title: The effect of cold-light-activated bleaching treatment on enamel surfaces in vitro.
abstract: This in vitro study aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal (Group LP), disto-buccal (Group P), mesio-lingual (Group NP) and disto-lingual (Group L) specimens. These four groups were treated using the standard cold-light bleaching procedure, a bleaching agent, a peroxide-free bleaching agent and cold-light, respectively. Before and after treatment, all specimens were analyzed by high-resolution, micro-area X-ray diffraction and scanning electron microscopy. Using a spectrometer, tooth color of all specimens was measured before and after treatment. The phase of the enamel crystals was identified as hydroxyapatite and carbonated hydroxyapatite. After treatment, specimens in Groups LP and P showed significantly weaker X-ray diffraction peaks, significant reduction in crystal size and crystallinity, significant increase in L* but decrease in a* and b*, and obvious alterations in the surface morphology. However, specimens in Groups NP and L did not show any significant changes. The cold-light bleaching treatment leads to demineralization in the enamel surface. The acidic peroxide-containing bleaching agent was the major cause of demineralization, whereas cold-light did not exhibit significant increase or decrease effect on this demineralization.
authors.affiliation: State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Xin-Chang
authors.initials: XC
authors.lastname: Shi
authors.forename: He
authors.initials: H
authors.lastname: Ma
authors.forename: Jing-Lin
authors.initials: JL
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Li
mesh_terms: D003116:Color; D003461:Crystallography; D003743:Dental Enamel / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure; D017886:Durapatite / Q000528:radiation effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide / Q000494:pharmacology; D013057:Spectrum Analysis; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000145:classification / Q000494:pharmacology*; D017001:Tooth Demineralization / Q000473:pathology; D014961:X-Ray Diffraction
chemical_list: D058205:Tooth Bleaching Agents; D012822:Silicon Dioxide; D017886:Durapatite; D006861:Hydrogen Peroxide