The International Journal of Prosthodontics, 06/2023

Purpose: To investigate the association between the orofacial implant position distance (ID) and facial bone crest thickness (FBCT) in single-tooth implant crowns (STICs) placed in the esthetic zone and to predict the presence of facial bone above the implant shoulder, as well as its impact on Pink and White Esthetic Scores (PES and WES) and patient-related outcome measures (PROMs). Materials and Methods: In this cross-sectional study, all patients treated with STICs in the esthetic zone between 2006 and 2013 with at least 12 months postloading were invited to enroll. CBCTs were used to assess ID and FBCT. Esthetic outcomes included the PES and WES. PROMs included a participant satisfaction questionnaire with 13 questions formulated for this study. Descriptive statistics and receiver operating characteristic curve analysis were used. The associations between ID, FBCT, esthetic outcomes, and PROMs were calculated. Results: Data were available for 60 implants. Mean ID was 2.02 mm (SD = 0.77). Mean FBCT at the implant shoulder was 0.99 mm (SD = 0.98). FBCT was significantly associated with higher PES scores (P = .040), but not with WES scores (P = 0.149). FBCT was significantly associated with ID (P = .009), and implants positioned ≥ 1.6 mm palatal in relation to the adjacent teeth were likely to have higher FBCT. Conclusions: FBCT influences PES and is more predictable if implants are positioned ≥ 1.6 mm palatal in relation to the adjacent teeth.

Purpose: To compare volumetric changes in buccal soft tissue and pink esthetic scores after immediate implant placement performed with a socket shield technique (SST) or the conventional technique (CT). Materials and Methods: This parallel-arm, randomized controlled trial included 22 participants requiring replacement of a single maxillary incisor with an immediate implant. Immediate implants were placed via either the SST or the CT, with patients randomly allocated to one of the two groups. All implants underwent an immediate loading protocol. Definitive crowns were placed 6 months after implant placement. Scans of casts were recorded with a digital white light scanner before implant placement and at the end of 12 months. Volumetric changes to soft tissues on the buccal aspect were assessed by superimposition of the scanned cast. Esthetic evaluation of the soft tissue was done by evaluating the pink esthetic score (PES) before implant placement and 6 and 12 months after implant placement. Statistical analysis of the data was performed using statistical software (Stata 16.0, StataCorp). Results: The mean volumetric change in buccal soft tissues at the end of 12 months in the SST group was –0.1520 ± 0.86 mm, and in the CT group, it was –0.643 ± 0.35 mm. The difference was statistically significant (P = .001). Higher PES was observed in the SST group at all time intervals. The difference was statistically significant at 6 months (P = .001) and 12 months (P = .007). Conclusions: The results of this study showed less volumetric changes in buccal soft tissues and higher PES when the SST is used rather than the CT.

Purpose: To evaluate the effect of obturator bulb thickness on the masticatory performance and weight of obturator prostheses in edentulous hemimaxillectomy patients. Materials and Methods: A randomized, single-blind, three-period crossover trial was conducted with 17 edentulous patients. Each patient was provided with three definitive 3D-printed obturator prostheses. Obturators were divided into three groups: group 1 (G1; 1-mm bulb); group 2 (G2; 2-mm bulb); and group 3 (G3; 3-mm bulb). After fabrication, the weight of each obturator was measured with a digital analytical balance. The patients used each obturator for a period of 2 weeks without a passive period (ie, they did not stop using the obturator). The masticatory function of each obturator was evaluated with an adapted Sato questionnaire and the sieve test. Data were analyzed using one-way ANOVA and Pearson correlation analysis (α = .05). Results: According to the results of the Sato questionnaire and sieve test, G1 demonstrated the highest masticatory function scores (70.88 ± 9.39; 1.06 ± 0.06), while G3 exhibited the lowest scores (48.23 ± 7.69; 0.92 ± 0.05; P < .001). The weight of the obturators was significantly different between groups (G1 = 31.58 ± 1.09 g; G2 = 33.99 ± 1.21 g; G3 = 36.57 ± 1.13 g; P < .001). The correlation between masticatory function and the weight of the obturator was significant (P < .05). Conclusions: This study revealed that 1-mm obturator bulb thickness was an effective fabrication method for improving masticatory function and reducing the weight of obturator prostheses in edentulous hemimaxillectomy patients.

Purpose: To investigate the influence of a novel scanning strategy—using two new intraoral scanner devices with different operators—on the full-arch scanning accuracy for a dentate maxilla. Materials and Methods: Two scanning strategies, a test and a control strategy, were used to produce full-arch impressions of the dentate maxilla of a study patient. Two intraoral scanning (IOS) devices were used. Five expert operators performed a total of 40 scans. The scan time was recorded for each. A reference model was obtained from the patient’s maxillary arch with an analog impression. The model was later scanned with a high-precision laboratory scanner to create a digital reference model (DRM). The scanning accuracy was analyzed with 3D-analysis software using a root mean square (RMS) calculation method, and qualitative analysis was executed using machine learning software. Results: The mean RMS result for the test strategy was 82.8 ± 16 μm compared to 81.5 ± 16 μm for the control strategy. The mean RMS results were 84.7 ± 15 μm for Primescan (PS) and 79.6 ± 17 μm for 3Shape (3S). As such, the scanning strategies and IOS devices did not influence the scanning accuracy. Yet, a significant difference was found when the two strategies’ scanning times were compared (P = .001), as well as the IOS devices (P = .001). The operator was found to have no influence on the scanning strategy. Conclusions: The accuracy of digital impressions is not influenced by different strategies, devices, or operators, in contrast with the scanning time, which is influenced by both strategies and devices.

Purpose: To present prosthetic complications observed in the medium and long term in patients treated with metal-acrylic resin implant-supported fixed complete dentures (MAIFCDs). Materials and Methods: A total of 87 patients who were treated with MAIFCDs were included. Acrylic resin (denture teeth and base) fracture, screw loosening (prosthetic or abutment), screw (prosthetic or abutment), and framework fracture were analyzed for descriptive statistics. Product-limit survival estimates were used for the cumulative no-complication rate (CNCR) of prostheses. All results were assessed using α = .05. Results: The average observation time was 42.9 months (range: 19 to 153). Of 597 implants, 8 mandibular (44.4%) and 10 maxillary implants (55.6%) failed. In total, 29 patients (33.3%) experienced no complications in an average of 7 years, and 58 patients (66.6%) experienced at least one complication. The average time for the first complication to occur was 23 months (range: 1 to 97 months). The average number of complications was 5.9/patient. Acrylic resin complications were the most frequent, followed by screw loosening, screw fracture, and framework fracture. Of those patients with complications, 9 (16%) had maxillary MAIFCDs with an average of 4 complications. In total, 28 patients (48%) had only mandibular MAIFCDs with an average of 5 complications, and 21 patients (36%) had both arches treated with MAIFCDs with an average of 9 complications. Mandibular MAIFCDPs in women had a higher CNCR compared to maxillary MAIFCDs of both women and men and when both arches of women were treated with MAIFCDs (P < .05). Conclusions: The CNCR of MAIFCDs differed depending on the arch treated and sex. Mandibular MAIFCDs in women had a lower complication rate than MAIFCDs in other arch-sex pairs. Acrylic resin related complications were commonly observed as well as prosthetic screw loosening.

Purpose: To assess two types of abutment materials routinely used in daily practice—direct polymethyl methacrylate (PMMA) and a zirconia-on—Ti-base abutment—and their effects on peri-implant soft tissues and bone remodeling in a minipig model. Materials and Methods: A total of 40 implants were placed in five minipigs in a single-stage surgery. Four different types of abutment materials (n = 10 per group) were used: (1) titanium (control); (2) zirconia (control); (3) PMMA (test 1); and (4) Ti-base (zirconia bonded to a titanium framework; test 2). After 3 months of healing, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attachment) were assessed on each abutment mesially and distally, and the distance from the implant margin to the first bone-to-implant contact (BIC) was measured. Results: No statistically significant differences were found among the four groups regarding soft tissue dimensions (P = .21), and a long junctional epithelium (mean: 4.1 mm) and a short connective tissue attachment (mean: 0.3 mm) were found in the majority of abutments. In some samples, the junctional epithelium extended all the way to the bone level. The measured peri-implant bone remodeling was similar in all four groups (P = .25). Conclusions: The present findings indicate that both direct PMMA and zirconia-on–Ti-base abutments seem to allow soft tissue integration similar to that of titanium and zirconia abutments. However, clinical studies are warranted to either confirm or refute the observed findings and to further investigate the influence of different materials on mucointegration.

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 ANOVA (α = .05). Fracture modes were examined under a stereomicroscope (×25 magnification) and recorded. Results: The mean ± SD fracture loads ranged from 642 ± 190 N (one wall, glass fiber, 5 mm) to 1,170 ± 130 N (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). Conclusions: 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 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 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.

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 examine and compare the fracture strength of implant-cemented fixed partial denture (FPD) prostheses fabricated with digital vs conventional chairside methods. Materials and Methods: Three groups of seven specimens each were produced: group A (3D printing); group B (milling); and group C (conventional chairside manufacturing), which served as a control. All groups were cemented to standard implant abutments placed in artificial bone blocks. Fracture strength testing was performed using a universal testing machine. Statistical analysis of the resultant maximum forces was performed using SPSS version 25 software (Mann- Whitney U test, P < .05). Results: The mean fracture load value of the group A FPDs was 260.14 N ± 28.88, for group B was 663.57 N ± 140.55, and for group C was 266.65 N ± 63.66. Conclusions: Milled provisional FPDs showed a higher fracture resistance compared to 3D-printed and control groups. However, no such difference could be detected between the 3D-printed and control groups.

Purpose: To identify and map the scientific evidence regarding factors associated with the nonadaptation of completely edentulous patients to mandibular complete dentures. Materials and Methods: This scoping review followed the PRISMA-ScR statement for Scoping Reviews and was based on guidelines proposed by Arksey and O'Malley and the Joanna Briggs Institute Manual for Evidence Synthesis. The methodology was registered on the Open Science Framework. An electronic search strategy was conducted in PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library, Virtual Health Library, ClinicalTrials.gov, Google Scholar, and ProQuest databases was conducted. Studies that evaluated factors associated with adaptation to and acceptance of mandibular complete dentures were included, such as sociodemographic, psychologic, patient-related, and denture-related items. Results: The search conducted in March 2022 yielded 9,978 studies. In total, 24 studies were included for data extraction. Sociodemographic factors did not interfere with adaptation to a mandibular complete denture. Psychologic factors and patient-related aspects showed greater association with nonadaptation to mandibular complete dentures than denture-reported factors. Conclusion: Although it is suggestive that psychologic and patient-related factors have higher association with the acceptance of new dentures, data must be interpreted with caution due to the variability of methodologies of the studies included in this review.

Purpose: To identify the most effective protocol for bonding denture bases and artificial teeth made with different computer-aided design and manufacturing (CAD/CAM) materials (milled and 3D-printed) and conventional heat-polymerized resins. Materials and Methods: This review was performed according to the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) criteria and registered in the International Prospective Registry of Systematic Reviews PROSPERO (CRD42021276084). An electronic search was performed independently by two examiners in PubMed/MEDLINE, 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, 589 articles remained. Four articles met the eligibility criteria to be included in this study. After evaluating the different combinations of denture base materials and artificial teeth, it was found that IvoBase CAD Bond (Ivoclar Vivadent) was effective for bonding CAD/CAM denture bases to prefabricated acrylic resin teeth, which showed no differences compared to the heat-polymerized resin denture base bonded to prefabricated acrylic resin teeth (χ2: 68.56; I2: 96%; P < .001). Conclusions: The IvoBase CAD Bond bonding system can be used for the fabrication of CAD/CAM denture bases with prefabricated acrylic resin teeth.

Two clinical cases involving the fracture of a natural tooth and one of a ceramic crown are presented and discussed based on fractography principles. In the first case, a patient reported intense pain in a sound third molar where a longitudinal fracture was identified, and the tooth was extracted. In the second case, a posterior rehabilitation using a lithium silicate ceramic crown was carried out, and the patient returned after 1 year with a fractured piece of the crown. Both were analyzed under microscopy to identify the origins of fractures and their causes. The fractures were critically analyzed so that relevant information could be generated from the laboratory to the clinic.

Purpose: To compare the accuracy of milled versus 3D-printed complete denture bases and teeth and to assess the position of the teeth in relation to the corresponding denture bases. Materials and Methods: Two different manufacturing techniques were used in this study. In Group A, 10 complete dentures were digitally designed and fabricated by milling prepolymerized blocks of polymethyl methacrylate (PMMA). In Group B, 10 complete dentures were digitally designed and fabricated using a 3D-printing technique. The accuracy of the maxillary and mandibular denture bases and teeth and the positions of the teeth in relation to the corresponding denture bases were evaluated using Geomagic Control X software (Oqton). Data were presented as mean and SD values. Statistical analysis of the resultant data was performed using Student t test. The significance level was set at P ≤ .05. Results: With regard to denture bases, lower surface deviation values were found in the maxillary and mandibular milled denture bases (Group A), with values of 0.158 ± 0.024 and 0.117 ± 0.022, respectively. However, regarding the denture teeth, lower surface deviation values were found for printed teeth (Group B), with values of 0.18 ± 0.016 for the maxillary teeth and 0.153 ± 0.02 for the mandibular teeth. For positioning of the teeth in relation to the corresponding denture bases, the values were 0.4 ± 0.08 for the maxillary teeth and 1.003 ± 0.027 for the mandibular teeth. Conclusions: The milling technique yields complete denture bases with superior accuracy, whereas printing technology produces denture teeth with better accuracy and positioning in the corresponding denture bases.

Purpose: To evaluate and compare the effect of accelerated aging and coffee immersion on the microhardness and gloss of a new computer-aided design and computer-aided manufacturing (CAD/CAM) hybrid material (Crystal Ultra) to those of contemporary restorative materials. Materials and Methods: A total of 160 specimens (12 × 14 × 1 mm ± 0.05 mm) were obtained from IPS e.max (IPS), VITA Enamic (VE), Crystal Ultra (CU), Lava Ultimate (LU), and CeraSmart (CS) high-translucency CAD/CAM blocks. The Vickers microhardness and gloss of the specimens were determined after thermocycling and coffee immersion. Data analysis was performed using SPSS (α = .05). Results: IPS and CS specimens exhibited the highest (572.66 ± 11.30) and lowest (61.92 ± 3.91) microhardness, respectively. The highest gloss was observed with IPS specimens (3.31 ± 0.32), and LU specimens showed the lowest gloss (2.33 ± 0.06). A significant difference in gloss was observed between the materials at all measurement intervals (P < .01), except at T0 (P = .43). IPS specimens showed no significant changes in either group at any measurement interval. Conclusions: The microhardness and gloss of the new CU material were comparable to those of the tested contemporary hybrid restorative materials. Glass-ceramic showed superior hardness and gloss compared to hybrid restorative materials. Accelerated aging with thermocycling and staining significantly affected the microhardness and gloss of all tested CAD/CAM materials.

Purpose: To examine the effects of anodization and different surface modifications of titanium on bond strength to 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) resin cement. Materials and Methods: Grade 5 titanium alloy disks (n = 160) were assigned to one of five prebonding surface treatment study groups (polished; polished and anodized; polished, etched, and anodized; sandblasted; sandblasted and anodized). Disks were adhesively bonded with 10-MDP resin cement (Panavia 21; bonding area: 3.3 mm in diameter) to composite resin cylinders. In each study group, tensile bond strength tests were conducted after 24 ± 1 hours and after 6 months (180 ± 2 days) of water storage (n = 16 specimens per water storage subgroup). Debonded specimens were stereomicroscopically analyzed to determine their fracture mode. Statistics included one-way and multifactorial ANOVA and Tukey post hoc tests (α = .05). Results: Anodization and water storage did not significantly (P ≥ .389) affect tensile bond strength. Although subgroups of polished samples had significantly (P ≤ .031) lower bond strengths (subgroup mean values: 20 to 26 MPa) than etched or sandblasted samples (subgroup mean values: 29 to 33 MPa), they nonetheless exceeded the empirical threshold of 10 MPa used as a criterion for clinical recommendation. The fracture mode of all test specimens was predominantly cohesive. Conclusions: Anodization of titanium surfaces can be performed without weakening the adhesion of 10-MDP–based resin cement to titanium.

Purpose: To evaluate the effect of thermomechanical dynamic loading on the retention of telescopic mandibular overdentures with different metallic and nonmetallic material combinations. Materials and Methods: Four groups were tested: (1) ZP (zirconia abutments/PEEK framework); (2) PP (PEEK abutments/PEEK framework); (3) TP (titanium abutments/PEEK framework); and (4) TG (titanium abutments/gold copings/cobalt-chromium framework). Each specimen contained four implants positioned over a polyvinylchloride-cylindrical base. After 10,000 removal/insertion cycles, the specimens were subjected to thermomechanical dynamic load in a chewing simulator for 1,200,000 loading cycles, corresponding to 5-year clinical fatigue. A screw was used to receive the chewing load, and 0.5 mm was permitted between the screw and the metal top fixed into the base to simulate the resilience of the posterior residual ridge tissues. Vertical chewing loads of 60 N were applied at a speed of 30 mm/second. Thermocycling was applied with a temperature ranging between 5°C and 55°C. The retentive force was measured using a universal testing machine 10 times before and after the thermomechanical dynamic loading test with a speed of 8 mm/second. Results: The mean retentive force increased significantly from 13.2 (± 4.6) N to 16.4 (± 6.1) N in group ZP (P = .002), while in group TP, it decreased significantly from 4.9 (± 2.1) N to 3.3 (± 1.7) N (P = .046). There was no statistically significant change in the retentive force for groups PP and TG. Conclusions: The investigated metallic and nonmetallic combinations of double-crown-retained mandibular overdentures maintained acceptable levels of retention after thermomechanical dynamic loading. Further laboratory and clinical studies are needed before their routine clinical use can be recommended.

Purpose: To analyze the potential association between the occlusion features and the incidence of temporomandibular joint (TMJ) arthralgia in patients with partial dentures. Materials and Methods: A total of 101 partial denture wearers were collected, 45 with unilateral TMJ arthralgia diagnosed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Binary logistic regression analysis was adopted. The TMJ asymptomatic group (n = 45) was quantified as 0, while the TMJ arthralgia group (n = 56) was quantified as 1. In total, 13 occlusion variables were analyzed: gender, age, number of prosthetic teeth, number of dentition quadrants with a prosthetic tooth, anterior or posterior prosthesis location in maxillary or mandibular dentition, occluded prosthesis pair, anterior overjet, and overbite relation. Simple and multiple binary logistic models were adopted, accordingly, for the risk impact of them on TMJ arthralgia. Results: Overbite (OR = 2.238) and maxillary anterior prosthesis (OR = 0.305) were entered into the simple binary logistic model; while overbite (OR = 2.774) plus maxillary anterior prosthesis (OR = 0.347), overbite (OR = 3.425) plus unilateral maxillary posterior prosthesis (OR = 4.672), and overbite (OR = 3.476) plus overjet (OR = 0.436) and mandibular anterior prosthesis (OR = 0.177) were entered into the multivariate logistic regression model (all, P < .05). Conclusions: Partial denture wearers with a deep overbite, especially those with a unilateral maxillary posterior prosthesis, had a higher prevalence of unilateral TMJ arthralgia.

Purpose: To develop an instrument for the assessment of perception of orofacial appearance and psychologic issues that can affect people’s judgment. 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 a university (n = 261; 26.4% men and 73.6% women) in the 14- to 28-year age range. Internal consistency, construct validity, responsiveness, and temporal stability were assessed. Results: Factorial analysis and Cronbach alpha identified four dimensions (self-esteem, perfectionism, body image, and smile appearance concern) that could be best addressed using 17 items. Internal consistency was good (α in the .70 to .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 decrease esthetic concern (P < .05). Conclusions: The newly created instrument, Orofacial Appearance Perception Questionnaire, is a consistent and reliable short instrument that measures psychologic issues related to the perception of orofacial appearance.

Purpose: To investigate the bending moment of implants restored with a directly screwed single-unit fixed dental prosthesis (FDP) compared to implants restored with an FDP polymerized to a titanium base before and after thermomechanical aging. Materials and Methods: A total of 240 implants (120 with and 120 without a titanium base) were restored with FDPs manufactured from conventionally sintered 3Y-TZP, 5Y-TZP, 4Y-TZP, and CoCrMo, as well as high-speed sintered 4Y-TZP. Half the specimens per subgroup were aged using chewing simulation combined with thermocycling (1,200,000 cycles at 50 N; 6,000 cycles at 5° to 55°). Initial and aged fracture load were measured. The bending moment was calculated and subjected to statistical analysis (Kolmogorov-Smirnov test, one-way ANOVA followed by post hoc Scheffé, t, and chi-square tests; P < .05). Failure types were analyzed. Results: Implants without a titanium base showed higher bending moments for all initially tested zirconia groups compared to implants with a titanium base. The highest initial values were observed for 4Y-TZP FDPs regardless of implant type. High-speed sintered FDPs demonstrated higher initial bending moments compared to conventionally sintered FDPs. Artificial aging led to a decrease of the bending moment in most subgroups. After aging, no differences were found within the restoration materials, sintering protocols, or implant types. Implant deformation occurred mainly with directly screwed FDPs, whereas FDP mobility was predominantly observed among implants with a titanium base. FDP fractures were mainly observed for 5Y-TZP. Conclusions: Both implant types exhibited similar values after aging. Thus, implants without a titanium base seem to show equally sufficient stability for clinical applications with all tested materials.