A Comparison of the Effectiveness of Toothbrush Sanitizing Methods
Ellen Dufresne and Bethany Hirst
Gustavus Adolphus College
Dentists and other health professionals recommend tooth brushing 2-3 times per day with ADA approved toothpaste for maintaining proper oral health. Toxin-producing bacterial growth along the gum line is associated with gingivitis as well as acid-induced dental caries. The plaque found on the enamel and along the gum line may solidify to form calculus or tartar. Although utilized for promoting dental health, the Center for Disease Control suggests that toothbrushes can harbor pathogenic organisms even after being rinsed visibly clean. Toothbrushes, though one of the main defenses against dental problems, can contain bacteria and viruses that cause cross-infection between brushes and re-infection during illness. This is most hazardous to those individuals with periodontal disease or compromised immune systems.
Previous research conducted to examine the effectiveness of chlorhexidine gluconate and sodium hypochlorite as disinfectants for pediatric toothbrushes found that both solutions were successful at disinfecting the brushes from mutans streptococci. Further studies were also conducted on a product known as Purebrush, a UV sterilization kit for toothbrushes, at the University of NY and the University of Oklahoma. Their findings are conducive to the product’s claim that it kills 99.9% of all yeast, molds, viruses, and illness causing bacteria growing on toothbrushes.
Warren and her colleagues studied the effectiveness of triclosan-toothpaste as disinfectant against Porphyromonas gingivalis, Prevotella, and Actinobacillus actinomycetemcomitans, three microbes associated with periodontal disease. Their research suggested that though not significantly different, the toothpaste containing toothbrushes had less bacterial growth than the control. From their findings they concluded that patients with periodontal disease should disinfect or replace toothbrushes frequently.
Many companies are beginning to offer a variety of methods to decrease and control oral bacteria. The Murdock Laboratories, Inc has developed an antibacterial toothbrush storage system, Purebrush, which utilizes germicidal UV light to eliminate 99.9% of the disease-causing bacteria, yeast and molds typically found on toothbrushes. Efferdent, sold for cleaning and reducing the odor-causing bacteria on dentures, is advertised as having a similar antibacterial effect. The company Pfizer produces a common antibacterial agent found in the cabinets of many families. Listerine mouthwash claims to reduce plaque and gingivitis by up to 34% over brushing and flossing alone through rinsing for only 30 seconds twice a day. With all of these methods claiming control and elimination of possibly harmful oral bacteria, we became interested in knowing how the different methods compared in their effectiveness. In this study, we compared the success of water, Listerine, Efferdent, and Purebrush at eliminating oral bacteria commonly found on toothbrushes.
Materials and Methods
Oral bacteria were cultured from oral/gingival swabs in TSA broth for 48 hours. Twenty-five toothbrushes were dipped into the broth for 10 seconds to introduce a replicable number of bacteria to the bristles, and were tapped four times to rid excess broth. Five brushes were placed immediately into 5ml of biological saline [8.5% NaCl]. The remaining twenty brushes were placed in the following treatments: 5 in deionized water for 1 minute, 5 in 30ml Listerine for 1 min, 5 in Efferdent for 15 min as directed, and 5 in the Purebrush system for 1hr (a gift from Murdock Laboratories, Inc). The brushes were placed in saline and then the ultrasonicator for 15 minutes at room temperature. Serial dilutions of 10-1 to 10-5 were made with biological saline. 1ml portions of the dilutions were aliquotted into melted Tryptic Soy agar (TSA), poured into plates, and allowed to solidify. The plates were incubated for 48 hrs, the colonies counted, and concentration of bacteria on the toothbrushes was determined. The concentrations of initial plates were compared to the treated plates to evaluate the relative level of effectiveness of each treatment.
All methods of toothbrush sanitation had a significant decrease in the number of bacteria counted on plates (Water, p=0.0298; Listerine, p=0.0169; Efferdent, p=0.0140; Purebrush, p=0.0138; See Fig. 1). On average, water was 84% effective, Listerine was 94% effective, Efferdent was 98% effective, and Purebrush was 99% effective in killing bacteria present in the original toothbrush. In addition to the statistically significant difference between the background and all treatments, there was also difference in effectiveness between water and Efferdent (p=0.0338) and Purebrush (p=0.0380) but not a statistically significant difference between water and Listerine (p=0.1340; See Fig. 1). There was no statically significant difference in the number of bacteria present after treatment between Listerine, Efferdent, or Purebrush.
The UV treatment using the Purebrush unit was the most effective of the methods tested killing 99% of bacteria on toothbrushes. All treatments, including the water rinse, eliminated a significant amount of bacteria. It was assumed that most people rinse their toothbrushes with water; therefore, each treatment could then be compared to the water rinse treatment. In this comparison, the Polident and Purebrush toothbrushes had significantly reduced the amount of bacteria that can be grown on TSA plates at normal incubation conditions by 97.7% and 99% respectively.
Although “Kills 99% of Germs” to the average consumer sounds like a good method of sterilization, the fact remains that thousands of bacteria still reside on the bristles of toothbrushes despite rinsing with water, Listerine, Efferdent or sterilizing with germicidal UV lights. Bacteria often survive sterilization methods by forming endospores or biofilms on the bristles. Further sterilization methods would need to negate these resistance tactics by acting on the glycocalyx of biofilms most typically found near the gingival crevices or sulcus.
Bacterial growth accumulates on toothbrushes when the bristles are introduced to the biofilms on the surface of teeth and in gingival crevices; however, the method of sterilization as well as storage methods may contribute to the net oral flora remaining on the brush. Moist toothbrushes stored in close proximity may cross-contaminate other brushes. Although the Purebrush system only kills 99% of the bacteria found on toothbrushes, it does provides a sterile environment to prevent cross-contamination from other brushes as well as from external sources in the bathroom.
An individual with a healthy immune system should be relatively unaffected by the amount of bacteria remaining on the toothbrush. However, immune-compromised individuals, chronically ill patients, and individuals with gingivitis or other periodontal diseases may be more susceptible to residual bacterial growth. These individuals may benefit from the 97-99% reduction in bacteria provided by either Efferdent tablets or the Purebrush system. With either of these methods, the toothbrushes should be replaced every three to four months because of wearing of the bristles. To effectively combat gingivitis or periodontal disease, proper storage and sterilization of toothbrushes should be accompanied by daily flossing and regular visits to the dentist.
This study followed the bacterial reduction in vitro by introducing microorganisms through an oral bacterial broth rather than prolonged use in vivo. Although this technique provided replicable and consistent results, it did not target or select for disease-causing microorganisms. The bacteria that were eliminated during this experiment were those that were viable on TSA plates grown in the incubator at 37°C. Some oral bacteria would be unable to optimally grow in these conditions and would not be represented in the significant growth reductions. Further study would target disease-causing bacteria by growing them on appropriate media, testing the effectiveness of each system on the bacteria separately. Also, future research would include in vivo testing of the responsiveness of these methods to regular brushing.
Conclusions and Clinical Implications
Efferdent and Purebrush significantly reduced the bacteria on toothbrushes in comparison to those only rinsed with water. The storage of toothbrushes may contribute to overall bacterial growth. For those with immune-compromised or patients with periodontal disease, cleaning Efferdent combined with a sterile storage method or utilizing the Purebrush sterilization and storage system may be effective in preventing re-infection and cross-contamination in these patients.
Murdock Laboratories Inc. for their gift of two Purebrush units
St. Peter Family Dental Center for their gift of toothbrushes
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