Using duplication method, vertical force was applied from 1-5.5 N in linear mesial-distal brushing motion at 4 strokes per second for 5 seconds Force was increase 0.5 N in every testing until plaque was completely removed from enamel surface

The toothbrush holder was adjusted allowing toothbrush bristle to press onto the tooth surface until the loading monitor indicated the designated vertical loading force. Loading force was applied from a minimum of 1 N, with an increment of 1 N to a maximum of 6 N. The optimum force which remove all dental plaque from tooth surface will recorded.