Development of a Rat Model for Pulpitis-derived Root Resorption

Root resorption following traumatic dental injuries, whether located along the root surface or within the root canal appears to be a sequel to wound healing events, where a significant amount of the PDL or pulp has been lost due to the effect of acute trauma. Although it is known that pulp inflammation results in a loss of tissue components within the pulp increasing the risk of root canal resorption, the molecular events leading to the resorption are not known. Objectives: In this study we present initial efforts towards developing a rat animal model for further studies to analyze the molecular determinants of root resorption due to pulp inflammation. Methods: Pulp inflammation was induced by opening the root canal from the maxillary and mandibular first molars using first a hand piece with a round bur # 1/2 to access the root canal followed with a very small file to rich the pulp. The root canal was left open for two weeks. The animals were sacrificed after 0, 3, 7, 12, 14, 21 and 28 days of the treatment and after decalcification, paraffin sections were prepared for histological analysis. Results: Our results indicate that root resorption was seen as early as 7 days after the treatment. Conclusions: This rat model is now being used for other studies directed at analyzing gene expression as result of pulpitis leading to root resorption. This study was supported by a grant from the American Association of Endodontists.