WEAR RATES OF REGULAR AND TEMPERED COMPOSITES

Objectives: One of the reasons for using composite inlays is that rest orations can be tempered. Composites tempered with heat and light have , at least initially, an enhanced degree of cure which, it is claimed, improves their physical properties, including wear resistance. The ai m of this study was to compare the wear rates of a selection of compos ites in their regular and tempered conditions. Methods: Two hybrid com posites (Brilliant Dentin, Coltene; Occlusin, ICI) and a microfilled m aterial (Heliomolar, Ivoclar-Vivadent) were chosen to provide a variet y of filler particle and resin systems. Regular composites were cured normally with light while tempered composites were given an additional 8 min secondary cure at 120 degrees C in the Coltene DI500 heat and l ight oven. Specimens of an amalgam (Dispersalloy, Johnson & Johnson) a nd a heat/pressure cured composite (Isosit, Ivoclar Vivadent) were use d for comparison. The specimens were stored for either 7 days or 1 yea r to determine if prolonged water storage affected wear rate. Wear tes ting was carried out in a two-body wear machine using a steatite abrad er as an enamel substitute. ANOVA was used to test the effects on wear rate of tempering, storage time and type of material. Results: Signif icant differences were found in wear rate between materials (p < 0.001 ), but not for tempering or prolonged storage time. Conclusion: These findings agree with clinical studies which have shown that tempering h as little or no influence on the occlusal wear of composite inlays. (C ) 1997 Elsevier Science Ltd.