The effect of debonding and/or bleaching on enamel color - an in-vitro study

There are various studies in the literature on bonding brackets to bleached teeth and on the effect of bleaching material on the color of compomers. The purpose of this study was to investigate changes in tooth color depending on the process of bonding - debonding and/or bleaching.

Ninety crowns of lower bovine permanent incisors were divided into nine subgroups. Three bonding materials (chemical, light- and pressure-cured) and three bleaching materials (15% CP, 35% CP, or 38% HP) were applied to the teeth, whereby each tooth was divided into quarters: untreated, bleached only, bonded-debonded only, and bleached after a bonding-debonding procedure. The Easyshade spectrophotometer was used to determine CIELCh coordinates (lightness, color, and hue) three times for each area. The areas' differences in color were expressed as the Euclidian distance DeltaE. Four examiners (two orthodontists and two dentists) rated each tooth concerning color differences in the four areas. The data collected was subjected to the sign and Wilcoxon or the Kruskal-Wallis and Mann-Whitney U tests using the SPSS 12.0 program.

Examiners found significant differences between those areas with and those without bleaching within each group of specimens (p < 0.05), but there were no differences concerning the bonding and debonding procedures (p > 0.05). Furthermore, digital tooth-shade measurements revealed no statistically-significant group-associated differences between those areas treated with bonding material and those not so treated, nor between bonded and debonded areas (p > 0.05). Nor did we observe any statistically-significant differences between bleached areas and those areas bleached after bonding and debonding procedures (p > 0.05).

The processes of bonding and debonding alone do not seem to have any statistically-significant influence on the tooth color of bovine enamel using these testing materials, nor does the subsequent bleaching procedure.