Influence of colonization with mutans streptococci on caries risk in Japanese preschool children: 24 month survival analysis.

PURPOSE This study evaluates how various microbial- and salivary-related risk factors influenced the hazard for caries development in preschool children. METHODS The study population consisted of 131 subjects (age: 0.5 to 6.0 yrs). Oral examination, including two bacterial tests and buffering capacity test, was conducted at six month intervals over 24 months. A survival analysis was used to describe caries hazard over a 24-month follow-up period. A Cox proportional hazards regression analysis was performed to test the influence of salivary mutans streptococci (MS), aciduric bacteria, buffering capacity and age on caries development. RESULTS Of the total subjects, 60 children (46%) were found to be caries-free at baseline. Caries hazard correlated significantly with salivary MS levels at baseline (relative risk, 1.7; P = 0.003), but not with aciduric bacteria and buffering capacity. This analysis showed that all of children with high colonization of MS at baseline had dental caries 15 months later. CONCLUSION The results suggest that salivary MS level at baseline influenced caries hazard in preschool children.