Retrospective comparison of posterior fixed dental prostheses supported by two different titanium abutments on tissue level implants

Statement of problem: Clinical studies comparing compatible computer-aided design and computer-aided manufacturing (CAD-CAM) titanium abutments (CAs) and original prefabricated 1-piece titanium abutments (PAs) for posterior fixed dental prostheses (FDPs) on Straumann Tissue Level (STL) implants are sparse.

Purpose: The purpose of this retrospective clinical study was to compare the performance of posterior FDPs supported by CAs and PAs on STL implants after a mean observation period of 7.2 years.

Material and methods: Patients who received STL implants and posterior FDPs by using CAs or PAs between January 2002 and December 2012 and returned for follow-up between January 2017 and September 2018 were included in this study. Technical and biological complications of FDPs were examined and recorded. Radiographs were used for the measurement of marginal bone loss (MBL) of each implant. Variables, complication rates, and MBL of the 2 groups were analyzed by using a generalized estimating equation and multivariable linear mixed model.

Results: Ninety-nine patients with 195 implants in the CA group and 75 patients with 143 implants in the PA group were included. The mean functional time of FDPs was 6.5 ±1.1 years for the CA group and 8.1 ±2.6 years for the PA group. No implant failure was noted in either group. The technical complication rate was 20.8% in the CA group and 26.3% in the PA group. Abutment screw loosening (ASL) was noted in the CA group (8.5%). The decementation rate was significantly higher in the PA group (14.1%) than that in the CA group (3.1%) (adjusted odds ratio=4.40, confidence interval=1.41 to 13.69, P=.011). No significant differences were found between the 2 groups in terms of the rates of ceramic chipping, peri-implantitis, peri-implant mucositis, or mean MBL.

Conclusions: Using CAs or PAs to support posterior FDPs on STL implants has no significant effect on the incidence rate of biological complications. However, a higher ASL rate and a lower decementation rate were noted with CAs than with PAs.