A Case of a Dentigerous Cyst in the Anterior Mandibular Region of a 3-year-old Child

<p>Dentigerous cysts are developmental cysts that rarely occur in the anterior teeth of the mandible and are rarely reported in children younger than 5 years old. Here, we report a rare case of a dentigerous cyst caused by the left central incisor of the mandible with malposition of the adjacent tooth germs in a 3-year-old child.</p><p>A 3-year 10-month-old boy presented to our clinic with a chief complaint of swollen gingiva in the region of the mandibular anterior teeth. Upon examination, a bulge was observed in the oral cavity extending from the lingual gingiva of the anterior mandibular teeth to the floor of the mouth; the bulge had a parchment-like texture. Computed tomography (CT) findings revealed a transmission image of 17.8 × 12.9 × 14.7 mm size in the anterior teeth of the mandible, with clear boundaries and labiolingual protrusion of the cortical bone with discontinuity of the cortical bone in some parts. The transmission image contained the mandibular left central incisor tooth germ, which was compressed by the lesion and largely displaced and twisted centrifugally. After extraction of the mandibular left deciduous central incisor and deciduous lateral incisor under general anesthesia, the lesion including the mandibular left central incisor tooth germ was removed. A histopathological diagnosis of dentigerous cyst with inflammation was considered. Micro CT findings of the mandibular left deciduous central incisor indicated that the restoration found at the incisal margin reached the pulp, and an absorption fossa extending nearly half of the apical side was detected on the lingual side of the root. We believe that the dentigerous cyst was formed at an early stage and developed gradually, the inflammation from the dental pulp spread to the cyst through the apex, and the exudate rapidly entered the cyst and expanded. One year following the operation, no recurrence of the cyst was observed, and the position of the mandibular left lateral incisor tooth germ moved towards the central position with new bone formation; thus, the patient demonstrated a favorable clinical course.</p>