A randomized, two-compartment
calculus clinical study of twelve-weeks duration was conducted among a group of
calculus-forming subjects in the St. Louis area. The purpose of this parallel and double-blind clinical study was to compare the effect of a
dentifrice containing 5.0%
potassium nitrate, 1.3% soluble
pyrophosphate, 1.5%
PVM/MA copolymer and 0.243%
sodium fluoride in a
silica base, to that of a placebo
dentifrice, with regard to supragingival
calculus formation. The study examiner, using the Volpe-Manhold
Calculus Index, selected a panel of
calculus-prone men and women who had completed a one-month placebo regimen. The Volpe-Manhold
Calculus Index scores and the number of completely
calculus-free sites were recorded. One-hundred and fifteen subjects were entered into the study. After an oral soft and hard tissue examination, the subjects were given a complete oral prophylaxis and randomly assigned to use either the placebo or test
dentifrice for a 12-week home-use period. They were prohibited from using any other means of
oral hygiene during the study. After completing 12 weeks of twice-daily brushing at home using their assigned
toothpaste and a standard soft-bristled toothbrush, subjects were again assessed for supragingival
calculus deposits and
calculus-free sites. The
dentifrice containing 5.0%
potassium nitrate, 1.3% soluble
pyrophosphate, 1.5%
PVM/MA copolymer and 0.243%
sodium fluoride in a
silica base, inhibited supragingival
calculus formation by 54.4%, as compared to a 0.243%
sodium fluoride silica-based placebo
dentifrice. The mean Volpe-Manhold
Calculus Index scores were compared statistically and the difference indicated statistical significance at probability of 0.01 by means of an analysis of covariance (ANCOVA). The number of
calculus-free sites, a second parameter of efficacy, also was compared and demonstrated an absolute difference of 32.6% in favor of the group using the
dentifrice containing
potassium nitrate, soluble
pyrophosphate and
PVM/MA copolymer compared to a placebo
dentifrice (37.8% vs 5.2%, respectively). An analysis of covariance indicated that this improvement showed statistical significance at a probability of 0.01.