Apoptosis activation in human carious dentin. An immunohistochemical study

The exact mechanisms and enzymesinvolved in caries progression are largelyunclear. Apoptosis plays a key role in dentinremodelling related to damage repair; however,it is unclear whether apoptosis indecayed teeth is activated through theextrinsic or the intrinsic pathway. This exvivo immunohistochemical study exploredthe localization of TRAIL, DR5, Bcl-2 andBax, the main proteins involved in apoptosis,in teeth with advanced caries. To evaluateTRAIL, DR5, Bcl-2 and Bax immunoexpressionstwelve permanent carious premolarswere embedded in paraffin andprocessed for immunohistochemistry. Theresults showed that TRAIL and DR5 wereoverexpressed in dentin and in pulp vesselsand mononuclear cells; strong Baximmunostaining was detected in dilateddentinal tubules close to the lesion, and Bcl-2staining was weak in some dentin areasunder the cavity or altogether absent. Thesefindings suggest that both apoptosis pathwaysare activated in dental caries. Furtherstudies are required to gain insights into itsbiomolecular mechanisms