| Summary: | Hydrogen peroxide as the bleaching material which is applied to the teeth
has raised questions as to possible adversed effect on tooth structure. This study
evaluated the effects of 30%, 35% and 38% hydrogen peroxide on enamel
hardness.
A total of 32 extracted human incisors were randomly divided into 4
groups of 8. An in-office bleaching was conducted where the groups I , II and III
were treated with 30%, 35%, and 38% hydrogen peroxide respectively. Thirty
minutes bleaching sessions were conducted which were irradiated with halogen
lamp with a distance of 30 cm. Group IV was not exposed to any bleaching
system and served as the control group. After bleaching the subjects were washed
and sectioned at cervical level. The crowns were imbedded in acrylic resin with
facial surfaces facing up. Enamel microhardness measurements were carried out
using Vickers Hardness Tester on 3 points of labial surface of each tooth which
were incisal, middle and apical one-third. Data was analyzed using one-way
ANOVA and t-test at a 0.05 significance level.
The mean enamel hardness in the control group 490.9988 ± 57, 33 511
VHN, in group I (H2O2 30%) 351, 8338 ± 37, 61 337 VHN, in group II (35%
H2O2) 233, 7925 ± 38, 83 932 VHN, on group III (38% H2O2) 194, 7075 ± 24,
77 265 VHN
Results with one way ANOVA showed significant differences between
groups of hydrogen peroxide 30%, 35%, and 38% (p <0.05). The results with ttest
shows the differences between the treatment group (p <0.05). The higher the
concentration of hydrogen peroxide, the greater the reduction in enamel hardness.
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