The Nuts and Bolts of Toothbrushes
The right tool is critical for maximum plaque removal
Head and Bristles
The toothbrush head is an extension of the handle and is contoured to position the bristles. Bristles are typically round nylon filaments. The degree of hardness or stiffness of the brush is determined by the filament characteristics—especially diameter—and length as well as elasticity. Because larger diameters are stiffer, they do not bend and, therefore, exert greater pressure on the soft tissues and do not extend as easily into hard-to-reach areas. Round-ending of bristle tips was introduced in the 1940s after it was reported that trauma could occur from sharp bristle tips. The end-rounded bristle was the standard for the remainder of the 20th century. Brushes with round-ended bristles were tested in many studies, which demonstrated they were not able to penetrate much beyond 1 mm into the gingival sulcus.1
In the quest to clean hard-to-reach areas, innovation in bristle technology and design introduced fine-diameter bristles, which taper to a very narrow, rounded end. In these extremely tapered bristles, the diameter of the base of the bristle is 0.2 mm, and the tapering commences at 6 mm from the bristle tip and reduces smoothly to a diameter of 0.01 mm at the tip (Figure 1). The tapering of the bristle allows greater flexibility and slenderness to reach deep into the sulcus. In comparison, the end of a traditional and most commonly encountered round-ended bristle is tapered only for 0.5 mm of the upper part, and the smallest diameter of the bristle is 0.02 mm. This is a significant contrast in size (double) and shape (tapered). The extremely tapered end-rounded bristles not only reach into the depth of the sulcus, but also penetrate more deeply into the interproximal spaces. In commonly accepted laboratory tests, these extremely tapered bristles have been shown to reach as deeply as 2.75 mm into the sulcus (Figure 2 and Figure 3). Also, they have been shown in the same studies to reach further into the interproximal areas than regular bristles (1.43 mm versus 0.85 mm).2 Another recently introduced bristle has a feathered tip, where the single filament splits into five to seven much finer endings, providing up to 70% more surface contact with the tooth and thus yielding greater cleaning power. Configuration of the bristles is also important. Positioning tufts to be 10 degrees to 20 degrees away from the vertical axis increases interproximal penetration. A dome-shaped head of bristles, where the bristles in the center of the head are raised, has been shown to increase plaque removal and clinical indices3,4 (Figure 4).
The design of the handle is also critical to effectiveness and patient compliance. The ideal handle grip should aid the patient in holding the brush at the correct angle so that the bristles are presented at 45 degrees to the long axis of the tooth.5 Some handle designs are available to support the patient in this endeavor and to comply with some of the most commonly recommended oral hygiene techniques (Figure 5). The length of the handle is also important. It should be long enough to provide adequate grip to give full control, and the distance between the grip area and the head should enable easy access to the most posterior teeth.
Toothbrushing is the major behavior performed by patients to fulfill their needs to feel clean and fresh and to avoid dental problems. While patients depend on their dental team to protect their oral health, they spend far more time brushing their teeth than they do receiving care in the dental office. For these reasons, the dental professional should be prepared to provide comprehensive advice not only on the most effective brushing techniques, but also on the design and selection of the brushes their patients use.
The figures for this article were provided by Sunstar Americas, Inc (www.gumbrand.com/).
1. Yankell SL, Barnes CM, Xiuren S, Cwik J. Laboratory efficacy of three compact toothbrushes to reduce artificial plaque in hard to reach areas. Am J Dent. 2011; 24:195-199.
2. Bauroth K, Charles CH, Mankodi SM, et al. The efficacy of an essential oil antiseptic mouthrinse vs. dental floss in controlling interproximal gingivitis: a comparative study. J Am Dent Assoc. 2003;134(3):359-365.
3. Bass CC. The optimum characteristics of toothbrushes for personal oral hygiene. Dental Items of Interest. 1948;70:696.
4. Reynolds HS, Zambon JJ. Microbiological and clinical alterations from using Butler GUM toothbrushes [abstract]. J Dent Res. 1997;76(special iss). IADR Abstract 1753.
5. Poyato-Ferrera M, Segura-Egea JJ, Bullón-Fernández P. Comparison of modified Bass technique with normal toothbrushing practices for efficacy in supragingival plaque removal. Int J Dent Hyg. 2003;1(2):110-114.