الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Background: Resin infiltration for the treatment of white spot lesions (WSLs) may interfere with tooth bleaching. .Objective: To evaluate the uniformity of the tooth color affected by WSL when the lesion was treated with resin infiltration followed by bleaching and when the tooth was bleached first.
Material and Methods: WSLs were created in the right middle buccal half of the enamel surface of 40 sound extracted human premolars. Thus, each specimen showed a sound enamel surface and a lesion side. The teeth were randomly assigned to 2 groups (n = 20) treated by: (I) resin infiltration followed by chemically activated office bleaching, (II) chemically activated office bleaching followed by resin infiltration. Color differences ∆E* between the affected and sound halves of the tooth were assessed by a spectrophotometer at 4 time points: baseline (T0), after WSL formation (T1), after first treatment (T2), after second treatment (T3). Each tooth was examined visually and a scoring system was used to assess the homogeneity of the tooth color: 0 for uniform enamel color or clinically accepted or 1 for non-uniform enamel color warranting further intervention.
Results: The mean color difference ± SD of ∆E* between the 2 halves of the tooth in group I was 7.27 ± 3.99 at baseline, increased to 15.68 ± 6.14 after decalcification, then decreased after resin infiltration to 7.49 ± 2.74 and increased to 11.55 ± 5.91 after bleaching. In group II, ∆E* was 6.37 ± 2.78 at baseline, increased after decalcification to 16.68 ± 7.36. A slight reduction was seen after bleaching (∆E* = 12.52 ± 4.18) with greater reduction after resin infiltration (∆E* = 7.33 ± 3.73). The mean differences of ∆E* between the 2 groups was significant after the second treatment (P = 0.01*) and group I had a higher color difference between the 2 halves of the tooth compared to group II with a mean difference ± SE of 4.21 ± 1.56. When comparing the ∆E* after the second treatment to the baseline, a significant difference was found in group I (P = 0.01*) while no significant difference was found in group II (P = 1.00). The visual score showed that the tooth color in group II was 5 times more likely to be homogenous
Conclusions: Based on the results of the current study, it can be concluded that when bleaching was applied before resin infiltration, more uniform tooth color was achieved compared to bleaching after resin infiltration.
Key words: Office bleaching, color difference, enamel, resin infiltration, Icon, white spot lesions.