Response to Intracanal Medication in Immature Teeth with Pulp Necrosis: An Experimental Model in Rat Molars

Abstract Introduction The present study aimed at developing an experimental model in rat molars for evaluating treatment strategies in necrotic immature teeth. Methods To define the periods to be adopted in the experimental procedures and to confirm induction of periapical lesions and interruption of root embryogenesis, the left lower first molars of 4-weeks-old Wistar rats underwent pulpectomy and were left open to the oral environment. Comparisons with the right lower first molars (vital teeth) were performed in animals with ages of 7, 10, 13, and 16 weeks. In another group of animals the teeth were left open for 3 weeks, and then interventions for disinfection including the use of an antibiotic paste were carried out. Root formation was then assessed after 3 and 6 weeks on the basis of radiographic and histologic evaluation. Results Vital teeth showed increase of root length and hard tissue thickness throughout the experimental periods. On the other hand, induction of necrosis arrested root formation. Teeth subjected to disinfection with sodium hypochlorite associated with the triple antibiotic paste showed significant reduction of periapical lesions, gain in root length, and increased wall thickness compared with the control ( P < .05). Conclusions The root canal disinfection protocol used was able to reduce periapical lesion size and improve root development. The experimental model presented should contribute to studies that aim at improving therapeutic strategies for necrotic immature teeth by using a rat model.