OBJECTIVEThe aim of this study was to explore ultrastructural characters of the newly formed bone in the correction of cleft palate (CP) bone defect by distraction osteogenesis (DO).

METHODSThe CP experimental animal models (12 cats) were established surgically, and were divided randomly into the experimental group (10 cats), in which the hard palate bone defects were corrected with DO procedure at the rate of 0.4 mm x 2/day. The specimen retrieval with euthanasia was carried out at 2, 4, 6, 8, 12 weeks after completion of distraction. Ultrastructural study was then performed; the experimental control group (2 cats) was kept for 6 weeks before euthanasia without any correction, the other extra 2 cats were used as the negative control.

RESULTSNew bone formation appeared in early 2 weeks. Exclusively intramembranous bone formation was observed in all specimens. The remodeling activities were keep observed throughout the period of study, and the bone structure matured gradually till 12 weeks after the completion of DO. No repair was observed in experimental control group.

CONCLUSIONThe reconstruction of CP bone defect by means of DO could get active intramembranous bone formation and remodeling, which adapted to normal functional activities.