The Significance of the Pre-Alveolar Cleft in Assessing A Prognosis in Future Maxillary Development

Abstract

In isolation, the prealveolar cleft carries little significance with re— gard to maxillary development and the maxilla can be expected to reach normal proportions. Where a postalveolar cleft is present and associated with a prealveolar cleft on one or both sides, it is unusual to see a lag in development either of the maxilla or of the mandible. Micrognathia has, for instance, never been reported in the presence of such a cleft. Where complete unilateral clefts of the lip and palate are present, a large number of jaw deformities are to be found: a) collapse of the upper alveolar arch medially; b) disturbance of downward growth of the maxilla with resultant raising of the occlusal plane on the cleft side; and c) maxillary retrognathism. These deformities will occur even when surgical closure is not attempted as Innis (5) showed in his studies of unrepaired clefts. His findings revealed that the smaller maxillary element was underdeveIOped and displaced medially and upward. Collapse of the upper arch may occur very early and is probably due to a combination of factors: the presence of the defect in the bony plate, the pressure of the buccal muscles and early forward growth of the nasal septum. Later collapse following surgery may be caused by tightness of the lip closure, scarring in the alveolar area and possibly tension in the palate following palate closure. The fact that collapse does not occur in all cases may be attributable to a variety of causes such as the width of the cleft, rate of growth, the action of the tongue within the mouth and the " built—in " development part of the maxilla itself. The failure of downward growth of the maxilla is probably a manifestation of the same failure of development giving rise to the cleft. As such, the prealveolar cleft is an expression of this same process.