Microhardness Evaluation of a Direct/Indirect Hybrid Composite Resin at Complementary Activation in Light or Heat

This investigation aims at determining the microhardness value of the hybrid direct/indirect composite resins submitted to conventional light curing and post-cured using two different methods, a light source from a laboratory light curing unit and a conventional oven heating, and the obtained results were compare to an indirect composite resin. A hybrid direct/indirect composite resin (Filtek P60 TM – 3M-ESPE, St. Paul, USA), and an indirect composite resin (Artglass TM – Heraeus Kulzer, Germany) were used. The Filtek P60 TM was polymerized using: a conventional light curing for 80 seconds; the complementary polymerization methods were applied using a laboratory light curing for 360 seconds, and an oven curing at 125°C for 600 seconds. The Artglass TM composite was polymerized using a laboratory light curing unit for 360 seconds. The post-curing method produced higher values of Vickers Hardness Number (HV) for both light and heat post-curing treatments, shown that increase in hardness is independent of the post-curing methods (laboratory light curing unit or heat curing using a conventional oven heat). Microhardness was determined by the Vickers indentation technique with a load of 50 gram-force for 15 seconds. The Filtek P60 TM resin showed higher hardness values than Artglass TM resin. The employment of post-curing using heat methods on Filtek P60 TM resulted in similar mechanical properties (microhardness) that were comparable to laboratory light curing unit, and the laboratory light curing unit is much more expensive than oven heat.