Evaluation of apical biofilm and root resorption in primary teeth

Objectives: The aim of this study was to evaluate, by scanning electron microscopy (SEM), the presence of biofilm and root resorption on the external surfaces of the apical third of roots of human primary teeth with vital or necrotic pulps with and without radiographically evident periradicular pathosis. Methods: Eighteen teeth were selected: group I – normal pulp (n=5), group II – pulp necrosis without radiographic evidence of periapical pathosis (n =7) and group III – pulp necrosis with well-defined radiographic periapical pathosis (n =6). After extraction, the teeth were washed with saline and immersed in 0.03g/mL trypsin solution for 20min.The teeth were then washed in sodium cacodilate buffer and stored in receptacles containing modified Karnovsky solution. The teeth were sectioned, dehydrated in an ethanol series, critical-point dried with CO₂, sputter coated with gold and the external root surface in the apical third examined by SEM. Results: In the teeth of groups I and II, the apical root surfaces were covered by collagen fibers, with no evidence of bacteria and root resorption (100%). In the teeth of group III, the root apices had no collagen fibers but revealed resorptive areas containing microorganisms (cocci, bacilli, filaments and spirochetes) in all cases (100%). Conclusion: It was observed that apical biofilm and root resorption were detected only in primary teeth with pulp necrosis and radiographically visible periapical pathosis.