Healing of autogenous bone and e-PTFE membranes. Fluorochrome labeling study

Objective:was to verify the differences in new bone formation and bone block substitution dynamics between autogenous bone block (B) and autogenous bone block covered with e-PTFE membrane (MB). Methods:Thirty male “wistar” rats were used. After surgery every animal received: 5mg/Kg of calcein (Ca) zero hour, 60 mg/Kg of xylenol orange (XO) after 14 days and 10 mg/Kg of tetracycline (T) after 28 days. A second flurochrome injection was applied eight hours following the first one. Animals were sacrificed at zero hour, 7, 14, 21 and 45 days after surgery. Specimens were not demineralized and histologic processing was done by the cutting and grinding technique. Results: bone labeling with calcein could be seen after seven days, in groups B and MB. Fourteen days following surgery calcein labeling was shown at the surface periphery of the bone block and at the bone bed surface. Vascular channels present inside the bone block have also shown bone mineral deposition. After 21 days differences between groups B and MB could be observed. Xylenol orange labeling was noted at the newly formed bone bridging the bed and the bone block and at the periphery of the bone block, under the membrane. Group B also showed marked XO labeling between the bone block and the receptor bed however, bone resorption was noted at the borders of the bone block. After 45 days, tetracycline labeling could be depicted between the membrane and the bone block, at the MB group, indicating that a continuous mineral deposition was taking place. No tetracycline labeling could be detected at the B group. Conclusion:coverage of the bone block with an e-PTFE membrane allows continued bone formation in addition to the original area of the bone block, after 21 days. FAPESP Grant n° #99/04367-7.