title: Effect on enamel microhardness of two consumer-available bleaching solutions when compared with a dentist-prescribed, home-applied bleaching solution and a control.
abstract: BACKGROUND
  There exists limited data in the literature regarding the efficacy and safety of consumer-available, paint-on bleaching solutions.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the effect of two consumer-available, paint-on bleaching products on enamel microhardness against a control and a dentist-prescribed, home-applied (DPHA) bleaching product.
  
  
  METHODS
  Eighty enamel slabs were obtained from extracted human teeth and randomly divided into four treatment groups: (1) control; (2) Opalescence (Ultradent Products, Inc., South Jordan, UT, USA); (3) Crest Night Effects (Procter & Gamble, Cincinnati, OH, USA); and (4) Colgate Simply White Night (Colgate-Palmolive Co., Piscataway, NJ, USA). Opalescence is a carbamide peroxide DPHA product, whereas Crest Night Effects and Colgate Simply White Night are consumer-available products. The specimens in groups 2 to 4 underwent 2 weeks of treatment for 8 h/d. Specimens were maintained in artificial saliva at 37 degrees C between treatments. Subsequently, one-half of the specimens in groups 2 to 4 (n=10) underwent an additional seven treatments for 8 h/d, while the other half were stored in artificial saliva, receiving no further treatment. Microhardness was measured as Knoop hardness numbers (KHNs) at baseline and after 1, 7, 14, and 21 treatment days. The results were analyzed for statistical significance both intra- and intergroups using analysis of variance (p=.05).
  
  
  RESULTS
  A statistically significant reduction in mean KHN was observed compared with baseline at 1, 7, 14, and 21 treatment days for group 4 and at 7 treatment days for group 3. When compared with the control or DPHA product, group 4 was the only treatment that resulted in significantly lower mean KHNs at 7, 14, and 21 treatment days.
  
  
  CONCLUSIONS
  When evaluating enamel microhardness, consumer available, paint-on bleaching solutions may adversely affect enamel microhardness compared to a control and 10% carbamide peroxide DPHA bleaching solution.
  
  
  CONCLUSIONS
  With numerous consumer-available bleaching products on the market, it is crucial to be judicious in their selection and use. The results of this in vitro study showed that the consumer-available, paint-on bleaching solutions adversely affected enamel microhardness at some time during the study. Consumers should be made aware of this effect on enamel.
authors.affiliation: Department of Diagnostic Sciences and General Dentistry, UNC School of Dentistry, Chapel Hill, NC 27599-7450, USA. ralph_leonard@dentistry.unc.edu
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Leonard
authors.forename: Erica C N
authors.initials: EC
authors.lastname: Teixeira
authors.forename: Glenn E
authors.initials: GE
authors.lastname: Garland
authors.forename: André V
authors.initials: AV
authors.lastname: Ritter
mesh_terms: D000077463:Carbamide Peroxide; D002254:Carbonates / Q000627:therapeutic use; D003743:Dental Enamel / Q000187:drug effects*; D003747:Dental Enamel Solubility / Q000187:drug effects; D004338:Drug Combinations; D011307:Drug Prescriptions; D006244:Hardness; D006801:Humans; D004366:Nonprescription Drugs / Q000627:therapeutic use*; D016877:Oxidants / Q000627:therapeutic use*; D010545:Peroxides / Q000627:therapeutic use; D012449:Safety; D012464:Saliva, Artificial / Q000494:pharmacology; D012646:Self Administration; D013997:Time Factors; D014073:Tooth Bleaching; D016896:Treatment Outcome; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use
chemical_list: D002254:Carbonates; C485070:Colgate Simply White Night; C479358:Crest Night Effects; D004338:Drug Combinations; D004366:Nonprescription Drugs; D016877:Oxidants; D010545:Peroxides; D012464:Saliva, Artificial; D000077463:Carbamide Peroxide; D014508:Urea