Changes of Palatal and Alveolar Arch Form during Predental Period in Infants

To understand the development of oral function and the growth and development of dentition and occlusion, it is important to know the characteristic growth-related changes of the alveolar arch and palate in infants. The purpose of this study was to investigate the morphological characteristics of the palate before teething in infants and how palatal form changes are influenced by the feeding methods during the first three months after birth. Thirty-seven upper jaw cast models from infants were used in the study. Subjects' ages ranged from 1.3 to 9.3 months and were divided into three groups by age in months (i.e., 1 and 2 months, 3 and 4 months, and 5 months and older). Three-dimensional measurements of the palate were performed on each cast model using a semiconductor laser.Results were as follows : A three-dimensional image of the palate could be precisely rebuilt on a computer, and it was used for performing detailed measurements. In addition, three-dimensional models for each group were created in a synthetic resin by applying CAD-CAM technology. The length in the front part of the palate (A−CC') significantly increased with age, whereas no changes were found in the rear part of the palate. As to the width of the palate, three items (B−B', M−M', C−C') out of four significantly increased. Palate depth and surface area did not differ among the three groups. The curve of the palatal medial plane could be expressed significantly with the sixth-order approximation. Frequency of a sucking fossa was 70.3% altogether, and no differences were found in either the frequency or the width of the sucking fossa among age groups. Palatal form in infants was also not related to feeding methods.In conclusion, significant changes of palatal and alveolar form due to growth were found in the predental period in infants, i.e., increases in both length and width of the front part of the palate. Because these characteristic changes occurred after two months of age, it suggests that growth of the anterior primary teeth and intraosseous eruption could be related to changes of palatal and alveolar form.