Mechanical stability of all-ceramic abutments retained with three different screw materials in two-piece zirconia implants-an in vitro study.

OBJECTIVES: To measure the abutment rotation and fracture load of two-piece zirconia implants screwed with three different abutment screw materials. MATERIAL AND METHODS: Thirty-six zirconia implants with 36 zirconia abutments were distributed into 3 test groups: group G connected with gold screws, group T with titanium screws, and group P with peek screws. In the first part of the study, the rotation angle of the abutments was measured. The second part of the study measured the maximum fracture force of adhesively bonded lithium disilicate crowns after artificial aging and fracture modes were reported. RESULTS: In group G, the median rotation angle was 8.0 degrees , in group T 11.6 degrees , and in group P 9.5 degrees . After artificial aging, no screw loosening, crown, abutment, or implant fracture occurred. The median fracture force in group G was 250 N, in group T 263 N, and in group P 196 N. CONCLUSIONS: Rotation angles and fracture loads of two-piece zirconia implants with gold, titanium, or peek screws showed no significant differences; however, fracture loads showed inferior results for group P. CLINICAL RELEVANCE: The indication for the material peek as an abutment screw is still questionable and should be considered carefully.