Effect of chlorhexidine and lanthanum on plaque formation.

The present study included rinses with aqueous solutions of lanthanum prior to and after traditional chlorhexidine mouthrinses. Lanthanum has an extremely high affinity for phosphate, and the experiments were designed to examine the role of this anion as a receptor site for chlorhexidine in the oral cavity. The results indicate that from 1/3 to 1/2 of the chlorhexidine retained in the oral cavity may be bound to phosphate groups.