Mesiodens preventing eruption of a permanent central incisor

A maxillary midline supernumerary tooth is the most common type of supernumerary tooth. We present a case of a mesiodens, preventing eruption of a permanent central incisor. The aetiology, diagnosis and the effect of these developmental anomalies upon the dentition are discussed. 3 and are five times more common in the maxilla, with a male to female ratio of 2:1.4 Supernumerary teeth are less common in the deciduous dentition, with an incidence of 0.3% to 1.7%.5 A supernumerary deciduous tooth is followed by a supernumerary permanent tooth in 35% - 50% of cases. The majority of supernumerary teeth remain unerupted. It has been stated that only 25% of anterior supernumerary teeth erupt spontaneously.6 Multiple supernumerary teeth may be a feature of a syndrome, such as; cleidocranial dysostosis, Gardner's syndrome, cleft lip and palate, Fabry-Anderson's Syndrome or chondroectodermal dysplasia (Ellis-van Greveld Syndrome). 2,7 A mesiodens is an accessory supernumerary tooth present in the midline of the maxilla between the two incisors. It is the most frequent supernumerary tooth with an overall prevalence of 0.15% to 1.9%.8 It may occur individually or as multiples (mesiodentes). A mesiodens that is palatally located is the most common type, and is usually unerupted. This type of supernumerary tooth often prevents the maxillary incisors from contacting each other, resulting in the formation of a mid-line diastema.