Evaluation of the clinical performance of different occlusal device materials.

STATEMENT OF PROBLEM: Computer aided technologies have been used to fabricate occlusal devices. However, the clinical behavior of the newly developed materials developed for occlusal devices is unknown. PURPOSE: The purpose of this prospective, double-blind study was to assess the clinical efficacy of recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) materials for the fabrication of occlusal devices. MATERIAL AND METHODS: A total of 24 participants were divided randomly into 2 study groups; polyetheretherketone (PEEK) and polymethyl methacrylate (PMMA), and a control group (CG). Conventional impressions and gypsum casts were obtained from all participants. In the study groups, the casts were digitalized with an extraoral digital scanner, designed with a software program (Bite Occlusal Device Module; exocad GmbH) and milled from PEEK and PMMA blocks. Clear resin sheets were used for occlusal device fabrication in the CG. The baseline measurements were made during the initial appointments. After 6 months, the participants returned for follow-up evaluations. Clinical performance based on surface roughness, wear of the antagonist teeth, occlusal device fit and therapeutic effect, as well as participant satisfaction were compared using the 1-way ANOVA test between the main groups (α=.05). The post hoc and Kruskal Wallis-H tests were used to compare the nonparametric group. RESULTS: The therapeutic effects of the occlusal devices did not differ. All participants showed improvement in palpation and mandibular movement scores, but no statistically significant differences were found among the groups (P>.05). PEEK and PMMA had statistically less surface wear than CG (P<.001) and led to less antagonist tooth wear. No significant participant satisfaction difference was seen among the groups (P>.05). The control group had the best fit (P<.001). CONCLUSIONS: Recent CAD-CAM materials exhibit clinically acceptable outcomes, and their performance is comparable with that of traditional materials. CAD-CAM materials appear suitable in terms of accuracy, surface wear, and therapeutic efficacy.

Investigation of Conventional vs Nonoriginal CAD/CAM Bars with Production Stage Differences: An In Vitro Precision Study Using a Novel Technique.

PURPOSE: The aim of this study was to evaluate the precision of fit of bar frameworks fabricated using three different production processes and the effect of changes in the CAD/CAM process steps on the precision of the resulting bar frameworks. MATERIALS AND METHODS: Four implants were applied to a mandibular phantom model, and three different production techniques were used to fabricate 30 bar frameworks. In the first group, the bar frameworks were fabricated with the conventional production process (the lost-wax technique; n = 10). In the second group, a CAD/CAM production process was used with digital data collected individually from the master model for the production of each of the final bar specimens (n = 10). In the third group, a CAD/CAM production process was used with the master model being scanned once, and the single resulting data value was used for the production of all final bar specimens (n = 10). The marginal gap between bar frameworks and implants was digitally calculated (ATOS So High-End 3D Digitizer for Small Objects, GOM Inspect). Newman-Keuls multiple comparison tests, a Tukey multiple comparison test, and Pearson correlation tests were applied to the data with a level of significance of P < .05. RESULTS: The mean marginal gap value of group 1 was 95.25 ± 76.15 µm, which was statistically significantly lower than the other groups (P = .0001). For group 2, the mean marginal gap value was 152.00 ± 97.19 µm, whereas for group 3, the mean marginal gap value was 156.7 ± 78.70 µm. Among group 2 and group 3, no statistically significant difference was observed at the mean marginal gap value. CONCLUSION: The marginal gap values in the CAD/CAM bar framework groups were significantly higher than the conventional bar framework group. Among the CAD/CAM groups, the mean marginal gap values were not statistically significant.

Impact of peri-implant bone resorption, prosthetic materials, and crown to implant ratio on the stress distribution of short implants: a finite element analysis.

The purpose of this study was to determine the effects of prosthetic materials and crown/implant (C/I) ratio on short implants with a marginal bone resorption. Three-dimensional finite element analysis was used to simulate stress distribution under static loading in non-resorption and resorption scenarios (3-mm vertical bone loss) in implants restored with single crowns and C/I ratios of 1:1, 1.5:1, and 2:1 were evaluated. Different crown materials were used: porcelain-fused to metal, porcelain-fused to zirconia, monolithic zirconia, and zirconia-based crown veneered with indirect composite resin. The C/I ratio, the peri-implant bone resorption, and the loading conditions were the key factors affecting the generated stress in short implants. In non-resorption models, von Mises stress ranged between 50 and 105 MPa whereas in resorption models, the values ranged from 168 to 322 MPa, both increasing with the higher C/I ratio under oblique forces. Under axial loading, the C/I ratio did not influence the stress values as the presence of resorption was the only parameter increasing, 57 MPa for the non-resorption models and 101 MPa for the resorption models, respectively. Preference of a prosthetic material was ineffective on the distribution of stress in the bone and implant structure under static loading in any models. The peri-implant bone resorption and a higher C/I ratio in short implants increase the stress values under both axial and oblique forces, whereas the crown material does not influence stress distribution in the surrounding bone and implant structure.

Zygoma Implant-Supported Prosthetic Rehabilitation of a Patient After Bilateral Maxillectomy.

Maxillectomy defects may vary from localized to extensive soft and hard tissue loss. In addition to physical and psychologic damages, functional and aesthetic aspects must be restored. This clinical report describes the rehabilitation of a patient with a zygoma implant-supported obturator prosthesis caused by a subtotal bilateral maxillectomy due to a squamous oral cell carcinoma. Prosthetic rehabilitation of this patient was performed after zygoma implant surgery. A maxillary obturator prosthesis supported by 2 osseointegrated zygoma implants was fabricated. Despite limited mouth opening and anatomic deficiencies, the patient's aesthetic and functional demands were fulfilled.