Supernumerary teeth as mesiodens could develop concurrently with the natural teeth and have root formation(conical type) or develop late with incomplete root formation (tuberculate type). Of mesiodens, 90-98% occur in the maxilla with a particular predilection in the maxillary anterior region.
The purpose of this study was to examine clinical and histopathologic study of 24 mesiodens, which were not odontectomized. For undemineralized resin sections, specimens were fixed in 10% buffered neutral formalin, dehydrated by 70-80% alcohol and aceton, embedded with Spurr low viscosity resin, 500㎛ resin sections cut by low speed diamond wheel saw, grinded up to 100-150㎛, and examined by LM and PM. The results were as follows.
1. Clinical study showed the sex predilection of mesiodens for males over females(2 : 1), while age distribution was ranged from 3 to 9 years. Conical type were 18 cases, tuberculate were 6 cases. The vertical impaction of mesiodens was more than the horizontal impaction. It was usually located between the central incisors usually and its impaction depth was below the periapical area.
2. Light and Poralized microscopy features showed irregularly arranged enamel prisms, prominant striae of Retzius, and untypically Hunter-Schreger bands in the mesiodens. In many cases, lingual enamel of mesiodens is thicker than labial enamel.
3. The dentin of mesiodens in the periapical area was usually composed of regularly arranged dentinal tubules, and was hypomineralized in PM observation.
4. Cementoenamel junction of mesiodens was hypomineralized. Conical type of mesiodens showed irregular cellular cementum but tuberculate type of mesiodens only showed acellular cementum.
5. Mesiodens usually showed relatively shorter root length and incomplete root development.
From the aboving results, we suggest that mesiodens which have underdeveloped roots and irregularly calcified cementum, will be difficult to erupt into the oral cavity in the proper process. Therefore, we thought that early extraction of mesiodens would be recommended.
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