Abstract:

Objective To investigate the effect of Chinese tradition medicine on mandibular distraction osteogenesis. Methods Sixteen beagles were randomly divided into medicine group and control group. A customized component distraction device was applied to the right side of mandible, and the transverse osteotomy was performed in all animals. After 7 days, distraction was started at the rate of 0.5 mm each 12 h and continued for 10 days. The beagles in medicine group drank Chinese tradition medicine from the first day after postoperation to the last of the trial. 2 animals were killed at week 1, 2, 3, and 4 after consolidation. The mandibles were harvested to examine the distraction tissues histologically, bone histomorphontry measures and detect of osteocalcin（OC）. Results 1）Observation of the general specimens: During the 1-2 weeks of the fixed period, no significant difference was shown between the two groups. The distraction gap was covered with a thick layer of collagen connective tissue, and there was a slight movement of distraction gap. In the 3 weeks, from the two group samples, the proliferated periosteal get thinner, and the movement of two bone stumps disappeare could be observed. After the 4 weeks, the thickness of the periosteum at distraction gap of the two groups gradually returned to normal. It was difficult to identify the two-cut stump of the bone. New bone tissue of the medicine group was better than that of the control group, and bone tissue at the distraction gap was more dense and smooth. 2）Histomorphological changes：In the 1st and the 2 weeks of the fixed period, there was no significant difference between the two groups. In the 1st week, a small part of distraction zone was filled with honeycomb connective tissue, and close to the nearly cut of marrow department, new membranous bone formed. In the 2 weeks, the distraction gap from the center to both sides, showed three clear bands: The fiber zone, finger osteoid zone and newborn trabecular zone. In the 3 weeks, new bone formation can be seen in most of the distraction regions. In the medicine group, new bone formation within the distraction gap was active, new bone trabecular was thick, and new bone tissue was also more mature. In the 4 weeks, the three typical bands at distraction gap were disappeared, replaced by the new parallelly ranked trabecular bone. In the medicine group, bone trabecular ordered densely, thick and uniform in shape, while the control group, bone trabecular was sparse and uneven thickness. 3） Bone histomorphometry analysis：In the 1st and the 2 weeks of the fixed period, trabecular bone’s area, trabecular bone’s perimeter, and trabecular bone surface’s density had no statistically significant difference between two groups. In the 3-4 weeks, in the medicine group trabecular area, trabecular perimeter and area density were significantly higher than those of the control group. 4）The detect of OC：Oc mRNA was mainly expressed on osteoblast and the surfaces of new bones. In the 1st week of the fixed period, the expression of oc mRNA had no statistically significant difference between the two groups. In the 2, 3, 4 weeks of the fixed period, the expression of oc mRNA of medicine group was significantly higher than that of the control group. Conclusion Chinese tradition medicine can effectively accelerate the formation and maturity of new bone of mandibular distraction through increasing osteogenic gene expression.

Key words: beagle, Chinese tradition medicine, osteocalcin, distraction osteogenesis, histomorphology