Abstract
In orde r to clarify the cause of inhibition of maxillary growth in the cleft palate, the maxillary growth resection to the midpalatal suture, which has been considered to play an important role in the lateral growth of the palate, was studied histologically in rats.
The animals were randomly divided into group A of untreated control, group B with elevation of the palatal mucoperiosteum, group C with bone resection of the palate except for the midpalatal suture, group D with bone resection including the midpalatal suture.
The results are summarized as follows.
1. The lateral growth of the palate took place exclusively by the additional ossification at the midpalatal suture toward the midline.
2. The amount of additional ossification at the midpalatal suture tended to decrease with age.
3. Although the perichondrium of the maxillary bone at the midpalatal suture was clearly observed at 30 days after birth, it became thinner at 70 days and only a trace was found at 200 days. Both ends of the pala tal bones which were parallel to each other at 30 days after birth became fused with interdigitation at 70 days. The interdigitation became more pronounced with age.
4. In group B, the wound healed promptly, and left no evident adverse effects on the lateral growth of the palate.
5. In group C, the wound healed completely by 40 days after the operation. However, the amount of additional ossification at the midpalatal suture was much less than that of the untreated group.
6. After resection to the midpalatal suture, the flat ends of the palate remained separated by coarse collagen fibers with no tendency to regeneration of the original suture.
7. The results suggest that the midpalatal suture of the rat has roles to buffer the physical force as well as to control the bony growth of the palate.
