Regeneration in surgically produced cleft palate in rabbits. A microscopical study

In order to study the effects of surgical procedures on the regeneration process in cleft palate, an artificial cleft was made in 4-weeks old female New Zealand rabbits. The 47 animals were divided into 5 groups: group 1: controls, group 2: cleft made in the bony palate, using a dental burr (phi 3 mm), group 3: cleft as in group 2, oral mucosa stitched, group 4: cleft made without perforating the nasal mucosa; oral mucosa stitched ("Veau"), group 5: cleft made as in group 4; before stitching the oral mucosa pieces of autologous rib bone were introduced into the cleft ("Schuchardt"). At the ages of 4, 5, 6, 8, 12, 18 and 24 weeks, one or two animals per group were sacrificed. The palatal region was microscopically studied using 10 mu paraffin sections stained according to Herovici. It was found that it is difficult to make a reproducible cleft on the histological level. A large interindividual variation in local damage due to the surgical procedure was observed; this might contribute to the variation in growth results of the facial skeleton reported in literature. Signs of excessive bone resorption were found. The presence of bone in places where sutural tissue should be present, observed in some growing animals, will contribute to reduction of palatal width, medial collapse of the palate and asymmetry of the facial skeleton. There appeared to be no striking differences between the three methods of repair, used in group 3, 4 and 5 respectively.