The undisturbed supragingival plaque formation was recorded twice over a 100 hours period in 14 healthy dental students; first after induction of gingival inflammation and a second time starting from a healthy gingiva. During each experimental segment plaque formation was recorded on 42 randomly selected and clean teeth at the start and after 6, 12, 24, 30, 36, 48, 54, 60, 72, 84, and 96 hours. Four hours later all teeth up to the first molars were examined. The presence of disclosable plaque was calculated planimetrically as percent of the total labial surface area of the tooth. The rate of plaque formation was found to be significantly greater (P = 0.001) in the presence of gingival inflammation (+ 29.0%). Moreover, this study indicates an important variation in the plaque growth rate within the dentition; the highest scores were found for the upper premolars, the upper molars, and the lower front teeth. Finally, the rate of plaque formation was found to decrease during the night.