title: The effects of etching, micro-abrasion, and bleaching on surface enamel.
abstract: Conservative techniques for improving the appearance of discolored teeth have become popular in the past decade. These include: in-office bleaching with 30% hydrogen peroxide, which is applied on etched enamel with a gauze pad and then exposed to a bleaching light; home bleaching with a mild form of peroxide, such as 10% carbamide peroxide, which is applied on the tooth surface with custom-made mouthguards; and enamel micro-abrasion with 18% hydrochloric acid, which is applied in a pumice slurry. In this study, the in-office bleaching and enamel micro-abrasion techniques were performed on extracted teeth for investigation of their microscopic effects on the surface enamel. Specimens treated only with 37% phosphoric acid showed an enamel loss of 5.7 +/- 1.8 microns. The specimens treated with 37% phosphoric acid followed by 30% hydrogen peroxide showed enamel loss of 5.3 +/- 1.6 microns; this loss was probably not caused by the hydrogen peroxide, but rather by the etching with 37% phosphoric acid which preceded the hydrogen peroxide application. A direct application of 18% hydrochloric acid for 100 s resulted in a loss of 100 +/- 47 microns. The extent of enamel loss was much greater when the 18% hydrochloric acid was applied in a pumice slurry for the same period of time (360 +/- 130 microns), and the effect was time-dependent. Thus, the pumice and rotary prophy cup used in conjunction with the 18% hydrochloric acid contributed markedly to the loss of surface enamel, enhancing the non-selective stain-removing action of the hydrochloric acid. Therefore, the hydrochloric acid-pumice technique must be used clinically with caution.
authors.affiliation: Department of Children's Dentistry & Orthodontics, Faculty of Dentistry, University of Hong Kong, Sai Ying Pun.
authors.forename: L S
authors.initials: LS
authors.lastname: Tong
authors.forename: M K
authors.initials: MK
authors.lastname: Pang
authors.forename: N Y
authors.initials: NY
authors.lastname: Mok
authors.forename: N M
authors.initials: NM
authors.lastname: King
authors.forename: S H
authors.initials: SH
authors.lastname: Wei
mesh_terms: D000134:Acid Etching, Dental / Q000009:adverse effects*; D000293:Adolescent; D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D002648:Child; D003743:Dental Enamel / Q000187:drug effects* / Q000648:ultrastructure; D004338:Drug Combinations; D006801:Humans; D006851:Hydrochloric Acid / Q000009:adverse effects; D006861:Hydrogen Peroxide / Q000009:adverse effects; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D010545:Peroxides / Q000009:adverse effects; D010756:Phosphoric Acids / Q000009:adverse effects; D017640:Silicates; D012824:Silicic Acid / Q000009:adverse effects; D014073:Tooth Bleaching / Q000009:adverse effects* / Q000379:methods; D014075:Tooth Discoloration / Q000628:therapy; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives
chemical_list: D004338:Drug Combinations; D010545:Peroxides; D010756:Phosphoric Acids; D017640:Silicates; D012824:Silicic Acid; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C030242:phosphoric acid; C005144:pumice; D006851:Hydrochloric Acid