Association of salivary mutans streptococci with DMFT index in elderly

Objectives:

Salivary mutans streptococci level has been reported to be associated with the prevalence of caries in children or young adults. However, microbiological etiology of caries in elderly people has not yet been fully clarified.

The purpose of this study was to examine the association of the salivary mutans streptococci (S. mutans and S. sobrinus) levels with decayed, missing, filled teeth (DMFT) index in a sample of independent-living elderly.

Materials & Methods:

The study sample consisted of independently-living, cognitively healthy 240 elderly people (115 men and 125 women) aged 60-80 years. The number of natural teeth, including those with restorations, and their decayed lesion were determined without any additional cleaning. Stimulated whole saliva was collected by mastication method for 2 minutes. Salivary levels of S. mutans and S. sobrinus were estimated using the real time PCR (Saliva-check LAB PCR, GC Corp., Tokyo, Japan).

Differences in DMFT index were evaluated using the one way ANOVA, followed by multiple comparisons and the stepwise multiple linear regression analysis. P-values less than 0.05 were considered to be statistically significant.

Results:

Mean number of residual teeth and DMFT index were 25.0 (SD=5.4) and 15.3 (5.7), respectively. DMFT was significantly higher in subjects harboring 105 CFU/mL and more of S. mutans (34.6% of total subjects) and in subjects harboring 104 CFU/mL and more of S. sobrinus (18.8%).

The stepwise multiple linear regression analysis showed that DMFT index was independently associated with salivary S. mutans level (partial Beta=0.13, P<0.05) and with S. sobrinus level (partial Beta=0.18, P<0.01) after controlling for age, gender or salivary flow rate.

Conclusions:

These results indicate that the salivary levels of S. mutans and S. sobrinus are significantly and independently associated with DMFT index in the elderly.

This study was supported in part by a Grant-in-aid for Scientific Research (19390496) from

the Japan Society for the Promotion of Science.