A Pilot Animal Study Aimed at Assessing the Mechanical Quality of Regenerated Alveolar Bone

Purpose: Bone regeneration procedures are often evaluated based on biologic aspects only. As regenerated bone also has to ensure primary implant stability, the goal of this study was to determine the mechanical quality of regenerated bone. Materials and Methods: Six adult minipigs were allocated for this experiment with four mandibular study sites each established following tooth removal. Two different types of bovine bone mineral as well as autogenous bone were used for augmenting three-walled defects, while native bone served as the control. Implants were placed after 12, 18, and 24 weeks of healing, and bone quality was determined using intraoperative compressive testing (BoneProbe), insertion torque measurements, and resonance frequency analysis. The mandibles were then harvested for determining bone mineral density (BMD) and bone-to-implant contact (BIC). Statistical analysis was based on two-way analysis of variance of aligned rank transformed data and Spearman's rank correlation tests (α = .05). Results: The effects of the factors healing time and material on the parameters tested were too small to be significant (P ranging from .34 to .98). Weak correlations were observed for implant insertion torque with BoneProbe measurements in the cortical (0.481; P = .032) and in the trabecular area (0.639; P = .002). BoneProbe measurements in the trabecular part and in the cortical part also correlated with each other (0.477; P = .035). Conclusion: While differences may exist between bone regenerated using different biomaterials with respect to biologic behavior, differences in the mechanical properties determining primary implant stability seem to be minor. Implant insertion torque measurements appear to be a reliable tool for determining bone quality if only one specific implant type is considered. Keywords: bone augmentation, bone mineral density, bone-to-implant contact, compressive testing, mechanical bone quality