[Effect of different kinds of toothbrushes on toothbrushing pressure and plaque removal in the scrubbing method of toothbrushing (5). Toothbrushes with nylon bristles arranged in different lengths along the toothbrush shank and with different types of toothbrush bristle tip].

The purpose of this study (Report 5) was to investigate the effect of difference in the length of toothbrush shank and type of tip of toothbrush bristle on toothbrushing pressure and plaque removal in the scrubbing method. Four kinds of toothbrushes which were different in length of shank (30 mm, 40 mm) and type of bristle tip (round type, tapered type respectively) were used in this study. Referring to the results of our previous reports (1-4), the dimension of new toothbrushes were determined as follows, nylon bristles: 40 mm long and 0.20 mm in diameter, brushing surface: 30 mm long, bristles: 3 rows with 26 tufts, and a straight handle. Twelve subjects participated in this experiment. Plaque scores were measured before and after toothbrushing. Then plaque removal rates were calculated. Toothbrushing pressure was determined using Watanabe's method. The average toothbrushing pressure of the toothbrush with a 40 mm long shank (301.6 +/- 84.1 g/cm2) was higher than that with a 30 mm long shank (294.7 +/- 74.8 g/cm2), and that with a tapered bristle type (316.7 +/- 90.4 g/cm2) was higher than that with a round type bristle (279.6 +/- 61.7 g/cm2). However statistically significant differences were not found among the four toothbrushes in brushing pressure and in plaque removal on total teeth surfaces and on distal surfaces of the most posterior teeth (P less than 0.05; two-way ANOVA).