Differential rates of enamel formation of human tooth surfaces deduced from the striae of Retzius.
Ten permanent maxillary central and mandibular lateral incisor teeth were sectioned in labio-lingual or mesio-distal planes, and the amount of enamel between two striae of Retzius was measured in the vicinity of the dentine-enamel junction. In the initial third of crown formation of central incisors, both the thickness of enamel and the amount of cervical extension of enamel were always greater on the labial than on the lingual surface; the same applied to the thickness of enamel, but not to the amount of cervical extension of enamel, in the lateral incisors. The thickness of enamel together with its cervical extension was greater on the mesial than on the distal surface in the lateral, but not the central, incisors. In the cervical third of the crown, there was a general tendency for the thickness of enamel and its cervical extension to be greater on the lingual and distal surfaces than on the opposite surfaces. For the maxillary central incisors, it saw deduced that the labio-lingual reversion of the rate of development of enamel takes place at approximately the 60 per cent level of the crown formation.
D000566:Amelogenesis; D003743:Dental Enamel / Q000033:anatomy & histology*; D003804:Dentin / Q000033:anatomy & histology; D006801:Humans; D009811:Odontometry; D014070:Tooth / Q000033:anatomy & histology