Methods: Appropriate sized specimens for each test were polymerized and cured in their respective curing units according to the manufacturer's instructions. For toothbrush abrasion, a constant weight (M1) of the specimens (n=6) was obtained after which they were brushed in a toothbrush abrasion machine for 20,000 cycles and then weighed again to obtain a new constant weight (M2). Volume (V1 and V2) was calculated from M1 and M2. Six samples were tested for 400,000 cycles in the Alabama wear test machine and volume loss was measured with a Surtronic Profilometer. Statistical Analysis was performed using One-way ANOVA and pair-wise comparisions was done using Sidak's method (á = 0.05).
Results: Volume loss (mm3)was observed in all laboratory composites.Material along with their means and standard deviation() are shown below. Statistically similar groups are identified with similar letters in each test.
Toothbrush test: Belleglass[1.18 (0.21)a], Radica[1.75 (0.59)a,b], Gradia Indirect [2.42 (0.82) b] , Sculpture Plus[4.58 (1.18)]
Alabama Wear Test: Belleglass[.12 (0.04) a] Radica[.311 (0.13)a] Gradia Indirect [.658 (0.23) b], Sculpture Plus[.562 (0.11) b]
Conclusion:. Wear was observed in all four laboratory composites. Belleglass NG and Radica demonstrated the lowest volume loss in both tests