The objective of this study was to determine the effect of silicone thickness and the polymerizing
depth of light-polymerized composite resin on the Knoop Hardness Number and the percentage of
bottom-top Knoop Hardness Number of the resin. There were 4 groups of composite resin specimen
with different thickness of clear silicone (0.0, 2.0, 4.0, and 6.0 mm). There are also 4 subgroups in each
group with different polymerizing depth (0.25, 0.2, 0.4, and 6.0 mm). Ten specimens were made for
each subgroup. Therefore, there were 160 specimens altogether. Knoop Hardness Numbers and percentage
of bottom-top Knoop Hardness Numbers of the composite resin were measured and analyzed
using a Two-way analysis of variance, and Tukey’s HSD test (p < 0.01). There were significant differences
(p < 0.01) among mean Knoop Hardness Numbers and percentage of bottom-top Knoop Hardness
Numbers in all groups. Only 3 data points not less than 80 % were detected. In conclusion, the thickness
of clear silicone of no more than 4.0 mm and the polymerizing depth of no more than 2.0 mm
were used for adequate polymerization.