Electron-microscope study of changes and calcification in dental matrix with experimentally induced formative disturbances

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1. Disturbance in dentin formation (1) Vinblastine administration: within the apical predentin, segmental collagen aggregates 320nm in length and 200nm in width with a structure consisting of numerous symmetrical bands were observed. With the passing of time, this abnormal collagen shifted towards and was incorporated into the dentin. (2) Sodium fluouide administration: One hour after NaF adminisration, segmental collagen aggreagtes and a large amount of an amouphous material containing a substance positively stainable to ruthnium red (acid-mucopolysaccharide) appeard. Six hours after administration, fibrous long-spacing collagens with 160nm periodic striation were observed. When they approached the calcification front, these two abnormal kinds of collagen were calcified as a result of crystal deposition. Observation of decalified sections revealed a fine linear structure in the abnormal collagen and slack connections among collagen molecules.2. Disturbance in enamel formation (1) Vinblastine administration: Forming enamel crystals were more slender and the enamel demonstrated a lower degree of calcification 24 hours after administration. Five days after administration, the surface of mature enamel was irreglar, and the enamel contained large amounts of organic matrix and cell fragments. (2) Sodium fluoride administration: Enamel-rod structure in the forming enamel was indistinct and an abnormal enamelwith slender crystals had formed 24 hours after administration.