An Ex Vivo Model in Human Femoral Heads for Histopathological Study and Resonance Frequency Analysis of Dental Implant Primary Stability

OBJECTIVE This study was designed to explore relationships of resonance frequency analysis (RFA)-assessed implant stability (ISQ values) with bone morphometric parameters and bone quality in an ex vivo model of dental implants placed in human femoral heads and to evaluate the usefulness of this model for dental implant studies. MATERIAL AND METHODS This ex vivo study included femoral heads from 17 patients undergoing surgery for femoral neck fracture due to osteoporosis (OP) (n = 7) or for total prosthesis joint replacement due to severe hip osteoarthrosis (OA) (n = 10). Sixty 4.5 × 13 mm Dentsply Astra implants were placed, followed by RFA. CD44 immunohistochemical analysis for osteocytes was also carried out. RESULTS As expected, the analysis yielded significant effects of femoral head type (OA versus OA) (P < 0.001), but not of the implants (P = 0.455) or of the interaction of the two factors (P = 0.848). Bonferroni post hoc comparisons showed a lower mean ISQ for implants in decalcified (50.33 ± 2.92) heads than in fresh (66.93 ± 1.10) or fixated (70.77 ± 1.32) heads (both P < 0.001). The ISQ score (fresh) was significantly higher for those in OA (73.52 ± 1.92) versus OP (67.13 ± 1.09) heads. However, mixed linear analysis showed no significant association between ISQ scores and morphologic or histomorphometric results (P > 0.5 in all cases), and no significant differences in ISQ values were found as a function of the length or area of the cortical layer (both P > 0.08). CONCLUSION Although RFA-determined ISQ values are not correlated with morphometric parameters, they can discriminate bone quality (OP versus OA). This ex vivo model is useful for dental implant studies.