Radial Implant-Abutment Gap Determination Through Serial-Sectioning Method

Significant attention has been devoted by the implantology and bioengineering research community regarding the implant-abutment gap, once such gap may provide a favorable environment for bacterial adhesion/proliferation and to degradation of the metallic substrate. Classically, this distance has been evaluated by means of scanning electron microscopy (SEM) along the implant perimeter and no information is revealed as a function of radius. Objective: The purpose of this study was to evaluate the implant-abutment gap as a function of radius by means of optical microscopy evaluation through a sequential sectioning technique. Methods: Six implants (3.75 mm in diameter) and abutments were screw connected and torqued to 20 N.cm. Outer radius measurements were recorded by SEM. The implants were then mounted in epoxy resin using a metallic fixture was to assure implant position (perpendicular to the vertical axis). Subsequently, each implant was abraded and polished parallel to its long axis at six different distance intervals. Implant-abutment gaps were obtained by optical microscopy (1000X mag.) and these distances were related to its radial position through trigonometric inferences. A 6th degree polynomial best line fit approach was used to determine the radial adaptation patterns for each of the implants. Results: The results showed that gap distances were not statistically different among the implants (P=0.05). The polynomial best line fit approach revealed that the implant-abutment gap distance increases as a function of implant radius and this increase is more pronounced in the outer ¼ radius, at the abutment beveled region. Also, communication between external and internal regions of the implant were found for all specimens. Conclusions: Based on these results, it was concluded that this methodology provided a broader scenario of the implant-abutment gap distance and that SEM evaluations may underestimate the gap value.