Fluoride, calcium and inorganic phosphorus concentrations in approximal plaque collected from young adults 1 and 24 h after toothbrushing with fluoride toothpastes.

A within-subject double-blind cross-over study was carried out to examine whether the chemical composition of approximal plaque was altered 1 and 24 h after brushing with fluoride toothpaste. Three fluoride toothpastes were tested, containing either sodium monofluorophosphate with calcium glycerophosphate supplement and calcium carbonate abrasive, a combination of sodium monofluorophosphate and sodium fluoride with the same supplement and abrasive or sodium fluoride with a silica abrasive. A fluoride-free toothpaste with a silica abrasive acted as the control. 19 subjects used the toothpastes separately in randomised order for 1 week each prior to collection of plaque. Contralateral half-mouth approximal plaque samples were collected 1 and 24 h after the last use of each toothpaste. Fluoride, calcium and inorganic phosphorus concentrations of plaque were estimated. The results indicated that brushing with toothpastes containing fluoride and/or calcium supplements resulted in increased concentrations of these constituents in approximal plaque 1 h after brushing. These elevated levels of inorganic ions were not observed in the samples collected 24 h after brushing. It was concluded that the potentially beneficial effect of a raised concentration of fluoride and calcium in approximal plaque observed soon after brushing is lost during the following 24 h.