Effects of commercial whitening toothpaste containing hydrogen peroxide and citric acid on dentin abrasion and erosion

Abstract

Abstract Background: Hydrogen peroxide (HP) and citric acid (CA), key contributors to toothpaste acidity, can lead to dental loss. This study is to compare the amount and pattern of abrasion or loss of dentin based on pH, buffering, and concentration of HP and CA in various commercial and experimental toothpastes after toothbrushing or immersion. Methods: Bovine dentin specimens were randomly assigned to nine solutions. The prepared solutions included two commercial toothpastes (whitening toothpaste [WT] with HP and CA; conventional toothpaste [CT] without HP and CA), reference slurry (RS), two CA solutions (0.1 M, CAS1; 0.00005 M, CAS2), basic solution (0.2 M sodium phosphate dibasic [SPDS]), CA phosphate buffer solution (0.1 M SPDS and 0.05 M CA [CAPB]), HP solution (1.33 M; HPS), and distilled water (DW). After 10,000 brushings and immersion for 1 h, the amount of dentin loss and surface pattern were measured and observed using noncontact profilometry. Data were analyzed using an analysis of variance and the Tukey test as a post hoc analysis (p<0.05). Results: WT with pH 5.0 had lower dentin abrasion than CT and RS after brushing but had higher dentin loss than both after immersion. While WT, CAS1, and CAPB surfaces exhibited comparable U-shaped patterns after brushing or immersion, a wedge shape was observed on CT and RS surfaces after brushing, with their surface patterns remaining intact after immersion. In addition, dentin abrasion, loss, and surface patterns of CAS2 and HPS, which had a pH of 5.0 like WT, did not significantly differ from those of DW after brushing and immersion. Conclusions: After brushing or immersion, the CA concentration may affect the erosive pattern on the dentin surface more than the HP concentration included in WT. The amount of abrasion or loss of dentin after brushing or soaking can vary based on the composition, concentration, and buffer in the solution, even if the pH levels are similar. With or without pH buffering, prolonged use of WT containing HP and high CA concentrations may cause further dentin damage beyond simple brushing.