The effect of postcuring on quantity of remaining double bonds, mechanical properties, and in vitro wear of two resin composites

Objectives: To determine the effect of different postcuring methods on degree of conversion, mechanical properties, and in vitro wear of two resin composites (Z100 and Charisma). The postcuring methods involved devices for inlay curing as well as devices present for other purposes in many dental laboratories or dental offices. Methods: Specimens of the resin composites were initially light cured and then postcured according to one of the following methods: Translux EC handheld curing unit (10 min), Translux EC light box (10 min), Triad II (10 min), 40°C (10 min), 70 or 110°C for 10 min, 1, 6, or 24 h. The properties were determined following storage of the specimens for 1 week in water at 37°C. The degree of conversion was determined using transmission IR. The mechanical properties tested were diametral tensile strength, flexural strength, and flexural modulus. In vitro wear was induced by a three-body wear simulator. Results: Most postcuring methods increased degree of conversion of both materials. Postcuring increased the mechanical properties and in vitro wear resistance of Charisma, whereas no effect of postcuring was found on these properties of Z100. Conclusion: Postcuring with the use of devices readily available in the dental laboratory and dental office increased the degree of conversion of Z100 and Charisma as well as the mechanical properties and in vitro wear resistance of Charisma. A heat treatment at 110°C for 10–60 min was found to be the most promising postcuring method.