The Effect of Coffee Brew on the Production of Superoxide Radical by Monocytes Exposed to Dental Bleaching Material

Background: The application of dental bleaching material produces free radicals that potentiate irritating gingival tissue, leading to chronic gingivitis. Coffee is a rich antioxidant beverage and might be able to inhibit free radical production.

Aims: This study aimed to analyze whether robusta coffee brew (RCB) can inhibit the production of free radicals (superoxide radicals) by chronic inflammatory cells (monocytes) exposed to dental bleaching material carbamide peroxide (CP).

Methods: This experimental ex vivo study used the post-test-only control group design. The object was the Ex vivo human monocytes isolated from peripheral blood veins using the gradient centrifugation method. The dental bleaching material was 10% CP. The coffee brew was prepared by steeping the roasted robusta coffee ground into 200 mL of boiled distilled water. Two concentrations of coffee brew were studied i.e. 3 g/200 mL and 6 g/200 mL. There were three experimental groups, i.e.,1) monocyte + CP (without RCB), 2) monocyte + 3 g/200 mL RCB + CP, and 3) monocyte + 6 g/200 mL RCB + CP. Production of superoxide radical was analyzed using the Nitroblue-tetrazolium (NBT) assay, which was indicated by the production of formazan (purple spots) by monocytes. The parameter was the number of monocytes that produced superoxide radicals (monocytes that expressed purple spots), which was identified under the light microscope. Data were analyzed using ANOVA and Least Significance Difference (LSD).

Results: Coffee groups demonstrated a significantly (p<0.05) lower number of monocytes that produced superoxide radicals.

Conclusion: Robusta coffee brew demonstrated an antioxidant effect against superoxide radicals produced by monocytes exposed to dental bleaching material carbamide peroxide. The antioxidant activity of coffee brew might suggest its potential as an agent for protecting gingiva from the irritating effect of dental bleaching material.