No abstract

Interglobular dentin formation, as described in textbooks of dental histology,' 2 is the result of normal matrix formation but failure of complete fusion of the calcospherites during the calcification period that follows.Schour and Poncher,3 Kronfeld and Schour,4 and Blackerby5 have observed that in deciduous teeth the prenatal dentin appeared homogeneous without interglobular spaces, whereas postnatal deciduous dentin contained varying intensities of interglobular space formation. These observations and the universal appearance of interglobular dentin in permanent teeth reported by Katayama,6 Nishiyama,7 Erva,8 and Nakajima9 have led to the assumption that, as far as dentin calcification is concerned, the prenatal period provides more optimum nutritional conditions than the postnatal period.It was the purpose of this study to examine serial ground sections from a large number of extracted deciduous central and lateral incisors, canines, and first and second molar teeth and to reveal the distribution of interglobular spaces in these organs. A histologic section and a historadiograph of a typical longitudinal ground section are also described. MATERIALS AND METHODSA large random sample of extracted deciduous teeth from native Japanese patients was examined. Most of these teeth were unidentifiable because of exfoliative root resorption and marked coronal attrition. Only recognizable typical teeth, including a few containing very small cavities, were used in this study. The top line of Table 1 shows that 41 central incisors, 47 lateral incisors, 42 canines, 47 first and 42 second molars, or a total of 219 teeth, were included.Each tooth was imbedded in plastic, and labio-or buccolingual longitudinal serial sections, each about 150 u thick, were cut with a thin sectioning machine.* At least four serial sections were obtained from each incisor and twelve from each molar. These serial ground sections were examined under a microscope using transmitted light, a 9X eyepiece and a 1oX objective.Each type of tooth was classified according to the frequency of occurrence of the interglobular spaces seen in the serial ground sections, and the values arranged in the table in one of three groups as follows: Group I, no interglobular spaces; Group II, a few interglobular spaces; and Group III, many interglobular spaces.