[Three-dimensional analysis of maxillary alveolar process in bilateral cleft lip and palate patients].

The collapsed maxillary alveolar arch in bilateral cleft lip and palate (BCLP) patients was quantitatively evaluated by three dimensional analysis. Materials were consisted of alveolar models taken from 15 Japanese boys (11 years old) with BCLP. The findings obtained were as follows: 1. Examination of the alveolar displacement in individual BCLP patients disclosed a marked tendency of inward and upward displacement of the lateral segments. On the other hand, premaxilla showed an upward displacement in the vertical dimension with a great deal of variation in the amount and direction of horizontal displacement. 2. Concerning the average amount of horizontal displacement, the premaxilla showed relatively little, but the lateral segment, especially the left one, showed a considerably large amount. In the vertical dimension, both the premaxilla and lateral segment were displaced markedly upward. 3. Patterns of collapsed alveolar arch in BCLP patients were classified according to the amount of horizontal displacement of the premaxilla into the following 4 types; type A (larger displacement towards the inside), type B (moderate or smaller displacement towards the inside), type C (moderate or smaller displacement towards the outside) and type D (larger displacement towards the outside). The order of prevalence of these 4 types was B,C,A,D in order. On the other hand, in the vertical dimension, the direction of displacement of the premaxilla was upward in all patients. 4. The anterior edge of the lateral segments showed the largest amount of displacement both in the horizontal and vertical dimensions. In a comparison of these results with those of Unilateral Cleft Lip and Palate (UCLP), the total amount of horizontal displacement of the maxillary alveolar process was larger in UCLP, while the vertical one was larger in BCLP. A remarkable difference between BCLP and UCLP was found in the displacement of the anterior region due to the premaxilla in BCLP.