Effectiveness of polymerization of a prosthetic composite using three polymerization systems

Statement of problem. Although properties of laboratory-polymerized composi te materials are influenced by the type of polymerizing unit, little inform ation is available regarding the comparison between use of a high-intensity light source and application of secondary heat treatment. Purpose. This study examined properties of a prosthetic veneering composite polymerized with 3 polymerizing systems to evaluate the effects of varying polymerization modes on hardness, solubility, and depth of cure. Material and methods. A composite material designed for a prosthetic veneer (Conques t Crown and Bridge) was polymerized using 3 methods: (1) exposure in the pr oprietary photopolymerizing unit with 2 halogen lamps (Cure-Lite Plus), fol lowed by heating in an oven (Conquest Automatic Curing Unit); (2) exposure in a photopolymerizing unit with a xenon stroboscopic light source (Dentaco lor XS); and (3) exposure in a photopolymerizing unit with 2 metal halide l amps (Hyper LII). Knoop hardness, water solubility, and depth of cure were determined for groups of 5 specimens, according to standardized testing met hods. Data were compared using analysis of variance and the Duncan new mult iple range test (P < .05). Result. The hardness number generated with the metal halide unit was statis tically greater than those produced by the other 2 methods, and material co mponent released into water was minimal when the material was exposed with the metal halide unit (P < .05). Among the 3 photopolymerizing units, the m etal halide unit consistently exhibited the greatest depth of cure. Conclusion. Certain properties generated with the use of the high-intensity polymerizing unit exceeded those obtained from a proprietary system that r equires a postheat treatment.