The Effect of Clinical Loading on Bone Regenerated by GTAM Barriers: A Study in Dogs

Regenerated bone around implants promoted by an e-PTFE barrier membrane technique was tested to evaluate its capacity to withstand loading. Twenty-four implants were placed into fresh extraction sockets with buccal dehiscences in four dogs. Twelve sites were augmented with barrier membranes. Histologic evaluation of 3-month-postoperative biopsies taken from two dogs showed significantly more bone formation for the augmented sites than for the nonaugmented implants (P .02). The augmented sites in the remaining two dogs demonstrated complete bone fill of the original defects. After 6 months of prosthetic loading, histologic evaluation of four augmented sites showed a decrease in bone fill from that at 3 months postoperative. Premature loading of immature bone was believed to be the primary reason for the bone loss. The remaining two implants in the augmented and non-augmented groups served as unloaded controls. After 6 months of further healing, the augmented but unloaded group demonstrated complete bone fill, with more mature bone quality than the 3-month histologic specimens. For the nonaugmented sites, no new bone formation occurred between the 3- and 9-month healing periods. The results from this study indicate that bone augmentation with barrier membranes should be allowed extended healing periods prior to loading. The precise time for loading of newly regenerated bone with e-PTFE membranes has not been determined. Keywords: bone regeneration, dogs, e-PTFE, loading, membranes, titanium implants