In vitro ultrasonic assessment of the biomechanical quality of the interface surrounding a dental implant

Abstract

Dental implants are widely used clinically and have allowed considerable progresses in oral and maxillofacial surgery. However, implant failures, which may have dramatic consequences, still occur and remain difficult to anticipate. Accurate measurements of implants biomechanical stability are of interest since they could be used to improve the surgical strategy by adapting the choice of the healing period to each patient. Empirical methods based on palpation are still used by dental surgeons to determine when the implant should be loaded because it remains difficult to monitor bone healing in vivo. The objective of this study is to investigate the potentiality of a quantitative ultrasound method to assess the biomechanical stability of a dental implant in vitro. A 10. MHz contact transducer is located at the implant extremity. For each ultrasound measurement, a quantitative indicator I is derived based on the time variation of the amplitude of the rf signal. Ten implants are initially completely inserted in the proximal part of a bovine humeral bone sample. The 10. MHz ultrasonic response of the implants is then measured and an indicator I is derived based on the amplitude of the rf signal obtained. Then, the implants are unscrewed by 2π radians and the measurement is realized again. The procedure is repeated and the indicator I is derived after each rotation of the implants. Analysis of variance (ANOVA) (p<10<sup>-5) tests revealed a significant effect of the amount of bone in contact with the implant on the distribution of the values of I. The results show the feasibility of QUS techniques to assess implant primary stability in vitro. This study paves the way for the development of a new biomechanical approach in oral implantology.