ULTRASTRUCTURE OF WOUND-HEALING FOLLOWING DIRECT PULP CAPPING WITH CALCIUM-BETA-GLYCEROPHOSPHATE (CA-BGP)

Tissue changes in rat incisors after direct pulp capping with calcium-beta-glycerophosphate (Ca-BGP) have been studied using light and electron microscopy. Immediately after pulp capping, Ca-BGP was converted to hydroxyapatite (HAP) at the cavity floor. At Day 1, the exposure site was covered with Ca-BGP-mediated mineralized tissue. Osteodentine had developed below this mineralized tissue at Day 3. Matrix vesicles (MV) were observed in the extracellular matrix between large cells and osteodentine. At Day 5, tubular dentine was observed below the osteodentine. Three days after the application of Ca(OH)2 in a control experiment, osteodentine had formed below the necrotic zone; however, tubular dentine was not observed at Day 5. These findings suggest that the applied Ca-BGP might be the source of Ca and inorganic phosphate (Pi) through hydrolysis by alkaline phosphatase (ALP), and that Ca-BGP-mediated mineralized tissue induces the early formation of tubular dentine.