IN-VITRO WEAR OF COMPOSITE WITH VARIED CURE, FILLER LEVEL, AND FILLERTREATMENT

For the clinical wear of composite filling materials to be reduced, co mpositional factors such as degree of cure, filler level, and silanati on level should be optimized. An oral-wear-simulating machine was used to explore the effects of these factors on abrasion and attrition wea r as well as on opposing enamel wear. The composites were made from Sr glass (1-2 mu m avg) and a 50/50 Bis-GMA/TEGDMA resin. Series I (A-D, E) were light-cured (Triad II) for 9, 12, 25, and 40 sec/side to prod uce degree of cure (DC) as measured by FTIR of 56, 60, 61, and 63%, re spectively. E received an additional heat cure (120 degrees C for 10 m in) to reach a DC of 66%. Series II (D, F-I) were filled to 62, 53, 48 , 37, and 28 vol%, respectively. Ln series III (D, J-M), the portion o f fillers treated with a silane coupler (MPS) was 100, 80, 60, 40, and 20%, respectively. Samples were cycled 50,000 times against an enamel antagonist in a poppy seed/PMMA slurry in the oral wear simulator to produce abrasion (load = 20 N) and attrition (load = 70 N) simultaneou sly. Wear depth (mu m; n = 5) was measured by profilometry. Results fo r each series were analyzed by ANOVA/Tukey's (p less than or equal to 0.05). The wear depths did reflect cure values, though only the abrasi on difference for E < A was significant. Greater wear was correlated w ith lower filler levels (r(2) = 0.88; p < 0.05), significantly increas ing below 48 vol% (G). Wear increased linearly as the percent of silan e-treated fillers was reduced (r(2) = 0.99; p < 0.05). Abrasion and at trition did not differ significantly for any composite. Wear of the op posing enamel was largely unchanged by these factors. Compositional fa ctors including degree of cure, filler level, and silanation directly affected the wear resistance of dental composites evaluated in an oral wear simulator.