Objective: This study evaluated various physical properties of two resin composites polymerized by either an argon laser or a conventional visible light. Materials and Methods: A hybrid composite, Herculite XRV (Kerr Corp., Orange, California), and a microfill composite, Durafill VS (Kulzer, Wehrheim, Germany), were used in this study. Three physical properties, diametral tensile strength, compressive strength, and flexural strength, were tested. Five specimens of each composite resin were made for each set of physical properties tested, for a total of 18 groups and 90 specimens. Specimens were fabricated according to the American National Standards Institute and American Dental Association Specification No. 27 for each property tested. The composite was polymerized with either an argon laser (power density of 1000 mW/cm2) for 10 or 20 seconds or a conventional visible light (power density of 354 mW/cm2) for 40 seconds. Specimens were stored in water in light‐proof containers at 37°C for 7 days before testing with a Zwick (Atlanta, Georgia) universal testing machine. Results: The physical properties of Herculite XRV were not affected by the light source or exposure time. For Durafill VS, no significant differences were observed for the diametral tensile strength whether the argon laser or conventional light was used. However, the flexural strength of the microfill was significantly lower when polymerized with the argon laser a t 10 seconds compared with the two other curing methods (20‐second laser cure, 40‐second conventional cure). Also, the compressive strength of Durafill VS polymerized with the argon laser a t 10 seconds was significantly lower than when it was cured with the conventional light for 40 seconds. Conclusions: Hybrid and microfill resin composites cured with an argon laser for 20 seconds had physical properties comparable to composites polymerized with a conventional visible light unit for 40 seconds. Therefore, with adequate exposure time, the argon laser is a potential alternative to conventional visible light‐curing.

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