A unique case of Oehler’s type IIIB dens invaginatus in a mandibular premolar: A case report and comprehensive literature review

Background: Dens invaginatus (DI) is also known as dilated composite odontome, dilated gestant odontome, dens in dente, invaginated odontome, and dents telescopes. Although DI most commonly affects the permanent maxillary lateral incisors, it can also affect the molars. The cause is unknown; nevertheless, one possible explanation is focal growth retardation or localized external pressure on certain areas of the tooth bud, which causes the enamel organ to invade the dental papilla during the morphodifferentiation stage. The invagination of enamel organ is hypothesized to enhance the risk of caries, pulpal pathology, and inflammation of periodontium. Traditional conservative endodontic therapy can be attempted successfully in mild invagination. DI with pulpal or periapical pathologies typically entails periapical surgery with a retrograde filling, and extraction is indicated in complicated cases. The purpose of this study was to report a unique case of Oehler’s type IIIB DI in a premolar, accompanied by a comprehensive literature review. Case Presentation: An 11-year-old female child visited the Pedodontics clinic with the chief complaint of swelling on the left side of the jaw. The left mandibular region was tender on palpation and firm in consistency upon extraoral examination. Intraoral examination revealed a decayed, discolored tooth in the second premolar region with intraoral sinus and pus discharge on the buccal side. Radiographic examination revealed incomplete root formation with invagination and radicular dilation, along with an indistinct canal anatomy indicative of Oehler’s type IIIB DI. Conclusion: Extraction was the treatment of choice in this case due to chronic periapical abscess with poor prognosis of the tooth. Dental practitioners should evaluate the case thoroughly for proper diagnosis and treatment.