Differences in micromorphology of the implant-abutment junction for original and third-party abutments on a representative dental implant

Statement of problem. Evidence for micromorphology and precision of fit of third-party prosthetic components compared with the original manufacturer's components is lacking. Purpose. The purpose of this in vitro pilot study was to evaluate the micromorphological differences among different commercial brands of zirconia, titanium, and gold abutments for dental implants in terms of tight surface contact. Materials and method. The following abutments (n=3 per type) were preloaded on Straumann Bone Level implants according to the manufacturer's instructions for zirconia (Zr, Zr2, Zr3), titanium (Ti and Ti2), and gold (Gold 1, Gold 2). The micromorphology of the implant-abutment units was investigated by using scanning electron microscopy (original magnification x10 to x500) after microtome sectioning. After we calibrated, the length of the areas with tight contact (TC) (discrepancy <= 3 mu m) was calculated at the level of conical connection (CC), lower internal connection (LIC), and screw threads (STs). The interexaminer agreement was assessed by using intraclass correlation coefficient(s) (ICC). One-way ANOVA was used for the overall comparison of the Zr groups, and the Student paired t test was used for pairwise comparisons of the abutments of the same group. After we adjusted for multiple comparisons, the significance level for the overall and pairwise comparisons of Ti and Gold groups was set at a P value of .008 and a P value of .003 for the Zr groups. Results. Major differences were found among the different abutment types in terms of design and extent of surface contact. The TC showed significant differences among the abutments of Zr group, depending on the side and level of evaluation (Zr1 > Zr2 > Zr3 on the left side for CC; Zr1, Zr2 > Zr3 on the right side for CC, and, Zr2 > Zr3 on the right side for LIC; P<.003). In Ti group, no significant differences were found (P>.008). The Gold and Gold 2 groups had significantly greater contact on the left side of CC (P<.008). Conclusion. A difference in design of the abutments was apparent. The tight surface contact was significantly different among the examined abutments or abutment screws and the respective area of the inner surface of the implants.