Human root caries: histopathology of advanced lesions.

The histopathology of human root caries was examined in extracted teeth. The present study details several stages of advanced carious lesions in root dentin. Lesions of different severities were assessed by different optical methods. Four major root caries patterns were defined and significant differences between coronal and root caries elucidated. The patterns were distinguishable by (1) their location at the exposed root surface, (2) their mode of spreading towards the root canal and over the root surface, (3) their mode of bacterial spreading in dentin and (4) the role of dentinal defense mechanisms. In addition, a comparison of clinical and histological classification of lesions revealed that the carious process extended much deeper towards the root canal and had a higher degree of both bacterial infection and dentin demineralization than could be predicted by clinical examination.