Changes in the oral environment after placement of removable dentures in low caries risk patients

Abstract

Japan has a high distribution of aged citizens. Dental treatment significantly contributes to a high QOL in the elderly. Many people lose teeth because of caries and/or periodontal diseases. It is important to find the causes for this and to take preventive measures. In particular, systemic diseases in the elderly tend to worsen the oral environment, leading to an increased risk of caries. The caries activity test is useful in understanding the oral environment. A simple chairside test can measure the patient’s unstimulated and stimulated salivary flow rate, unstimulated and stimulated salivary buffering capacity, and salivary microbial counts, including mutans streptococci, lactobacilli and Candida. Information on these oral environment factors can aid in preventing caries based on individual risk, and extending the life of dental restorations. In Japan, missing teeth are usually replaced by fixed or removable prostheses. Using the saliva test, Narhi reported that salivary microbial counts were greater in elderly with dentures than in those with natural dentition. Our cross-sectional study, which used the same saliva test, reported that there were large differences in the number of cariogenic bacteria in the oral environment of elderly with fixed prostheses compared with those who had removable prostheses. Although these studies suggested that removable dentures may influence salivary microbial counts, it is still unknown whether they contribute to an increase in the counts. We did a follow-up study that examined the oral environment over time of low caries risk patients after initial placement of removable prostheses.