Investigations on the palatal rugae pattern in cleft patients. Part I: A morphological analysis

The characteristics of the palatal rugae zone (number of rugae, relief type, posterior limitation) were investigated on the maxillary casts of 44 patients with unilateral cleft lip and palate and 28 patients with bilateral clefts by means of reflex microscopy, a three-dimensional, computer-assisted, touch-free measuring system for the metrical registration and analysis of the parameters directly on the maxillary casts for the segments of the 2 cleft groups. The features "number of palatal rugae" and "relief type" (primary rugae) were determined both before and after surgical repair of the cleft palate. Both segments in unilateral cleft lip and palate and both lateral segments in bilateral clefts most commonly had 4 to 5 palatal rugae. The number of rugae in cleft patients is thus in a range that other authors have reported for non-cleft individuals. Following palatal cleft repair, the rugae counts per segment decreased significantly in patients with unilateral and bilateral cleft lip and palate but the 3rd rugae was never lost after surgery. The relief type identified in unilateral and bilateral cleft lip and palate was the same as in isolated cleft palates and did not differ from that in non-cleft subjects. The posterior limitation of the palatal rugae zone was determined both in a tooth-defined manner and as an absolute linear distance (at all time points). The most frequent tooth-defined posterior limitation of the rugae zone in unilateral and bilateral clefts was the second deciduous molar, which is also the position identified for non-cleft individuals. The linear distance from the tuberosity line to the rugae zone increased in all segments of unilateral and bilateral clefts during the interval up to palatal cleft repair, indicating sagittal maxillary development in the posterior area of the palate. Surgical repair of the cleft palate resulted in a significant shortening of the distance in both segments of the unilateral cleft, most likely due to the displacement of mucosa and periosteum required to cover the palatal cleft.