Examination of the Bone-Implant Interface in Experimentally Induced Osteoporotic Bone

Implant use has gained wide popularity for treatment of partially and fully edentulous patients. However clinical reports of implant use under a variety of compromised bone states are mixed. OBJECTIVE: The objective of this study was to explore the hypothesis that osteoporotic-like (OP) conditions have a negative effect on osseointegration (OI). METHODS: Using an ovariectomized (OVX) rat model the extent of OI using histological and histomorphometric analysis (HMA) under a variety of OVX conditions was assessed. Five experimental groups (n=10 rats per group) were used: (1) OP control; (2) OI control; (3) OI followed by OVX treatment to induce OP (OI-OP); (4) OP induction followed by OI (OP-OI) ; and (5) OP induction simultaneously with OI (OI=OP). Using undecalcified plastic embedded cross sections of the implant site, HMA was performed to determine the percent of bone contact (BC) at the implant-tissue interface and percent of bone area (BA) immediately (3mm diameter) surrounding the implant site. RESULTS: The implant control resulted in the highest level of OI (BC= 79%; BA=87%), while all groups in which OVX was performed resulted in a reduction in BA (BA=70-75%). High levels of BC were observed in established OP conditions (OP-OI; BC=79%); however, following OI, induction of OP conditions (OI-OP) led to a significant reduction in BC (50%). In each of the OP tx groups, a diminution of cortical bone and increased trabecularization of the host bone site was observed. CONCLUSIONS: The results of this work indicate that while OI is possible under a variety of OP-like conditions simulating implant placement, the long-term biomechanical stability of implants under these conditions is not known. Further efforts to understand implant use in the complex boney environment under OP like conditions is encouraged. Supported by UI Dental Research Award (MR, PC), P30-DE10126-09 (GBS, JCK) and P60-DE 13076-04 (JCK,GBS).