Influence of Light-polymerization Systems on Surface Properties of Indirect Composite

Objectives: The aim of current study was to evaluate the influence of laboratory polymerization systems on Knoop hardness, toothbrush abrasion resistance, and gloss change of an indirect composite. Methods: An indirect composite (Sinfony) was polymerized with nine polymerization modes using the five polymerization systems (Visio system, Hyper LII, Pearlcure Light, Twinkle MIII, and UniXS II). After light exposure, Knoop hardness number, wear depth, and change of gloss were determined (n=6). The results were analyzed by one-way ANOVA and Tukey HSD test (P=0.05 level). Worn surfaces were also observed by scanning electron microscope. Results: Specimens polymerized with the Hyper LII (120 s) and Pearlcure Light (120 s) units demonstrated greatest hardness number, whereas specimens polymerized with Visio system and UniXS II (60 s) units demonstrated the smallest value. The highest wear resistance to toothbrush abrasion was recorded with six groups (Hyper LII 60 and 120 s, UniXS II 120 s, Pearlcure Light 60 and 120 s, Twinkle MIII 120 s) and the lowest wear resistance was obtained with two groups (Visio system and UniXS II 60 s). Gloss of the composite did not depend on the polymerization modes before wear testing. The surface gloss was significantly reduced for all polymerization modes by toothbrush dentifrice abrasion, and gloss values of worn surface were significantly different by polymerization modes. Conclusion: It can be concluded that the Sinfony composite is polymerized properly by means of high-intensity light polymerization units.

This work was supported in part by Special Research Grant for the Development of Distinctive Education from the Promotion and Mutual Aid Corporation for Private School of Japan (MM, 2008).