Effects of particle size of corn and sugar diets and of mastication on caries incidence in Osborne-Mendel rats

Rodent model in caries research

The rodent model of dental caries has made fundamental contributions to the understanding of the etiology, pathogenesis, and prevention of this disease. In conducting animal-based investigations, important details considered essential for successful outcome are occasionally overlooked. Adequate number of animals of appropriate age should always be included to ensure sufficient statistical power to draw valid conclusions. Attention should be paid to litter source as it is clear that litter origin may have a profound effect on the outcome. Inclusion of additive in diet may also affect eating pattern. A range of special techniques are available which can expand the role of animals in exploring the pathogenesis of dental caries. The arrival of genetically altered microorganisms along with availability of knock-out rodents offers exciting challenges to further explore the pathogenesis of this still too common disease.

Morphological study on dental caries induced in WBN/KobSlc rats (Rattus norvegicus) fed a standard laboratory diet

In our previous studies, WBN/KobSlc was characterized as a rat strain in which only males began to develop pancreatitis, and then presented with diabetic symptoms. In the course of studying their pancreatic inflammation, we detected molar caries in prediabetic males feeding on a standard diet (CRF-1) widely used for experimental animals. The purpose of this study is to confirm whether the WBN/KobSlc strain is caries-susceptible to the diet reported to be non-cariogenic, and to examine the effect of a prediabetic condition on their dental caries. For a morphological study, 25 male WBN/KobSlc rats aged 3.2–7.8 months and 24 females of the same strain aged 3.3–6.6 months were used, along with 10 males and 10 females of 8.2-month-old F344 rats. Marked dental caries were detected in the mandibular molars of male and female WBN/KobSlc rats regardless of pancreatitis, although no similar changes were observed in any teeth of the F344 strain fed the same diet. Soft X-ray examination revealed that the caries began in the crown and progressed horizontally and vertically, and that a severe radiolucent lesion extensively expanded to the entire crown, corresponding to a macroscopically deleted molar. The caries had gradually developed mainly in the second mandibular molar from more than 3.5 months of age, while none were seen in any rats before that time. The WBN/KobSlc rats were caries-susceptible even to the standard laboratory diet, and pancreatitis was not directly associated with the onset of dental caries in this strain.

Fermentation of carbohydrates in different flours by Streptococcus mutans

The ability of Streptococcus mutans to ferment carbohydrates and to produce acid was investigated in different flours in vitro. The amounts of acid produced suggest a possible ecological role of the tested flours in the occurrence of Strep. mutans in dental plaque.

A method for the intraoral determination of the cariogenicity of foodstuffs: a preliminary report

A technique is described for testing the cariogenicity of various foodstuffs. With this method carious attack can be observed in its early and clinically undetectable stages.

Effect of sweet biscuits on the incidence of dental caries in rats

1. Biscuits baked to a recipe requiring only sucrose, white flour and water were ground to a powder and mixed with the remaining ingredients of a standard rat diet. The control diet contained the same dry-weight amounts of all ingredients, but the sucrose and flour were not baked into biscuits. Eighty-four rats were divided into two matched groups and fed on the diets for 8 weeks from weaning.

2. The biscuit diet produced significantly more caries than the control diet, with a total of about twice as many lesions, and also many more advanced lesions. Nearly all the lesions were in the molar fissures, suggesting that the cooked and powdered biscuit was impacted and retained in the fissures.

Effects of sodium chloride and sucrose on caries activity in rats

Studies of caries activity in caries-susceptible white rats fed sucrose diets and drinking water that contained sodium chloride suggest that sodium chloride may alter the cariogenicity of sucrose.