Sinus floor elevation outcomes following perforation of the Schneiderian membrane. An experimental study in sheep

Objective: To assess the influence of a collagen membrane covering a perforation of the sinus (Schneiderian) membrane on the outcome (bone fill) of a sinus floor elevation. Materials and Methods: Eighteen Pelibuey sheep were used. The animals underwent sinus floor elevation on both sides of the upper jaw. A perforation of 5 9 4 mm in dimension of the sinus mucosa was performed on both sides and, at a randomly selected test site, a collagen membrane was placed to cover the perforation. A graft of biphasic calcium phosphate (60% HA/40% betaTCP) was subsequently placed bilaterally, and the access window was closed with a membrane made of polylactic acid and a citric acid ester acetyl. The sacrifices were performed after 2, 4, and 12 weeks of healing. Results: After 2 weeks of healing, the augmented volume was filled with biomaterial surrounded by connective tissue and minimal new bone was detected. After 4 weeks of healing, new bone was found mainly in connection with the sinus bony walls with percentages of 18.0 12.9% at the test and 12.3 7.9% at the control sites. After 12 weeks of healing, similar amounts of newly formed bone were found compared to the previous healing period, namely 16.7 8.0% and 13.7 10.1% at the test and control sites, respectively, with the highest amount detected in the bottom of the sinus cavity. The newly formed bone was distributed more evenly within the sinus cavity also including the central areas. The differences between test and control sites did not reach statistical significance. Conclusion: Even though there were trends for more bone formation when applying a collagen membrane on a sinus mucosal perforation of relatively small dimensions, this study failed to establish the absolute necessity of such a procedure to achieve bone fill in the sinus cavity