Abstract

Five fetal maxillas were obtained from the autopsy file of fetal postmortem examination, and were examined by serial micro-sections of frontal plane and horizontal plane. Especially the area around the incisive canal of the maxilla was carefully observed. The results are as follows. 1) In 5 fetal maxillas extra-dental laminas and supernumerary tooth germs which are severely malformed in shape are found in the dilated incisive canal, where prominent vessels and nerves are distributed. 2) The supernumerary tooth germs disclose almost normal histo-differentiation of odontoblast and ameloblast, and there shows relatively abundant perifollicular fibrosis in the place of perifollicular bone. 3) It is observed that the over-growth of the extradental lamina from the dental ridge of deciduous central incisor frequently tends to direct toward the incisive canal that includes prominent vessels and nerves.

• Keywords: Supernumerary tooth germ;Mesiodens;Incisive canal;Fetus;