The effect of citric acid on retained plaque and calculus. A short communication.

Five extracted human teeth with clinically demonstrable calculus were used. One proximal surface of each tooth was partly scaled, leaving a small amount of calculus. The crown was then cut off at the cementoenamel junction and the scaled proximal surface was divided vertically into two segments using a thin separating disk. One segment was treated by rubbing cotton pellets soaked in citric acid (pH1) over the surface for three minutes and then immersing the segment in saline to stop the reaction. The other (control) segment was treated by rubbing cotton pellets soaked in saline over the surface for three minutes. When viewed under a scanning electron microscope, the control sections displayed scaling striations, considerable surface debris, and large numbers of bacteria at the borders of the residual calculus. Citric acid-treated specimens displayed little debris on cementum or residual calculus and virtually no bacteria at the junction between calculus and cementum. The surface morphology of the citric acid-treated calculus varied from layered-like to honeycomb.