Use of highly nonlinear solitary waves for the assessment of dental implants

Abstract

This paper presents a noninvasive technique based on the propagation of highly nonlinear solitary waves (HNSWs) to monitor the stability of dental implants. HNSWs are mechanical waves that can form and travel in highly nonlinear systems, such as one-dimensional chains of contacting spherical particles (i.e., granular crystals). In this study, a granular crystal-based actuator/sensor, designed and built at the University of Pittsburgh, was used to introduce HNSWs into dummy implants that were inserted into either hardened plaster or treated beef bones. The waves reflected at the interface between the particle and implant were monitored to estimate the change in stiffness of the material. The hydration of the plaster was monitored because it can be considered largely similar to the osseointegration process that occurs in the oral connective tissue once a dental-endosteal threaded implant is surgically inserted. In the experiment using bone, the implant-bone system was immersed in an acid bath causing decalcification of the bone and, therefore, reduced stiffness of the bone itself, simulating the inverse of osseointegration. Positive correlations were found, in both experiments, between certain properties of the HNSWs and the stiffness of the test object, demonstrating that HNSWs show promise for use in assessment of dental implants.