Microleakage of bacteria in different implant-abutment assemblies: an in vitro study

The aim of the present in vitro study was to evaluate the leakage observed for 2 different microbial species at the level of the implant–abutment (I-A) interface, and the marginal fit and size of microgap at the I-A interface in 2 different implant connections.

Ten specimens of each group were tested. The inner parts of 5 implants per group were inoculated with 0.1 μL of a viable Enterococcus faecalis suspension and 5 implants per group with Aggregatibacter actinomycetemcomitans. All of the vials containing the control specimens were incubated at 37°C under aerobic condition for E. faecalis and 37°C in presence of 5% CO₂ for A. actinomycetemcomitans. They were maintained for 14 days, and the possible penetration of bacterial suspension into the surrounding solution was determined by the observation of turbidity of the broth. The I-A interface was evaluated for size of microgap and measured under SEM. Five implants of each group were evaluated. The marginal fit between implant and abutment was measured at 8 random locations in each assembly, under different magnifications at the interface.

No leakages through the I-A interface were demonstrated for either type of connection evaluated. The microgap values of all I-A interfaces ranged from 0.008 to 2.009 μm; the differences between the 2 systems were statistically significant.

The present study demonstrated that a good marginal fit of implant components seemed to be able to prevent bacterial leakage.