The Colgate Precision toothbrush was compared to the Crest Complete toothbrush for interproximal access efficacy using a laboratory device designed to simulate clinical toothbrushing motions and weights. Each vertical and horizontal brushing motion was timed for one minute for each of the three brushing weights tested; 250, 500 or 750g. Pressure-sensitive paper was placed around all simulated tooth surfaces to record the brushing strokes. The measurements of the recorded brushing strokes provided the interproximal access efficacy of all brushes. A total of twenty-four Colgate Precision toothbrushes and twenty-four Crest Complete toothbrushes were tested for both brushing motions, both tooth shapes and all three brushing weights, resulting in a total of 576 measurements. With vertical brushing motion using both tooth shapes tested and at all brushing weights, the Colgate Precision toothbrush had significantly greater interproximal access efficacy (p < 0.01 by ANOVA) than the Crest Complete toothbrush. With horizontal brushing motion on both tooth shapes tested, at the 500 and 750g brushing weights, the Colgate Precision toothbrush had significantly higher interproximal access efficacy (p < 0.01 by ANOVA) than the Crest Complete toothbrush. When total interproximal access efficacy means (comparing results of all weights tested) were evaluated, the Colgate Precision toothbrush was superior (p < 0.01) to the Crest Complete product for both brushing motions and tooth shapes tested.