Microabrasion of human enamel in vitro using hydrochloric acid and pumice.

The rubbing application of a hydrochloric acid-pumice mixture has been advocated for the removal of fluorotic-like areas of permanent teeth. However, there have been no previous reports as to the amount of enamel removed during this process. The objective of this project was to measure the amount of enamel lost during successive rubbing applications of an 18% HCl-pumice mixture. Nine extracted permanent molars were mounted in die stone, and each was subjected to 10 sequential 5-sec rubbing applications of an 18% HCl-pumice mixture. After rubbing for 5 sec, the teeth were rinsed with water for 10 sec and then thoroughly dried. Enamel loss was measured to the nearest micron utilizing a measuring microscope with 3-dimensional digital stage positioning. Measurements were taken at the consistent x,y coordinates of three points on the tooth surface after each application. The change in the z coordinate, representing the spatial change in the location of the enamel surface, was recorded for each point after each application on the tooth. Regression analysis revealed enamel loss of 12 microns after the initial application, and an average of 26 microns of enamel loss after each successive application. The regression coefficient was significant at P less than 0.001.