Pathomorphological changes in dentine covered with artificial crown were studied in 40 decalcified teeth extracted from patients aged 35-61 years. The study of the decayed dentin microscopic structure revealed the uniform mineralization of dentinal tubules in 20% of cases, while in the absence of visually apparent caries it was present in 80% of cases. Irregular dentin structure was seen in 45% of caries cases and in 30% of observations with no signs of caries. Predentine distrophy and odontoblasts elimination in the decayed teeth was found in 55% of the observations while in the absence of caries lesions these features were seen in 70% of cases.