Effect of Implant Design on Fracture Resistance, Mode, and Crystal Structure of One- and Two-Piece Zirconia Implants With Ceramic or Titanium Abutment Screws: An In Vitro Study.

OBJECTIVES

To evaluate the fracture resistance, fracture modes, and crystalline phase changes of zirconia one-piece implants (OPI) and bone-level (BLTPI) or tissue-level, two-piece implants (TLTPI), with ceramic (C) or titanium (T) abutment screws after dynamic preloading in a moist environment.

MATERIALS AND

METHODS

Dynamic preloading under moist conditions and subsequent static load-to-fracture testing were performed to evaluate fracture resistance and fracture mode. Scanning electron microscopy (SEM) analysis of fracture surfaces was employed to supplement the observations of macroscopic fracture modes. Crystalline phase changes were assessed using micro-Raman spectroscopy. Specimen preparations were performed in accordance with ISO 14801:2016. Five different ceramic (zirconia) implant designs were divided into the following groups: OPI, BLTPI (BLC, BLT), TLTPI (TLC, TLT). One-way and two-way ANOVA tests were used for comparisons and factor effect analysis.

RESULTS

Fracture resistance (N) and bending moment (N cm) differed significantly among the implant groups (p < 0.001), following the order TLTPI (775.2 ± 71 N) > OPI (605.7 ± 37 N) > BLTPI (498.3 ± 93 N). Within the two-piece implants (TPI), tissue-level designs (TL) outperformed bone-level designs (BL), while designs with different abutment screw materials showed no significant difference (p = 0.982).

CONCLUSIONS

Within the limitations of this in vitro study, the evaluated zirconia-based OPI, BLTPI, and TLTPI systems demonstrate sufficient fracture resistance to support further clinical investigation. Implant-level design (TL vs. BL) influences mechanical performance, whereas the influence of abutment screw material (ceramic vs. titanium) is less pronounced and varies according to the implant-level design.