Comparative Evaluation of Microleakage at the Interface of Titanium and Zirconium Abutments Following Oblique Cyclic Loading: An in vitro Study

Abstract Background and aim: Oral microbiota could proliferate the microspace between the implant and abutment, thereby cause inflammation in the peri-implant tissues and adjacent bone. This study aimed to investigate the effect of two types of abutments (zirconia and titanium) on microleakage at implant-abutment interface area under oblique cyclic loading in vitro. Materials and methods:In this in vitro study, 12 implant-abutment assemblies were used, each containing six sets with either zirconia or titanium abutments and vertically mounted in the modified resin blocks of auto-polymerized polyester base. The specimens were then subjected to oblique cyclic loading of 75 N at a 30 ± 2 degrees angle to the longitudinal axis of the implant with a frequency of 1 Hz in 500,000 cycles, equivalent to 20 months of human mastication. To determine the penetration of fuchsine into the implant-abutment interface, the implants were cut by cutting machine from the middle. Then, the rate of penetration of fuchsine in each sample was measured by a stereomicroscope with a magnification of 75 × at three points of each semicircle, and the average of these six points was recorded as a microleakage. For comparison of the microleakage after loading, t test was used. All tests were performed in SPSS ver.22 software and a significant level of 0.05 was considered. Results: The amount of microleakage after oblique cyclic loadingwas statistically significantly higher in the zirconia abutments (66.08±11.66) compared to the titanium abutments (39.17±10.65)following force application (P = 0.002). Conclusion: The microleakage following oblique cyclic loading is different depending on the type of abutment, so that the titanium abutments showed significantly less microleakage than the zirconia abutments.