Mammals exhibit marked morphological differences in the muscles surrounding the jaw bone due to differences in eating habits. Furthermore, the myofiber properties of the muscles differ with function. Since the muscles in the oral region have various functions such as eating, swallowing, and speech, it is believed that the functional role of each muscle differs. Therefore, to clarify the functional role of each masticatory muscle, the myofiber properties of the adult mouse masticatory muscles were investigated at the transcriptional level. Expression of MyHC-2b with a fast contraction rate and strong force was frequently noted in the temporal and masseter muscles. This suggests that the temporal and masseter muscles are closely involved in rapid antero-posterior masticatory movement, which is characteristic in mice. Furthermore, expression of MyHC-1 with a low contraction rate and weak continuous force was frequently detected in the lateral pterygoid muscle. This suggests that, in contrast to other masticatory muscles, mouse lateral pterygoid muscle is not involved in fast masticatory movement, but is involved in functions requiring continuous force such as retention of jaw position. This study revealed that muscles with different roles function comprehensively during complicated masticatory movement.

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The purpose of the present study was to investigate the relationship between infant sucking habits and the prevalence of caries in Japanese preschool children.
The study was designed as a prospective, longitudinal study starting with 592 children aged 18 months. Information on sucking habits and patterns of feeding was collected from parents in the form of a questionnaire. Children who continued breastor bottle-feeding at 18 months of age were eliminated prior to the evaluations. The children were divided into 3 groups according to their sucking habits at 18 months of age: Group 1: children with a finger-sucking habit (n=151); Group 2: children who used a pacifier (n=45) and Group 3: children with no oral habit (n=205). Clinical examinations were carried out by one of the authors.
Mean dft and prevalence of caries were not statistically significant among the 3 groups at 18 months of age. However, only 10.6% of the children in Group 1 exhibited caries at 36 months of age, compared with 17.1% in Group 3 and 24.4% in Group 2. Group 1 children showed the smallest mean dft at 0.30 among the 3 groups at 36 months of age, and those in Group 2 showed 1.18; the difference was statistically significant (p<0.01).
The results suggest that children with a finger-sucking habit are more likely to be free of caries by the age of 3. However, use of pacifier at 18 months of age is a potential risk factor for the development of dental caries in children.

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In this study, to clarify the influence of the maxillo-mandibular bones and cranium on airway morphology, maxillo-facial morphology in patients with jaw deformation was measured using cephalograms and X-ray CT imaging data. Subjects consisted of 25 adult women in whom cephalograms and X-ray CT were taken to diagnose jaw deformation. The data obtained were classified based on skeletal and facial patterns according to Ricketts analysis, and changes in internal diameter, height and volume of the middle pharyngeal airway were observed. The results showed that the internal diameter of the inferior airway expanded anteriorly when the mandibular bone was in the anterior position, and was slightly constricted and elongated vertically when the mandibular bone was posteriorly rotated. This suggests that airway volume is influenced by the anteroposterior position of the mandibular bone, in that it compensates for decreases in its volume by extending its height inferiorly to cope with posterior deviation of the mandibular bone.

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Malignant mucosal melanoma (MMM) still has the poorest prognosis. There is a paucity of molecular biological studies on MMM of the head and neck. We investigated free-circulating DNA microsatellites with loss of heterozygosity (LOH) in the blood of MMM patients. Cancer-related DNA is found in plasma, with cancer patients showing a higher level of free-circulating DNA than normal subjects. However, it is difficult to obtain sufficient amounts of such DNA for PCR analysis. We have searched for ways to improve all stages of such research, and detected new microsatellite alterations by triplicated whole genome amplification (WGA) and triplicated PCR amplification. In order to achieve a better understanding of the extent of the alterations affecting chromosomes we determined the occurrence of LOH at the following gene loci: D1S243, D6S311, D9S161, and D19S246; only 4 out of the 20 microsatellite markers usually used in MMM were used in this study. We determined LOH in 17 MMM patients.
It was possible to confirm LOH on at least one marker in 12 (70.6%) out of the 17 patients. Metastasis or recurrence was confirmed in 3 (17.6%) out of the 17 patients, and all of them were found to have LOH. LOH at microsatellite markers D1S243, D6S311, D9S161 and D19S246 in the plasma of these patients statistically correlated with MMM.
The results of this study suggest that these loci are suitable for identifying cancerrelated DNA of MMM, and that analysis of LOH in plasma DNA released into the circulation may be useful as a screening tool.

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The present study describes treatment of intrabony periodontal defects with enamel matrix derivative (EMD) in private practice. Ten patients with clinical diagnosis of chronic periodontitis were subjected to data analysis. A total of 18 teeth with various osseous defects received regenerative therapy with EMD, and were followed for a minimum of 2 years. Treatment of the intrabony defects with EMD led to a statistically significant improvement in the mean value of probing depth at 1-year when compared with at the baseline (p<0.01). Reduction in probing depth was achieved with minimal recession of the gingival margin, and was maintained over the 2-year observation period with no significant change. Mean values of attachment gain at 1 and 2 years were of clinical significance: 3.39±1.46 mm and 3.22±1.40 mm, respectively. Although one tooth was extracted because of subsequent loss of attachment and bone, most teeth treated have been successfully maintained for 2 to 7 years with no significant signs of disease progression. In conclusion, EMD treatment of intrabony osseous defects yielded clinically favorable responses. The gain in clinical attachment can be longitudinally maintained in a private practice setting. Further controlled studies are needed to elucidate the clinical significance of EMD treatment.

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