Background Considering that the Lactobacillus casei group is strongly associated with caries progression, the use of lactobacilli as probiotics must be balanced due to their possible involvement in dental caries. Objective This study aimed to detect and quantify L. paracasei, L. rhamnosus, and L. casei group species in the active and arrested dentinal lesions of preschoolers. It also aimed to determine the expr...