Association between implant abutment microgap and implant circularity to bacterial leakage – an in vitro study using tapered connection implants.

Background: The presence of gaps at the implant‐abutment interface (IAI) favors accumulation of bacterial biofilm, which may result in inflammation of the peri‐implant tissues. Bacterial biofilm accumulation at the IAI may lead to deleterious inflammation within the surrounding tissues, adversely affecting treatment outcome and interfering with long‐term esthetics and function. Therefore, the risk of bacterial leakage should always be at the forefront of investigations. Aim/Hypothesis: The aim of this study was to evaluate bacterial leakage at the IAI of 4 tapered connection implant systems associating it with the microgap between implant and abutment as well as possible conformational errors of the implant platform. Material and Methods: Four brands of implants with tapered abutment connection were tested. Bacterial leakage was assessed using 0.3 µL of _I_Escherichia coli_i_ suspension inoculated into the abutment screw chamber of the implants, which were then torqued and incubated at 37°C for 14 days. All specimens used for the microbiological experiment were then cut lengthwise and the microgap measured at three points on each side of the sample using scanning electron microscopy (up to 5000×). Microtomography was used to assess implant platform circularity to validate the microscopic findings qualitatively. Results: Two samples from the Nobel Biocare system, four from the Ankylos system, four from the Neodent system and five from the Conexão system were positive for bacterial leakage, with no significant difference between groups. The Neodent system had the highest mean microgap values (5.84 ± 9.83 µm), followed by Nobel Biocare systems (5.17 ± 4.10 µm) Ankylos (3.47 ± 3.28 µm) and Conexão (2.72 ± 3.19 µm), with no significant difference between systems. All systems showed conformational errors of circularity on microtomography images. Conclusions and Clinical Implications: The tapered connection systems evaluated herein were not able to halt bacterial leakage nor were they free from conformational errors. [ABSTRACT FROM AUTHOR]