Measurement of gap between abutment and fixture in dental conical connection implants. A focused ion beam SEM observation

Background: The aim of the authors was to examine the abutment-fixture interface in Morse-type conical implants in order to verify gaps at this level using a new microscopical approach.Material and Methods: In this in vitro study, 20 abutment-fixture complexes were prepared by sectioning (longitudinal and cross-sectional to the long axis) with a microtome and then with a focused ion beam (FIB). This is amicrometric machine tool that uses gallium ions to abrade circumscribed areas to dig deeper into the cuts obtainedwith the microtome in order to eliminate cut-induced artifacts. This is because the FIB abrasion is practically freefrom artifacts, which are normally generated by the action of the microtome blades or other techniques. Sampleswere then observed by scanning electron microscopy (SEM).Results: The observation of the abraded parts with the FIB permitted measurement of the real gap between theimplant-abutment components. A variable amount of gap was retrieved (from 0 to 3 μm) by the observations,confirming the non-hermetic nature of the connection. It has to be pointed out that in approximately 65% of cases,the gap accounted for less than 1 μm.Conclusions: The reported data confirmed that the analyzed connection system allowed for minimal gap. However, from the evidence of the present analysis, it cannot be assumed that the 2 parts of a Morse-type conical implantare fused in 1 piece, which would create a perfectly matched hermetic connection.