Histological and Analytical Study of the Fused Tooth of Upper Second Molar and Third Molar

Abstract

The fusion of mandibular central and lateral incisors is most common. The fusion of other teeth is quite rare. The purpose of this study is to investigate the structure of the fused permanent tooth of the upper right side of a male 26 yeas old patient. In the pulp cavity of third molar, enamel was observed. The direction of enamel prism was irregular and enamel prism pattern was scale-shaped. By x-ray analytical microscopy, the enamel cavity was more radiolucent than normal enamel. This enamel had a low content of phosphorus in the element dot map. The interlobular dentin was observed remarkably in third molar. Vasodentin was present at the junction between the second molar and third molar. It is considered that this fused tooth was formed by the fusion of second molar germ in early development stage.