Time reversed elastic nonlinearity diagnostic applied to mock osseointegration monitoring applying two experimental models

Abstract

This study broadens vibration-like techniques developed for osseointegration monitoring to the nonlinear field. The time reversed elastic nonlinearity diagnostic is applied to two mock models. The first one consists of tightening a dental implant at different torques in a mock cortical bone; the second one allows one to follow glue curing at the interface between a dental implant and a mock jaw. Energy is focused near the implant interface using the time reversal technique. Two nonlinear procedures termed pulse inversion and the scaling subtraction method, already used successfully in other fields such as contrast agents and material characterization, are employed. These two procedures are compared for both models. The results suggest that nonlinear elasticity can provide new information regarding the interface, complementary to the linear wave velocity and attenuation. The curing experiment exhibits an overall low nonlinear level due to the fact that the glue significantly damps elastic nonlinearity at the interface. In contrast, the torque experiment shows strong nonlinearities at the focus time. Consequently, a parallel analysis of these models, both only partially reflecting a real case, enables one to envisage future in vivo experiments.

Nonlinear ultrasound: Potential of the cross-correlation method for osseointegration monitoring

“…3,6 A nonlinear resonant method, 6 performed on a model made of two weakly damped materials, confirmed the greater sensitivity of the nonlinear response to the contact quality and demonstrated that a broad frequency band is useful to increase the sensitivity range. A more realistic interface composed of a dental implant and a bone phantom was then studied.…”

“…2 Among these measurements and as detailed in Ref. 3, nonlinear elasticity could be of interest in providing information regarding contact integrity because the nonlinearity likely comes from frictional effects and/or clapping sources. Several groups have attempted measurement of nonlinear parameters at an interface bone/hip prosthesis.…”

“…A more realistic interface composed of a dental implant and a bone phantom was then studied. 3 Despite less favorable conditions to the presence of nonlinearity (strong attenuation and greater difference in elasticity between both materials in a) Author to whom correspondence should be addressed. contact), a focusing technique based on time reversal provided the means for the extraction of a nonlinear parameter sensitive to the implant stability.…”

“…contact), a focusing technique based on time reversal provided the means for the extraction of a nonlinear parameter sensitive to the implant stability. Nevertheless, there existed drawbacks regarding this study, 3 such as the manner of mimicking the osseointegration or the fact that the focusing technique requires substantial equipment.…”

“…This manner of monitoring allows one to change only the normal stress at the interface during the tightening. It is thus more realistic than a screw/plate-based system, 3 which induces a unwanted vertical change between both materials due to the helicoid motion. Results are averaged over three procedures, while removing of the implant between each procedure.…”