Abstract
Cytotoxic effects of unpolimerized composite resin which was given through the dentin tubules to the human pulp tissue were evaluated in vitro.
Human fibroblast-Like cells(pulp cells) were isolated from extracted primary and permanent tooth pulp. The Bovine permanent tooth was cut into a dentin slice(thickness: 2 mm), and a cavity(diameter: 2 mm, depth: 1.7 m) was prepared in the slice. The cavity was filled with a composite resin (AP-X®), B-2, Kuraray Co. ) which was either light-polymerized or unpolimerized. Pulp cells on which the dentine slice containing composite resin was placed by using the cell-culture insert®(Falcon)were cultured for 24 hours.
The number of surviving cells was counted after Trypan blue staining. In order to determine whether or not apoptosis occured in the cultured cells, fragmented DNA was extracted and electrophoresis was performed using 2% agarose gel. Concentration of IL-1β in the conditioned medium was determined by enzyme-linked immunosorbent assay(ELISA).
The number of surviving cells decreased in both primary and permanent pulp cultures when the dentin slices filled with unpolimerized resin were applied. Polymerized resin had no cytotoxic effect on the cultured cells in the same culture condition. DNA fragmentation was not observed even when the unpolymerized resin affected the viability of the cells. IL-1β, which is often produced by inflamatory tissues, was detected in neither of the resin-treated cell cultures.
These results indicated that unlike polymerized resin, unpolymerized resin components could pass through the dentin tubules and had cytotoxic effects on cultured cells. We conclude that the unpolymerized resin-induced cell death was apoptosis, as revealed null DNA fragmentation, but necrosis.
