Ultrastructure of initial calcification in wound healing following pulpotomy.

Initial calcification in healing amputated tooth pulps was examined in a transmission electron microscope (TEM). The process is characterized by an abundance of extracellular matrix vesicles (0.1-0.2 micrometer in diameter) distributed between forming cells and the surface of the amputated pulp. Osmiophilic material and needle-like crystals within the vesicles was followed by disappearance of the vesicular membrane and accumulation of crystals and aggregate into calcified fronts. Ca and P were detected in these needle-like crystals by an electron probe X-ray microanalyzer. This finding suggests that the crystals were produced during the calcifying process. The healing of amputated tooth pulps is essentially similar to initial calcification events that occur in other normal and pathologic calcified tissues.