Comparison of marginal and internal adaptation in the frameworks of three-unit implant supported fixed partial denture produced by using CAD/CAM systems

Purpose: The purpose of this study was to compare the marginal fit and internal adaptation of frameworks produced with different techniques in implant supported fixed partial denture. Material and Method: In order to exemplify the partial edentulism, two dental implants were implanted into the teeth region number 35 and 37 on the lower jaw made of epoxy resin, and then cemented abutments were screwed on the implants. The obtained master model was scanned by the laboratory scanner and transferred to the design programme for the production of the framework. For six different types of frameworks, totally sixty pieces of frameworks were produced having ten of each group (n=10). These frameworks were produced by using different CAD/CAM systems. Group 1 represents the Co-Cr framework produced by using traditional metal casting method (control group). Group 2 represents the Co-Cr framework produced by using CAD/CAM milling. Group 3 represents the Co-Cr framework produced by direct metal laser sintering (DMSL). Group 4 represents the titanium (Ti) framework produced by CAD/CAM. Group 5 represents zirconium (Zr) framework produced by CAD/CAM. Group 6 represents the polyether ether ether ketone (PEEK) framework produced by CAD/CAM. The silicone replica technique was implemented so as to evaluate the marginal and internal adaptation of the frameworks. The measurements for evaluation was carried out by a stereomicroscope (at ×20 magnification). An intergroup comparison was made in concern with the marginal and internal gap obtained from the photomicrographs. Intergroup comparisons were made by using ANOVA test and Tukey's Post Hoc Test (multiple comparison test). As for the differences between the abutment teeth, Independent T Test was carried out. Results were evaluated at a significance level of p<0.05. Results: According to the result of this study, significant differences were observed between PEEK and titanium groups in the marginal gap (p<0.05). On the other hand a statistically significant difference was not found among the other groups (p>0.05). A significant difference in the measurement of internal gap was found among the groups of PEEK, DMLS and Co-Cr framework produced by CAD/CAM milling (p<0.05), whereas no significant difference was found among the other groups (p>0.05). However, only for the titanium groups statistically significant difference was observed in abutment teeth (p<0.05), no significant difference was found among the other groups (p>0.05). Conclusion: All of the marginal and internal adaptation values, which were acquired by traditional metal casting method and CAD/CAM techniques, were within the clinical limit values as affirmed in the literature. Key Words: CAD/CAM, Dental implant, Internal adaptation, Marginal fit, Fixed partial denture