Dental decay is the most prevalent oral disease worldwide since more than 2.4 billion people suffer from caries of permanent teeth. Therefore, any details about its progression into the hard-dental tissues could contribute to unravelling the mechanisms underlying this process. We have analyzed dental tissue sections with and without caries in order to detect structure differences corelating them with clinical aspects observable from the tooth surface. Our working hypothesis was based on finding a link between the process of tertiary dentin laying (as a response to coronal caries) and the subsequent obliteration of dentin tubules. We have selected N=10 extracted teeth with/without coronal caries, resin-embedded and sectioned them. A specific software was used to digitally quantify the density of unobliterated dentin tubules reaching the dentin-enamel junction (DEJ), considering as positive threshold criteria the presence of the odontoblast process inside the analyzed tubule. This study showed the differences between the healthy and carious-affected hard-dental coronal tissues. More odontoblast processes reached the DEJ in unaffected teeth. Using specific software, we have quantified their density decrease near a lesion. We have studied the dynamics of the carious study and measured the consequent structural modifications of the dentin. In conclusion, there is a significant difference between the number of dentin tubules containing odontoblast processes that reach the DEJ in healthy∕altered tissues. The tooth reacts not only by production of tertiary dentin to protect the pulp chamber, but also by obliteration of dentin tubules, thus reducing the number of odontoblast processes reaching the DEJ. This pilot study could serve as the starting point in developing a dedicated software that could deliver a personalized pattern for decay progression by analyzing one single tooth and extrapolate the result to all the patient's remaining ones.