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.
Hypodontia (the common dental term) describes a situation when fewer than 6 permanent teeth are missing, the term Oligodontia is used when more than 6 permanent teeth are missing (they were never formed). The most common missing teeth are the third molars (otherwise known as the Wisdom Teeth), followed by the premolars and the lateral incisors. Although it is not uncommon to have one missing tooth, patients with multiple missing teeth generally have a strong genetic component and it has been linked to conditions such as Ectodermal Dysplasia and several syndromes. Because early recognition aids in proper treatment, your dentist will refer you to specialists (orthodontist, oral surgeons, etc) that will determine which options suit you best to replace the missing teeth.