An analytical model to measure dental implant stability with the Advanced System for Implant Stability Testing (ASIST)

A non-invasive method of quantitatively assessing dental implant stability is important to monitor its long-term health. The Advanced System for Implant Stability Testing (ASIST) is a noninvasive technique that couples the impact technique with a linear vibration model of the implant system, such that the measured signal can be used to determine a matching analytical response. The purpose of this study was to evaluate the ASIST technique by comparing stability estimates obtained from artificial implant installations with various abutments. Two Straumann dental implants were installed in four densities of uniform polyurethane foam, and the stability of each installation was measured using different healing abutments and artificial dental crowns. With the ASIST, values for the estimated interfacial stiffness increased with foam density and did not significantly change with abutment type for a specific sample. This provides evidence that the analytical model is representative of the physical system. Current methods, such as resonance frequency analysis, interpret the interface stiffness based on a single frequency measurement. With the ASIST, the measured signal provides information about the first and second modes of vibration of the implant system, both of which are influenced by the properties of the corresponding abutment. The consideration of both modes allows the technique to reliably measure the interfacial stiffness independently of the system components. As a result, the ASIST technique may provide an improved non-invasive method of measuring the stability of dental implants.