Effect of caries‐preventive measures in children with high numbers of S. mutans and lactobacilli

On the basis of the number of Streptococcus mutans and lactobacilli, 645 children 9–12 years old were divided into five groups. The children with the highest number of S. mutans and lactobacilli were considered to be at a high caries risk and were divided into three groups with 49 children in each. One group received preventive measures from a specially trained nurse twice a month, one group was treated once a month and the third group served as a control. The other 498 children with lower numbers of S. mutans and lactobacilli were considered to be at a lower caries risk and were divided into two groups. One group was treated once a month while the other was a control. The children with originally high numbers ofS. mutans and lactobacilli developed significantly more new carious lesions after 1 and 2 years (2.5 and 4.3) than the children with low counts in the control groups (1.9 and 2.8). All the children in the test groups which had received the preventive program developed significantly less caries than the corresponding control group. In the test risk group treated twice a month the caries activity was extremely low during the 1st year with an average of 0.34 new carious lesions. After 2 years the average was 0.92. The microbial conditions as well as the saliva secretion rate, buffer capacity and saliva pH did not seem to be influenced by the preventive program.