Cyclic Laboratory Model to Measure the Chemical Cleaning Power of Seven Grades of Sodium Bicarbonate

Objective: This study was to determine the chemical cleaning power water-soluble abrasives such as sodium bicarbonate in isolation from the mechanical cleaning power of the abrasive system. The Indiana Method (Stookey et.al. JDR 61:1236,1982) has been the recognized and preferred laboratory method to assess the cleaning power of toothpaste and toothpaste abrasive systems. The Indiana method is basically an assessment of mechanical cleaning occurring with 800 double strokes with a soft bristle toothbrush with a 150 gm load with an oral simulated dental stain on etched bovine teeth. While it is possible that some chemical cleaning occurs during the ~ 5 min. of brushing, the results are usually considered mechanical cleaning. Wülknitz (Adv Dent Res 11:576,1997) reported that the correlation of abrasion and cleaning was 0.66 and suggested that abrasive type, particle surface and size as well as chemical influence affected cleaning. Method: The experimental methods used a chicken eggshell simulated enamel mount equilibrated in fresh, pooled human saliva for 20 min. and then swirled at 140 rpm in treatment for 5 min. and then in tea stain for one min. After each treatment, the surface was scanned with a Minolta 503i Spectrophotometer from 400-700mµ. Results: As little as 0.5% sodium bicarbonate reduced stain accumulation. Smaller particulate grades were somewhat more effective in controlling stain, but all grades were effective. Bicarbonate was similar to soluble polyphosphate in controlling stain, but the kinetics were different. Conclusion: This laboratory study using a cyclic stain model has shown that sodium bicarbonate can control stain by chemical means. This study was supported in part by the Church & Dwight Co, Inc. hefferen@ku.edu