The most common of the supernumerary teeth in humans are mesiodentes, which arise in the midline of the maxilla between the central incisors. The most common pathologic findings associated with a mesiodens are retention of the adjacent incisors, malposition, and diastema. The development of a dentigerous cyst in association with an impacted mesiodens is relatively uncommon. We report the case of a 35-year-old man with an extensive dentigerous cyst associated with a mesiodens who presented with a painful swelling in the left nasolabial area. We discuss the imaging findings in this case, particularly the contribution of computed tomography, and we review the literature on this interesting condition.