Dentin resorption in replanted monkey incisors. Morphology of dentinoclast spreading in vivo.

Dentinoclast colonization of a dentin surface was examined with special reference to changes in plasma membrane morphology during spreading and development into actively resorbing cells. Experimental cavities on the root surfaces of freshly extracted and replanted monkey incisors with infected pulps were examined with scanning electron microscopy after predetermined time intervals. The surface morphology of the dentinoclasts during the different spreading stages, and the fact that the stages appeared in a time-related mode indicated that dentinoclasts follow the general pattern of cell attachment and spreading on solid substrata, with a few exceptions unique to mineralized tissue resorbing cells. As a result, a 3-stage spreading model was proposed. In stage 1, dentinoclasts were characterized by an abundance of filopodia projecting towards the dentin surface. The cells appeared to be exploring the surface to find an area suitable for resorption. This was followed by an increase in cell size accompanied by a progressive disappearance of the peripheral filopod fringe (stage 2). Stage 3 apparently represented the final stage of adaptation and was characterized by an active resorption of the dentin surface.