Objective: To determine the cytotoxicity, antimicrobial potential and peroxide content of four tooth whitening mouthrinses.
Methods: Listerine Whitening Refresh (LWR), Crest 3D White (C3W), Colgate Optic White (COW), Rembrandt Deep Whitener (RDW) were purchased over the counter. L929 fibroblasts were used to examine the cytotoxicity using agar diffusion method. Fifty microliter samples were tested as-is and at 1:1 dilution. Sterile MiliQ water and 3% H2O2 served as negative and positive controls for both cytotoxicity and antimicrobial potential. Cytotoxicity was observed after 24- and 48-hr. Kirby Bauer Test was used to determine antimicrobial potential of mouthrinses in C. albicans, E. faecalis, E. viscosus and S. mutans. The zone of inhibition (ZOI) was measured in mm after 24- and 48-hr. H2O2 content of TWMR was measured using the sodium thiosulfate titration
Results: H2O2 content of mouthrinses ranged from 1.66% to 2.24%. Cytotoxicity was detected of all four mouthrinses and 3% H2O2 as-is and at 1:1 after 24- and 48-hours. Substantial antimicrobial effect was detected for all four mouthrinses as-is and at 1:1 dilution, which was comparable to that of 3% H2O2 in four microorganisms tested. COW induced the largest ZOI on C. albicans (16.75±0.87) and S. mutans (37.63±4.50); C3W (40.88±3.66) on A. viscosus; and LWR (17.75±3.48) on E. faecalis; all were significantly greater than those of the negative control in all four microorganisms (p<0.05).
Conclusions: Under the condition of the present study, it is concluded that: 1). All four tooth whitening mouthrinses provide a significant antimicrobial effect comparable to 3% H2O2 on C. albicans, E. faecalis, A. viscosus and S. mutans; 2). The four mouthrinses can induce cytotoxicity, which is most likely originated from their H2O2 content; the clinical significance of the detected cytotoxicity of these mouthrinses needs further evaluation.
Key Words: cytotoxicity, antimicrobial, whitening mouthrinse, peroxide and microorganism