Abstract Odontomas are mixed odontogenic Tumours composed of mineralized tissue of ectomesenchymal origin. These are usually detected in routine radiographs and may have a variable Aetiology such as local trauma, genetic mutation, or infection. They are classified into two main types: complex and compound. Complex odontomas are rare and they rarely erupt into the oral cavity as they lack periodontal ligament. This is the report of one such case of complex odontoma where an 11‑year‑old girl reported with an asymptomatic swelling, in relation to the left angle of the mandible. The case report highlights the clinical and radiographic findings, investigations done to arrive at the diagnosis and the treatment rendered. This report is of clinical importance because of its rare association with the agenesis of a molar tooth.