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 floorelevation on both sides of the upper jaw. A perforation of 5 9 4 mm in dimension of the sinusmucosa was performed on both sides and, at a randomly selected test site, a collagen membranewas 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 membranemade of polylactic acid and a citric acid ester acetyl. The sacrifices were performed after 2, 4, and12 weeks of healing.Results: After 2 weeks of healing, the augmented volume was filled with biomaterial surroundedby connective tissue and minimal new bone was detected. After 4 weeks of healing, new bone wasfound mainly in connection with the sinus bony walls with percentages of 18.0 12.9% at the testand 12.3 7.9% at the control sites. After 12 weeks of healing, similar amounts of newly formedbone 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 thesinus cavity. The newly formed bone was distributed more evenly within the sinus cavity alsoincluding the central areas. The differences between test and control sites did not reach statisticalsignificance.Conclusion: Even though there were trends for more bone formation when applying a collagenmembrane on a sinus mucosal perforation of relatively small dimensions, this study failed toestablish the absolute necessity of such a procedure to achieve bone fill in the sinus cavity