Evaluation of the Effect of Zirconia and Titanium Abutments on Microleakage of Implant- Abutment Interface Under Oblique Cyclic Loading In Vitro

Oral bacteria can proliferate in the implant-abutment interface (IAI) and cause inflammation in the peri-implant tissues and adjacent bone. This study aimed to assess the effect of zirconia and titanium abutments on the microleakage of the IAI under oblique cyclic loading conditions. Materials and Methods: In this in-vitro study, 12 implant-abutment assemblies with zirconia and titanium abutments, in two groups of six, were vertically mounted inside resin blocks modified with autopolymerizing polyester base. The specimens were subjected to 75N oblique cyclic loading at an angle of 30±2° to the longitudinal axis of the implant at a frequency of 1 Hz at 500,000 cycles, which is equivalent to 20 months of human masticatory force. Fuchsine solution was used to evaluate the microleakage. To examine the penetration of fuchsine into the IAI, the fixtures were cut from the middle using a cutting machine. Then, the amount of fuchsine penetration in each of the samples was measured with a stereomicroscope at ×75 magnification at three points in each semicircle (cut implant), and the average of these six points was recorded as microleakage (μm). T-test was used to compare the microleakage after load with the significance level set at 0.05. Result: The microleakage rate after cyclic loading was 66.08±11.66 μm in zirconia abutments and 39.17±10.65 μm in titanium abutments, which was significantly higher with zirconia abutments (P=0.002). Conclusion:Microleakage after oblique cyclic loading varies depending on the type of abutment. Titanium abutments showed significantly less microleakage than zirconia abutments.