1578 Cytotoxicity of tooth whiteners with various peroxide concentrations
W. ZHANG, and Y. LI, Loma Linda University, CA, USA
Objective: To determine cytotoxicity of tooth whiteners in relation to their peroxide content. Methods: A total of 12 whiteners, including eight at-home and four in-office formulations, were examined for their cytotoxicity. Six of the eight at-home gels contained carbamide peroxide at concentrations ranging from 10% to 20%, while the active ingredient in the other two was 7.5% hydrogen peroxide. Three in-office gels were hydrogen peroxide-based formulations, with concentrations at 15% or 35%, while the other gel contained 35% carbamide peroxide. L929 fibroblasts (ATCC CCL1) were cultured in Eagle's MEM, supplemented with fetal bovine serum (FBS), non-essential amino acids, Lglutamine, penicillin, streptomycin and amphotericin B. A minimum of six doses were examined for each whitener, and culture media and phenol served as the negative and positive controls, respectively. The cultures were treated and then incubated for 24 hours, and the cytotoxicity was evaluated using the MTT tetrazolium assay. The 50% inhibitory dose (ID50) was calculated using the absorbance data. The experiment was conducted using six cultures in each group.
Results: The ID50 of at-home whiteners containing 10% carbamide peroxide ranged from 55 to 71 µg/mL, which were slightly higher or comparable to those with 15% or 16% carbamide peroxide. Gels with 20% carbamide peroxide or 7.5% hydrogen peroxide were more cytotoxic than those containing 10% to 16% carbamide peroxide. The in-office formulations are highly cytotoxic; the ID50 values of the two gels with 35% hydrogen peroxide were 10 and 7 µg/mL, respectively.
Conclusion: The cytotoxicity of whiteners increases with the content of peroxide, which appears to be the major source responsible for the observed cytotoxicity of whiteners. However, other ingredients in the formulation may also affect the cytotoxicity of the whitener. Seq #146 - Oral Tissues, Toxicology I 3:45 PM-5:00 PM, Thursday, 7 March 2002 San Diego Convention Center Exhibit Hall C