[A histological observation of the primary teeth with enamel hypoplasia resulting from perinatal disturbance].

Two primary teeth with enamel hypoplasia from two cerebralpalsied children were subjected to histological examination. One primary tooth was B and the other was C. The location of enamel hypoplasia in these teeth was considered to coincide with the neonatal line reaching the enamel surface. The purpose of this study was to examine the location of the enamel hypoplasia in these teeth in relation to the neonatal line, and to detail the histological structure of the teeth. They were examined morphologically as well as histologically, by using a stereoscopic microscope, SEM, a light microscope and a microradiogram. The results obtained were as follows: 1. The size of the tooth crown of these teeth was smaller than the normal standard, but the form of tooth crown was normal. 2. Based on streomicroscopic observation, enamel hypoplasia was found on the labial and lingual surfaces in B, and on labial surface only in C. In B, the enamel hypoplasia on labial surface was extended widely to incisal 2/3 of the crown, while that on the lingual surface was minimum. In C, there were two spots of enamel hypoplasia located on the mesial and distal incisal edges respectively. 3. Based on SEM observation, the hypoplastic enamel was formed right after their birth. 5. Based on microradiographic observation, the neonatal lines were radiolucent, and the adjacent areas of the neonatal line did not show any poor calcification. 6. From these histological observations, it was found that the perinatal disturbance directly affected the tooth enamel formation and these enamel hypoplasias were positively caused by the cerebral palsy of these children.