Animal experimental study on repairing alveolar clefts by using rectilinear distraction osteogenesis

The aim of this study was to evaluate the clinical applicability of rectilinear distraction osteogenesis for repairing alveolar cleft models. Alveolar process distraction surgery to produce bilateral clefts was performed on six adult cats. In our study, the left side with the distraction device was the experimental side, and the other side without a distraction device was the control side. After a 6-day latent period, animals underwent gradual distraction at a rate of 0.6mm per day (distraction was performed twice each day, at a rate of 0.3mm each time), until the tissue on the two sides of the cleft touched, then the distraction strength was maintained for 2 days. Two cats were sacrificed at 2 weeks, 6 weeks and 10 weeks postoperatively. Gross anatomical, histological and radiographical analyses were performed after the animals were sacrificed. In addition, the arch width was measured both before setting the distraction device and after distraction was complete. Two weeks after the distraction was complete, the soft tissue of the two sides of the cleft region on the experimental side touched, and it began to coalesce. The extremities of the two sides of the cleft region on all the experimental sides drew close to each other, but there was no bony conjunction. New bone formation appeared in the distraction region. The arch width at the front of the maxillary bone on the distraction side after distraction was smaller than before distraction. The alveolar cleft could be closed by rectilinear distraction osteogenesis. Two sides of the cleft touched each other and only soft tissue coalesced, but we did not observe bone coalescing. This phenomenon suggested that it might be difficult to achieve complete bony repair by rectilinear distraction osteogenesis. However, rectilinear distraction osteogenesis can minimise the size of the alveolar cleft and make bone grafting advisable for those patients who are not suitable for bone grafting before distraction osteogenesis.