Laboratory evaluations of toothbrush interproximal penetration ratios

Access to interproximal tooth surfaces by toothbrush bristles has been associated with plaque removal. The ability of toothbrushes to assess the interproximal area was assessed with a new laboratory apparatus by measuring the extent of bristle-to-tooth contact in simulated toothbrushing with ink-coated toothbrush bristles. Toothbrush types evaluated were the bi-level trim Advanced Design Reach Soft, the ripple trim Crest Complete Large Soft, the flat trim Colgate Plus Full Head Adult Soft, and the flat trim Oral-B 35. Six replicates of each toothbrush were tested. Denture teeth in a Columbia Dentoform, mounted at 45 degrees, were brushed at a 300 g brushing weight for 15 horizontal strokes. Tooth #15 (upper left second molar) was then removed for measurement and the interproximal distance of ink deposition was determined under 10x magnification from the plane of the buccal contour, along the mesial side of the tooth in the lingual direction at the approximate vertical midpoint of the proximal surface. This was compared in ratio to the same measurement from the buccal contour to the midline. Mean penetration ratios were 0.84 for the Advanced Design Reach, 0.79 for Crest Complete, and 0.78 for both Colgate Plus and Oral-B 35 (overall standard error = 0.01). A one-way ANOVA showed a highly significant difference (p < 0.001) demonstrating that Advanced Design Reach penetrated significantly farther than the toothbrushes with flat or ripple trim bristle patterns. The data suggest the bi-level trim in the Advanced Design Reach toothbrush offers better penetration into the area between teeth, and may provide superior clinical or plaque removal compared to the other toothbrushes tested.