The composite was placed in a 1.5-mm thick aluminum mold and the upper
surface was covered with a celluloid strip. Composite was light cured for 60 seconds, then a layer of
approximately 200 μm thick was ground away from the lower surface and polished. The hardness of the
upper composite surface that was polymerized under a celluloid strip and the polished lower surface were
measured with Vickers hardness measuring instrument 15 minutes, 6 hours, and 6 days after light curing.
The hardnesses of polished and celluloid strip–finished surfaces were compared using a paired t test. Oneway
ANOVA and Tukey was used for tests for the significant differences in hardnesses between 15 minutes,
6 hours, and 6 days after light curing for a given surface.