The purpose of the experiment was to determine which mouthwash kills bacteria better. To determine which mouthwash was better, four petri dishes with agar, and sixteen sterilized, paper disks were needed. With sterile cotton swabs, bacteria from teeth and gums were transferred onto the agar of the four dishes. Four paper disks were soaked in each brand of mouthwash (Scope, Listerine, Peroxyl) and water for ten minutes. Then, the disks were placed on the petri dishes, so that each group of disks had their own petri dish, and each disk had a fourth of a petri dish. The petri dishes were incubated at 37 degrees Celsius, for 48 hours. The inhibition zones were measured then averaged.
After the expirement was completed, the mouthwash brand Peroxyl had the largest average zone of inhibition (23.5 mm). Listerine was the second most efficient mouthwash brand (4.5 mm). Scope had a small inhibition zone (3.75 mm), and was the least efficient mouthwash brand, while the control (water) had no effect on the bacteria (0 mm).