Prevalence of root caries in a selected population of older adults in Japan.

In this study, the prevalence of root caries in a sample of Japanese elders was investigated along with various aetiological factors. Two hundred and eighty-seven independently living elderly people over the age of 60 years were examined for the prevalence of active, inactive, and filled root lesions as well as the number of teeth. General health, oral status and brushing habits were surveyed, and salivary flow was determined in terms of flow rate and subjective feeling of dry mouth during eating. About 39% of the subjects had one or more decayed roots and 53.3% had at least one decayed or filled lesion. Root caries was seen most frequently on canine teeth followed by the first premolar. The number of decayed or filled lesions increased with increasing number of residual teeth (Kruskal-Wallis test, P = 0.033), however, there was no association between the proportion of teeth with root decay and the number of teeth. For subjects with 20 or more teeth, the number of decayed roots is likely to be lower in subjects who reported brushing frequently (P = 0.058), and higher in subjects with low salivary flow (P = 0.059) or subjective feeling of dry mouth (P = 0.052) (Chi-squared). The presence of decayed lesions is likely to be related to dry mouth (P = 0.057, odds ratio 3.13) and brushing frequency (P = 0.088, odds ratio 1.76) (Multiple logistic regression analysis). The results indicate a high frequency of root surface caries in this Japanese community-dwelling older population. Oral hygiene status and low salivary flow or perceived dry mouth were potential risk factors for disease.