Effect of Bleaching Gel Viscosity on Tooth Whitening Efficacy and Pulp Chamber Penetration: An In Vitro Study

Oper Dent. 2018 May/Jun;43(3):326-334. doi: 10.2341/17-099-L.

Abstract

Objectives: Whitening efficacy has been related to hydrogen peroxide (HP) diffusion into tooth structure. However, little information is available relating rheological properties to whitening efficacy. The purpose was to evaluate the whitening efficacy and HP penetration level of a 10% HP gel at three different viscosities and to compare them to a strip delivery system.

Methods and materials: Extracted molars (n=120) were randomly assigned into five groups (n=24/ group): NC_MED (negative control; median): medium viscosity gel without HP; LOW: 10% HP gel (low viscosity experimental gel, Ultradent Products Inc); MED: 10% HP gel (medium viscosity experimental gel, Ultradent); HIGH: 10% HP gel (high viscosity gel, Ultradent); and CWS: Crest 3D Whitestrips 1-Hour Express (Procter & Gamble). All teeth were subjected to five 60-minute whitening sessions. Instrumental color measurements were performed at baseline (T0), and 1-day after each application (T1-T5), and 1-month after whitening (T6). HP penetration was estimated with leucocrystal violet and horseradish peroxidase. A Kruskal-Wallis test and post hoc Bonferroni test were performed to assess the difference in tooth color change and HP penetration among the groups (α=0.05).

Results: Hydrogen peroxide penetration levels and overall color changes at T6 were 0.24 μg/mL / 2.80; 0.48 μg/mL / 8.48; 0.44 μg/mL / 7.72; 0.35 μg/mL / 8.49; 0.36 μg/mL / 7.30 for groups NC, LOW, MED, HIGH, and CWS, respectively. There was a significant difference for HP penetration, while there was no significant difference among the four experimental groups for tooth color change.

Conclusion: Rheological properties should be considered when developing new whitening formulations.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Dental Pulp Cavity / metabolism*
  • Dentin Sensitivity / chemically induced
  • Gels / pharmacokinetics
  • Gels / therapeutic use
  • Humans
  • Hydrogen Peroxide / chemistry
  • Hydrogen Peroxide / pharmacokinetics
  • Hydrogen Peroxide / therapeutic use*
  • In Vitro Techniques
  • Tooth Bleaching / methods*
  • Tooth Bleaching Agents / chemistry
  • Tooth Bleaching Agents / pharmacokinetics
  • Tooth Bleaching Agents / therapeutic use*
  • Tooth Discoloration / drug therapy
  • Treatment Outcome
  • Viscosity

Substances

  • Gels
  • Tooth Bleaching Agents
  • Hydrogen Peroxide