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UBC Theses and Dissertations

A morphological study of the formation of the dentino-enamel junction in the rat molar : the role of dentin in enamel formation Robinson, Bruce William


This thesis is a morphological study detailing the initial formation of the dentino-enamel junction (DEJ) in the rat molar. It was undertaken to determine how enamel apatite crystals are initiated during tooth development. The DEJ was investigated along its developmental gradient so that both the spatial and temporal sequences of dentin and enamel mineralization could be observed. For this investigation both conventional and selected-area dark-field electron microscopy were applied. The results of this study indicate that enamel crystals arise by epitaxial growth from preformed dentin crystals. This is supported by the temporal relationship beween dentin and enamel where dentin mineralization preceeds enamel mineralization and the intimate spatial relationship between the apatite crystals of dentin and enamel at both the newly formed and the more mature dentino-enamel junction. These results also suggest that the terminal portions of collagen fibrils in the pre-dentin matrix undergo some alteration prior to mineralization which may be related to their function in presenting dentin apatite to the enamel matrix. The interrelatonship between both the inorganic and organic matrices of dentin and enamel are presented in a working model and discussed in light of the mechanisms by which mineralized dentin may promote the formation of enamel crystals.

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