Different types of bioresorbable and non-resorbable membranes have been widely used for guided tissue regeneration (GTR). An alternative could be the use of silk-membranes (Fig. 1) which exhibit several advantages. During manufacturing individual modifications are possible, no infection risks are associated with their implantation and the mechanical characteristics are excellent.^1-9 In this study we examined the binding of hydroxyapatite (HA) and beta-tricalcium phosphate (ß-TCP) to silk-membranes and evaluated the effects on cell proliferation in vitro and effects on facilitating bone formation and defect repair during guided bone regeneration.

Materials and methods

Two calvarian bone defects of 12 mm (Fig. 2) in diameter were created in each of a total of 38 rabbits and four different types of membranes, (silk-, hydroxyapatite-modified silk-, β-TCP-modified silk- and conventional collagen) were implanted to cover one of the two defects in each animal. Hematology, body weight and general health were monitored throughout the ten weeks of the study period which were all within the normal range for all animals and histologic analysis did not show any adverse reactions in any of the defect sites, demonstrating good biocompatibility of all silk protein membranes.

Results

After ten weeks, the collagen membrane was resorbed in all cases, while the silk membrane was still visible in 1/5 (20 %) and the hydroxyapatite-silk membrane in 4/5 (80 %) cases in the micro-CT scans. β-TCP-modified silk membranes remained visible in all cases. Histomorphometric evaluation revealed significantly higher (p = 0.002) new bone ingrowth into defects covered with β-TCP modified silk membranes compared to new bone ingrowth into defects without any barrier membrane cover. The highest rate of new bone ingrowth was observed in defects protected with β-TCP silk membranes (Fig. 3 and 4).⁹