramic crowns showed a fully satisfactory result after 60 months of follow-up. Keywords: Amelogenesis imperfecta; Full-mouth rehabilitation; CAD-CAM; Orthognatic surgery; Case report

Objectives To evaluate and compare bacterial growth on zirconia versus titanium healing caps. Material and methods S. sanguinis (Ss) and F. nucleatum (Fn) were grown on titanium and zirconia healing caps that were fixed to the cover of a 96-well microtiter plate. A drop (10 μL) of bacterial suspension was placed on each healing cap and allowed to dry for 1h at 37°C. After this time, the cover was replaced on the plate such that the caps were completely immersed in fresh liquid medium. Each plate contained only one bacterial strain, with 2 control groups. Bacterial growth was monitored over 18h by following the optical density at 650nm. A one-way ANOVA comparison test was used for statistical analysis. Scanning electron microscope (SEM) images of healing caps of each material were taken after a 48h incubation with Ss or Fn to assess bacterial attachment and with no bacteria as control. Results Ss growth was similar in both types of healing cap with no significant differences between these groups and the control (P=0.990). However, there was significantly less growth of Fn on the zirconia caps than on the titanium samples (P<0.0001) or the control (P<0.0001). SEM imaging revealed obvious differences in the surface characteristics of the titanium and zirconia caps. The number of bacteria attached to the rough apical area was particularly high. Conclusions The use of zirconia healing caps may reduce the growth of some bacterial species compared to that seen on titanium healing caps. Keywords: Implants, healing caps, Bacterial growth, titanium, zirconia

Purpose. To compare the masking ability of monolithic CAD-CAM veneers placed over different resin cement shades and substrate colors. Material and methods. Veneers were milled of four different monolithic CAD-CAM restorative materials: feldspathic ceramic (VMII), lithium disilicate ceramic (Emax CAD), zirconia-reinforced lithium silicate ceramic (VS), and high translucency zirconia ceramic (YZ-XT). Veneers (n=9) were luted on natural tooth colored (ND1) or discolored substrates (ND3 or ND5) using two different resin cement shades (white opaque or translucent). Color parameters were obtained using a dental spectrophotometer before and after luting. Color differences (ΔE00) were calculated using CIEDE2000 formula and compared to perceptibility (P =0.81 ΔE00 units) and acceptability (AT=1.77 ΔE00 units) visual thresholds. Color variation data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U tests with Bonferroni-Holm correction (α=.05). Results. The highest ΔE00 value was obtained in VMII group placed over discolored substrate, followed by the groups of Emax CAD, YZ-XT, and VS. The effect of material types on ΔE00 values was significantly observed when the veneers luted on discolored substrates using translucent resin cement (p<.05). Conclusions. Restorative material type, substrate color, and resin cement shade affect the masking ability of monolithic CAD-CAM laminate veneers.

Purpose. The purpose of the study was to assess the clinical performance of CAD-CAM laminate veneers placed by a single operator and systematically evaluated for up to 10 years. Material and methods. A total of 197 laminate veneers fabricated using either feldspathic ceramic (VMII) or lithium disilicate ceramic (EmaxCAD) were followed up to 10 years in 32 patients. Technical, esthetical, and biological findings of each restoration were evaluated using modified United States Public Health Service criteria. The survival and complication rates were assessed using Kaplan–Meier survival analysis and compared using the Log Rank test. Statistical significance was set at p<0.05. Results. The estimated Kaplan-Meier survival rate was 91.9% after the mean observation period. According to ceramic system used, the estimated Kaplan-Meier survival rate amounted to 92.7% for Emax-CAD and to 89.1% for VMII. Survival rates were significantly affected by the location of veneer according to Log Rank test (p < 0.05). A range of survival rates between 83.3% and 98.6% were observed based on the location of veneer. Conclusions. CAD-CAM laminate veneers milled of feldspathic or lithium disilicate ceramics have comparable long-term survival rates. Oral positioning affects the survival of veneer. Veneers of incisors have higher survival rates than the veneers of maxillary canines and premolars.

Purpose: To evaluate the effect of polymerization unit, polishing, and coffee thermocycling on the color and translucency of additively manufactured polyurethane-based resins with different viscosities. In addition, their color behavior was compared with the color of the shade tab throughout the fabrication steps and aging. Materials and Methods: Disk-shaped specimens (Ø10x2 mm) were fabricated from polyurethane-based resins with different viscosities (Tera Harz TC-80DP and C&B permanent) (N=30). Baseline color coordinates were measured after cleaning. The specimens were divided into 3 to be polymerized with different polymerization units (Otoflash G171, FLN; Wash and Cure 2.0, CLED1; CARES P Cure, CLED2) (n=10), polished, and subjected to coffee thermocycling. Color coordinates were remeasured after each process. Color differences (ΔE00) and relative translucency parameter (RTP) values were calculated. Data were statistically analyzed (α=.05). Results: Time points and polymerization units affected the ΔE00 for each material (P≤.049). ΔE00 of each polymerization unit pair had significant differences within and among different time points within each material (P≤.024). ΔE00, when compared with the shade tab, and RTP were mostly affected by polymerization units and time points within both materials (P≤.042). Conclusion: Tested polymerization units, polishing, and coffee thermocycling affected the color difference and translucency of tested resins. Color differences ranged from moderately unacceptable to extremely unacceptable and the differences in translucency values mostly ranged from perceptible to unacceptable according to previous thresholds. In addition, tested resin-polymerization unit pairs had unacceptable color differences when compared to the shade tab. CLED1 may enable higher color stability for tested resins.

Purpose: The association of Temporomandibular disorder (TMD) and somatic symptoms with the psychological variables of personality, coping, and distress were analyzed in young adults. Physical and psychological correlates were also explored along with the risk factors for TMDs/somatization. Materials and Methods: Participants were enlisted from a local university and the presence of TMDs and somatic symptoms was determined with the Short-form Fonseca Anamnestic Index and Patient Health Questionnaire-15. The psychological variables of personality, coping, and distress was assessed with the Big-Five Personality Inventory-10, brief-COPE Inventory, and Depression, Anxiety, Stress Scales-21 accordingly. Statistical evaluations were performed with the Mann-Whitney U test, Spearman’s correlation, and logistic regression analyses (α = 0.05). Results: Among the 455 participants (mean age 22.7 ± 1.2 years), 18.2% and 5.7% had TMDs and medium-to-high somatization respectively. Participants with TMDs exhibited substantially higher somatization and psychological distress scores than those with no TMDs. Significant differences in TMD, conscientiousness, extraversion, and psychological distress scores were observed between participants with no-to-mild and medium-to-high somatization. The association between TMD and somatization scores, albeit significant, was weak. Neuroticism and dysfunctional coping style were moderately correlated to general distress, depression, anxiety, and stress (rs = 0.44-0.62). Conclusions: Findings suggest that anxiety is the main risk factor for the presence of TMDs and medium-to-high somatization in non-clinical young adults while conscientiousness is a protective factor for somatization. Keywords: Temporomandibular disorders, somatization, personality, coping behavior, psychological distress.

Purpose: The objective of the study was to determine the values of 15 craniofacial linear distances in the Serbian ethnic group and the correlations between them that are predictive or can serve as proxy for OVD using and compare two methods of face-anthropometric and digital 2D face-photogrammetric measurement. Material and methods: A total of 90 adults were selected. Facial distance as a tool to measure the OVD was Sn-Gn - distance between septum of the nose (Sn) and tip of the chin (Gn). Face-anthropometric measurements were made with a Boley Gauge (Buffalo Dental Manufacturing Co.NY,USA). Digital 2D photogrammetric facial measurements were performed using the computer program DrCeph (FYI Technologies, USA). Results: Determined mean value for the distance Sn-Gn by face-anthropometric was Sn-Gn(f) X=63.55 and by face-photogrammetric was Sn-Gn(ph) X=63.56. Multivariate regression analysis revealed that Sn-Gn(f) depended on ExL-ExR(f) p<0.001, ZyL-ZyR(f) p=0.077, N-Sn(f) p=0.096, Sn-Sto(f) p=0.043 and gender and that Sn-Gn(ph) depended on ExL-ExR(ph) p<0.001, EnL-EnR(ph) p=0.029, N-Sn(ph) p=0.013, Sn-Sto(ph) p=0.001 and gender. Conclusions: A comparison of facial anthropometry and digital 2D facial photogrammetry reveals no statistical significance differences in the values obtained and shows that facial photogrammetry could be a reliable method as a facial anthropometry. Keywords: Occlusal vertical dimension; Anthropometry; Photogrammetry

Purpose. A Comparison of Occlusal Schemes with Condylar Inclination and Anterior Guidance in Dentate Individuals Methods. Twenty-six dentate patients between the ages of 18 to 30 of Indian Origin with canine-guided occlusion and 26 patients with group function occlusion were included in the study. The School of Articulator Munich (SAM) Axioquick system was used to assess the condylar guidance and eccentric tracings of the patients. For analyses, Student’s t-test was used. For quantitative data, the mean and standard deviation were calculated. For all the statistical analysis the probability of type-I error of 0.05 was considered statistically significant. Results. The mean condylar guidance for canine guided and group function occlusion on the right side was 38.4 ±12.7 and 30.5 ±12.5 and on the left side was 36.5 ±13.0 and 27.5±12.0 degrees with statistically significant difference [P value: 0.01]. The condylar guidance, incisal guidance, Bennett angle, protrusion, left lateral, right lateral, and left and right lateral angles were analyzed statistically between the two types of occlusions. The results showed a statistically significant difference between the two groups for all parameters except right condylar guidance. Furthermore, all the parameters were higher in canine guided occlusion group over group function occlusion. Conclusions. Within the study limitations, it was concluded that the condylar guidance was steeper in canine guided occlusion than in group function occlusion. The eccentric parameters were steeper in canine guided occlusion than in group function occlusion. Clinical Significance: This study showcases that the condylar guidance might not play a major role in determining the occlusal scheme but, the incisal guidance determines the occlusal scheme predominantly in class 1 occlusion patients. Keywords: Anterior Guidance; Condylar Guidance; Bennett Angle; Axioquick

Purpose: To investigate the effect of recycling of lithium disilicate (LD), surface treatment and thermocycling (TC) on the bond strength (SBS) to resin cement. Materials and Methods: Blocks of LD were made according to the recycling cycle, with 24 blocks for each strategy: Control-conventional sintering; 1R (1 recycling cycle) and 3R (3 recycling cycles). For the recycling groups, blocks were waxed (10x10x3mm), mounted in a silicone ring, poured with investment material, and then residues of sintered LD blocks were pressed by the lost wax technique. The residual LD was reused as described until reach 3R. Afterwards, the blocks were embedded in acrylic resin, sanded and divided (n=15) according to the factors “surface treatment” (HF20s+Silane and HF120s+Silane and Monobond Etch&Prime- MEP) and TC (with/10.000 cycles and without). After surface treatment, cylinders (Ø:2mm) of resin cement were made and submitted to SBS test (100KgF,1mm/min). Data (MPa) were analyzed by 3-way ANOVA, Tukey's test (5%) and Weibull analysis. Failure analysis was performed with stereomicroscope. Results: ANOVA revealed that all factors were significant (P=.000*). The group 3RMEP(105.09±19.49) presented the highest SBS among the experimental groups. 1RHF20sTc(7.50±1.97) group had the lowest SBS, similar to the CHF20sTc(15.69±3.77), 1RHF20s(15.12±3.03), 1RHF120sTc(14.60±3.43) and 3RHF20sTc(15.65±0.97). The Weibull modulus and characteristic strength varied among the experimental groups (P=0.0). Failure analysis revealed adhesive and mixed types. Conclusion: The recycling of DL ceramics increases the SBS to resin cement when the ceramic is treated with HF120s+S or MEP. Keywords: Shear Strength, lithium disilicate, recycling.

Purpose: To measure and compare the mean temperature values due to heat generated during the grinding of different prosthetic materials with diamond burs using a high-speed instrument with and without water cooling. Materials and Methods: In total, 120 disk-shaped specimens (10 × 2 mm), each with a smaller disk in the center (3 × 2 mm), were fabricated from yttrium-stabilized zirconia, monolithic zirconia, glass-ceramic, indirect composite, polyetheretherketone (PEEK), and cast metal (Ni-Cr alloy). The specimens were divided into six groups (n = 20) according to material type. The specimens in each group were ground continuously with a high-speed handpiece and diamond burs with (n = 10) and without (n = 10) water cooling until the smaller disks were removed. Two different methods (thermocouple and thermal camera) were used to measure the temperature during the grinding process. Results were analyzed using two-way ANOVA and paired samples t test (P < .05). Results: PEEK had the lowest mean temperature values and metal had the highest values, both with and without water cooling, according to data measured with a thermocouple. Zirconia and monolithic zirconia samples without water cooling had the highest mean temperature values when measured with a thermal camera. Both with and without water cooling, composite samples had the lowest mean temperature value for thermal camera measurements. Conclusion: Water cooling is strongly recommended when grinding all prosthetic materials. The heat transferred to the supporting teeth may depend on the thermal conductivity of the material used.

Purpose: To evaluate the accuracy of complete-arch digital implant impressions using different intraoral scan body (ISB) materials and intraoral scanners (IOSs). Materials and Methods: The mandibular dental cast of an edentulous patient with six tissue-level dental implants was used as master cast. Two types of ISBs, polyether-ether-ketone (PEEK) and plasma-coated medical titanium, were used with five IOSs: TRIOS 4 (T4), Virtuo Vivo (VV), Medit i700 (Mi700), iTero5D (i5D), and Primescan (PS). To assess accuracy, digital impressions (n=10) with each IOS and ISB were compared to two reference models obtained by digitizing the master cast with each ISB type using a desktop scanner (IScan4D LS3i) and importing the scan data into metrology software (Geomagic Control X). Root-mean-square (RMS) error was employed to evaluate overall deviation values (trueness), while precision was determined using the standard deviation (SD) of RMS values. Statistical significance was set at P < 0.05. The Kruskal-Wallis test was used, followed by the pairwise comparison method with Bonferroni correction (α=.05). Results: An interaction between ISB material and IOS was found (P=0.001). Plasma-coated medical titanium ISBs demonstrated significantly higher trueness and precision compared to PEEK ISBs with T4 (P=0.001), Mi700 (P=0.001; P=0.004), and i5D (P=0.001). Conversely, VV exhibited higher trueness and precision values with PEEK ISBs (P=0.005; P=0.003). PS provided the highest trueness and precision regardless of the ISB material (P=0.912). T4 showed the lowest accuracy for PEEK ISBs, and VV for plasma-coated medical titanium ISBs. Conclusion: Except for PS, all IOSs showed significant differences between ISB materials. PS demonstrated the highest accuracy with both ISB materials, whereas T4 had the lowest accuracy for PEEK ISBs, and VV showed the lowest accuracy for plasma-coated medical titanium ISBs.

Purpose: Removable partial dentures (RPDs) are widely used in clinical dental practice as a cost-effective treatment to restore the oral function. Clear understanding of the effect of partial dentures on masticatory performance is important for clinical decision making in prosthodontics. The purpose of this systematic review is to evaluate the impact of RPDs on masticatory performance (MP) of partially edentulous subjects. Material and methods: Electronic database and hand searches were conducted to explore clinical trials reporting the evidence of the effect of metal and acrylic based removable partial dentures on mastication. The validated objective and subjective measures of assessment of mastication were included. The article selection, data extraction and assessment of risk of bias were conducted by two reviewers independently.  Results: Out of 11200 studies, one randomised control trial and 23 clinical trials met the inclusion criteria. Positive impact on different parameters of masticatory function after RPD treatment, was reported in 14 studies. Subjective evaluation of chewing ability (CA) displayed an improvement in 83.3% of studies, while improvement was evidenced only in 69.5% of studies upon objective evaluation. Majority of the studies were reporting data on free end saddles. Out of the 13 studies associated with bilateral free end saddle dentures, 9 studies showed a positive effect on masticatory efficiency. Various factors were found to have an impact on the masticatory performance (MP) of RPDs. Conclusion Subjective evaluation displays higher positive impact of RPDs in MP than objective evaluation. Assessment of patients’ perspectives is important in clinical decision making. Multiple factors affect the MP with RPD treatment. I

Purpose: To evaluate how the crown-to-implant (C/I) ratio affects the loss of crestal bone at single-crown implants and bridges in patients with periodontal disease. Materials and Methods: Thirty-nine patients treated for periodontitis were rehabilitated with 108 implant-supported single crowns and bridges. Each patient was examined over a 5- to 20-year period on a 3 to 6-month recall schedule. At each session, we recorded periodontal clinical parameters. In addition, intraoral radiographs were taken after superstructure insertion (baseline) and then at 1, 3, 5, 10, 15, and 20 years. The study population was divided by anatomical C/I ratio (C/I ≤1, group 1 or C/I 1, group 2). Results: Implants had a 96.2% 5-year survival rate, and 92.6% 20-year survival rate. The overall prevalence was 10.1% for mucositis and 1.1% for peri-implantitis. The survival rate (p = 0.68), mucositis (p = 0.325), or peri-implantitis (p = 0.077) did not significantly differ in the group comparison. The mean annual peri-implant bone loss was 0.09  0.41 mm and not significantly different between the groups. Mean bone loss was not significantly different until the 10th year of observation, during which group 2 presented significantly less bone loss. The correlation of annual bone loss and clinical C/I ratio showed a small but significant negative effect throughout the entire study period (R = -0.217; p <0.01). Conclusion: Increased crestal bone loss was not observed with implants with higher C/I ratios, both anatomical and clinical, and they even showed signs of less crestal bone loss.

Purpose: The aim of the current study is to evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intra-coronal preparation designs. Materials and Methods: An examination of the marginal adaption of two materials, lithium disilicate (IPS e.max CAD) (EX) and polymer infiltrated ceramic network material (PICN; Vita Enamic) (EN), and two preparation designs where D1 represents MOD inlay preparation with no cusp reduction and D2 in addition of the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. 4 sub-groups (EX-D1), (EX-D2), (EN-D1), (EN-D2) were  conducted. Forty (n=40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, standard deviation (Sd), minimum, maximum, and 95% confidence interval. Pair-wise comparisons using Tukey's Post-Hoc test were performed following a significant analysis of variance (ANOVA) P ≤ 0.05. Results: The results revealed that lithium disilicate (IPS e.max CAD) showed statistically significantly higher mean gap distance than polymer infiltrated ceramic network material (PICN; Vita Enamic) (61µm to 99µm). Pair-wise comparisons showed that D2 design has statistically significant higher mean gap values than D1. Conclusions: Both lithium disilicate (IPS e.max CAD) or polymer infiltrated ceramic network material (PICN; Vita Enamic) provided marginal adaptation within clinical accepted range. Polymer infiltrated ceramic network material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional Preparation. 

Purpose. To evaluate the published literature on tooth–tissue supported removable partial dentures (RPDs) and determine the attachment system that provides the best clinical outcome. Materials and Methods. A comprehensive search of studies published up to November 2021 was performed in the PubMed/MEDLINE, Web of Science, and Cochrane Library databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The study protocol was approved and was registered in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42021268449). The PICO question was, “What is the best attachment system used in Kennedy class I and II removable partial dentures?” Results. The search identified 871 articles, of which 21 met the inclusion criteria. The evaluation period in the studies ranged from 3 to 282 months. A total of 1,357 patients were included, of which 526 used prostheses with attachments. The mini SG attachment (extracoronal) was the most commonly used attachment, and the survival rate ranged from 37% to 98.1% in 10 studies, with no significant differences between the systems. Among the 10 studies selected for quantitative analysis, the meta-analysis revealed an overall failure rate of 16.6% (95% confidence interval: 10.4−25.4%), and heterogeneity of I²=65.725 (Q-value: 26.258, P=.002). Conclusion. Clinical studies comparing different attachment systems for rehabilitation are lacking. Our findings suggest that attachment-retained RPDs have good retention and better esthetics than conventional RPDs and that the extracoronal attachment system is the most viable choice for treatment at the free end. 

Purpose. Lithium disilicate (LD) and lithium silicate (LS) glass-ceramics may show a different acid etching behavior and mechanical integrity after aging. This study evaluated the influence of aging on the fracture load and reliability of glass-ceramics after different etching protocols. Materials & Methods. Specimens were fabricated and divided according to the etching time (10% hydrofluoric acid (HF) for 20s, 40s, and 60s). Etched surfaces were examined under microscopy. The ceramics were resin cemented to a dentin analog material. Samples were tested after 24 h (I) (n=20) or stored in 37°C water for 1 year (A)(n=20). A compressive load (0.1 mm/min) was applied to the samples until failure was detected by acoustic emission. The influence of aging on the fracture load (Lf) was tested by 2-way ANOVA and Tukey tests (α=0.05). The characteristic fracture load (L0) and Weibull modulus (m) values were calculated. Results. LS etching for 20 s resulted in the highest immediate Lf, which was significantly decreased after aging (P≤0.05). Water-storage had no effect in this glass-ceramic Lf etched for 40 and 60s (P0.05). For LD, the etching time had no significant effect on the immediate and aged Lf (P0.05). The Lf was significantly reduced after aging (A) for LD (P≤0.05). Radial cracks were the predominant failure mode. Surface topography was more regular after lower etching times for LD, at after higher times for LS. Conclusions. After 1-year water-assisted aging, the evaluated etching times had no influence on the load-bearing capacity and structural reliability of resin-bonded glass-ceramics. 

Purpose: This study aimed to propose and evaluate standardised polishing protocols for in vitro experiment using a custom-made apparatus under controlled force to create consistent surface roughness on titanium and zirconia disks. Methods: A total of 160 discs were manufactured with a diameter of 10mm, 80 titanium (Ti), and 80 zirconium oxide (Zr). Specimens were categorised into 2 groups: controlled force (CF) and without controlled force (WCF). Specimens in the CF group were polished with a custom apparatus incorporating a tension gauge on the Ti and Zr disc surfaces to achieve consistent roughness. The WCF was polished without the use of a tension gauge. Each group had 4 subgroups (10 disks in each): control/machined (C) with no polishing, rough (R), smooth (S) and very smooth (VS). The subgroups were processed using a sequence of diamond-impregnated polishing burs and polishing paste. Results: CF group showed consistent surface roughness and a gradual decrease in surface roughness. Control (Ra=6.5±0.03µm) in Ti and (Ra=5.4±0.04µm) in Zr; R (Ra=3.5± 0.06µm) in Ti and (Ra=3.2± 0.07 µm) in Zr; S (Ra=1.5±0.04µm) in Ti and (Ra=1.1±006µm) in Zr; VS (Ra=0.05± 0.002µm) in Ti and (Ra=0.02±0.005µm) in Zr. There were significant differences for R, S, and SV under CF and WCF in Ti and Zr surfaces. Conclusion: The specimens polished under control force produced significantly more uniform surface roughness than those polished without controlled force and were produced with a higher degree of consistency. 

Purpose. The aim of this study is to investigate the prevalence of (TMD) as well as their potential risk factors among postgraduate students. Materials and Methods. In this cross-sectional and correlation study, 1255 postgraduate students from different universities were recruited to answer Fonseca’s anamnestic index (FAI) in addition to collected demographic data and relevant dental history. Fonseca’s anamnestic index (FAI) was used to classify their TMD severity. Five hundred ninety-three participants, that had previous clinical/radiographic TMD reports, out of 1255 were included. Chi-square and fisher’s exact tests investigated the relation between each predictor and TMD at P≤.05. A logistic binary regression analysis examined the model fit using -2Log likelihood and Pseudo R2 tests at P≤.05. Results. Based on previous clinical/radiographic reports and on FAI, 73.4% of the participants had TMD, of which 57% had mild dysfunction, followed by moderate (31.7%), and severe  (11.3%). There was a statistically significant association between sex, depression, lip/object biting and clenching with TMD (P <.001), where females were 2.302 times more likely to develop TMD than males. The combination of lip biting and clenching in a female dramatically increases the risk of TMD (-2 Log Likelihood =385.7, P<.001 and a Cox and Snell value = 0.315 and a Nagelkerke value = 0.395). Conclusion. TMD seems to be highly prevalent among postgraduate students in Egypt, whereby female postgraduate students who bite their lips and/or grind their teeth are particularly highly prone to the condition. Object biting and depression could be also considered as risk factors. 

PURPOSE. The purpose of the study was to compare the translucency parameters and masking abilities of different monolithic CAD-CAM ceramics placed on different colored substructures. MATERIALS AND METHODS.  Squared-shaped specimens (12x12x1.5 mm) were prepared from feldspathic (C), leucite (Emp), lithium disilicate (e.max), zirconia reinforced lithium silicate (VS), resin nano ceramic (LU), polymer infiltrated ceramic (VE), nanoparticle resin hybrid (GC), monolithic zirconia (TZI), and composite resin (TC) blocks (n=10). After mechanical polishing, the translucency parameter (TP) was calculated. Then, each ceramic specimen was measured on 8 substructures and the color difference between ND2 and each substrate was calculated with CIEDE2000 formula. TP values were analyzed with 1-way ANOVA and Games-Howell tests and the color differences indicating masking ability were analyzed with 2-way ANOVA and Tukey HSD tests. RESULTS. The highest TP was observed in TC, and followed by LU, Emp, C =GC, e.max, VS, VE, and TZI. The ∆E00 color difference values of TZI, VS, and VE on all abutment colors, except for ND9, were below the acceptable threshold value. CONCLUSION. All of the monolithic ceramic materials used in the study masked the ND1 and ND3 substrates. The ND9, representing the severely discolored or devitalized preparations, could not be masked by any of the monolithic CAD-CAM ceramics used in the study. 

Purpose: To realize a systematic review with prospective meta-analysis aiming to compare the accuracy of static fully guided implant placement depending on the drill key modality (conventional drill key surgery systems versus newer keyless systems) and evaluate the impact of deviations factors. Materials and methods: An electronic systematic search was conducted to identify prospective clinical trials matching inclusion criteria. The variables of interest were coronal global, apical, vertical, and angular deviations. The types of edentulism, and surgical guide support were investigated as deviation factors. Meta-regression (mixed-effect model) was performed. Heterogeneity was assessed using Cochrane’s I² test and interpretation thresholds. Results: A total of 1233 implants in 475 patients were analyzed (18 studies included). Coronal global deviation was significantly lower in the keyless group than in the key group (-0.36 mm; 95% confidence interval [CI] -0.62, -0.09; p=0.008). Angulation control of the keyless system was superior to that of the key system (-0.36 degrees; 95% CI -0.75, 0.02; p=0.063). Non-significant differences were found between both groups in apical (p=0.684) and vertical deviations (p=0.958). Significant influence of the type of edentulism (single, partial, total) and surgical guide support (tooth, mucosa, bone) on the overall amount of coronal global, apical, and angular deviations was found (p<0.001). Lowest deviations were found in partial edentulism and tooth-supported surgical guide groups. (p<0.001). Conclusion: Keyless static fully guided surgical systems allowed significantly better control of coronal and angular deviations than conventional systems. The types of edentulism and surgical guide support seemed to influence the positioning accuracy. 

Purpose: The objective of the study was to determine the values of 15 craniofacial linear distances in the Serbian ethnic group and the correlations between them that are predictive or can serve as proxy for OVD using and compare two methods of face-anthropometric and digital 2D face-photogrammetric measurement. Material and methods: A total of 90 adults were selected. Facial distance as a tool to measure the OVD was Sn-Gn - distance between septum of the nose (Sn) and tip of the chin (Gn). Face-anthropometric measurements were made with a Boley Gauge (Buffalo Dental Manufacturing Co.NY,USA). Digital 2D photogrammetric facial measurements were performed using the computer program DrCeph (FYI Technologies, USA). Results: Determined mean value for the distance Sn-Gn by face-anthropometric was Sn-Gn(f) X=63.55 and by face-photogrammetric was Sn-Gn(ph) X=63.56. Multivariate regression analysis revealed that Sn-Gn(f) depended on ExL-ExR(f)  p<0.001, ZyL-ZyR(f) p=0.077, N-Sn(f) p=0.096, Sn-Sto(f)  p=0.043 and gender and that Sn-Gn(ph) depended on ExL-ExR(ph) p<0.001, EnL-EnR(ph) p=0.029, N-Sn(ph) p=0.013, Sn-Sto(ph) p=0.001 and gender. Conclusions: A comparison of facial anthropometry and digital 2D facial photogrammetry reveals no statistical significance differences in the values obtained and shows that facial photogrammetry could be a reliable method as a facial anthropometry.

Purpose: To evaluate the behavior of hybrid abutment crowns fabricated from monolithic lithium disilicate ceramic (LDC) and to compare the influence of different in-vitro artificial aging protocols. Material and methods: 32 monolithic hybrid abutment crowns of monolithic LDC were fabricated. 24 were artificially aged applying 3 different protocols up to a 20 year-simulation (1.2 × 106, 2.4 × 106, 4.8 × 106 chewing cycles, thermocycling), one control group underwent no artificial aging (N=32, n=8). Load-to-failure tests were conducted for all specimens and failure values were compared (p<0.05). Results/conclusions: All specimens passed in-vitro aging. Mean failure load values between 532.6 and 562.8 N were found but did neither differ significantly among the test groups nor from the control group. Within the limitations of this in-vitro pilot study, hybrid abutment crowns manufactured from monolithic LDC seem to offer appropriate long-lasting mechanical stability over a simulation period up to 20 years. The failure values and complication pattern seem to be independent of several aging protocols in this test set-up. 

Purpose: This study aimed to evaluate the tensile strength of five different thicknesses of two resin cements placed between two titanium surfaces, before and after ageing. Materials and Methods: One hundred titanium 5 grade models composed of two surfaces simulating a semiprecision attachment for overdenture and its housing in the framework, were used. Samples were cemented using two different resin cements (SoloCem and OT-Cem). Five groups representing five different cement thicknesses (from 50 to 250μm) were created by varying the housing diameter. A half of the sample underwent to a tensile strength test 24h after luting, while the other half after 30000 thermic cycles from 5°C to 55°C. Shapiro-Wilk and ANOVA with post-hoc tests were performed to relate the tensile strength to the variables: cement type, thermal ageing and cement thickness (p <0.05).   Results: Statistical differences were found between the cements both at T0 and T1; the mean values of tensile strength of SoloCem were three times higher than those of OT-Cem. The thermic cycles determined a reduction of the tensile force values for both cements; statistical evidence was found only for the SoloCem except for the 100μm thickness group. Significant differences were also found between the cement thicknesses of both cements, with 50µm and 100μm expressed the best tensile strength. Most of the fractures were of cohesive nature. Conclusion: SoloCem showed a higher tensile strength than OT-Cem but has been more stressed by the ageing. For each group the cement thickness influenced the tensile strength values with an inverse relationship.

Purpose: To evaluate radiographic changes around six implants (Two posterior zygomatic and four conventional implants) used with fixed detachable restorations in patients with severe maxillary posterior resorption with either Polyether ether ketone (PEEK) or titanium frameworks. Materials and methods: Twelve maxillary edentulous patients were rehabilitated with six implants, including two posterior zygomatic and 4 conventionally placed implants for each patient following all-on-six distribution, and opposing mandibular all-on-four implant retained fixed detachable prostheses. A two-stage surgical unloaded healing protocol was performed. According to framework and teeth materials, there were two groups; Group I: CAD-CAM milled framework from modified BioHPP PEEK, bonded to polymethylmethacrylate crowns. Group II: screw-retained CAD-CAM milled framework from titanium, bonded to zirconium crowns. Bone loss evaluation for six implants was performed using cone beam computed tomography at the time of insertion (T0), after one year (T1), and after three years (T2). Results: There was a statistically significant difference in bone loss between PEEK and titanium groups. Less bone loss in PEEK groups around anterior conventional implants at buccal surfaces (P =0.01), at mesial surfaces (P <0.001), at distal surfaces (P <0.001), and zygomatic implants at buccal surfaces (P =0.004), and at palatal surfaces (P =0.003). Conclusions: Within the limitations of the study, the full-arch PEEK and titanium frameworks of fixed-detachable prostheses used with an All-on-Six distribution using zygomatic implants for rehabilitation of maxillary edentulous atrophied posterior arches was a promising treatment approach. Less bone loss was observed with the PEEK framework restorations combined with the PMMA crowns group.

Purpose: To assess wear, fatigue, and fracture resistance of different CAD/CAM onlays, milled from monolithic Zirconia (Zr), hybrid ceramic (EN), and lithium disilicate (LS), when used as abutments for removable partial denture frameworks fabricated from acetal resin (AR) or cobalt-chromium (Co-Cr). Methods: Standard onlays and RPD framework were designed and milled using CAD/CAM. Onlays were cemented with resin cement to identical teeth models. The RPD’s occlusal rest surface and the ceramic onlays’ rest seats were both 3D scanned before and after 750,000 mechanical load cycles (50 N) and 8,000 thermal cycles (5-55°C) in a chewing simulator. The volumetric loss was measured using 3D image processing software, and the failure of the samples was detected using a stereomicroscope. The fracture resistance was tested by loading to failure in a universal testing machine. The fatigue failure results were analyzed with Fisher's exact probability test and the wear and fracture resistance data were analyzed using two-way ANOVA and Bonferroni Post-hoc test (P<0.05). Results: A significant difference (p<0.05) was found between the tested experimental groups in wear, fatigue, and fracture resistance. Zr/Co-Cr combinations exhibited the least wear and the highest fatigue and fracture resistance (P<0.05), while the highest wear and least fatigue and fracture resistance were recorded for EN/AR group (p<0.05). Conclusions: Zr onlays demonstrated a conservative treatment option with superior mechanical behavior when used as an onlay abutment, regardless of the RPD framework material used. The AR framework is not recommended in the posterior region for removable partial dentures. Keywords: CAD/CAM, Onlay, RPD, Fatigue, fracture, wear, Lithium Disilicate, Zirconia, Hybrid Ceramic.

Purpose. The purpose of this in vitro study is to evaluate the effect of tea tree oil into denture liners on Candida albicans and bond strength to the acrylic denture base. Material and methods. Disc-shaped specimens were fabricated from silicone based resilient liner (Tokuyama, Molloplast), acrylic based hard liner (GC Reline) and acrylic based soft liner (Visco-gel) and tea tree oil was incorporated into liners at varying concentrations (0%-control, 2%, 5%, 8%). Candida albicans were counted by viable colony count and optical density (OD) was measured by spectrophotometer. The tensile strength to heat polymerized acrylic denture base was measured in a universal testing machine. The compliance of the data to the distribution of normality was evaluated using the Shapiro Wilk test. Two-way ANOVA, Bonferroni correction, paired sample t-test were performed (α=.05). Results. Tea tree oil addition into liners provided a significant decrease in the OD values (p <.001). The control groups of liners presented the highest colony counts, whereas increasing tea tree oil decreased the results (p <.01). According to tensile bond strength test, 8% tea tree oil addition resulted significant decrease for Tokuyama (p <,01) and Molloplast  liners (p <.05), while 2% TTO resulted significance for GC Reline (p <.001). Conclusions.  Denture liners containing tea tree oil presented lower Candida albicans colonies by the increasing amount, besides decreased the bond strength to denture bases. While using the antifungal activity of the oil, the amount of addition should be carefully selected as the tensile bond strength may be affected.

Purpose: To evaluate the effect of restoration design on fracture resistance and stress distribution of veneered and monolithic 3-unit zirconia fixed partial dentures (FDPs) using finite element analysis (FEA). Materials and Methods: Identical epoxy resin replicas of mandibular second premolar and second molar (to serve as abutment for the 3-unit bridge) were divided into four groups (n = 10): monolithic zirconia (MZ) restorations; conventional layering veneering technique (ZL), heat-pressed technique (ZP), or CAD/CAM lithium disilicate glass ceramic  (CAD-on). Specimens were subjected to compressive cyclic loading on the mesio-buccal cusp of the pontic (load range 50 to 600 N; aqueous environment; 500,000 cycles) in a universal testing machine. Data were statistically analyzed at 5% significance level with Fisher exact test and Kaplan-Meier survival analysis. 3D models were constructed in accordance with experimental groups. The stress distribution in each model was analyzed and evaluated according to the location and magnitude of the maximum principal stresses (MPS) using ANSYS software. Results: Specimens from ZL and ZP groups failed at different stages of the 500,000 cycles fatigue, while CAD-on and MZ restorations survived fatigue test. Statistically, there was a significant difference between the groups (P < .001). The MPS were located under the mesial connector in both monolithic and bilayered 3-unit zirconia FDPs. These stresses were found to be higher in monolithic geometries compared to bilayered zirconia FDPs. Conclusion: Monolithic 3-unit zirconia and CAD-on zirconia frameworks resulted in superior fracture resistance. Restoration design significantly affected the stress distribution of 3-unit zirconia FDPs. 

Purpose: To compare abutment screw loosening in 24-degree angulation-correcting and straight implants subjected to nonaxial cyclic loading. Materials and methods: Seven external connection 24-degree angulation-correcting implants (AI) and seven external connection straight implants (SI) were embedded in acrylic resin within a brass housing. A hemispherical titanium fatigue abutment was secured to each implant using a titanium abutment screw tightened to 32 Ncm. Each implant-abutment complex was positioned within a tooth wear machine and subjected to 1,000,000 cycles of 50-Ncm nonaxial loading to simulate 1 year of function. The abutment screw removal torque values were measured before and after cyclic loading, and the differences were statistically analyzed using two-way ANOVA and post hoc pairwise Dunn tests. Scanning electron microscopy and finite element analyses were performed to assess the wear of the abutment screws. Results: The mean torque loss for the AI group was 21.44% (P < .001) compared to 24.56% (P < .001) for the SI group. There was a statistically significant difference between the AI and SI groups (P = .006). Conclusion: Both groups exhibited significant abutment screw loosening. Within the limitations of this study, 24-degree angulation-correcting implants resisted screw loosening significantly more than straight implants.

Digital or CAD/CAM workflows and protocols are being increasingly utilized because of their improved efficiency and reproducibility. For the fabrication of complete dentures, digital workflows can reduce treatment time and clinical visits while enhancing the reliability and reproducibility of the laboratory phase and materials. However, establishing centric relation (CR) and vertical dimension of occlusion (VDO) in a reproducible way is still a challenging step for complete denture fabrication in both analog and digital workflows. This clinical report describes a digital workflow utilizing an individualized gothic arch tracing device (GATD) using open-source software for the fabrication of complete dentures. With this workflow, clinicians can offer customized solutions according to patient rehabilitation, with good reproducibility using gothic arch tracing to be implemented in the digital workflow.

Purpose: To evaluate the accuracy of intraoral scanners by comparing the marginal fit of 70 all-ceramic crowns fabricated from both conventional impressions and intraoral scans. Materials and Methods: A total of 70 posterior teeth requiring single-crown restorations randomly underwent either intraoral scanning or conventional impression-taking followed by laboratory scanning of the casts in a parallel-group RCT. Subsequently, 70 monolithic all-ceramic crowns were CAD/CAM fabricated; only the impression technique differed. Marginal fit, internal fit, adjustment time required for insertion and occlusal contacts, and visual analog scale (VAS) scores assessing dentists’ satisfaction with all of the crowns were clinically evaluated by a blinded and calibrated examiner. Data were analyzed using independent-samples t test and likelihood ratio test or Fisher exact test. All tests were performed with α = .05. Results: The mean marginal fit with intraoral scanning (57.94 ± 22.51 μm) was better than with diagnostic cast scanning (82.98 ± 21.72 μm). The difference was statistically significant (P = .000). The differences in internal fit, adjustment time for crown insertion and occlusal contacts, and VAS scores were also significant, and the secondary outcomes were in favor of intraoral scanning. Conclusion: Within the limitations of this clinical trial, CAD/CAM–fabricated single-tooth restorations in the posterior region produced by an intraoral scanning technique using TRIOS was found to be a more accurate and efficient alternative to restorations based on conventional impressions in combination with the laboratory scanning technique.

Purpose: To determine the average time it takes for patients to adapt to mandibular complete dentures and the factors associated with this critical period. Materials and methods: A total of 108 completely edentulous patients were rehabilitated using complete dentures. Adaptation was evaluated based on the following criteria: mastication, comfort, speech, and swallowing with dentures. Kaplan-Meier analyses were used to estimate the average time to adaptation. Log-rank test was used to assess the adaptation period and associated factors. Results: Of the 108 rehabilitated patients, 89 had adapted to mandibular complete dentures at the 6-month follow-up. The mean time to adaptation estimated from the Kaplan-Meier curve was 78.54 days (95% CI: 71.04 to 86.04). The factors associated with the adaptation period were previous experience with a mandibular denture (P = .032), the professional who made the previous complete dentures (P = .034), frequency of appearance of traumatic lesions after 15 days of rehabilitation (P = .023), posterior mandibular ridge height (P = .005), and regular use of the new dentures (P = .002). Conclusion: Most patients adapted to mandibular dentures after 2.6 months. No prior mandibular denture experience, use of old dentures made by a dental technician, occurrence of traumatic injuries 15 days after complete denture delivery, presence of a resorbed posterior mandibular ridge, and nonregular wear were associated with longer adaptation time to the new mandibular complete dentures.

Purpose: To report on the follow-up of two earlier published RCTs on the performance of screw-retained monolithic zirconia restorations on Ti-base abutments based on intraoral optical scanning or conventional impressions. Materials and Methods: A total of 54 patients receiving 89 restorations (44 single crowns [SC]), 21 splinted crowns [2-FDP], and 24 three-unit fixed partial dentures (3-FDP)] were included in the 1- to 3-year follow-up period. The restoration survival and technical complications were documented. Results: A total of 50 patients with 84 restorations completed the 3-year follow-up. One 3-FDP from the IOS group was lost. This resulted in survival rates of 97.9% for the test and 100% for the control restorations and an overall survival rate of screw-retained monolithic zirconia restorations on implants of 98.8% after 3 years. There was no statistically significant survival difference between the test and control groups (P = .362). When evaluated separately, a 100% survival rate for SCs and 97.7% rate for 2-FDPs was reported. One decementation and three occurrences of screw loosening occurred over the 1- to 3-year follow-up. The multiple-implant restorations showed higher (23.3%) complication rates at the restoration level than the SCs (4.9%) after 3 years of function (P = .026). Conclusion: Screw-retained monolithic zirconia restorations on Ti-base abutments show promising survival rates after 3 years of function. Restorative complications of screw-retained monolithic zirconia restorations on Ti-base abutments are more likely to happen in the first year of function and are more common in multiple-implant restorations than solitary crowns. The impression (IOS or conventional) does not seem to influence these results.

Purpose: To identify the most effective bonding protocol between the denture base and artificial teeth made with different CAD/CAM materials (milled and 3D printed) compared to conventional heat-cured materials. Materials and methods: This review was performed according to the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) criteria and registered in PROSPERO (CRD42021276084). An electronic search was performed independently by two examiners in the MEDLINE/PubMed, Cochrane Library, Scopus, Web of Science, ProQuest, and OpenGrey databases for articles published up to and including December 2021. Results: The electronic search returned 806 articles, and after duplicates were removed, the total was 589 articles. Four articles were selected according to the eligibility criteria. Evaluating the different combinations of denture base materials and artificial teeth, the IvoBase CAD Bond (Ivoclar Vivadent) was effective for bonding the CAD/CAM denture bases to prefabricated acrylic resin denture artificial teeth. There were no differences compared to heat-cured denture base bonding to prefabricated acrylic resin denture artificial teeth (χ2: 68.56; I2: 96%; P < .001). Conclusion: IvoBase CAD Bond as a bonding system can be an alternative for using new technologies in the fabrication of α CAD/CAM base with prefabricated acrylic resin denture artificial teeth.

Purpose: To compare the accuracy of two digital workflows for producing resin patterns to be cast into metal frameworks compared to an identical framework manufactured conventionally from a wax pattern. Materials and methods: Nine casts were duplicated from a maxillary master cast of a partially edentulous arch. Their accuracy was determined by measuring the same points in two and three dimensions using a reflex microscope, which was also used to measure all frameworks to an accuracy of 4 μm. The same design was used throughout. Three casts were used to make a framework conventionally from an invested wax pattern. Six casts were scanned, and a digital pattern created. Three patterns were milled from a resin block, and three were 3D printed with resin. Then each pattern was cast. Results: The sample size precluded direct statistical conclusions, but no significant differences were found. Duplicate models showed minimal differences compared to the master cast. All patterns and all frameworks showed some level of difference compared to the master cast, but no differences were greater than those reported in the literature as being clinically acceptable. The maximum overall discrepancy between the cast frameworks was 0.64 mm, and at the rest seats was 0.262 mm. Conclusion: Within the limitations of this study, given the very small actual differences both within and between the groups of the three different workflows, the use of digitally produced resin patterns prior to their being cast as metal frameworks is both feasible and well within the accepted limits for clinical acceptability.

This case report describes a novel approach combining orthodontic and implant digital treatment planning workflows to enable prosthetically driven implant placement before orthodontic treatment is performed or completed. The computer-assisted implant placement is performed using a static surgical guide based on the future positions of the teeth after completion of orthodontic treatment. This innovative approach allows for select partially edentulous patients to undergo fixed prosthetic rehabilitation before orthodontic treatment is completed.

Purpose: To compare the fracture resistance of five different groups of chairside CAD/CAM molar crowns fabricated from various lithium disilicate ceramic materials (LDC): one conventional precrystallized CAD/CAM LDC, two novel precrystallized LDCs, and one fully crystallized LDC tested both with and without optional sintering. Materials and methods: A total of 60 chairside CAD/CAM lithium disilicate molar crowns (n = 12 per group) with 1.5-mm occlusal thickness and a 1.0-mm chamfer finish were designed and fabricated with a chairside CAD/CAM system (CEREC, Dentsply Sirona). The restorations were divided into five groups: (1) IPS e.max CAD; (2) Amber Mill; (3) Straumann n!ce; (4) Straumann n!ce with optional sintering; and (5) Supreme CAD. Restorations were cemented using conventional resin luting cement and primer system to 3D-printed resin dies. Bonded restorations were loaded for 100,000 cycles with 275-N force, and the load at break (LB) and peak load (PL) until fracture were measured. SEM images of fracture surfaces on the printed dies were obtained. Results: Fracture resistance was significantly different depending on the material. Supreme CAD showed the highest fracture resistance (LB: 1,557.2 N; PL: 1,785.8 N), followed by Amber Mill (LB: 1,393.0 N; PL: 1,604.2 N) and IPS e.max CAD (LB: 1,315.7 N; PL: 1,461.9 N). Straumann n!ce without (LB: 862.4 N; PL: 942.9 N) and with the optional sintering (LB: 490.4 N; PL: 541.0 N) showed significantly lower fracture resistance than the others. Conclusion: The fracture resistance of chairside CAD/CAM lithium disilicate molar crowns varied depending on the material, and the novel materials did not perform as well as the conventional equivalents. Fully crystallized lithium disilicate ceramic block materials showed lower fracture resistance than precrystallized counterparts and should be used with caution in the clinic, especially with optional sintering.

Purpose: To assess the impact of fatigue loading on the internal and marginal fit of CAD/CAM-fabricated endocrowns for restoring endodontically treated molars using different machinable blocks. Materials and methods: A total of 72 mandibular first molars were prepared using a standardized method and were divided into four groups (n = 18), each restored with a different CAD/CAM material: group V = polymer-infiltrated ceramic (Vita Enamic); group K = partially stabilized tetragonal zirconia (Katana); group E = lithium disilicate ceramic (IPS e.max CAD; and group B = polyetheretherketone (BioHPP). Endocrowns were subjected to thermomechanical fatigue loading. Internal and marginal adaptation of the endocrowns were examined at 66 points using the sectioning technique and a stereomicroscope. Data were analyzed using one-way ANOVA and Tukey post hoc test (α = .05). Results: Statistical tests showed that adhesive cementation resulted in significantly increased marginal and internal gap values in all regions in all four tested groups (P < .001). After thermomechanical fatigue loading, all regions in groups B and K showed a statistically significant difference, while no significant differences were found in the regions in group V (P > .05). In group E, the marginal (F = 71.00) and pulpal (F = 28.065) regions showed statistically significant differences (P < .001). Conclusion: Polymer-infiltrated ceramics showed the lowest gap even after thermomechanical fatigue loading and may therefore provide enhanced clinical survival of the restored tooth, favoring the use of this material for fabricating endocrown restorations.

Purpose: To evaluate the effects of two different lasers and their use in combination with hydrofluoric acid (HF) etching on the surface roughness of zirconia-reinforced lithium silicate (ZLS) ceramics and their shear bond strength (SBS) to composite resin. Materials and methods: The five study groups were as follows: (1) Group H = HF etching; (2) Group N = Nd:YAG (neodymium: yttrium-aluminum-garnet) laser; (3) Group NH = Nd:YAG laser + HF gel; (4) Group E = Er:YAG (erbium: yttrium-aluminum-garnet) laser; and (5) Group EH = Er:YAG laser + HF gel. Surface roughness was assessed using a noncontact profilometer, and SBS tests were conducted with a universal testing machine. Results: The mean SBS values were 16.23 ± 1.77 MPa for Group H, 17.1 ± 1.65 MPa for Group N, 16.65 ± 1.11 MPa for Group NH, 8.08 ± 1.12 MPa for Group E, and 11.58 ± 0.82 MPa for Group EH. There were significant differences between groups E and EH (P < .001), but no significant differences (P > .05) among the other groups. Conclusion: Clinicians may prefer Nd:YAG laser or the combination of Nd:YAG and HF to intraorally repair fractured areas.

Purpose: To evaluate the effect of tooth brushing and dentifrice fluoride (F^-) concentration on changes in color and translucency (ΔE₀₀ and ΔT₀₀, respectively), surface gloss (GS), surface roughness (Sa), and microstructure of a glazed CAD/CAM ceramic. Materials and methods: Ceramic blocks (e.max/CAD) were sectioned into rectangular plates (14 x 12 x 1 mm), and one surface of each sample was glazed. Samples were divided into three groups according to the F- concentration in the dentifrice (0, 1,100, and 5,000 μg/g) and were then subjected to 60,000 tooth brushing cycles. Luminosity and color were measured using a spectrophotometer at baseline and after every 20,000 cycles to obtain their ΔE₀₀ and ΔT₀₀ values. Another set of samples was prepared to measure the GS with a gloss meter and the Sa with a confocal laser microscope. The GS and Sa results were subjected to analysis of variance, Tukey test, and Dunnett test (α = .05). Results: After 60,000 tooth brushing cycles, all of the variables were clinically acceptable, and there were no significant differences in the ΔE₀₀, ΔT₀₀, GS, or Sa among the fluoridated dentifrices. The GS values decreased significantly as the number of tooth brushing cycles increased. Conclusion: The ΔE₀₀, ΔT₀₀, GS, and Sa values were all clinically acceptable after the glazed e.max/CAD ceramic had been subjected to 60,000 tooth brushing cycles with dentifrices containing up to 5,000 μg/g of F^-.

Purpose: To compare the CIE L*a*b* values of two different dental shade guides using two shade-matching spectrophotometers. Materials and methods: SpectroShade Micro (MHT) and Easyshade (VITA Zahnfabrik) were tested. One calibrated operator performed 30 measurements of each tab from three batches of two guides, VITA Classical (VC) and VITA 3D-Master (VM). Receiver operating characteristic (ROC) curves and intraclass coefficients (ICC) between the different batches were calculated. Results were given as mean and SD of the L*a*b* values and the respective color differences according to the CIEDE 2000 formula (ΔE₀₀) for each of the shade tabs in the two spectrophotometers, then analyzed with independent student t test (α = .05). Results: A total of 1,440 and 2,610 measurements for VC and VM, respectively, were performed per spectrophotometer. There were statistically significant differences between the two devices for all L*a*b* values, with the exception of: L* for 3R1.5; a* for 2R1.5, 3L1.5, 2L2.5, 3M2, 3L2.5, 4L1.5, and 4L2.5; and b* for D3, 1M2, and 3M2. When assessing the same shade guide, differences in ΔE₀₀ were detected between devices above the acceptability threshold (ΔE₀₀ ≥ 1.8) for all shade tabs except for VC (C1, C2, D3, A3.5, C3, and A4) and VM (4M1, 3R2.5, 4L2.5, and 4M3). The overall mean of the inter-device ΔE₀₀ was 2.2 ± 1.0 for VC and 2.5 ± 1.0 for VM. Conclusion: The two dental spectrophotometers presented high ICC and ROC values, which validates their indication as auxiliary tools. However, there are discrepancies in the hues D (VC) and R (VM) with interdevice variability when evaluated for the L*a*b* component.

Purpose: To evaluate the effects of post length, post material, and substance loss on the fracture resistance of endodontically treated mandibular premolars. Materials and methods: A total of 96 extracted human mandibular first premolars were endodontically treated and divided into 12 test groups (n = 8 each) based on the number of residual walls (one/two), post material (glass-fiber/titanium), and post length (5 mm, 7.5 mm, and 10 mm). After luting the posts, specimens received a composite resin core and a crown preparation with a 1.5-mm ferrule. Cast cobalt-chromium crowns were cemented using glass-ionomer cement. After 1,200,000 chewing cycles with a load of 49 N and simultaneous thermocycling (5°C to 55°C), specimens were quasi-statically loaded at 30 degrees to the longitudinal axis of the tooth until fracture. Fracture loads were analyzed using three-way, two-way, and one-way analysis of variance (α = .05). Fracture modes were examined under a stereomicroscope (×25) and recorded. Results: Fracture loads ranged from 642 ± 190 N (one wall, glass fiber, 5 mm) to 1,170 ± 130 (two walls, titanium, 7.5 mm). The mean fracture load of titanium posts was significantly higher than that of glass-fiber posts (P < .001), and the 7.5-mm post length exhibited significantly higher fracture loads than groups with 5-mm and 10-mm post length (P = .008). Conclusion: Teeth restored with titanium posts revealed considerably higher fracture resistance than teeth restored with glass-fiber posts, especially if 7.5-mm-length posts were used.

Purpose: To assess whether implant-retained prostheses produced with a laser-sintering technique present accuracy and passive fit comparable to their milled counterparts. Materials and methods: Two Regular Neck Straumann analogs were placed in a block of polymethyl methacrylate (PMMA) at 15 mm of distance and parallel to one another. The PMMA block was then scanned, and two groups of cobalt-chromium (Co-Cr) screw-retained, three-unit implant prostheses were fabricated using milling (control) and laser sintering (test) techniques. The prostheses were then screwed on the PMMA block, and the vertical marginal gap between the prostheses and the analogs at the implant-abutment junction was measured twice: (1) when only one screw was tightened, and (2) when both screws were fully tightened. The mean marginal gap measurements were compared to assess the difference in terms of passive fit between the laser-sintered and milled prostheses. Results: The mean marginal gap of the milled and laser-sintered groups was 23.18 μ (SD = 6.2) and 23.71 μ (SD = 19.5), respectively. Conclusion: Laser-sintered prostheses presented a marginal fit comparable to milled.

Purpose: To assess the retention and adaptation of milled and printed denture bases and to compare them to conventional ones. Materials and methods: A total of 24 completely edentulous patients were selected. For each patient, three maxillary denture bases were constructed. Three groups were defined according to fabrication technique: group I = denture bases were constructed by a conventional technique; group II = denture bases were milled from prepolymerized blocks of polymethyl methacrylate; and group III = denture bases were fabricated by a 3D printing technique. A digital force gauge was used for measuring the retention of the denture bases intraorally, while Geomagic Control X 64 software was used to evaluate the adaptation of the denture bases with their corresponding master casts. Analysis of variance for repeated measures was used for comparison among the groups, followed by pairwise comparison with Bonferroni correction as a post hoc test. The significance level was set at α = .05. Results: Statistical analysis showed significant differences among the three groups regarding retention and adaptation. The highest values of retention and adaptation of denture bases were found in group II (milling group). Conclusion: Within the limitations of this study, the following could be concuded: milled denture bases demonstrated better retention and adaptation than the conventional heat-polymerized and the printed denture bases; and printed denture bases showed better adaptation but similar retention to conventional heat-polymerized denture bases.

Purpose: To measure the influence of postpolymerization condition (dry or submerged in water) and time (2, 10, 20, and 40 minutes) on the accuracy of additively manufactured model material. Materials and methods: A bar standard tessellation language file was used to manufacture the resin specimens (E-Model Light, EnvisionTEC) using a 3D printer (Vida HD, EnvisionTEC). Two groups were created based on the postpolymerization condition: dry (D group) or submerged in water (W group). Each group was divided into four subgroups (D1 to D4 and W1 to W4) depending on the postpolymerizing time (2, 10, 20, and 40 minutes; n = 20 each; N = 160). The specimen dimensions were measured using a low-force digital caliper (Absolute Low Force Caliper Series 573, Mitutoyo). The volume was calculated: V = l × w × h. Shapiro-Wilk test revealed that the data were not normally distributed. Data were analyzed using Kruskal-Wallis and pairwise Mann-Whitney U tests (α = .05). Results: Significant differences in length, width, height, and volume values were found among the subgroups (P < .0018). In all groups, the width dimension (x-axis) presented the worst accuracy compared to height (z-axis) and length (y-axis) (P < .0018). The D2 and D4 subgroups obtained the closest dimensions to the virtual design; additionally, no significant differences were found between the two subgroups (P < .0018). Dry condition showed higher manufacturing accuracy compared to the water-submerged condition. In the water-submerged subgroups, the highest accuracy was obtained in the W2 and W4 subgroups (P < .0018). Conclusion: Postpolymerization conditions and time influenced the accuracy of the material tested. Dry postpolymerization condition with a time of 10 and 40 minutes obtained the highest accuracy.

Purpose: To evaluate the performance of fully (Celtra Duo, Dentsply Sirona) and partially (VITA Suprinity, VITA) crystallized zirconia-reinforced lithium silicate and partially sintered lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging. Materials and methods: Specimens of each glass-ceramic were subjected to polishing with rubber cups (POL), glazing (GL), or control (C; no treatment) and afterwards aged with 18,000 thermal cycles (5°C to 55°C). The average roughness (Ra), 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated by atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and flexural strength test (n = 10), respectively. Data were analyzed using two-way analysis of variance and Tukey test (α = 5%). Results: POL promoted lower Ra than glazing, and Celtra Duo presented higher Ra than IPS e.max CAD (P < .05). Surfaces without polishing promoted higher Ra than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glass-ceramic. Irrespective of the treatment, the contact angle was higher in Celtra Duo, and regardless of the material, there was higher biofilm formation and lower flexural strength of unpolished compared to POL or GL ceramics. Conclusion: Polishing with rubber cups promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the glazed surface. In general, Celtra Duo and VITA Suprinity showed similar behavior to IPS e.max CAD, which makes zirconia-reinforced lithium silicate glass-ceramics a good option for indirect restorations.

Purpose: To investigate the physical and mechanical behavior of polyether ether ketone (PEEK) before and after thermocycling and its potential use as a more durable prosthetic component for implant-supported and -retained removable dental prostheses (I-RDP). Materials and methods: Roughness and surface hardness were evaluated in specimens obtained using the subtractive method (n = 20) with Ø 9 mm and 2 mm of thickness, and retention force was measured in attachments with Ø 4 mm and 3 mm of height. For fatigue resistance test, a polyurethane matrix with two ball-abutment implants (MDL, Intra-Lock International) was used to simulate the mandibular alveolar ridge. A total of 40 attachments (n = 20 pairs) were captured in acrylic resin blocks using a technique analagous to the direct clinical pick-up of overdenture female attachments and submitted to 2,900 insertion/removal cycles to simulate 24 months of overdenture use. Physical analyses were performed by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and differential scanning calorimetry (DSC) before and after thermocycling (5° C to 55°C for 10,000 cycles). After normal distribution was verified by Shapiro-Wilk test, one-way analysis of variance (ANOVA) was applied to analyze the surface roughness and hardness, and two-way ANOVA with Bonferroni adjustment was used to assess the retention force (α = .05). Results: Thermocycling did not change the PEEK surface roughness or hardness (P > .05). As for the retention force, the highest average was observed after the thermocycling test (P = .006). Conclusion: Based on the FTIR, XRD, and DSC results, PEEK crystallinity decreased after thermocycling, and the physical and mechanical behavior of this polymer was compatible with the proposed application, attesting that it is a component of greater durability for I-RDPs.

Purpose: To develop an instrument for the assessment of perception of orofacial appearance and psychologic issues that can affect peoples' judgments. Materials and methods: A panel composed of five members (one psychologist, two prosthodontists, one orthodontist, and one final-year dental student) generated 31 items that could draw specific hypothetical dimensions. The questionnaire was self-administered by individuals attending local high schools and university (N = 261; 26.4% men) in the 14- to 28-year age range. Internal consistency, construct validity, responsiveness, and temporal stability were assessed. Results: Factorial analysis and Cronbach's alpha identified four dimensions (self-esteem, perfectionism, body image, and smile appearance concern) that could be best fitted by 17 items. Internal consistency was good (α in the 0.70 to 0.80 range). The dimensions were correlated with existing instruments that measure similar constructs. In responsiveness testing, tooth whitening did not induce changes in perfectionism or body image; however, it did increase self-esteem and decreased esthetic concern (P < .05). Conclusion: The newly created questionnaire is a consistent and reliable short instrument that measures psychologic issues related to the perception of orofacial appearance.

Purpose: To evaluate the application of chitosan as a cleanser in the control of biofilm formation on cobalt-chromium (Co-Cr) alloy and acrylic resin surfaces. Materials and Methods: In total, 172 Co-Cr discs and 172 acrylic resin discs (14 mm x 3 mm) were contaminated with Streptococcus mutans, Staphylococcus aureus, Candida albicans, or Candida glabrata and incubated for 48 hours. Then, specimens were randomly divided into groups and immersed in the following solutions for 15 minutes: WC = solution without chitosan (control); CH = chitosan solution (5 mg/mL); CN = chitosan nanoparticle solution (3.8 mg/mL); and ET = effervescent tablet. Biofilm recovery rates (n = 9) were evaluated by counting the colony-forming units (CFU/mL). Biofilm morphology was evaluated using scanning electron microscopy. Data were compared with Kruskal-Wallis or analysis of variance followed by Tukey post hoc tests. Results: For acrylic resin, ET showed the lowest number of CFU for S aureus and S mutans (P < .001). CH exhibited intermediate values for S mutans, S aureus, and C albicans, and CN exhibited intermediate values for S mutans and S aureus. For C glabrata, there was no statistical difference between the solutions (P = .264). For Co-Cr, ET showed the highest level of antimicrobial action against all microorganisms (P < .001), and CH showed an intermediate level of action against S mutans and S aureus. Against C albicans and C glabrata, there was no significant difference among CH, CN, and WC. Conclusion: Although ET had a broader spectrum of antimicrobial action, the chitosan solution showed promise as a denture cleanser. Int J Prosthodont 2021.

Purpose: To examine and compare the fracture strength of digitally produced interim materials to the conventional chairside method for implant-cemented fixed partial denture prostheses. Materials and methods: Three groups of seven specimens each were produced: group A, 3D-printed with VarseoSmile Temp material (Bego); group B, milled using Telio CAD material (Ivoclar Vivadent), and group C, conventional chairside manufacturing method using Luxatemp material (DMG). All groups were cemented using FujiCEM 2 (GC) to Standard Abutments (SIC) placed in artificial Sawbones blocks. The fracture strength was performed using universal testing machine Z010 (ZwickRoell). Statistical analysis of the resultant maximum forces was performed using SPSS (version 25.0, IBM) software (Mann- Whitney U test, P < .05). Results: The mean fracture strength of the printed provisional fixed partial dentures was 260.14 ± 28.88 N, of the milled interim fixed partial dentures was 663.57 ± 140.55 N, and for the control group reached 266.65 ± 63.66 N. Data showed a significant deviation of the normal distribution Kolmogorov-Smirnov test > .05 for all groups. Conclusion: Milled provisional fixed partial dentures showed a higher fracture resistance compared to 3D-printed and control chairside groups. However, for 3D-printed and control groups, no such difference could be detected.

Purpose: To evaluate the efficacy of cleaning protocol in decontamination of organic compounds from polished zirconium oxide samples. Materials and methods: A total of 24 rectangular plate specimens were sintered from zirconium oxide. All samples were polished with commercially available polishers (course, fine, and superfine) and polishing paste. During the first step of the protocol, all specimens were cleaned with steam. After that, samples were randomly assigned to one of three groups (n = 8 each): A, B, and C. In group A, no additional cleaning was performed, while specimens of group B underwent an ultrasonic cleaning in distilled water. Group C specimens were cleaned in an ultrasonic bath with a special detergent solution. After washing, samples were subjected to energy-dispersive x-ray spectroscopy (EDX) and scanning electron microscope examination. In order to detect organic materials, the level of carbon atoms was measured. Results: EDX analysis revealed that samples in group A had the highest percentage levels of carbon atoms (9.57 ± 3.67) on the surface compared to the other cleaning protocols. The group B cleaning protocol resulted in lower carbon levels (4.73 ± 3.56), but the difference was not significant from only steam-blasted ones (P = .439). All specimens in group C had no detectable carbon atoms (0), which implies that all wax molecules had been removed (P < .05). Conclusion: Only following the group C cleaning protocol can total decontamination of the polished zirconium surface from organic compounds be expected. Therefore, it is advised to employ an ultrasonic bath with detergent solution for cleaning procedures of zirconium abutments before delivery.

Purpose: To clinically evaluate oral implant restorations placed by undergraduate students in the dental clinical curriculum at KU Leuven (Belgium) in terms of function and esthetics. Materials and methods: A retrospective observational cohort study was designed. The esthetic and functional evaluations of implant-supported restorations placed in the framework of the undergraduate implant dentistry clinical training program using White/Pink Esthetic Score (WES/PES) and visual analog scale (VAS) scoring was performed. Furthermore, complications were registered based retrospectively on the patient's medical file. The following research questions were stipulated: (1) How well do implant-supported restorations placed by undergraduate students perform esthetically? and (2) Which complications occurred and how were these managed? Results: Between August 2008 and July 2014 (6 academic terms), 251 implants (Brånemark System Mk III, Nobel Biocare) were placed in 113 patients by 155 students (> 40% of all students enrolled in the training program). Of these implants, 228 were restored in 101 patients by 118 students with varying restoration types. Esthetic scoring of the restorations in 83 of these patients revealed a satisfying mean WES of 8.14 ± 2.09 (out of 10) and PES of 9.56 ± 3.14 (out of 14). Complications were registered in 18.9% of the cases. Discussion: Clinical training in implant dentistry for undergraduates contributes to the development of advanced skills in the dental student's Master education. Overall, patients were satisfied with their implant-supported restorations. Implant and restoration success rates and complication incidence were confirmed by long-term data in the oral implant literature.

Purpose: To investigate the influence of occlusal interference in dental prosthetics using finite element analysis (FEA). Materials and methods: The FEA model designed for this study centered on an all-ceramic, bi-layered, fixed partial denture (FPD) retained on the maxillary first premolar and molar, with the second premolar replaced by a pontic. The surrounding structures, such as the neighboring teeth, antagonists, and periodontium, were modeled. Four different load cases were designed at occlusal interferences of 0, 8, 12, and 24 μm, loaded by a simulated bite force of 300 N. Principal and von Mise stresses, as well as strain, were evaluated for all included structures. Results: For interferences of 12 and 24 μm, failure-relevant tensile stresses in the veneering layer were observed at the occlusal surfaces. Stress found in the zirconia FPD did not reach fatigue or flexural strength for any test load. Conclusion: Peak tensile stress was observed in close proximity to occlusal contact points, increasing with increasing occlusal interference. The FEA results suggested that the majority of occlusal stress is absorbed by the deformation of the periodontal ligament. Framework failure caused by the simulated interferences was not expected. Surface defects may ultimately lead to failure due to fracture or chipping, especially in cases of weaker ceramics or veneering.

Purpose: To compare in a randomized controlled trial the 5-year clinical outcomes of (1) 3-unit fiber-reinforced resin-bonded fixed dental prostheses (RBFDPs) to 3-unit metal-ceramic RBFDPs; and (2) 3-unit fiber-reinforced RBFDPs to 2-unit cantilevered metal-ceramic RBFDPs. Materials and methods: A consecutive sample of 50 young adult patients with tooth agenesis or trauma in the anterior region was included. The recruitment period was from 2005 to 2009, during which a total of 62 RBFDPs were inserted. In group A, 27 participants were randomly treated with 18 metal-ceramic 3-unit RBFDPs and 15 3-unit fiber-reinforced RBFDPs. In group B, 23 participants were randomly treated with 16 metal-ceramic 2-unit RBFDPs and 13 3-unit fiber-reinforced RBFDPs. All patients were followed up at baseline registration and at 1, 3, and 5 years. The primary outcome parameter was survival rate of the RBFDPs, and the secondary outcome parameters were periodontal and technical/esthetic outcomes and patient-reported evaluation of the RBFDPs. Results: Seven patients dropped out of the study during the 5-year observation period. In group A, the fiber-reinforced RBFDPs had a cumulative survival rate of 23% after 5 years, which was significantly less than for the 3-unit metal-ceramic RBFDPs. In group B, the cumulative 5-year survival rate was 36% for the fiber-reinforced RBFDPs and 91% for the 2-unit cantilevered metal-ceramic RBFDPs. Conclusion: The 3- and 2-unit metal-ceramic RBFDPs had a significantly higher 5-year survival rate than the 3-unit fiber-reinforced RBFDPs. The accessibility for oral hygiene practice was better with 2-unit compared to 3-unit RBFDPs, and the degree of gingivitis was lower. The esthetic outcome was better for the RBFDPs with ceramic pontics than the composite ones.

Purpose: To evaluate the effect of cavity tapering on the marginal and internal adaptation of endocrowns fabricated from two different ceramic materials. Materials and methods: Two mandibular molar model teeth were prepared with two different cavity tapers (5 and 10 degrees). Forty endocrowns in four groups (n = 10 each) were milled using lithium disilicate and zirconiareinforced lithium silicate ceramics for each cavity taper. The marginal and internal adaptation were measured with a stereomicroscope (×30) at 18 different points. The data were statistically analyzed using independent t test (P < .05). Results: A statistically significant difference was shown among the tested groups at 10 degrees of taper (P < .001). At 5 degrees of taper, the difference was insignificant. The greatest internal gap was observed on the pulpal floor in all tested groups. Conclusion: All materials had clinically acceptable internal and marginal gaps; however, lithium disilicate ceramic had significantly better adaptation at 10 degrees of taper.

Purpose: To evaluate the fracture behavior of monolithic crowns made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent; and Initial LiSi Block, GC) and zirconia-reinforced lithium silicate (Celtra Duo, Dentsply Sirona; and Suprinity, VITA) materials before and after cyclic fatigue aging. Materials and methods: Four groups (n = 22 per group) of CAD/CAM-fabricated maxillary incisor crowns were produced. All crowns were luted on metal dies with an adhesive dual-curing resin cement (G-CEM LinkForce [GC]). Half of the crowns in each group (n = 11) were statically loaded to fracture without aging. The remaining half were subjected to cyclic fatigue aging for 120,000 cycles (F_max = 220 N) and then loaded statically to fracture. Fracture mode was then visually examined. Scanning electron microscopy and energy-dispersive spectroscopy were used to evaluate the microstructure of the CAD/CAM ceramic materials. The data were statistically analyzed with two-way analysis of variance followed by Tukey honest significant difference (HSD) test (α = .05). Results: Before cyclic aging, there was no statistically significant difference in load-bearing capacity among the four groups (P = .371). After cyclic aging, the load-bearing capacity significantly decreased for all groups (P = .000). While the e.max CAD blocks had significantly higher load-bearing capacity (1,061 ± 94 N) than both monolithic ceramic crowns (P < .05), no significant difference was obtained compared to the Initial LiSi Block group (920 ± 140 N) (Tukey HSD P = .061). Conclusion: The mechanical performance of monolithic ceramic crowns fabricated from lithium disilicate was better than zirconia-reinforced lithium silicate after cyclic fatigue aging.

Purpose: To evaluate the fracture strength of endodontically treated molars filled with different composite resins, with or without fiber reinforcement. Materials and methods: A total of 60 intact mandibular molars were selected and endodontically treated. A standardized mesio-occlusal-distal cavity was prepared with cervical margins 1 mm above the cementoenamel junction and oral and buccal walls with 1.5-mm remaining thickness. Universal adhesive was used in all specimens in etch-and-rinse mode. Specimens were divided into four groups (n = 15 each) according to restoration technique: CSM group, adhesive overlay with hybrid ceramic (CeraSmart, GC); EXP group, direct composite restoration (Essentia U, GC) and everX Posterior (GC) as core material; ESU group, direct composite restoration (Essentia U); and EST group, direct composite restoration (Essentia U) reinforced with horizontal bidirectional glass fibers placed over the pulpal chamber floor (everStick-Net, GC). After 7 days of water storage, samples were loaded until fracture using a universal testing machine. The maximum breaking loads were recorded in Newtons (N), and statistical analysis was then conducted with two-way analysis of variance and post hoc Tukey test. Fragments were analyzed using scanning electron microscopy. Results: Mean fracture resistance was: CSM = 1,428.9 ± 316.90 N; EXP = 1,874.57 ± 299.47; ESU = 1,557.44 ± 355.65; and EST = 1,870.27 ± 145.11. CSM and EXP showed the highest strength values when compared to the other groups. The variable "fiber insertion" did not significantly alter the fracture resistance. Origins of the fractures were always located on the occlusal surface, mainly from the major contact loading area. Conclusion: The use of everX Posterior showed great improvement in fracture resistance, similar to cuspal coverage restoration. However, only short fiber-reinforced composite resins showed a favorable fracture pattern.

Purpose: To evaluate the dimensional discrepancy between the diagnostic wax-up and the resulting mock-up. Materials and methods: A maxillary model with misaligned teeth was scanned, and an initial cast was 3D printed. A total of 60 identical casts were 3D printed from the initial one after scanning, and based on a digital additive veneer wax-up on the 6 anterior teeth, 10 more casts were 3D printed. The specimens were allocated to seven groups (n = 10 each). Group 1: transparent silicone matrix with a flowable light-curing composite resin; group 2: same as group 1, with the addition of a prefabricated transparent tray; group 3: silicone impression putty (65 on the Shore A hardness scale) and light-body silicone impression material with a dual-curing bis-acryl resin; group 4: same as group 3 without light-body silicone; group 5: silicone laboratory putty (92 Shore A) with a dual-curing bis-acryl resin; group 6: silicone laboratory putty (92 Shore A) with PMMA; and group 7: wax-up casts (control). Scans from the mock-ups were co-registered, segmented, and superimposed with the scans from the wax-up. The difference of the mock-up compared to the wax-up was quantified using morphologic operations. The results were analyzed with Kruskal-Wallis test and Dunn post hoc test (P < .05). Results: All mock-ups were larger in size in comparison to the wax-up. Significant differences were found for every labial surface third. The incisal third was the most inaccurate third, while the middle third was the most accurate. The most accurate groups were 2 and 5, and the largest discrepancy was observed in group 6. Conclusion: The analog mock-up differed dimensionally from the wax-up, irrespective of the technique/materials used.