Abstract
Although the operating procedures for correction of cleft lip and palate are nearly perfected, a puzzling problem remains, namely, the hypogrowth of the maxilla which becomes conspicuous as the patient grows. Numerous animal experiments have been conducted to trace the causes of maxillary hypogrowth to palatoplasty. On the other hand, some clinical research and animal experiments have revealed that cheiloplasty also has some effect on maxillary growth. However, by surgical intrusion on the“soft tissue alone”, the influence exerted on facial growth is not known, therefore, the author conducted animal experiments to elucidate this phenomenon. Rats weighing 100 g were divided into a total of seven experimental groups, i.e. three basic groups and four others representing a combination of the three basic groups. Each of the three basic groups was characterized by the following: 1) broad undermining of the soft tissue, 2) removal of the periosteum and 3) excision of the upper lip. These experiments revealed that the growth of the premaxilla anteroposterior diameter was inhibited in all experimental groups, and this growth disturbance was found to exist irrespective of periosteal excision ; the impact of the surgery gradually diminished and no hypogrowth was found to occur. In a group of rats whose upper lips were excised by 0.6 cm, the growth distubance was found milder in severity than in the first group (rats with undermind soft tissue. Thus, it was found that undermining of the soft tissue has greater influence on maxillary growth than excision of the upper lip. Histological study revealed that the periosteum is regenerated at an early postoperative stage, and bone calcification made rapid progress without inhibiting osteogenetic activity, even right after surgery. From this, it was considered most likely that the direct cause of maxilla growth disturbance can be traced to physical pressure that arises around the maxilla and premaxilla.
