The Effect of the Injectable Bovine Collagens (Zyderm(R)) on the Repair of Critical-Size Defect in Rat Calvaria

This study was designed to examine the capacity of injectable bovine collagen(Zyderm(R)) to mediate the repair of critical size defects of rat calvaria. Thirty-six rats were randomized into six groups(n=6) and an 8-mm circular calvarial defect was made in each rat. In Group I, defects were left untreated. Defects in Groups II and III were implanted with Zyderm I(R) and Zyderm II(R), respectively. These three groups were evaluated in the 6th week after the operation. The defects in Groups IV, V, and VI received the same treatment as in Groups I, II, and III, respectively and were evaluated at postoperative 12th week. Results were examined by gross and histologic findings, simple radiographic study, and radiodensitometric analysis for bony density quantitatively. By gross and simple radiographic findings, defects with Zyderm(R) implantation showed thick coverage and focal radioopacity within defect area, but non-treated animals showed only fibrous healing. Histologically collagen pocket and woven bone were coexisted over the defect at postoperative 6th week, but the regenerating bone appeared much robust in Group III. At postoperative 12th week, there was a well-organized lamellar pattern of new bone formation, especially on the periosteal side of the defect. In the radiodensitometric analysis, all groups of Zyderm(R) implantation showed significant bony healing. There was also statistically significant difference between Group II and Group III at 6th week. Compared with Group V, however, Group VI did not show significant bony healing at 12th week. Additionally, prolonged implantation period allowed more complete healing of the defects with the same concentration of collagen. In conclusion, Zyderm(R) appeared to be an effective mediator of bone regeneration in this critical size calvarial defect model and its concentration had an effect on bone healing in the early period.

The Repair of Critical-Size Defect with Fibrin Sealant in Rat Calvaria

This study was designed to evaluate the capacity of fibrin sealant to mediate the repair of critical size defects of rat calvaria. Twenty-four rats were randomized into four groups(n=6) and an 8-mm circular calvarial defect was made in each rat. In Group I and II, as control groups, defects were left untreated and evaluated at postoperative 6th and 12th week, respectively. In Group III and IV, defects were treated with fibrin sealant implantation and evaluated at the same point of time as in Group I and II, respectively. Results were examined by gross and histologic findings, simple radiographic study, and radiodensitometric analysis for bony density quantitatively. By gross and simple radiographic findings, animals with fibrin sealant implantation generally showed thick coverage of defects and focal radioopacity within defect area, but non-treated animals showed only fibrous healing. Histologically, small amount of new appositional bone growth was only seen at the edge of the defect at 6th week in Group III, but in Group IV, there are substantial amounts of new immature bone with well-organized patterns within the defect at 12th week postoperatively. In the radiodensitometric analysis, there was no statistically significant difference between Group I and Group III at 6th week. Compared with Group II, however, Group IV showed significant bony healing (p=0.0225) at 12th week. In conclusion, the fibrin sealant appeared to be an effective mediator in bone regeneration of this critical-sized calvarial defect model, but long-term implantation period should be needed for optimal results.