a new method for evaluating the diffusion of ca2+ and oh- ions through coronal dentin into the pulp

introduction: ca(oh) 2 -containing/forming materials are conventionally used for indirect pulp-capping and are theoretically able to release ca 2+ and oh - ions for hydrolytic dissociation. however, no evidence exists for ion diffusion through the remaining coronal dentin. the aim of this study was to design an innovative experimental set-up to test the ability of ca(oh) 2 -containing and ca(oh) 2 -forming pulp-capping materials to generate pulpward ca 2+ and oh - ion fluxes through coronal dentin after indirect pulp-capping in vitro . materials and methods: standardized class 1 cavities were prepared in erupted sound human molars. pulp tissue was excised. a coronal remaining dentin thickness (rtd) (1±0.2 mm thick) was prepared within an occlusal-to-pulp cavity system (coronal rd system). the whole system/sample was treated with 17% edta to remove the smear layer and the external surface was covered by nail varnish. indirect pulp-capping was performed on coronal rdt using a conventional pulp-capping material covered by a glass ionomer cement, a composite and nail varnish. chemically different ca(oh) 2 materials were used to test the reliability of the set-up. the leached ca 2+ and oh - ions were measured using ion-selective electrodes after soaking for 3 hours, 24 hours, and 7 days in deionized water (10 ml, 37 ° c). results: calcium ions were detected and a rise in ph was observed in the treated water after a few hours for all tested materials. conclusion : the experimental set-up proved to be an easy and effective method for testing the different ca(oh) 2 -containing and ca(oh) 2 -forming materials ability to induce a pulpward flux of calcium and hydroxyl ions through coronal remaining dentin after indirect pulp-capping. the new system will allow the screening of current pulp-capping materials.