Osseointegration of Titanium Implants in Bone Regenerated in Membrane-Protected Defects: A Histologic Study in the Canine Mandible

In the present histologic study of the mandibles of five foxhounds, 15 nonsubmerged titanium implants were placed in bone regenerated in extended membrane-protected defects during a 6-month healing period. The clinical and radiographic evaluation demonstrated that all 15 implants achieved functional ankylosis within 3 months following implant placement. Subsequently, eight implants were restored with fixed partial dentures and were functionally loaded for 6 months, and seven implants were left unrestored. At the completion of the study, the histologic analysis demonstrated osseointegration with direct bone-to-implant contact for all 15 implants. Therefore, it can be concluded that bone regenerated in membrane-protected defects responds to implant placement like nonregenerated bone, and that this bone is capable of bearing and sustaining functional load. The histologic comparison of restored and unrestored sites demonstrated no apparent differences concerning bone remodeling activities. Furthermore, control sites without implant placement demonstrated bone atrophy underneath the membranes with a thin cortical layer and sparse bone trabeculae. Thus, it can also be concluded that the placement of an implant into regenerated bone stimulated bone maturation and bone remodeling, whereas implant loading did not influence bone remodeling in the present study model. Keywords: bone defects, bone healing, dental implants, guided bone regeneration, membranes, occlusal load, osseointegration