Interaction of hydraulic calcium silicate and glass ionomer cements with dentine

Abstract

Restoration of missing tooth structure may require the use of a dentine replacement material to protect the dental pulp. Hydraulic calcium silicate cements and glass ionomers have been reported to exhibit ion exchange at the interface, and this interaction may be enhanced by removal of the smear layer that is formed when dentine is cut. The nature of the interaction and effects of smear layer have not been investigated for hydraulic cements. Biodentine and Chemfil Rock were used as dentine replacement materials in human molar teeth. The dentine was either left untreated or was functionalized by application of 17% ethylene diamine tetracetic acid (EDTA) or 20% polyacrylic acid applied for 1 min. The interface and dentine interaction were assessed by confocal microscopy (CM) with Rhodamine B, atomic force microscopy (AFM), scanning electron microscopy (SEM) and elemental mapping and by bond strength evaluation. Two extra groups with Rhodamine B were observed by AFM and SEM to assess the effect of Rhodamine B on the material and interfacial characteristics. The addition of dye to the materials effected the material properties and modified the interfacial zone. The mineral infiltration zone is an artefact caused by specimen preparation for CM, thus the use of Rhodamine B is not recommended for assessment of tooth-material interface. Dentine functionalization with EDTA improved the Biodentine contact to the tooth structure. Silicon migration from the material to the tooth structure occurred for Biodentine and the clinical implications of this need to be investigated further. Statement of significanceThe interaction of pulp preservation materials with the underlying dentine is important for maintenance of pulp vitality. This interaction is usually based on ion exchange of calcium between the material and dentine and is affected by the smear layer which is formed when the dentine is prepared with rotary instruments. These interactions are studied by various microscopy techniques with the confocal microscopy being very popular as the fluorescent dye clearly maps out the material interaction with the substrate. Unfortunately, the fluorescent dyes affect the interface and the level of penetration. The presence of a mineral infiltration zone, which is linked to the hydraulic tricalcium silicate cements is an artefact. Dentine functionalization with calcium chelators could be an alternative to the use of weak acids and could be more clinically acceptable to avoid pulp damage in deep cavities.