Studies on the inhibitory action of sodium salicylate on dentine formation in rat incisor

Abstract

This study utilizing rat incisors was conducted in order to elucidate th e inhibitory action of sodium salicylate on dentine formation. The time marking method using lead salt was applied to analyze the dentine formation. The dose-response relationship was prominent from 250mg/kg s.c. to 650mg/kg s.c. Histochemical studies demonstrated that a narrow zone, intensely stained with hematoxylin, toluidine blue, and periodic acid-Schiff (PAS) reaction, appeared immediately after the administration of sodium salicylate (500mg/kg s.c.), the zone was followed by a faintly stained one. The faintly stained zone showed an intense staining ability for van Gieson stain and radiolucent properties. Although the serum level of 11-hydroxycorticosteroids after the administration of ACTH (100mg/kg i.m.) was higher than that of sodium salicylate (250mg/kg s.c.), the dentine formation was inhibited significantly in the case of sodium salicylate (p<0.01) but not in that of ACTH. Some structural changes in odontoblasts and/or mesenchymal cells in the pulp were noted 18 hours after the administration of sodium salicylate. These findings suggested that the dentine formation was inhibited by some direct action of sodium salicylate on odontoblasts or mesenchymal cells in pulp, rather than the secondary action through the stimulation of the pituitary -adrenal axis. Study of the structure-activity relationship also showed that the ortho position of the OH in the benzene ring is an important factor for the inhibitory action on dentine formation among the isomeric monoh droxy derivatives of sodium benzoate.