Study on Rehardening of Demineralized Dentin with the New Pulp-capping Agents Containing Bioactive Glass

Abstract

 Purpose: We measured the Knoop hardness of demineralized dentin over time using Cariotester to determine the effectiveness of several types of pulp-capping agent for atraumatic indirect pulp capping (AIPC).

 Methods: Extracted human molars were used to prepare dentin samples with a diameter of 10 mm and thickness of 2 mm. Sound dentin samples were immersed in lactic acid solution and were regarded as demineralized when the value obtained using Cariotester was approximately 20 KNH. A new bioactive glass-compounded pulp-capping agent (Shofu), Bio MTA cement (J. Morita), and NEX MTA cement (GC) were used as the pulp-capping agents in the present study. Each pulp-capping agent was applied to the surface of demineralized dentin and covered with Base cement. After the Base cement solidified, pulp-capped dentin samples and controls were divided into two groups: those placed in a container with 100% humidity and those immersed in remineralization solution, and stored at 37℃ in a thermostatic chamber for l month and 3 months. The hardness of the capping agent-applied region was then measured. Data were analyzed using a one-way analysis of variance and Tukey's test (α=0.001). Pulp-capping agent-applied surfaces were also observed under SEM.

 Results: The hardness of demineralized dentin increased with the application of a new bioactive glass-compounded pulp-capping agent, Bio MTA cement, and NEX MTA cement, and mineralized substance-like aggregates were deposited on the surface of and between collagen fibers. It is assumed that the demineralized dentin had remineralized as the bioactive glass-compounded pulp-capping agent was pasted.

 Conclusion: These results indicate the effectiveness of the new bioactive glass-compounded pulp-capping agent in the remineralization of demineralized dentin.