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.

Previous studies have shown that tooth size ratios are ethnicity-, race-, and sex-specific. This study was carried out to determine anterior and overall ratios in a Japanese population and to compare them with Bolton's ratios. Numerical data were obtained from 60 pairs of dental casts of 30 male and 30 female Japanese orthodontic patients. The mesiodistal widths from first molar to first molar were measured on each cast to the nearest 0.01 mm, by using digital calipers, and the anterior and overall ratios were calculated. The Kolmogorov-Smirnov test, the parametric t test, and Student t test were used for statistical analyses. No statistically significant difference between men and women was found in either the anterior or overall ratio. The combined male and female anterior and overall ratios were 78.39 +/- 2.18% and 91.60 +/- 2.11%, respectively. The combined male and female anterior ratio showed a statistically significant difference from the Bolton standard, whereas the overall ratio showed no statistically significant difference. Significant discrepancies in the anterior and overall ratios were found in 21.6% and 8.3% of patients, respectively. A high prevalence rate of an anterior tooth size discrepancy more than 2SD above Bolton's mean was found. Bolton's anterior ratio was not applicable to the Japanese population, and specific standard tooth size ratios for the Japanese population are needed.

There were significant differences in shear bond strength among different permanent and deciduous tooth types, but deciduous teeth could be used as anchor teeth in orthodontic treatment with sectional edgewise appliances.

We investigated how child patients take in information from a dentist's face and whether there is any age difference in the way of scanning the face. For this purpose, we used a non-contact type of eye movement measuring apparatus tradenamed FreeView ® and an upright photograph of a male dentist's face as the test image. The subjects consisted of a total of 90 children between the ages of 2 years 11 months and 12 years 11 months. The subjects were divided into three age groups-group A (below 7 years), group B (7-9 years) and group C (10 years or above), and their eye movements were measured and analyzed. Our findings are as follows. 1. The saccadic movements to the background of the photo and the fixation points in the background decreased most in group C, followed by group B and group A, in that order. 2. The overlapping of saccadic movements to the features of the face (the eyes, nose and mouth) was remarkably in all age groups. However, the subjects did not scan the whole of the appearance of the face (the hair, forehead, cheeks, ears and chin). 3. The fixation points on the appearance of the face were unevenly distributed. Many fixation points were found close to the features of the face. This peculiarity was common to all the groups. 4. The fixation points on the features of the face increased most in group C, followed by group B and group A, in that order. what he or she is wanting, and adjust yourself to the situation. In other words, one's face plays an important role in interpersonal communication. In the practice of pediatric dentistry, what is important is to establish a trusting relationship between the dentist, child patients and their mothers in the sociocultural context. Therefore, it is essential for the dentist to set the time and place to communicate with the patient enough to deepen mutual understanding. Regarding this, there are many published studies 2-6). Some researchers delved into how a human perceives another human's face 7,8) ,