In Vitro Studies of Sodium Bicarbonate in Relation to Certain Factors Concerned with Dental Caries

Abstract

Because the empirical use of NaHCO3 as a dentifrice warrants an investigation of this substance in relation to dental caries, the following in vitro studies were made. Diffusion of NaHCO3 through bacterial plaques was studied by dialyzing NaHCO3 solns. through sheets of cellophane on which artificially produced plaques had been deposited. The deposition of plaques was accomplished by immersing the cellophane sheets in saliva, changed daily, for a period of three weeks. The findings indicate that plaques inhibit but do not prevent the passage of NaHCO3 across the dialyzing membrane. The effects of NaHCO3 on acid production and growth of Lactobacillus acidophilus, in culture broth and on agar plates, respectively, were also studied. The results were compared with those obtained when other alkaline reagents of similar concentration were tested. The findings indicate that NaHCO3 inhibits the growth and acid production of L. acidophilus, in vitro, by virtue of pH changes that result following incubation of the media.