A 3-month, double-blind, randomized, longitudinal, parallel clinical study was conducted to compare the effects on supragingival
calculus deposits of a
dentifrice containing soluble
pyrophosphate to a control MFP
dentifrice, which did not contain
pyrophosphates. During the pre-test phase, 247 teachers were examined for presence of
calculus on the lingual surfaces of the 6 lower anterior teeth, using the Periodontal Probe Method of
Calculus Assessment (Volpe et
al. 1965). Statistical methods employed were the two-way analysis of variance as well as the paired and unpaired t tests. The level of statistical significance chosen was p less than 0.05. At the end of the 3-month pre-test phase, 88 candidates with the highest
calculus index scores met the initial criteria and were stratified into two balanced groups based on their age and sex. Each group received an oral prophylaxis and participants were assigned to use either the
dentifrice containing the
pyrophosphate or the MFP and instructed to brush their teeth twice daily at home for the next 3 months (test phase). The results showed that the group using the
pyrophosphate dentifrice experienced a 20% greater reduction in
calculus formation when compared to the MFP control There was also a greater number of
calculus-free subjects and tooth surface sites in the soluble
pyrophosphate group. The change in the Volpe-Manhold Index revealed significant differences for both the
pyrophosphate group (change = 1.7111; p = 0.0010) as well as, though less prominent, for the control group (change = 1.4186; p = 0.0313).