The labial enamel thickness of the maxillary central incisor, lateral incisor and canine of Chinese teeth obtained from Shanghai was measured for serving as a guide for porcelain laminate veneer restoration in China. The enamel reduction amount in the upper central incisor can be 0.3 mm at the cervical third region and then increased to 0.5 mm toward the incisal edge the same as the guidance reported for Japanese. The enamel thicknesses of lateral incisor and canine were thick enough to be 0.5 mm from the middle thirds to the incisal edge the same as that of central incisor, but thinner at the cervical thirds as compared with the central incisor, which suggests that the enamel at the cervical region is better to be rduced within 0.25 mm in order to avoid exposure of the dentin. The mesial enamel thickness and the labial enamel thickness showed a significant correlation at both the middle third portion and the cervical third. This result suggests that the labial enamel thickness can be predicted from the mesial enamel thickness obtained by the X-ray photograph.

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Synthetic hydroxyapatite (HAP) was stirred in the soulution having various concentrations of fluoride ion. The fluoride products were qualified by X-ray diffraction (XRD), and fluorapatite (FAP) was quantitatively determined by two methods : Oniki's ESR technique and Caslavska's CaF_2 extraction method. The FAP production could be accurately quantified by ESR technique when the concentration of fluoride ion in the solution was below 100 ppm. This technique, however, was not valid at the higher concentration of fluoride ion exceeding 200 ppm since the FAP signal became obscure with an interference by the increased CaF_2 precipitates. These findings in ESR were well suported by the XRD analysis. The CaF_2 extraction method by KOH, on the other hand, showed considerably different results from those in ESR. It seemed that all the precipitated CaF_2 could not be completely removed by 1 M KOH employed in this study.

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Odontoma, a typical one of odontogenic tumors, is not rarely found in our clinical procedure. It commonly occurs in the jaw bone. This case was recognized as exposed odontoma on the overlying mucosa of the mandible with inflammation in a 15 year-old male. Histopathological diagnosis was complex odontoma with dental caries-like lesion.

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Dry mouth is a symptom with dryness in the oral mucosa. Dry mouth should be essentially approached by every dentist, but few clinics are prepared to cope with it in Japan to date. Most recently, patients with complaints of oral dryness, have much increased in our hospital. In this review, we present recent findings concerning the prevalence of subjective dry mouth, the association with saliva, medication, and systemic diseases, as well as treatment and prevention.

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