Koshi Sato

Growth of mandibular prognathism after pubertal growth peak

This study deals with the growth changes of the Japanese face associated with mandibular prognathism during 3 years after the pubertal growth peak. The investigation was based on the serial lateral cephalometric roentgenograms of prognathic and normal males and females, respectively. Maturational stages of the pubertal growth were determined individually by the ossification events taken from hand-wrist radiographs. Results indicate that the morphologic characteristics of the mandibular prognathism, which are established before the pubertal growth peak, are strongly maintained during the period studied. However, mandibular prognathism seems to show a manner of growth change fairly similar to that of the normal after the pubertal growth peak.

Predicting mandibular growth potential with cervical vertebral bone age.

This study assessed the possibility of using cervical vertebral bone age determined from cephalometric radiographs to predict mandibular growth potential. The subjects were 2 groups of 20 Japanese girls and young women: one group to derive a formula for predicting mandibular growth potential, the other to compare predicted values with actual values. Each group included subjects in the initial stage of the pubertal growth period and the final stage of growth in early adulthood. A formula for predicting mandibular growth potential that included cervical vertebral bone age and the actual growth of the mandible (condylion-gnathion) was determined with regression analysis. Cervical vertebral bone age, bone age on hand-wrist radiographs, and chronological age were inserted into the formula, and actual values and values predicted with these parameters of the formula for mandibular growth potential were compared. The formula found mandibular growth potential (in millimeters) = -2.76 x cervical vertebral bone age + 38.68. The average error between the value predicted by cervical vertebral bone age and the actual value (1.79 mm) was significantly less (P <.001) than that between the actual value and the value predicted by chronological age (3.48 mm) and approximately the same as that between the actual value and the value predicted by bone age (2.09 mm). The formula derived from this study might be useful for treating orthodontic patients in the growth stage.

Comparison of mandibular growth with other variables during puberty

The purpose of this investigation was to compare growth characteristics of the mandible during puberty with growth characteristics of the hyoid bone, cervical vertebrae, hand bones and standing height. Data were compiled from serial lateral cephalometric roentgenograms, hand-wrist roentgenograms and body height records of 33 Japanese girls between 9 and 14 years old. Records were updated annually. The mandibular growth rate differed from the other growth rates. The timing of maximum growth velocity of the mandible varied more widely than the timing of maximum growth velocity of the other parameters measured, and the total amount of mandibular growth did not correlate to any other measurement. The timing and magnitude of circumpubertal growth acceleration of various components of the body vary within a certain range of difference. However, the amount and timing of mandibular growth seems to be more variable than the other areas studied.

Bone Maturation Reflects the Secular Trend in Growth

The aim of this study was to compare a series of X-rays from the mid–1990s with another taken in the mid–1980s in order to test the possibility that environmental causes affect the skeletal maturation. The first group of subjects included a total of 1,057 girls and 1,055 boys participating in a project for Japan and China health research in 1986. The second group of subjects included a total of 382 girls and 629 boys participating in a project for bone mineral density research in 1996. The skeletal maturity score using the Tanner-Whitehouse 2-RUS method was used as the fundamental datum. This score was used to represent each group. The Wilcoxon’s rank sum test was applied to examine the significance of the difference between the 1986 and the 1996 groups. The 1996 children had not matured more than the 1986 children; children in both groups reached the given scores at almost the same ages. In girls, there was little difference between the groups at 7 years of age, but it declined from 8 years of age onward. Some apparent differences arose at ages 14 and 15, but ceased by age 16 in girls. In boys, no differences were found in those aged from 7 to 17 years, except for 12-year-olds. We did not detect much of a difference in bone maturation between the 1986 and 1996 groups of children, and no differences in height during the same period. Our findings suggest that bone maturation reflects the secular trend in growth.

Effects of Growth Hormone on Craniofacial Growth

OBJECTIVE This study determined the effects of growth hormone (GH) therapy on craniofacial growth in idiopathic growth hormone deficiency (GHD). MATERIALS AND METHODS Fifty-seven patients (33 boys and 24 girls; age range 4.5 to 16.7 years) with GHD were investigated and categorized into three groups according to the duration of GH therapy: the untreated group, the short-term therapy group, and the long-term therapy group. Their lateral cephalometric radiographs were studied, and craniofacial measurements were assessed by age and sex by using matched standard deviation scores. RESULTS In the untreated group, the anterior cranial base, total facial height, maxillary length, mandibular total length, mandibular body length, and ramus height were smaller than the standard values. In comparison with the untreated group, the long-term therapy group had a significantly larger upper facial height (P < .05), maxillary length (P < .01), and ramus height (P < .01) measurements. CONCLUSIONS Children who received long-term GH replacement therapy showed increased growth of the craniofacial skeleton, especially the maxilla and ramus. These findings suggest that GH accelerates craniofacial development, which improves occlusion and the facial profile.

Validation of a new method for automated determination of bone age in Japanese children.

BoneXpert, an automated method for analysis of hand radiographs of children, has recently been developed and validated in European children. It determines Tanner-Whitehouse (TW) and Greulich Pyle (GP) bone ages (BA). The purpose of this work is to validate BoneXpert BA in Japanese children and determine the following two properties of the method: (1) The accuracy of the BA, i.e. the standard deviation from an experienced Japanese TW BA rater. (2) The precision of the BA, i.e. BoneXpert’s ability to yield the same BA value on a repeated radiograph. The data consist of two studies: 185 radiographs of 22 normal children followed longitudinally from approximately 7 years to full maturity, and 284 radiographs of 22 patients with growth hormone deficiency treated with growth hormone and gonadotropin-releasing hormone analogue followed from an age of 4–11 years to almost full maturity. All radiographs were rated manually according to the TW-Japan system. BoneXpert processed all images, and the accuracy (SD) of TW-Japan BA was 0.72 years (95% CI 0.68–0.76). The precision error (SD) on a single determination of GP BA was 0.17 years (95% CI 0.15–0.19). It is concluded that BoneXpert performs as well in Japanese children as it does in Caucasian children. This study accomplishes a calibration of BoneXpert to the TW-Japan standard, which performs well for the entire BA range from 4 years up to full maturity.

Occlusal asymmetries in children with congenital hip dislocation

Developmental dysplasia of the hip (DDH) has been associated with other congenital postural deformities and associated with asymmetric features in the body. The aim of this study was to examine the associations between developmental DDH and malocclusions in preschool and school children. The subjects were 60 children (40 girls and 20 boys) born during 1997-2001 in Northern Ostrobothnia Hospital District and having developmental DDH and treated by Von Rosen method. The control group consisted of 71 Finnish children (46 girls and 25 boys) matched by age and gender. Children participated the cross-sectional study at the age of 5-10 years; the mean age of the DDH children was 8.0 (SD 1.4) and controls 7.9 (SD 1.4) years. Dental examinations, intra-oral photographs, and clinical examination including growth measurements were carried out. The DDH children had significantly more lateral crossbites than controls (30/9.9 per cent; P < 0.003). Overall, 77.8 per cent of cases were unilateral crossbites and found more on the right side (50 per cent) compared to the left side (22.2 per cent). Girls had more crossbite compared to boys (77.8/22.2 per cent; odds ratio 2.53). Children with congenital hip dislocation are more predisposed to the asymmetric growth of occlusion and the development of crossbite. The genetic and environmental factors including intrauterine conditions in addition to the splint therapy may be possible influencing factors. This study will give additional information of the development of occlusal asymmetries and the multifactorial nature of the aetiology of lateral malocclusions.

Childhood intelligence and early tooth wear patterns

Abstract Objective: The aim of this study is to explore the relationships between early dental wear patterns and preschool IQ (Intelligence Quotient, by Stanford–Binet) of the child to illuminate the historic relationship of mental queries and bruxism. Methods: The dental study participants were 864 Euro-American preschool and school children whose IQs were tested for school maturity purposes at the age of 4 years, followed by dental data in a cross-sectional manner at the mean age of 7.8 years. Worn dentitions were classified as “symmetric” or “right-” and “left-sided,” based on the faceting of the teeth. Results: In general, the relationships of tooth wear and intelligence were scarce, reflecting social background factors. Statistically significant results between asymmetric wear and gender groups suggest that direction of jaw function has a role in the regulation of processes responsible for individual mental performance in childhood. Discussion: Increased left-side tooth wear and early advantage in the intelligence test in girls is intriguing due to the fact that they reach maturity earlier than boys in verbal articulation, controlled in most cases by the limited area on the left side of the brain.

Biomechanical effect of incisors’ traction using miniscrew implant

The purpose of this study was to compare the biomechanical effects of the incisor movement in three different types of traction by the miniscrew implants as an anchorage using 2D finite element method (FEM). The FEM model was made by tracing the maxilla including tooth, the wire, and the bracket. Three different types of hooks were set up in the model. We suggested that controlled incisor retraction is possible by changing the length and the position of the hooks soldered to the archwire when using miniscrew implants.

Difference of brain function between normal occlusions and malocclusions using NIRS

The mastication is not only related with the peripheral function, but also the central control system. The purpose of this study was to clarify the interface between the brain function and the occlusion by investigating the stimulation of the frontal association cortex, which relates to the function of the human nature. Subjects were healthy right-handed young adult volunteers with acceptable normal occlusion and class III malocclusion. Near-infrared spectroscopic topography (NIRS) was used to investigate the stimulation of the frontal association cortex during chewing gum without flavors. It was proved that the frontal association cortex was also stimulated by chewing gum. However, the behavior of the stimulation depended on the individual occlusion type. This study suggests that orthodontic treatment would improve the quality of life (QOL) of patients from the point of healthy brain function.