From the Initial Carious Lesion of Enamel to the Early Development of Coronal Dentin Carious Lesion

Abstract

Once the initial carious decay crosses the whole enamel thickness, diffusion occurs at the dentinoenamel junction, mostly in the mantle dentin direction where the dentinal carious decay displays an early development. After the collapse of the non-sustained enamel surface, a cavity starts to be formed, containing residual food debris (zone of degradation), above a zone of bacterial invasion. The demineralized dentin layer displays an infected zone, where dentinal tubules are enlarged. They are filled with active bacteria. Intertubular dentin is demineralized, removable manually by sharp curettes and forming the soft carious dentin. The affected zone is located beneath. Intertubular dentin is gradually recovering from the demineralization process. The lumens of tubules display normal diameter, and the peritubular dentin gradually reappears. In the sclerotic zone, either reprecipitation of non-apatitic mineral contributes to fill partially the lumen of the tubules or apatitic-like structures seal more or less homogeneously the lumen of tubules (intratubular mineralization). The subjacent layer contains lipid-loaded odontoblast processes. These cells contribute to the formation of reactionary dentin. They are implicated in slowing down the speed of diffusion of the carious lesion in the crown.