Studies on the Carbon Dioxide Component of Human Enamel. III. The Effect of Neutral and Acid Fluoride

¹ Eastman Dental Dispensary, Rochester, New York

Addition of more than 1 p.p.m. fluoride to acid acetate buffers increased the amount of CO₂ preferentially removed by acid or fluoride alone from enamel of very small-particle size. When calcium fluoride was not a major reaction product, almost equivalent portions of phosphorus accompanied that part of CO₂ removal in excess of the CO₂ normally removed preferentially in acid. Phosphate buffer suppressed this effect. It was theorized that acid fluoride penetrated below the exposed surface to effect, in some manner, the removal of subsurface CO₂. Although marked conversion to calcium fluoride occurred with acidulated 2 per cent sodium fluoride, in the absence of phosphate buffer more than 20 per cent of the CO₂ in the remaining unconverted enamel appeared to be preferentially removed.