The inhibitory activity of 2-phosphono-butane 1,2,4
tricarboxylic acid (
PBTA) in the formation of
hydroxyapatite (HA) was studied in vitro and in vivo.
PBTA, at 4 ppm, inhibited the spontaneous formation of HA in vitro from a supersaturated
solution.
PBTA, at 2 ppm, completely inhibited the crystal growth of HA; at lower concentrations, a direct relationship was found between the reduction of the initial precipitation rates and
PBTA concentrations in the
solution. The effects of
PBTA on human dental enamel in vitro were also evaluated at pH 5.0 and 7.5. Equimolar levels of
EDTA served as the controls. In comparison with
EDTA, the dissolution of enamel induced by
PBTA was negligible. One percent
solution of
PBTA was evaluated in a rat
calculus assay. In comparison with a placebo
solution, it significantly (p = 0.05) reduced
calculus formation when applied topically. It was also tested against
calculus formation in beagle dogs. A topical application once a day of a 1%
solution at pH 7.0 reduced
calculus formation by 84% for 16 weeks. Analysis of these data suggests that the agent effectively reduces
calculus formation in vivo.