Mesiodens is the most common type of 'supernumerary' (extra) tooth. It is typically discovered on routine radiographs taken in young children (3-6 years of age) and is always located in the mid-line between the upper permanent central incisors. The most common complications of all supernumerary teeth (including mesiodens) is delayed or lack of eruption of the adjacent permanent teeth. Only about 25% of mesiodens erupt spontaneously, therefore most of them require surgical management. Treatment of mesiodens is deferred until permanent incisors have at least 2/3 of root development (between ages 7-9), since early treatment can cause damage to the unerupted permanent incisors.