Bacterial colonization of the fixture-abutment interface (FAI) microgap may contribute to increased marginal bone loss. The contribution of loading on bacterial colonization has not been thoroughly evaluated with in vitro experiments. The aim of this study was to evaluate the effect of dynamic loading on the colonization of oral microorganisms in the FAI microgap of dental implants with internal Morse-taper connection. Forty implants were divided into two groups (n = 20/group) based on subjection to dynamic loading conditions. Both Group 1 and 2 were comprised of fixtures that connected to standard abutments and allowed to incubate in a bacterial solution of Escherichia coli . The specimens of Group 2 were loaded with 500 000 cycles of 50 N using a chewing simulator. Following disconnection of fixtures and abutments, microbial samples were taken from the threaded portion of the abutment, plated and cultured under appropriate conditions. One of the 20 implants of Group 1 and 4 of the 20 implants of Group 2 had FAI microgaps colonized by E coli . With the limits of this study, it indicates that implants with internal Morse-taper connection exhibited minimal bacterial penetration down to the threaded part of the FAI and that dynamic loading increases the potential for such bacterial penetration.
Keywords: bacterial counts; bacterial leakage; dental implants; in vitro; titanium.