Power Toothbrush Technology - State of the Art
Louis Malcmacher, DDS, FAGD
Power toothbrushes have been a welcome addition to the armamentarium for fighting dental disease. There has been much scientific debate over whether power toothbrushes are better than manual toothbrushes in helping patients fight dental disease, with some recent studies showing that powered toothbrushes with a rotation oscillation action reduce plaque and gingivitis more than manual toothbrushing.1 There is no question that, used correctly, manual toothbrushing can be as effective as power toothbrushing. Unfortunately, very few dental patients brush correctly. It has been the author’s experience with patients during the past 25 years of private practice that power toothbrushes are a valuable tool for those patients who either cannot or will not learn to brush correctly using the Modified Bass Technique.
During the past 12 years, a new and more comprehensive understanding of bacterial development, growth, and survival has evolved, and it is now understood that plaque is classified as bacterial biofilm. Biofilm has been extensively studied, which has deepened our understanding of dental plaque. This revolution in bacterial exploration is a result of confocal scanning laser microscopy technology, a process that allows investigators to visualize the complex structures and diversity of organisms that compose biofilm in three dimensions (height, width, and volume). Scientists, researchers, and biomedical engineers are challenged to find new methods for reducing, controlling, and/or destroying bacterial biofilm populations that exist in nature, within the human body, and within the oral cavity. Controlling biofilm is crucial to both oral health and systemic health and is compelling all dental professionals to explore improved methods of daily biofilm disruption. In a conversation with J. William Costerton, PhD, director of the Dental Biofilm Center at University of Southern California’s School of Dentistry, he recommended that biofilms be removed as soon as possible and as early as possible in their evolutionary development.
The effectiveness of traditional mechanical disruption of plaque biofilms with manual toothbrushing and flossing is largely dependent on patient instruction, technique, motivation, and compliance. Unfortunately, compliance with the recommended procedures is generally inconsistent and subsequently the positive impact on oral health status is minimized. The evolution of power toothbrush technology and concurrent research has demonstrated its ability to disrupt plaque biofilms, reduce gingivitis, and improve periodontal parameters.2,3 Researchers have additionally found that multi-directional and turbulent fluid action created by high-frequency and high-amplitude toothbrush bristle motion, such as those found in power toothbrushes specifically using sonic technology, stresses biofilms in multiple directions, resulting in a reduced ability of the biofilms to adapt to the flow and adhere to the surface.4 A detailed review of current power toothbrush and bristle movement technology contributes to a better understanding of their ability to disrupt biofilm communities made up of dental plaque in the oral cavity.
Two key principles - bristle movement and frequency and amplitude - impact the effectiveness of a power toothbrush’s ability to disrupt dental plaque biofilm. Frequency is defined as the number of cycles the power toothbrush bristles move within a unit of time, usually measured in brush strokes per minute. Amplitude is the sweep or distance covered by the power toothbrush bristles during their cycle of movement. Frequency multiplied by amplitude equals speed or in this case bristle tip velocity. Depending on the velocity achieved, there can be fluid-bubbling or hydrodynamic action, which has been shown to additionally disrupt biofilms from model dental surfaces.4,5 Defining power toothbrushes by frequency and amplitude is one way to evaluate and differentiate between the various models available in today’s market.
Disposable battery-operated toothbrushes can be an economical stepping-stone to encourage patients to use a power toothbrush rather than a manual toothbrush. And because their bristle action varies widely depending on the brand and battery strength, this review excludes their consideration.
Power toothbrushes can be divided into three categories of frequency and amplitude. The first category is high-frequency and low-amplitude, such as the Cybersonic® (Amden Corporation, Carson, CA). The second category is low-frequency and high-amplitude, such as the Oral-B® (Procter & Gamble, Cincinnati, OH), Rota-dent® (Professional Dental Technologies, Batesville, AR), or Interplak® (Conair Corporation, Stamford, CT). The last category is high-frequency and high-amplitude, such as the Oral-B® Sonic Complete® (Procter & Gamble) and Philips Sonicare® (Philips Oral Healthcare, Snoqualmie, WA).
The Cybersonic oscillates at 41,000 sonic strokes per minute with patented spring-action “cyberspring” bristles and brush head motion generated by the motor in the handle. The brush does not turn off automatically, and claims a “done in one” minute as sufficient time to effectively remove plaque. This brush demonstrates high frequency of 41,000 strokes per minute and low amplitude, or brush sweep.
Low-frequency and high-amplitude brushes such as the Oral-B provide a round, oscillating brush head with pulsating action. The oscillations range between 6,800 and 7,600 strokes per minute, while the pulsation is .024 in (1/2,400 of an inch), or .6096 mm (2/3 of a millimeter). A timer “stutters” at a 2-minute interval, but the brush does not turn off automatically. The Rota-dent has a rotational brush head movement which makes a continuous and slow circular sweeping action 1,400 times per minute. This brush has no timing mechanism and will not turn off automatically. The Interplak has counter-rotational bristle tuft movement, and each tuft group moves independently of each other in the opposite direction of the adjacent bristle group. Their frequency is 4,200 cycles per minute; it has a 2-minute timer and the brush automatically shuts off.
In the high-frequency, high-amplitude category, the Oral B Sonic Complete has varying frequencies ranging from 24,000 to 31,000 vibrations per minute, dependent on the mode selected. This brush has a 30-second “stutter,” a 2-minute timer and no automatic shutoff. The Sonicare Elite e9000 series brushes combine a high frequency of 31,000 brush strokes per minute with a wide amplitude (or sweep up to 4 mm) of bristle movement, creating bristle tip velocity that generates significant hydrodynamic fluid activity to disrupt dental plaque biofilm. The Sonicare has a Quadpacer® that signals to the user when it is time to move to the next quadrant, a 2-minute timer providing the patient with the ability to select another additional 30-second segment, and the brush automatically turns off.
Equally as important as frequency and amplitude, is the ability of a power toothbrush to be gentle while effectively disrupting biofilms. Manual toothbrush users apply anywhere from 200 g to 400 g of force on their teeth. Aggressive toothbrushers frequently exceed 400 g of force. Power toothbrushes require much less pressure, only 70 g to 150 g of force. Spinning, oscillating, and rotating brushes are designed to work best at approximately 150 g of force as per the manufacturers’ recommendations. Sonic tooth-brushes are on the lower end of the range at 75 g to 100 g.
Biofilm disruption is critical to establishing and maintaining oral health; however, consistent and thorough removal requires a high level of patient compliance. One of the biggest compliance challenges is the amount of time spent and required to achieve adequate brushing. Increased brushing times have been directly correlated to better plaque or biofilm removal.6,7 The feature of a timer is incorporated into several power toothbrushes (Interplak, Oral-B, and Sonicare). This is an important feature as it stimulates the patient to complete the full cycle of brushing until the unit signals the user that he or she is done.8 More sophisticated models signal 2-minute completion and shut off automatically. Customized brush heads including standard and more compact sizes designed for improved access to hard-to-reach areas may enhance biofilm disruption.
Successful clinical outcomes require dental professionals to continually review current research as the study of biofilms evolves and new methods for controlling dental disease are developed. Additionally, as dental experts, our patients depend on our knowledge and expertise, which evolves from our own clinical and personal experiences. Understanding the significance of biofilm disruption and adjusting clinical practice to embrace this science will enhance clinical outcomes for patients. To accomplish this, we need to understand that the choices our patients make for their oral care products are very important. Clinicians make specific recommendations to patients so they can achieve maximum oral health. Power toothbrushes have demonstrated the ability to do a thorough job of reducing biofilm and improving patients’ oral health. They are a wise recommendation for many patients and for ourselves.
1. Robinson PG, Deacon SA, Deery C, et al. Manual versus powered toothbrushing for oral health. In: The Cochrane Library of Systemic Reviews 2005. Chichester, UK: John Wiley & Sons, Ltd; 2005.
2. Heasman PA, McCracken GI. Powered toothbrushes: a review of clinical trials. J Clin Periodontol.1999;26(7):407-420.
3. Tritten CB, Armitage GC. Comparison of a sonic and a manual toothbrush for efficacy in supragingival plaque removal and reduction of gingivitis. J Clin Periodontol. 1996;23(7):641-648.
4. McInnes C. Water world. Scientific American 2002 (Special Issue: Emerging Trends in Oral Care, The Biofilm Revolution). 2002;22-25.
5. Biofilms on Oral Surfaces: Implications for Health and Disease. 14th International Conference on Oral Biology. Monterey, California, March 18-20, 1996. Adv Dent Res. 1997;11(1):1-85
6. Barlow AP, Zhou X, Barnes JE, et al. Pharmacodynamic and pharmacokinetic effects in gingival crevicular fluid from redosing during brushing. Compend Cont Educ Dent. 2004;25(10 suppl 1):21-27.
7. Van der Weijden FA, Timmerman MF, Snoek IM, et al. Toothbrushing duration and plaque removal efficacy of electric toothbrushes. Am J Dent. 1996;9(spec no):S31-S36.
8. Rethman J, Neuser F, Bar AP. Brushing compliance with a novel integrated power toothbrush and toothpaste oral hygiene system. Compend Contin Educ Dent. 2004;25(10 suppl 1):28-35.
|About the Author|
Louis Malcmacher, DDS, FAGD