A Rare Case of Concrescence of Mandibular Third Molar and Supernumerary Fourth Molar

Abstract

Concrescence reveals a rare developmental anomaly in which two fully formed teeth are joined along the root surfaces by cementum, and generally occurs in maxillary molars, especially in a third molar and a supernumerary tooth. Very few cases have been reported about the concrescence of a third molar and a supernumerary fourth molar. Based on our available knowledge, this case report described a rare presentation in which concrescence is observed between a third molar and a supernumerary fourth molar in the mandible by diagnosing with cone-beam CT and histological examination.

Figure 1

Preoperative CBCT examination. (a) A fourth molar in the mandible left third molar distal; (b–d) the relationship between roots and mandibular canal in coronal, transversal, and sagittal planes.

Figure 2

Surgery process and follow-up. (a) No wisdom teeth erupting, bleeding, or purulent secretion in the mouth. (b–f) Teeth extraction and alveolar reconstruction. (g) The fragment of teeth. (h, i) Removed stitches without severe complication and the defect of the alveolar socket healed well.

Figure 3

Photomicrographs of histological sections stained with the hematoxylin–eosine stain exhibiting the point of cementum fusion, revealing a real concrescence. Images obtained using (a) a 10x microscope and (b) a 20x microscope.

Figure 4

(a) Immediate postoperative panoramic examination showed the empty tooth socket; (b) after six months, CBCT examination showed good bone formation, and the alveolar bone healed well. (c) Transverse section shows increased bone density in empty alveolar bone; (d, e) Coronal and sagittal plane shows increased height of the alveolar bone.