Measurement of plaque growth following toothbrushing

A method measuring plaque by area has been developed which can be used to evaluate the antiplaque effect of agents such as dentifrices when used in combination with toothbrushing. The extent of disclosed plaque 24 hours after treatment on tooth surfaces previously cleaned of all observable plaque was drawn by the examiner onto accurate enlarged scale drawings of the outline of the labial surfaces of all incisors, canines, premolars and 1st molars. Areas were then measured by an electronically recording planimeter. Three separate blind crossover trials were performed using this plaque area measurement in which a minimum of 15 subjects brushed normally on one occasion only, with either a calcium carbonate dentifrice or water. Compared with when subjects brushed with water, a statistically significant reduction of 45%-52% in plaque was observed in subjects 24 hours after brushing with the dentifrice in each of the three trials. In a study with 27 subjects, the periodontal condition of the papillae was found to be related to plaque present on labial surfaces on adjacent teeth as measured by this method. The teeth adjacent to papillae which bled on probing had 77% greater plaque area than teeth adjacent to papillae which did not bleed. Plaque area measured by this method on a continuous scale has a sensitivity advantage over the commonly used four-point plaque indices, especially when comparing effective antiplaque treatments or combination of treatments.