Association of advanced hypodontia and craniofacial morphology in Japanese orthodontic patients

The purpose of this study was to examine the effects of advanced hypodontia on craniofacial morphology in Japanese patients. We defined advanced hypodontia as a congenital absence of four or more permanent teeth, excluding the third molars. Lateral cephalometric radiographs of 20 female orthodontic patients (age range, 8.5 to 19 years; mean age, 13.9 years) were examined. Twenty-eight angular and 37 linear measurements were taken from each cephalogram, and these cephalometric data were statistically analyzed and compared with the Japanese cephalometric standards. The most frequently missing teeth were the mandibular and maxillary second premolars, followed by the maxillary first premolars and the maxillary first molars, in that order. Compared with the Japanese standards, a smaller cranial base length and angle, a shorter maxillary length, a slightly prognathic and upward-rotated mandible, and retroclination of the upper and lower incisors were found in the patients studied. These craniofacial anomalies should be taken into consideration in treatment planning and mechanotherapy.