Clinical, radiographic, and histological observation of a human immature permanent tooth with chronic apical abscess after revitalization treatment.

INTRODUCTION Revitalization procedures have been widely used for the treatment of immature permanent teeth with apical periodontitis. The treatment procedures appear to be capable of encouraging continued root development and thickening of the canal walls. The nature of tissues formed in the canal space and at the root apex after revitalization has been shown histologically in several animal studies; similar studies in humans were recently reported. METHODS A 9-year-old boy had a traumatic injury to his upper anterior teeth. Tooth #9 suffered a complicated crown fracture with a pulp exposure, which was restored with a composite resin. The tooth developed a chronic apical abscess. Revitalization procedures were performed on tooth #9 because it was an immature permanent tooth with an open apex and thin canal walls. Twenty-six months after revitalization, the tooth had a horizontal crown fracture at the cervical level and could not be restored. The tooth was extracted and processed for routine histological and immunohistochemical examination to identify the nature of tissues formed in the canal space. RESULTS Clinically and radiographically, the revitalization of the present case was successful because of the absence of signs and symptoms and the resolution of periapical lesion as well as thickening of the canal walls and continued root development. The tissue formed in the canal was well-mineralized cementum- or bone-like tissue identified by routine histology and immunohistochemistry. No pulp-like tissue characterized by the presence of polarized odontoblast-like cells aligning dentin-like hard tissue was observed. CONCLUSIONS The tissues formed in the canal of revitalized human tooth are similar to cementum- or bone-like tissue and fibrous connective tissue.