title: The Effect of Delivery System and Light Activation on Tooth Whitening Efficacy and Hydrogen Peroxide Penetration.
abstract: To evaluate the whitening efficacy of a new two-layer technology in-office system compared to a conventional gel-type system and determine hydrogen peroxide penetration (HPP) into the pulp cavity.
  
  
  
  Extracted molars (n = 60) were assigned to group NC: glycerol gel; group QPRO: 20% HP varnish (Zoom Quick Pro, Philips Oral Healthcare); group ZOOM_NL: 25% HP gel (Zoom Chairside Whitening); and group ZOOM_WL: 25% HP gel (Zoom Chairside Whitening) with light-activation. HPP levels were estimated with leucocrystal-violet and horseradish-peroxidase. Instrumental color measurements were performed at baseline (T0), 1-day post first whitening (T1), 1-day post second whitening (T2), 1-day post third whitening (T3), and 1-month post whitening (T4). One-way analysis of variance followed by post hoc Tukey's HSD test was performed to detect difference in ΔE* and HP penetration levels (α = 0.05).
  
  
  
  ΔE* of NC was lower than other groups, whereas ΔE* of ZOOM_WL was greater than the other three groups, at T3and T4. Mean HPP level obtained from ZOOM_WL (1.568 ± 0.753 μg/mL) was significantly greater than those obtained from the other groups, whereas the mean HPP level observed in NC group (-0.131 ± 0.003 μg/mL) was significantly lower than the other groups.
  
  
  
  Tooth whitening efficacy and HPP levels vary based on whitening systems used.
  
  
  
  The two-layer technology in-office varnish system may be an alternative whitening option to reduce chair time in the office. (J Esthet Restor Dent 28:313-320, 2016).
authors: Dentistry, University of Iowa College of Dentistry & Dental Clinics, Iowa City, Iowa, USA.
authors: Soyoung
authors: S
authors: Park
authors: Associate Professor, Program Director, Student Research Program, Loma Linda University School of Dentistry Center for Dental Research, 11175 Campus Street CSP A1010C, Loma Linda, California, 92350, USA. sorankwon@llu.edu.
authors: So Ran
authors: SR
authors: Kwon
authors: Associate Research Scientist/Adjunct Assistant Professor, Division of Biostatistics and Research Design and Department of Preventive and Community Dentistry, University of Iowa College of Dentistry & Dental Clinics, Iowa City, Iowa, USA.
authors: Fang
authors: F
authors: Qian
authors: Professor, Oral Pathology, Radiology and Medicine, Dows Institute for Dental Research, University of Iowa College of Dentistry & Dental Clinics, Iowa City, Iowa, USA.
authors: Philip W
authors: PW
authors: Wertz
mesh_terms: D003116:Color; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D014073:Tooth Bleaching; D058205:Tooth Bleaching Agents / Q000494:pharmacology*
chemical_list: D058205:Tooth Bleaching Agents; D006861:Hydrogen Peroxide