Abstract:

Objective:The purpose of this study was to observe the roentgenographic characters of distraction osteogenesis (DO) correc- tion of cleftpalate (CP), to study the expression of BMP proportional to fixation period time intervals, and to explore the newbone formation mechanism in CleftPalate bone shelf.Methods:12 catswere used to establish the CP animal model surgically, and then were assigned randomly to (1) Experimental group(12 cats): CP defects were DO repaired at the rate and rhythm of 0.4 mm@ 2/day. Specimen retrieval at 2, 4, 6, 8, 12 weeks after completion of distraction, roentgenography and Anti-BMP immunohisto- chemistry studies were performed; (2) Experimental control group (2 cats): CP defects without any treatment procedures, and (3) Empty control group of 2 cats.Results:Anti-BMP immunohistochemistry study showed positive DAB dye in early 2 weeks and most extensively positive expression of BMP in 4 to 6 weeks. The expression of BMPwore off gradually through 8 to 12 weeks. The roentgenography showed that the newly mineralized bone was developed from the cut bone edges bilaterally to the central transpar- ent zone, and the newly formed bone bridged the defect area completely at the end of the study. The CP bone defect was recon- structed and the distraction gap was filled with de nove osteogenesis. No new bone formationwas observed in experimental control group.Conclusion:The process of new bone formation in the distraction area is dynamic. Being stimulated primarily, the process was kept highly active till quiescence phase finally. The X-ray examination shows that there is distinctively low roentgenopeque. Nevertheless, roentgenography is so far a very effective and convenient method to evaluate and monitor the DO correction efficiency.

Key words: distractionosteogenesis, cleftlip/palate, immunohistochemistry, bonemorphogeneticprotein