This study examined properties of four composite veneering materials polymerized with two different photo-curing units for the purpose of evaluating curing performance of the combination of composite material and curing unit. Two microfilled (Dentacolor and Thermoresin LC II) and two hybrid (Cesead II and Solidex) composite materials designed for prosthetic veneer were selected. The respective light sources of the units were a xenon (Dentacolor XS) and a metal halide (Hyper L II) lamp. The composite materials were exposed with the photo-curing unit for 60 s on each side (i.e. from top and bottom). Knoop hardness, compressive strength, flexural strength, flexural modulus, water absorption and water solubility were determined according to standardized testing methods. The specimens exposed with the metal halide unit generally exhibited greater Knoop hardness number, and compressive strength and lower solubility than those exposed with the xenon unit. A microfilled material (Thermoresin LC II) cured with the metal halide unit exhibited significantly improved results for all tests as compared with the same material cured with the xenon unit.

Properties of laboratory-cured composite materials are affected by the type of activation system as well as by the photo-curing unit light source. This study examined curing depth of a composite veneering material polymerized by means of various photo-curing units with the aim of evaluating the curing performance of the light sources. A microfilled composite material designed for prosthetic veneer was cured with seven photo-curing units. The light sources of the units were halogen/fluorescent, xenon, metal halide, fluorescent, halogen, halogen and mercury lamps. Exposure periods were 20, 30, 60 and 90 s. The curing depth of the material was determined using the method described by the International Organization for Standardization (ISO 4049). Two-factor analysis of variance revealed that the depth of cure was influenced both by the type of curing unit and by the exposure period (P = 0.0001). Among the seven photo-curing units, a metal halide curing unit consistently exhibited the greatest depth of cure. For all units, longer exposure increased the depth of cure.

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