Mechanical Complications Related to the Retention Screws of Prefabricated Metal Abutments With Different Angulations: A Retrospective Study With 916 Implants.

Objectives: The present retrospective study assessed the clinical performance of abutment screws from prefabricated metal abutments and compared technical complication rates between straight and angled abutments. Materials and Methods: Dental charts were selected for patients with dental implant rehabilitations delivered between 1998 and 2012. Abutment angulation, prosthetic screw type, and presence of complications that occurred during the selected time period were collected. Technical complications registered included abutment screw loosening and/or fractures detected during clinical and radiographic examinations. The chi-square test was used for statistical analysis. Results: Abutment angulations were divided into 2 groups: G1) prefabricated straight abutments and G2) prefabricated angled conical mini UCLA-type abutments. A total of 916 implants (799 straight and 117 angled conical mini UCLA-type abutments) were evaluated. G1 showed 91.1% had absence of failures, which were clinically defined as any screw loosening or fracture; and 8.9% reported some type of technical complication. G2 showed 92.3% and 7.7%, with and without technical complications, respectively. Conclusions: No significant differences were observed between abutment angulation and technical complications.