Effects of Enamel Matrix Derivative on Bioactive Glass in Rat Calvarium Defects
Tissue engineering-based bone grafting has emerged as a viable alternative to biologic and synthetic grafts. The purpose of this study was to evaluate the effect of enamel matrix derivative (EMD; Emdogain gel, Biora AB, Malmö, Sweden) on bioactive glass in enhancing bone formation in rat calvarium defects. Twenty rats were used in the study. In all animals, 2 standardized critical-sized calvarial defects (5.0 mm diameter) were created surgically. The animals were randomly allocated into 4 groups of 5 animals each. Group AI: one calvarial defect was filled with bioactive glass plus EMD, while the contralateral defect was filled with bioactive glass alone. The healing period was 2 weeks. Groups AII and AIII: the animals were treated in the same manner as in group AI, but the healing periods were 4 and 8 weeks, respectively. Group B: one calvarial defect was filled with EMD only, while the contralateral defect was empty (CSD). The healing period was 8 weeks. New bone formation was evaluated by radiomorphometry and histomorphometry. Results of radiomorphometry showed no significant difference in the mean optical density between bioactive glass with EMD and bioactive glass alone; no defect completely regenerated with bone. The histologic analysis revealed that defects filled with bioactive glass plus EMD in all groups contained slightly more percentage of new bone than those filled with bioactive glass alone; however, the difference was not statistically significant. The highest percentage of new bone formation was present at 8 weeks in the bioactive glass plus EMD group. Bioactive glass particles, used with or without EMD, maintained the volume and contour of the area grafted in CSD. However, they did not lead to a significant difference in bone formation when compared with CSD 8 weeks postoperatively.Abstract
Reference markers were made 2 mm anterior and 2 mm posterior to the margin of the defects.
Mean optical density of rat calvarial specimens from radiographic film.
Figure 3 . Sagittal histologic section through the calvaria showing defect after a healing period of 2 weeks. The bone edge of the defect presented an irregular morphologic appearance, with small areas of reparative bone neoformation. Note the bony ingrowth from the margins' defect and the new bone supradural region. (Specimens were stained with hematoxylin and eosin.) Figure 4. Healing of defect group AI (2 weeks) demonstrating a large number of residual of bioactive glass particles. Dense fibrous tissue around the particles and new bone deposited at the margin of the defect. (Specimens were stained with hematoxylin and eosin, original magnification ×5.) Figure 5. Sagittal histologic section through the calvaria showing defect after a healing period of 4 weeks. The histologic observations were similar to the 2-week observation. Bone neoformation was mostly restricted to the borders of the surgical edge. (Specimens were stained with hematoxylin and eosin.) Figure 6. A specimen from group AII (4 weeks) demonstrating bioactive glass particles surrounded by cellular connective tissue. The bioactive glass particles were presented with cracks and thin connective tissue within the cracks. Pink amorphous material was also found within some of the particles. (Specimens were stained with hematoxylin and eosin, original magnification ×20.)
Figure 7 . Sagittal histologic section through the calvaria showing defect after a healing period of 8 weeks. At the bone edges of the defect, bone neoformation with extension toward the center was noted. A lower number of residual bioactive glass particles within the bone defects and a greater amount of dense, organized connective tissue were observed. (Specimens were stained with hematoxylin and eosin.) Figure 8. A specimen from group AIII (8 weeks), bioactive glass particles presented with cracked appearance. (Specimens were stained with hematoxylin and eosin, original magnification, ×20.) Figure 9. Sagittal histologic section through the calvaria showing defect after a healing period of 8 weeks. Surgical defect with fibrous connective tissue was thinner than the original calvaria. A thin fibrous connective tissue across the defect with small amounts of new bone being occasionally seen at the bony margin of the defect. (Specimens were stained with hematoxylin and eosin.) Figure 10. A specimen from group B at 8 weeks, demonstrating minimal inflammatory infiltrate of the thin fibrous connective tissue. All specimens were well vascularized and rich in fibroblasts with oriented collagen fibers. (Specimens were stained with hematoxylin and eosin, original magnification, ×20.)
The data of histomorphometric analysis (mean percentage of new bone area) in groups A and B.
Contributor Notes