Influence of thermal cycling on OCA wear of composite restoratives

This study investigated the effects of thermal cycling on wear of four comm ercial composite resins (Silux, Z100, Ariston and Surefil). Specimens of ea ch material were divided into three treatment groups comprising a control a nd two different thermal cycling regimes. Control specimens were stored in distilled water at 35 degreesC for 178 hours. Thermal cycled specimens were stored in distilled water at 35 degreesC for 173 hours and subjected to fi ve hours (300 cycles) of a thermal cycling regime consisting of the cycle A BAC, where A and B represent the fixed temperatures of 35 degreesC (28 seco nds) and 15 degreesC (two seconds) and C, depending on the treatment group, was either 45 degreesC or 60 degreesC (two seconds). All specimens were su bsequently subjected to wear testing at 20 MPa contact stress against SS304 counterbodies with distilled water as the lubricant. Wear depth (mum; n=6) was measured using profilometry every 2,000 cycles up to 10,000 cycles. Re sults were analyzed using ANOVA/Scheffe's test (p<0.05). The effect of ther mal cycling on wear was material-dependent. The wear of Silux and Z100 were not significantly affected by thermal cycling. Thermal cycling of Ariston at an upper temperature of 60<degrees>C significantly decreased wear resist ance. Thermal cycling affected only the early wear resistance of Surefil.