The effect of vitamin C on urinary level of an oxidative stress biomarker during at-home tooth bleaching process: a randomized double blinded clinical trial

Abstract

Introduction: Oxidizing agents which are used as tooth whitening agents can induce an oxidative stress, a situation that initiates some systemic diseases. This clinical study aims to evaluate the effect of ascorbic acid (vitamin c) on urinary level of an oxidative stress biomarker during the athome tooth whitening period. Material and methods: Thirty healthy patients who requested for the tooth whitening were involved in this trial. Specified bleaching trays were fabricated for both arches after making an impression. Each participant was given two syringes containing 15% carbamide peroxide gel and instructed to apply it for 6 h per night for 14 consecutive nights. Patients were divided into two equal groups. In the experimental group, the patients applied two tablets containing 500 mg of vitamin C every night along with the tooth whitening period. Urine samples were obtained in the morning before the study was started and were repeated in 5, 10, 15th days and five days after the expiration of the bleaching period. TBARS test was employed to evaluate the urinary level of malondialdehyde (MDA) as an oxidative stress biomarker. Data were analyzed by means of independent sample t-test and repeated measurement analysis. Results: Twenty-nine subjects completed the study. The MDA level increased during the bleaching period in both groups; however, the difference was not significant (P>0.05). In addition, the ascorbic acid application could not present a significant difference in the MDA level (P= 0.34). Conclusion: The application of 15% carbamaide peroxide did not significantly elevate the oxidative stress biomarker in human urine (IRCTID: IRCT2012113011618N1).