RESUMEN
AIM: The aim was to assess the characteristics and outcomes of infections affecting the structures of carious primary molars. MATERIALS AND METHODS: Forty primary molars were used and classified according to the following clinical situation: With profound caries lesion, with bone loss at the furcation region, with perforation of the pulp chamber floor, and residual roots. The teeth were demineralized, cut, and stained with both haematoxylin-eosin and Brown and Brenn staining techniques. Assessment was performed using optical microscopy. RESULTS: Statistical analysis of the data by means of the Chi-square test suggests that there was a significant relationship (P<0.001) between the intensity and localization of infection and the level of destruction of dental structures. A significant difference was also observed in the intensity and localization of infection between the groups regarding crown, furca, and root (P<0.001). CONCLUSION: More intense and profound the infection, more severe is the dental destruction. The groups of residual roots showed the most severe bacterial infection compared to other groups.