Effect of TiF4 solutions on bacterial growth in vitro and on tooth surfaces

The purpose of this study was to assess the antimicrobial effect of TiF4 as compared with equimolar solutions of NaF, APF, and SnF2 and to evaluate the effect, if any, on bacterial growth on topically treated tooth surfaces. In an in vitro study, paper discs impregnated with 20 microliters of equimolar solutions of SnF2, NaF, APF, and TiF4 were placed on blood agar plates seeded with Streptococcus mutans and Bacteroides gingivalis. Sterile saline was used as control. Similar growth inhibition zones were found for all fluorides. In the second part of the study six volunteers carried intraoral appliances containing enamel and root surface specimens treated with 1% TiF4 and untreated specimens for 18 h. Scanning electron microscopic examination of the experimental tooth surfaces showed great variation in bacterial growth between subjects, but no systematic difference between fluoride-treated and untreated specimens. Bacteria from test and control specimens were grown under aerobic and anaerobic conditions on blood agar and on mitis salivarius agar. Colony-forming unit counts showed great interindividual variations, but no differences could be observed between treated and untreated enamel or root surfaces. Thus, the hypothesis that the presence of a Ti-rich coating may influence bacterial colonization on TiF4-treated tooth surfaces could not be substantiated.