Dental implantation:: Ultrasound transmission velocity to evaluate critical bone quality -: An animal model

Purpose: In dental implantology, preoperative evaluation of bone quality is an important aspect for the long-term success of the treatment. The insertion of implants into regions with a great portion of poorly mineralised cancellous bone, in particular, increases the risk of subsequent implant failure. The measurement of Ultrasound Transmission Velocity (UTV) proved to be a noninvasive and valid method for the assessment of mechanical properties of bone. The aim of this study was to correlate conventional histomorphometric bone properties with UTV-values from mandibular and iliac crest bone specimens in an animal model. Materials and Methods: 12 native (no sample preparation) porcine specimens from mandibular bone and 14 from iliac crest bone, respectively, were studied both by UTV measurement and by conventional histomorphometry. UTV-values were measured bicortically by three different investigators four times at each site. Bone samples from identical sites were obtained and ground down to a thickness of approx. 50 mu m. Transmission light microscopy was used to assess the overall percentage of mineralised bone. Mineral bone density less than 40% was defined as critical. Results: The median bone density was 43% for mandibular bone and 23% for iliac crest bone, respectively. The median UTV values of the mandible (1756 m/sec) were significantly higher than those of the iliac crest specimens (1613 m/sec). Intra-individual correlation testing illustrates a positive, statistically significant correlation between presurgical UTV measurement and the grade of mineralisation (r = 0.54). ROC analysis defined a UTV breakpoint of 1767 m/sec to identify critical bone with a sensitivity of 75 %. Conclusion: In this ex-vivo model, UTV measurements have proven to be a reliable method for identifying critical bone quality prior to implantation.