Pulsed oscillation technique for assessing the mechanical state of the dental implant-bone interface

The sensitivity of a vibrational test for in vivo assessing the interfacial rigidity of a biocompatible dental root implant was studied using models. Aluminium alloy rods of 4 mm diameter and 7 mm long were root implant models. Cyanoacrylate and epoxy adhesives were hard interface models. Soft interfaces were modelled in a soft silicone adhesive, a gel, adhesive tapes and direct loose contact. Blocks of bovine and canine jaw-bones chemically treated and dried were models of a human alveolar bone. It was found that the minimum average thickness of a soft interface layer distinguishable from a hard interface depends on load directions and positions and ranges from 0 to 160 microns. The sensitivity was rather low in the direction for which a normal load was applied to the bone, reflecting a mechanical difference of the surrounding bone and/or the interface. Therefore, it is desirable that the assessment by the vibrational test is done in the direction, too, for which a shearing load is applied to the interface.