Mechanical behavior of subtractively and additively manufactured zirconia and polyetheretherketone implant abutments after thermomechanical aging.

Abstract

Statement of problem: Zirconia and polyetheretherketone (PEEK) implant abutments, manufactured using both subtractive and additive methods, have been introduced. Although the restorative materials could play an important role in the mechanical behavior of implant-supported prostheses, relevant in vitro studies are lacking.

Purpose: The purpose of this in vitro study was to compare the fracture resistance and failure mode of the 1-piece custom titanium abutment and 2-piece custom zirconia and PEEK abutments (with a titanium base) according to the manufacturing techniques (subtractive and additive).

Material and methods: A maxillary central incisor was simulated for this study. A total of 50 custom abutments were prepared using 3 different abutment materials (titanium, zirconia, and PEEK) and 2 different manufacturing techniques (subtractive and additive) divided into 5 different groups: Group C; control group, premilled titanium abutment, Group SZ; subtractively manufactured zirconia, Group AZ; additively manufactured zirconia, Group SP; subtractively manufactured PEEK, and Group AP; additively manufactured PEEK. Adhesive resin cement was used to cement the custom abutment to the ti-base and cobalt chromium crown to the custom abutment. The specimens were exposed to thermomechanical aging according to the ISO standard 14801. A static force was then applied with a crosshead speed of 1 mm/minute. Failure mode of the specimens was recorded. The fracture resistance values were analyzed with the Kruskal Wallis test, and multiple comparisons were made with the Dunn test (α=.05).

Results: The following average fracture resistance values were found (fracture load [N]/bending moment [Ncm]): Group C (711/523), group SP (504/381), group SZ (460/347), group AZ (362/273), and group AP (199/150). The fracture resistance values of the C group were significantly higher than those of the AZ and AP groups (P<.05) and those of the AP group were significantly lower than those of the SP and SZ groups (P<.05). Screw fracture was the predominant cause of failure in all test groups except the AP group, in which abutment fracture without complete separation was observed.

Conclusions: The C group was the most mechanically durable. The SZ, SP, and AZ custom abutments had the potential to withstand the physiological occlusal forces that occur in the anterior region, whereas that of AP did not meet the occlusal forces.