Sulcal Caries Research Articles

Pre- or Post-Eruptive Effects of Strontium Alone or in Combination with Fluoride on Dental Caries in the Rat

Doses of strontium were given pre-eruptively to rats at 0.0, 2.5, 5.0 and 10.0 μg Sr/10 g body weight, with or without fluoride at 1.0 μg/l0 g body weight by esophageal intubation. In a second experiment strontium at concentrations of 0, 50, 100 and 150 mg Sr/l, with and without fluoride at 10 mg/l, were given via the drinking water post-eruptively. Caries scores were made for buccolingual, morsal, sulcal und proximal lesions in all rats. Slight reductions in buccolingual caries scores were seen in rats given 5.0 μg Sr/10 g body weight pre-eruptively. Rats given post-eruptive doses of strontium only showed marked reductions in buccolingual scores with 50 mg Sr/l, and 10 mg F/l. No effect was seen on morsal, sulcal or proximal caries scores for any of the treatment regimens. The greatest reductions in buccolingual caries scores were found when a combination of 50 mg Sr/l and 10 mg F/l was given post-eruptively.

Pre-eruptive effects of Mo, B, Sr and F on dental caries in the rat

Pre-eruptive effects of trace elements on dental caries have not been extensively evaluated. To investigate the effect of Sr, Mo or B alone or in combinations with F, male rat pups were intubated oesophageally daily from 4 to 17 days of age. The rats were fed a high sucrose, caries-promoting diet from 18 to 35 days of age, killed and the first and second mandibular molars evaluated for carious lesions. Fluoride ( 100 μg 10 g body wt/day) reduced buccal enamel lesions by 50 per cent but did not reduce sulcal caries. Strontium and Mo at 500 and B at 150 μg 10 g body wt/day increased buccal dentine-enamel (Ds) lesions by 80, 85, and 43 per cent, respectively, and increased sulcal caries slightly. Strontium. Mo, or B, given in combination with F, increased buccal (Ds) caries by 63, 56 and 145 per cent, and increased sulcal (Ds) lesions by 27, 43 and 48 per cent, respectively, as compared to control values. The results demonstrate that administration of Sr, Mo or B, at these levels throughout the pre-eruptive period only, causes an increase in dental caries. Concomitant administration of F was ineffective in reversing the effect of Sr, Mo or B. In fact, sulcal lesions were augmented by each of the combinations and deep buccal caries was greatly enhanced when both B and F were given together. These data have important implications concerning pre-eruptive systemic exposure of teeth to F in the presence of other elements.

Variable experiences in immunization of rats against Streptococcus mutans-associated dental caries

Studies were conducted to test possible immunization of rats against Streptococcus mutans strain 6715-associated dental caries. Rats were infected with streptomycin-resistant virulent 6715 after formalin-killed cells of 6715 were injected subcutaneously distant from the salivary glands. High humoral agglutinin titres were elicited and a salivary antibody response was observed both by agglutination and by indirect fluorescent antibody techniques. No differences could be detected in the recoveries of Strep. mutans from the teeth or in the amount of dental plaque on the teeth between infected-immunized and infected-un-immunized animals. Smooth surface caries was essentially dependent on infection by 6715. Sulcal caries, while not dependent upon infection by strain 6715, was augmented by it. There was an apparent although variable protection of rats against caries associated with Strep. mutans infection. The immunization regimen was associated not only with reduction of smooth surface caries scores, but also with reduction of sulcal caries scores when the contribution of Strep. mutans to the sulcal disease was most prominent. Absence of weight variations between animal groups suggested that the observed caries reductions could not be ascribed to alteration in food intake resulting from the immunization regimen.

Caries control in the albino rat with chlorhextdine gluconate (Hibitane)

Varying concentrations of chlorhexidine gluconate (Hibitane) were added to the drinking water of albino rats maintained on caries promoting diet MIT No. 200. Animals receiving chlorhexidine showed reductions in buccal caries scores ranging from 31 to 75 per cent. Animals receiving 0.2 per cent chlorhexidine were found to consume less liquid and exhibited an impaired ability to gain weight. Although sulcal caries scores in animals receiving chlorhexidine were lower than scores of controls, the effectiveness of chlorhexidine on sulcal caries did not seem as great as on buccal surface caries. An attempt to increase the animals' acceptance of chlorhexidine by adding sucrose to the liquid produced apparent changes in liquid intake, which could not be replicated, however. By the termination of the experiment, the animals consuming chlorhexidine displayed varying degrees of hair loss. In microscopic studies, some animals exhibited an enhanced translucency of the enamel. It is concluded that chlorhexidine gluconate effectively reduces the incidence of caries in the albino rat, but body weight and tissue changes suggest the need for additional toxicity studies.

Reduction of rat caries by trimetaphosphate on different tooth surfaces: Variations produced by diet and oral flora

Osborne-Mendel rats fed coarse particle Diet 585 developed mostly sulcal lesions and showed no increase in caries as a result of being inoculated with exogenous mixed cariogenic flora including a strain of Streptococcus mutans. Uninoculated rats fed high sucrose Diet 2000 developed mostly sulcal lesions, while the inoculated animals showed some increase in the sulci and a very pronounced increase on the smooth surfaces. The addition of TMP to both of the diets was associated with a limited, but significant, reduction in sulcal caries and almost complete elimination of smooth surface lesions, which were already low on Diet 585 and a highly significant reduction on Diet 2000.