No abstract

Objective: The purpose of this study was to explore the association of hypodontia patterns and variations in craniofacial morphology in Japanese orthodontic patients. Materials and Methods: A total of 50 girls with hypodontia (the total group) were selected and categorized into anterior, posterior, and anterior-posterior groups according to the location of the congenitally missing teeth. By using the lateral cephalograms of each subject, 28 angular and 37 linear measurements were made. The cephalometric data were statistically analyzed and compared among the groups and with the Japanese cephalometric standards from 36 age-matched female subjects without hypodontia or malocclusion (the control group). Results: Every hypodontia group showed shorter anterior and overall cranial base lengths, shorter maxillary length, greater retroclination and elongation of mandibular incisors, and a larger interincisal angle than the control group. The total and anterior-posterior groups especially exhibited a significantly more prognathic mandible, larger retroclination of maxillary incisors, and a more counterclockwise-rotated occlusal plane. Furthermore, these skeletal and dental deviations were more remarkable in the anterior-posterior group than in either the anterior or the posterior group. Anterior hypodontia exerted as much influence on craniofacial morphology as posterior hypodontia. Conclusions: When orthodontic treatment is performed on patients with hypodontia, not only the number but also the distribution of missing teeth should be taken into consideration, though there was no significant difference in craniofacial morphology between anterior hypodontia and posterior hypodontia.

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. Twentyeight 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.

Bolton's values can be used with confidence for the typical Japanese orthodontic population. The use of the actual millimeters of correction for the tooth size ratios could help orthodontists avoid underestimating the prevalence of clinically significant tooth size discrepancies.

We found few studies on the association between maxillary sinus size and malocclusion in an electronic search using PubMed. The purpose of this study was to investigate maxillary sinus size in different malocclusion groups and the association between maxillary sinus size and dentofacial morphology by the use of lateral cephalometric radiographs. A total of 120 lateral cephalograms were used. These radiographs were derived from subjects with skeletal Class I, Class II, and Class III malocclusions, classified on the basis of the A-N-B angle. Each malocclusion group consisted of 20 boys and 20 girls ranging in age from 12 to 16 years. Two linear measurements and three area measurements were made to evaluate maxillary sinus size, and four angular and eight linear measurements were made to evaluate dentofacial morphology. Analysis of variance and Pearson's correlation analysis were performed for statistical comparison. The maxillary sinuses showed no significant differences in size between the different classes of skeletal malocclusion or between sexes. However, the maxillary sinus measurements were significantly correlated with several dentofacial morphological measurements. When formulating an orthodontic treatment plan, orthodontists should take into consideration the fact that the patients 12 to 16 years old with large cranial bases and nasomaxillary complexes tend to have larger maxillary sinuses, but there is no significant association between maxillary sinus size and the A-N-B angle denoting the sagittal skeletal jaw relationship.