Evidence for a resorption inhibitor in dentin.

The ability of stimulated and unstimulated peritoneal macrophages to spread in vitro on different inorganic and organic components of dental tissues was studied in order to establish morphologic evidence in favor of a resorption inhibitor in dentin. Macrophages were seeded onto enamel, dentin, predentin, demineralized dentin and collagen-coated coverslips and examined with scanning electron microscopy after varying incubation periods. The cells readily attached and spread on enamel, dentin and collagen-coated coverslips. Cells attached but showed no signs of spreading when incubated on predentin or demineralized dentin. It was concluded that the resistance to resorption of predentin and dentin rests in the organic, non-collagenous component of the tissue, indicating the presence of a resorption inhibitor in dentin.