The International Journal of Prosthodontics, 06/2019

Purpose: To report on the 10-year clinical treatment outcomes for a strictly applied clinical protocol for pressable lithium disilicate glass-ceramic laminate veneers (LDLVs) placed by two experienced dentists. Materials and Methods: A 10-year follow-up assessment of 364 LDLVs placed in 41 patients was undertaken with the clinical criteria color/esthetic match of the porcelain surface, chipping and fracture occurrence, marginal discoloration, and integrity, assessed using the modified United States Public Health Service scoring system. Results: After 10 years, the survival rate was 97.4%. Complications occurred in 1.64% of the restorations (fractures and debonding in 0.55% and 1.09%, respectively). Conclusion: A strict, repeatable protocol for placing veneers with experienced dentists yielded good results.

Purpose: To determine the effectiveness of anterior repositioning splint (ARS) therapy on elimination of temporomandibular joint (TMJ) sounds in patients with internal derangement. Materials and Methods: A total of 26 patients with 44 TMJs with internal derangement according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were selected. These patients used an ARS for 6 weeks. The sounds of both the right and left TMJs were recorded with a specifically developed sound recording system before and after ARS therapy. The evaluation of sound was performed using evolutionary spectral analysis on the program MATLAB. Parameters such as sound type, amplitude, duration, and energy were evaluated in a time-frequency analysis. Changes in mean amplitude levels of opening/closing TMJ sounds before therapy and 6 weeks after insertion of splints were compared using paired-samples t test. The level of significance was set at 5%. Results: The patients showed a decrease in the mean amplitude and energy values of opening/ closing sounds after 6 weeks of ARS use (P < .05). According to evolutionary spectral analysis, the use of ARS was efficient for 7 of 19 right joints (37%) and 11 of 25 left joints (44%). Conclusion: The results suggest that the use of 6-week ARS reduced amplitude and energy parameters of TMJ sounds; however, it did not completely eliminate TMJ sounds.

Implant parallelism is considered a cardinal criterion for the successful rehabilitation of edentulous jaws with implant-retained overdentures (IODs), especially if freestanding anchorage systems (unsplinted attachments) are employed. This report aimed to demonstrate the successful use of a novel IOD attachment with a true-alignment capability in complex cases with large inter-implant angular discrepancies. The report further aimed to highlight the use of a novel polyetherketoneketone (PEKK) framework as a reinforcement material for fabricating a completely metal-free IOD. Although some freestanding attachments exploit their geometric form and/or use various retentive inserts to compensate for inter-implant angular discrepancies, a true-alignment correction is seldom achieved. The CM LOC FLEX (Cendres+Métaux attachment provides a true alignment correction and produces parallelism between implants in clinical situations where the implants are not parallel to one another. The functionality of the CM LOC FLEX was described in this case report for two different clinical situations: a conventional mandibular IOD retained by two implants, and a maxillary IOD retained by four implants. Both cases involved a complex clinical situation with compromised implant parallelism. The CM LOC FLEX abutment has a true-alignment correction mechanism that can be advantageous in clinical situations where the inter-implant axial alignments are not parallel. PEKK frameworks are lightweight, strong, and can be esthetic substitutes for conventional metal frameworks. However, welldesigned clinical studies are further needed to assess the clinical performance as well as the maintenance requirements of the illustrated novel attachment and the PEKK framework before advocating them as validated and standard protocols.

Purpose: To prospectively evaluate the effects of impression material, impression tray type, and partially dentate arch classification on the accuracy of fit of partial removable dental prostheses (PRDP) cobalt-chromium (Co-Cr) frameworks, as inferred from the number of fabricated frameworks required for achievement of acceptable fit. Materials and Methods: A total of 103 partially dentate patients provided with Co-Cr PRDP treatment for one or both arches (n = 142) by undergraduate dental students were clinically assessed by two examiners at the metal framework try-in stage, and the relevant data were recorded. Statistical analyses of data were performed using factorial analysis of variance (ANOVA) to study the associations of impression material (alginate, polyvinyl siloxane [PVS]), Kennedy class, and impression tray type (stock, custom) with the number of frameworks that needed to be fabricated for each patient (α = .05). Results: Statistical analyses of data derived from 142 (65 maxillary and 77 mandibular) treated partially edentulous arches revealed no significant correlation between the impression material, Kennedy class, or tray type with respect to the number of framework construction attempts needed (P ≥ .05). Post hoc Tukey test also did not demonstrate any significant differences between the different Kennedy classes in relation to the set outcome measure (P ≥ .05). Conclusion: Alginate as an alternative option to PVS and modified metal stock trays can be used for making final impressions to produce PRDP Co-Cr frameworks. Framework fit is unaffected by class of partial edentulism (Kennedy class).

Purpose: To compare maximum bite force, masseter thickness, and oral health-related quality of life (OHRQoL) in elderly patients rehabilitated with conventional complete dentures (CDs) and single-implant overdentures (SIOs). Materials and Methods: A paired design was conducted, and 12 elderly patients were selected. Initially, a set of new CDs was manufactured and placed. After a 2-month adaptation period, the mandibular CD was transformed into an SIO by inserting one osseointegrated implant into the symphysis region. All variables were evaluated 2 months after both treatments (CD and SIO). Maximum bite force was evaluated using pressure sensors, while masseter thickness was obtained via ultrasound during muscle contraction and relaxation. The Oral Health Impact Profile for edentulous people (OHIP-Edent) was used to measure OHRQoL. Data were analyzed using Student t test and Wilcoxon test. Pearson coefficient of correlation between bite force and masseter thickness was calculated. Results: Values for maximum bite force and masseter thickness during contraction increased significantly after SIO use (P < .001), indicating an improvement in muscle function. Considering OHRQoL, the general score and the domains functional limitation and physical pain were reduced (P < .05), indicating better perception of OHRQoL, with SIO use. Moreover, masseter thickness during contraction was moderately correlated with bite force (r = 0.480; P = .018). Conclusion: Using SIO increased the maximum bite force and masseter thickness of elderly patients, leading to an improved OHRQoL.

Purpose: To investigate the influence of splinted vs unsplinted designs for a maxillary overdenture supported by four implants in terms of the outcome measures implant survival, overdenture longevity, and patient satisfaction. Materials and Methods: A systematic search, complemented by a handsearch, was carried out in the Embase, MEDLINE (PubMed), and Web of Science databases from 2000 to 2018. The PRISMA statement and a PICO approach were adopted. Free-text words were used in the strategy search, including "4-implantretained overdenture," "4-implant-supported overdenture," "implant-supported overdenture," "implantretained overdenture," "maxillary overdenture," "splinted design," "un-splinted design," and their combinations. All selected articles provided at least a 1-year follow-up, 10 fully edentulous patients, and at least one of the following clinical outcomes: survival rate of implants, survival rate of overdentures, and/or patient satisfaction scores. Nonparametric Fisher test for unpaired data was adopted in order to analyze data deriving from the survival rates of implants and overdentures. Results: The initial electronic search produced a total of 2,922 articles. After applying the inclusion criteria, 14 articles were included. The mean follow-up time after implant placement ranged from 1 to 10 years. No statistical difference was detected in the survival rate of implants between the splinted implant group and the unsplinted implant group (P = .1). Only 4 included studies reported an overdenture survival rate of lower than 95%. It is interesting to note that among these 4 studies, 3 employed four splinted implants with a bar anchorage; however, no statistical difference was detected in the survival rate of overdentures between the splinted and unsplinted groups (P = .47). High scores were reported by all studies investigating patient satisfaction. Conclusion: Within the limits of this systematic review, it can be concluded that the survival rates of implants and overdentures and patient satisfaction with a maxillary overdenture supported by four implants were not influenced by the overdenture design, and no statistical difference was detected between the splinted and unsplinted groups.

Purpose: To investigate the shear bond strength (SBS) of various primer/resin cement systems to monolithic zirconia under different levels of storage. Materials and Methods: Disk-shaped specimens of monolithic zirconia (10 × 3 mm, n = 72) were polished with silicon carbide paper, and the bonding surfaces were sandblasted with aluminum oxide (Al2O3). The samples were divided into three groups (n = 24) according to primer/cement system: Z-PRIME Plus/DUO-LINK (Bisco); Clearfil Ceramic Primer Plus/PANAVIA SA (Kuraray); and Single Bond Universal Adhesive/RelyX Ultimate (3M ESPE). After bonding was completed, each group was divided into two subgroups (n = 12) under different levels of 24-hour storage and thermocycling. The specimens were embedded in acrylic molds, and SBS tests were conducted. Modes of failure were also evaluated. The data were analyzed using one- and two-way analysis of variance (ANOVA) and Tukey Honest Significant Difference test. Significance was set at P < .05. Results: The highest and lowest SBS values were observed in the Kuraray (12.52 ± 1.34 MPa) and Bisco (5.32 ± 0.54 MPa) systems, respectively, in the thermocycled groups (P < .05). Similarly, in short-term storage groups, Kuraray had the highest (16.47 ± 1.5 MPa) and Bisco the lowest (7.43 ± 1.06 MPa) SBS values (P < .05). Regardless of adhesive system used, thermocycling significantly decreased the SBS of all cement groups (P < .05). Of the failures, 49% were adhesive, 45% were mixed, and 6% were cohesive. Conclusion: A methacryloyloxydecyl dihydrogen phosphate-containing resin cement is recommended to provide a durable bond for monolithic zirconia.

Purpose: To compare the fabrication accuracy of clasps made using different CAD/CAM technologies. Materials and Methods: Five clasps were created using three CAD/CAM technologies: casting from a resin pattern using additive manufacturing; computer numerical controlled milling; and selective laser sintering (SLS). Differences between the scan data of the clasps and the CAD data were statistically analyzed. Results: There were significant differences in all parts of the clasps. The difference values were small overall for the SLS clasp. Conclusion: This study demonstrated that SLS for clasp fabrication is outstanding in terms of fabrication accuracy and reproducibility.

Purpose: To investigate whether (1) the curing mode and (2) the use of the corresponding or noncorresponding crown luting system have an impact on the microleakage of computer-aided design/ computer-assisted manufacture (CAD/CAM) composite crowns after chewing simulation. Materials and Methods: Two CAD/CAM composite blocks (Lava Ultimate [n = 20] and LuxaCam Composite [n = 20]) and their luting systems and curing modes (light curing [LC] or chemical curing [CC]) were investigated. A dye penetration test was used to detect the presence of microleakage. Results: Independently of the luting system, the LC groups showed a significantly lower microleakage compared to the CC groups (P < .05). Furthermore, the CC groups exhibited a reduction of microleakage if the CAD/CAM block and luting system were from the same manufacturer. Conclusion: For the CC mode, the corresponding block and luting system should be used.

Purpose: To investigate the need for photoactivation of the adhesive system inside ceramic laminates before the luting procedure and to evaluate the color stability, nanohardness, and elastic modulus of the adhesive interface activated with singlewave and polywave light-curing units. Materials and Methods: A total of 44 lithium disilicate ceramic veneers (7.0 mm × 8.0 mm × 0.6 mm) were fabricated, bonded to enamel, and sorted into four experimental groups (n = 11 each) according to the type of light-curing unit (Radii-Cal [singlewave] or Valo [polywave]) and mode of adhesive system activation (with or without previous photoactivation). Two luting agents were used: the Tetric N-Bond adhesive system and Variolink Veneer resin cement. A visible ultraviolet spectrophotometer was used to evaluate the color stability before and after UVB artificial accelerated aging for 252, 504, and 756 hours (n = 8 samples from each group). A nanohardness tester under a load of 1,000 μN was used to evaluate the nanohardness and elastic modulus (n = 3 samples from each group). Data regarding the color stability and the mechanical properties (nanohardness and elastic modulus) were subjected to analysis of variance and Tukey protected least significant difference test (α = .05). Results: Prior activation of the adhesive system, the distinct light-curing units, and different aging periods exerted no significant difference on the color stability or mechanical properties of the resin cement (P > .05), except for in the group activated with Radii-Cal after 756 hours, in which the nonprevious activation showed lower color alteration compared to the previous photoactivation (P = .0285). Without prior activation of the adhesive with Valo, the polywave unit promoted higher nanohardness and elastic modulus values in the adhesive system (P < .05). Conclusion: In general, singlewave and polywave light-curing units promoted no difference in color stability or the mechanical properties of the adhesive interface. The prior curing of an adhesive system inside ceramic laminate is not necessary.

Purpose: To evaluate the accuracy of a smartphone application as a low-cost approach for digitizing a facial defect for 3D modeling. Materials and Methods: A stone model of a facial defect was scanned using industrial computed tomography (reference scan) and was also scanned five times using a commercial laser scanner. A series of 24 sequenced digital photographs was taken five times by smartphone at two elevations. These images were uploaded and processed by a cloud-based server to create virtual 3D models. The 3D datasets were geometrically evaluated and compared to the reference data using 3D evaluation software. Mann-Whitney U test was used for statistical analysis, and the significance was set at P < .05. Results: The overall mean 3D deviation ± standard deviation for the smartphone dataset was 604.9 ± 123.5 μm compared to 67.5 ± 0.49 μm for the laser scanner. There was a significant difference in the accuracy between the commercial laser scanner and the smartphone application (P = .009). Conclusion: The results showed that within the limits of this study and in reference to standard computed tomography imaging, data acquisition with a smartphone for 3D modeling is not as accurate as commercially available laser scanning.

Recent attempts in the development of novel zirconia ceramics aim at improving its optical characteristics by increasing the yttria content to up to 5 mol% so that these ceramics can be used for the fabrication of stable and esthetic monolithic restorations. However, clinical evidence on the outcomes of such restorations is sparse. In this case report, monolithic inlays, partial crowns, tooth- and implant-supported single crowns, and fixed dental prostheses were fabricated out of a zirconia ceramic doped with 5 mol% yttria. The restorations in the present case history report showed a satisfying esthetic outcome and are in situ as inserted 18 months after insertion.