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The purpose of this retrospective study was to evaluate the incidence of mechanical complications of the posterior implant-supported fixed dental prosthesis (p-ISFDP) using computeraided design and computer-aided manufacturing (CAD/CAM) titanium customized abutments and to evaluate the influencing factors on complications. Material and Methods:The incidence and consequences of mechanical complications in p-ISFDPs over a mean follow up period of 54.43 ± 6.24 months were assessed based on electronic documentations f rom 138 patients with 266 implants. All p-ISFDP utilized CAD/CAM titanium customized abutments, and were fabricated with cement-retained prostheses with occlusal screw access holes. Statistical analyses were performed to identify the risk factors of mechanical complications.Results: During the observation period (3 -5 years), implant survival rates were 100%. Major mechanical complications were 8 abutment fractures (3.01%), 8 screw loosenings (3.01%), 2 screw fractures (0.75%), 11 chipping or fractures of veneering materials (5.58%), 23 decementations of the superstructure (11.68%). The relationship between the incidence of mechanical complications and the possible factors were not statistically significant(p > .05). Conclusion:There is no significant difference between each mechanical complication and the risk factors. P-ISFDP fabricated with CAD/CAM titanium abutments is a clinically acceptable treatment.

Accuracy of conventional and digital mounting of dental models: A literature reviewAccurate transfer of the maxillo-mandibular relationship to an articulator (i.e., mounting) is critical in prosthetic treatment procedures. In the current study, a PubMed search was performed to review the influencing factors for the maxillo-mandibular relationship's accuracy. The search included digital mounting as well as conventional gypsum cast mounting. The results showed that a greater amount of displacement was introduced during positioning the maxillary and mandibular models to interocclusal records rather than the dimensional change of registration material. Most intraoral scanners resulted in an accurate reproduction of the maxillo-mandibular relationship for posterior quadrant scanning; however, the accuracy was declined as the scan area increased to a complete arch scan. The digital mounting accuracy was also influenced by the image processing algorithms and software versions, especially for complete arch scans. (J Korean

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