Abstract
SD rats were continuously given only lactobacillus drinks (Calpis or Yakult) for 9 or 12 weeks from 5 weeks of age. After that, the occlusal surfaces of the lower molars were observed by microscopy, microradiography, and scanning electron microscopy.
Calpis and Yakult accelerated the attrition of left or right molars with the aid of occlusal functions and because of the habit of taking the water bottle in the mouth. The occlusal surfaces of the dentin showed remakable changes which were considerd the effects of acid erosion. In the fissures of enamel and dentin, decalcified zones resembling early caries were frequently observed. These lesions were more clearly recognized in the molars of recieving Calpis than in those recieving Yakult.
