Influence of Lifestyle Factors on Risk of Dental Caries among Children Living in Urban China.

The prevalence of dental caries has been decreasing among kindergarten children in Shanghai, China, over recent years, although it still remains at an unacceptably high level. The purpose of this study was to identify which factors were important in providing oral health guidance and achieving further improvement in the oral health status of kindergarten children in urban China. A survey was conducted on dental caries in 128 Japanese and 368 Chinese kindergarten children and a questionnaire given to their parents/guardians on each child's lifestyle and dietary habits from birth to the present. Correlations between responses to each questionnaire item and the status of dental caries were statistically analyzed. The dft index score (p=0.0016), prevalence of dental caries (p=0.0002), and percentages of children with decayed (untreated caries-affected) teeth (p<0.0001) were significantly higher in the Chinese than in the Japanese children. Many differences were observed in lifestyle factors between the two groups. The percentage of parents failing to control the child's snacking habits between meals was higher in China, and weaning was significantly delayed in China compared with in Japan. These lifestyle factors were considered to be associated closely with the high risk of dental caries in Chinese kindergarten children. These findings indicate that oral health guidance for kindergarten children in Shanghai, China, should focus on control of dietary habits, including control of inter-meal snacking, and breastfeeding practices. The results of this study may help improve the status of dental caries among Chinese children.

Volume measurement of crowns in mandibular primary central incisors by micro-computed tomography.

OBJECTIVE: To determine sex differences in the tissue proportions of crowns of mandibular primary central incisors in Chinese children and to quantify the volume of crown components in three dimensions using micro-computed tomography (micro-CT). MATERIALS AND METHODS: The specimens used in this study were 41 mandibular first deciduous incisor teeth with intact crowns (21 males and 20 females) obtained from patients between 5-6 years of age. Each specimen was scanned using micro-CT at a resolution of 0.05 mm and 3D-rendered images were created. The volume of each component of the crown was measured and examined for differences in different sex and ages. RESULTS: The pulp chamber volume decreased with age and the volume ratio of the pulp chamber to the whole crown was significantly smaller in 6-year-olds than in 5-year-olds (p < 0.05). CONCLUSIONS: Males had significantly larger tooth crown volumes and dentin volumes than females did (p < 0.001), while the volume of enamel showed no sexual dimorphism.

A follow-up study on three caries activity tests.

The purpose of this research was to study the efficacy of three CAT's (Dentocult SM, Dentocult LB and Dentobuff Strip) in revealing caries condition and predicting caries progress, and provide a reference for application by comparing the three tests. Oral condition and results of the three CAT's of 82 children aged 3 to 4 were recorded and followed up. The examination was checked again two years later. The caries incidence, dft and CSI data from the two examinations were analyzed statistically. The results were that each Dentocult SM degree showed significant variances in incidence rate, as did the dft and CSI results in the second examination. The dft and CSI of both examinations exhibited a high degree of statistical significance. The same may be said of the Dentocult LB findings for the two years. No noticeable variances in caries incidence rate, dft and CSI from the Dentobuff Strip test were observed in both years' study, nor was there any statistical significance drawn from the findings, except for those of the second exam. No gender differences were observed in the distribution by degree with the three CATs The conclusion is that Dentocult SM is the best of the three tests for the diagnosis of the presence of caries and prognosis of its progress, Dentocult LB is second best whereas the Dentobuff Strip shows no detection capability. The findings serve as an application reference.

Corrosion behavior of dental alloys in various types of electrolyzed water.

The corrosion behavior of dental alloys was examined in electrolyzed strong acid water, weak acid water and neutral water using a 7-day immersion test. The precious metal alloys, gold alloy. Au-Ag-Pd alloy and silver alloy showed the greatest surface color change and dissolution of constituents in the strong acid water and the smallest in the neutral water. The release of Au from gold alloy was especially marked in the strong acid water. Co-Cr alloy showed greater corrosion and tarnish resistance in the strong acid water rather than in the weak acid water and the neutral water. X-ray microanalysis revealed that the corrosion products on the precious metal alloys were silver chloride crystals and the thin brown products on Co-Cr alloy were cobalt and chromium oxides. Ti was sound in all three types of electrolyzed water. The neutral water appeared the least corrosive to metals among the three types showing equivalent bactericidal activity.