Effect of Bleaching on the Integrity of Enamel and Dentine

Objective: The aim of this study was to investigate safety concerns with bleaching procedures on enamel and dentine. Method: Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Enamel samples were treated with 35% hydrogen peroxide (HP) then citric acid (CA) or CA alone and water alone. Dentine specimens were brushed with HP, water or toothpaste, bleached with HP with or without brushing with toothpaste and immersed in orange juice and brushed with paste. Loss of enamel and dentine was determined by profilometry. Enamel and dentine specimens were hardness tested and studied under SEM prior to and post bleaching. Results: Bleaching had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion. Brushing/bleaching treatments produced little effect but orange juice/brushing caused significantly more dentine loss. There were no significant changes in hardness values or the SEM appearances. Conclusions: This high concentration HP bleaching did not produce any deleterious effects on enamel or dentine. Reported deleterious effects of bleaching may reflect the low pH of some fomulations.