Thermal conductivity of cement base materials

Abstract

This study was designed to determine the most efficient dentin-cement-restorative material system to minimize temperature changes from either a hot (58°C) or cold (4°C) source. Extracted human molar teeth were used to conduct the experiment utilizing a standard Class 1 occlusal preparation 3.5 mm in diameter with a remaining dentin thickness of 0.5 or 1.0 mm and a control dentin thickness of 2.0 mm. A bi-electrode thermocouple was utilized with one thermocouple mounted on the roof of the pulp chamber and the other on the occlusal surface of the specimen. The cements investigated were zinc oxide and eugenol (ZOE), zinc phosphate (ZP), glass ionomer (GI), and zinc polycarboxylate (ZPC) with a thickness of either 0.5 mm or 1.5 mm. Statistical analysis consisted of a one-way analysis of variance followed by a multiple means comparison test. For heated speciments consisting of cement and dentin only, ZOE was the least effective in limiting temperature change. When cold was applied, ZOE was the most effective. Statistically for cold application, the other three cements, ZP, Gl, and ZPC, and 2.0 mm of dentin were the same for limiting temperature change. When amalgam was used to restore the tooth, ZOE and Gl were most effective in limiting temperature change for cooled teeth. For heated teeth, all the cements were identical except for ZOE, which was the least effective. For composite restored teeth, all cements and dentin were identical in limiting temperature changes for either heating or cooling.