Abstract
Serial frontal and lateral cephalometric radiographs with implants and study models of 31 infants' who received orthopaedic treatment for unilateral cleft lip and palate, were analysed with an electronic XY reader. Partial data for 50 normal infants and 10 isolated palatal cleft patients were included to allow certain comparisons. The records at birth indicate that the size of the alveolar cleft in unilateral cleft cases is governed mainly by the degree of transverse segmental separation which is present and only to a lesser extent by deficiency of alveolar tissue, except in a minority of cases. It is clear that in the early months of life, the divided maxillary arch can be made to assume near normal dimensions by inward rotation of the anterior ends of the segments, at the alveolar and basal level, around axes in the tuberosity regions. Appositional growth of the cleft margins makes little contribution to the reduction in cleft size. The significance of the findings is discussed.