STUDIES ON SALIVARY LACTOBACILLI AND DENTAL CARIES IN CHILDREN DURING A DENTIFRICE TEST PROGRAM

¹ Dental Research Laboratory, College of Dentistry, The Ohio State University, Columbus, Ohio

1. A dentifrice containing a dichlorophenyl methane compound was tested, with a control dentifrice, for effect on dental caries increment and salivary lactobacilli in a group of school children. By comparison with the control, the experimental dentifrice had no effect on caries increment, on total number of salivary lactobacilli, on numbers of different colony types of salivary lactobacilli, nor on the ability of salivary lactobacilli to ferment sucrose in vitro.

2. The children showed increments of new carious lesions averaging 2.25 at 6 years, 2.23 at 7 years, 1.96 at 8 years, 2.08 at 9 years, 2.77 at 10 years, 3.22 at 11 years, 4.71 at 12 years, and 5.45 at 13 years. This increment of new lesions revealed by bite-wing x-rays and very careful clinical examinations may appear high when compared with results obtained by less exacting methods.

3. The study group of 394 Ohio children, aged 6 to 14 years, were examined for number and kind of salivary lactobacilli and for dental condition (DMFS) at the beginning and 339 of the children, at the end of a 1-year period. At both examinations, salivary lactobacilli counts of less than 10,000 per ml. were more common than higher counts in this group of children. Lactobacilli of smooth colony morphology were observed more frequently than those of intermediate or rough morphology in the saliva samples examined.

4. In individuals, total salivary lactobacilli counts at the first examination showed no apparent association with past caries history (DMFS scores) determined at that time.

5. Total restoration of carious lesions was found to be associated with lower salivary lactobacilli counts and lower subsequent caries incidence than was found in subjects who had only partial or no restorations of carious lesions.

6. In each child, the average of 3 salivary lactobacilli counts made at the first examination was compared to the dental caries increment during the following year. The data showed a relationship between magnitude of salivary lactobacilli counts and future dental caries, which was, however, apparent only in grouped data, and was not clearly expressed in individuals. The results indicated that 3 closely-spaced salivary lactobacilli counts could not be used for successful prognosis of future dental caries on an individual basis in this group of children.

7. A number of children in this study were found to have caries-free permanent dentition at the first examination. Neither salivary lactobacilli nor the history of caries in deciduous teeth could be associated with either caries attack or continued caries freedom in these children during the study year.