An experiment on the attrition of acid demineralized dentine in vitro

Background: A laboratory investigation was designed to test the hypothesis that acids increase the rate of wear caused by attrition on dentine. Methods: Dentine sections from 10 teeth were polished, cleaned in an ultrasonic bath and divided into 8 equally sized areas. The occlusal tip of a tooth, placed vertically in a wear machine and loaded at 150 N, was moved against each dentine section for 5000 return strokes with artificial saliva acting as a lubricant. Each dentine section was divided into 8 sections and half randomly immersed in a 1% citric acid solution (pH 2.3) for 20 minutes. The wear regime produced 8 wear scars in total per dentine sample. The volume of each wear scar was measured using a contacting digitizing profilometer. Results: A total of 80 wear scars were produced with 40 treated with acid and 40 acting as controls. The mean for wear volume of the dentine scars with acid was 4.84 mu m(3) (1.38) and for the non-acid surface 2.95 mu m(3) (0.86). This difference was statistically significant (p <0.05). Conclusions: These results support the hypothesis that acids increase the rate of wear caused by attrition on dentine.