It is generally believed that hard tissues such as bone or dentine is resorbed by multinucleated giant cells called clastic cells. However, resorption of the nonmineralized superficial layers of mineralized tissue such as osteoid tissue and predentine is still debated. Therefore, the fate of these superficial nonmineralized layers in the initial events involved in tooth resorption and characteristics of the associated cells were studied. The results obtained were as follows.
Before multinucleated giant cells appeared, nonmineralized predentine layer appeared to be intact and was covered with an odontoblastic layer. Concomitantly with beginning of resorption, odontoblasts began to degenerate, becoming atrophied or flattened. Multinucleated giant cells appeared on the predentine surface had ruffled border and clear zone. It formed typical resotption lacunae on the predentine surface. Completion of predentine resorption followed by dentine resorption by multinucleated cells.
These results suggest that superficial nonmineralized layers, such as predentine, also can be resorbed by multinucleated odontoclasts, probably in much the same way as dentine resorption.
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