title: Surface alteration of human tooth enamel subjected to acidic and neutral 30% hydrogen peroxide.
abstract: OBJECTIVE
  To investigate the effects of acidic and neutral 30% hydrogen peroxide (HP) on human tooth enamel in terms of chemical structure, mechanical property, surface morphology and tooth colour.
  
  
  METHODS
  Twenty-seven human dental blocks were obtained from premolars and randomly divided into three groups (n=9): Group acidic HP (30% HP, pH≈3.6), Group neutral HP (30% HP, pH≈7.0) and Group DW (distilled water, pH≈6.8). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, atomic force microscopy (AFM) investigation, microhardness test and colour measurements were carried out before and after treatments. ATR-FTIR and Raman spectroscopy were analysed and then the carbonate:mineral ratio (C:M), Raman absolute intensity (RAI), Raman relative intensity (RRI), and laser-induced fluorescence intensity (FI) were obtained for evaluation.
  
  
  RESULTS
  The C:M, percentage microhardness and percentage RRI of group acidic HP decreased more significantly than those of group neutral HP (P=0.02, P=0.001, P<0.001, respectively) and group DW (P=0.01, P=0.008, P<0.001, respectively). Whilst group neutral HP and group DW had no statistical difference in above terms (P=0.818, P=0.528, P=0.158, respectively). Significant morphological alterations were observed in group acidic HP. Group acidic HP and neutral HP had no significant difference in percentage FI (P=0.652) and ΔE (P=0.906).
  
  
  CONCLUSIONS
  This study suggested that neutral 30% HP had the same efficiency in tooth bleaching and it caused less deleterious effects on enamel than acidic 30% HP.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079, PR China.
authors.forename: Lili
authors.initials: L
authors.lastname: Sun
authors.forename: Shanshan
authors.initials: S
authors.lastname: Liang
authors.forename: Yue
authors.initials: Y
authors.lastname: Sa
authors.forename: Zhejun
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiao
authors.initials: X
authors.lastname: Ma
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Yining
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000704:Analysis of Variance; D003116:Color; D003743:Dental Enamel / Q000187:drug effects*; D006244:Hardness / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry* / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013059:Spectrum Analysis, Raman; D018709:Statistics, Nonparametric; D013499:Surface Properties / Q000187:drug effects; D014073:Tooth Bleaching / Q000009:adverse effects / Q000379:methods; D058205:Tooth Bleaching Agents / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D058205:Tooth Bleaching Agents; D006861:Hydrogen Peroxide