Many studies have shown the effects of chewing xylitol gum on mutans streptococci (MS) over short- and long-term periods in children; however, few studies have addressed long-term periods in adults. The objective of this investigation was to examine for 6 months the effects of chewing xylitol gum on MS in saliva and plaque in 127 adults (mean age 28.0 years). The participants were assigned to three groups according to gum type, in part taking preference for flavor into account and in part at random: xylitol (XYL), maltitol (MAL) and control (CR); 33, 34 and 27 subjects in each group, respectively, completed the trial. Daily gum use of the XYL and MAL groups was 7.9 and 7.1 g, respectively. MS levels, which declined significantly in saliva (p < 0.05) and plaque (p < 0.001) in the XYL group after 6 months, exhibited a significant increase in plaque in the MAL group (p < 0.001). Differences in relative changes of MS levels in plaque during the experimental period were significant between the XYL group and the CR (p < 0.05) and MAL groups (p < 0.001). Differences in relative change of amount of plaque during the experimental period were not statistically significant between the groups. The present study demonstrated that chewing xylitol gum for 6 months continued to inhibit the growth of mutans streptococci in adults.

The findings of this study conducted in 1987 in Japan parallel those reported by Dean et al. in the early 1940s.

These results indicated the presence of a striking association between smoking and pigmentation in the lip and gingiva, which was stronger with respect to gingival pigmentation. Health professionals could educate smokers, utilizing visible symptoms in the lip and gingiva.

Children who began rinsing at 4 or 5 years of age benefited the most from the program. The program was inexpensive, simple to implement and well accepted by families and teachers. The conservative treatment policy in the public clinic likely contributed to the benefits derived by participants.

Community differences in caries prevalence in deciduous teeth were investigated. The Community Organization Data Base System (CODB) includes the data of 3-year-old children's dental examinations from 112 communities (cities, towns and villages) in Niigata prefecture in 1983, 1984 and 1985.This CODB also includes the data of 141 items concerned with community characteristics.