Guided bone regeneration using demineralized laminar bone sheets versus GTAM membranes in the treatment of implant-associated defects. A clinical and histological study.

This study was designed to compare the regenerative potential at dehisced implant sites of the resorbable demineralized laminar bone sheets and non resorbable GTAM membranes. Twenty-six standard screw-type fixtures showing buccal dehiscences in 7 patients were treated using the GBR principles and received either laminar bone sheets (experimental) or GTAM (control) membranes. Twelve experimental and 10 control sites were available for evaluation at second stage surgery carried out 8 months following implant placement. Height and maximum width of the dehiscence defects were measured at the time of implant insertion and at second-stage procedure. Mean percentage of defect fill was 75.17% in the experimental dehiscences versus 86.70% in the control defects. A statistically significant difference in the percentage of defect fill could not be evidenced between the two treatment modalities. Complete fill was observed in 25% of the experimental versus 70% of the control sites. A significant difference was found in the median Density Index with the GTAM group showing a consistency similar to bone in a larger number of sites. Histologically, material with the same staining features of bone was evidenced inside the GTAM membranes in 3 cases while newly-formed bone was present in all instances under the control GTAM barriers. In the laminar bone-treated sites, the membrane maintained its integrity in almost all cases. Newly formed bone was found underlying the membrane in cases with a Density Index of 5 with no evidence of bony tissue adhering to the laminar sheets.