The Waterpik Sonic-Fusion unit combines brushing with water flossing.

Biofilm disruption: Water flossing reimagined

June 2, 2019
Regular, thorough debridement of pathogens through biofilm disruption is key to helping the body’s immune system fight inflammation. Learn who the microbial troublemakers are and how you can win the battle with daily oral irrigation.

The power of water to affect a surface is well known. One of the most beautiful spots in the world, the Grand Canyon, was created in part by the force of water flowing over stone. Power washing a concrete driveway demonstrates how fluid in motion can remove debris from surface irregularities. Electric dishwashers use spinning jets of water, combined with effective detergents, to clean. Powered dishwashers can effectively remove biofilm and debris from dental instruments or clean the pots and pans we used to prepare our last meal. The force of fluid in motion via a powered Waterpik irrigation device can be very effective and play a key role in achieving and maintaining oral health when daily water flossing is implemented as a self-care strategy.

Inflammation: The hot topic

Inflammation is the immune system’s defense against foreign invaders. Inflammation is also the body’s reaction to a pathogen overload. Gingival redness, swelling, and bleeding are cardinal signs of gingivitis, the body’s initial response to a dysbiotic microbial community that is teeming with gram-negative anaerobes, spirochetes, and other unsavory microbes.1 As the periodontal infection becomes more entrenched, the immune system’s ability to cope with inflammation becomes more and more compromised. At some point, the battle takes a turn for the worse, bone is lost, and soft tissue is destroyed.

The research spotlight is now fully focused on inflammation. Information is coming to light in numerous research publications that supports prevention, and elimination of inflammation is critical to either restore or maintain homeostasis.

Understanding dental biofilm and guided biofilm therapy

Here are highlights of recent research reports that demonstrate the complexity of polymicrobial oral biofilms and the unique capacity of microbes to adapt to changing and challenging environments.1

Microbial troublemakers

Today, there is a new level of understanding regarding the complexity of periodontal disease. It is now well accepted that gingivitis and periodontitis are complex biofilm-based infections. Even though Porphyromonas gingivalis is found in low abundance in periodontal disease-producing biofilm, it is now regarded as a keystone pathogen for disease development.2,3 Scientists believe P. gingivalis initiates the inflammatory response, contributes significantly to impairing the host’s immune system, and heightens the severity of the microbial attack.3-6

P. gingivalis is a microbial gangster. This sinister microbe recruits commensal organisms normally found in a healthy sulcus and sets the stage for commensals to convert to pathogens.7 The new pathogens are known as pathobionts. Pathobionts and other anaerobes create a dysbiotic community, which, by definition, is a symbiotic community primarily populated by pathogens that thrive in the presence of inflammation.8 In addition to increasing the dysbiotic community’s virulence,9 P. gingivalis has the unique ability to coat itself with polysaccharide and thus evade detection by the human immune system.10

Fusobacterium nucleatum is abundant in the oral cavity in both health and disease. F. nucleatum is the Dr. Jekyll and Mr. Hyde of the microbial world. Initially, it is classified as a subgingival commensal anaerobe; however, when F. nucleatum coaggregates with periodontal pathogens such as P. gingivalis or Tannerella forsythia, F. nucleatum converts to an anaerobic pathogen, and the virulence of the infection is further enhanced. The number of F. nucleatum microbes increases with the severity of the disease, the progression of inflammation, and increasing pocket depths. The oral cavities of smokers, patients with chronic periodontitis, and those with uncontrolled type 2 diabetes are typically teeming with F. nucleatum.11

Antimicrobial toothpaste and mouth rinse formulas kill large numbers of microbes during each use. There is sufficient evidence that the antimicrobial chemicals only kill bacteria in the outermost layers of biofilm.

A novel study, published in 2017, demonstrated that certain periodontal pathogens use the dead microbial biomass as a nutritional source. The growth of Prevotella intermedia and P. gingivalis were both enhanced in the presence of certain dead microbes. In addition, the virulence genes in P. intermedia and P. gingivalis were upregulated when coming in contact with dead bacteria, resulting in an increase in epithelial cytotoxicity.12 Incomplete removal of the dead microbe biomass has the potential to support the disease process over time.

Fluid dynamics in oral debridement

Water alone, or combined with the right chemistry, is a very effective way to clean a surface. While some clinicians still believe that biofilm can’t be dislodged or altered without using string floss, mounting evidence demonstrates that oral irrigation can disrupt and remove biofilm.

Through the years, research has demonstrated the overall value of using a water-jet oral irrigation device in combination with either a power or manual toothbrush. Results show a reduction in gingivitis,13,14 bleeding on probing,13,14 and the quantity of supragingival plaque biofilm13 when oral irrigation is used in conjunction with brushing to remove biofilm. A 2015 lab study demonstrated that oral irrigation removed more interproximal biofilm than a sonic brush.15

Seventy adults participated in a study to determine the effectiveness of water flossing versus string floss. All subjects used a manual brush. Half of the subjects used string floss, and the other half used water flossing. The water flosser was 29% more effective in overall biofilm removal than the string flosser, and, more specifically, more effective in interproximal plaque removal.16

Water flossing is also significantly more effective than air flossing in reducing bleeding and gingivitis. Those using oral irrigation had 28% less plaque accumulation than the air floss group when examined at week four of the study.17

An earlier study found those using water flossing in conjunction with a manual toothbrush were significantly more effective in all areas of plaque removal (whole mouth, marginal, approximal, facial, and lingual) as compared to the subjects using a manual brush and an air floss device.18 A small, two-week study comparing the effectiveness of oral irrigation versus interdental brushes found irrigation was more effective in reducing gingival bleeding.19 Another lab-based study demonstrated that oral irrigation could remove a polyspecies biofilm from a rough titanium surface, the metal that is used in dental implants.20

In 2018, two meta-analyses reviewed previous studies that looked at a variety of interproximal oral hygiene aids used to reduce inflammation. Studies on water-jet irrigation were included in both reports, and the authors concluded that oral irrigators ranked high in efficacy.21,22 It is important for clinicians to consider an individual patient’s wants, needs, and lifestyle, and then create custom recommendations for that individual. Clinicians should be prepared to offer alternatives, rather than insist on one universal approach for disrupting plaque biofilm.

Innovation and core technology

Through the years, many innovations have been made to the original Waterpik design, including specialty tips, more modern product design features such as sleeker reservoir shapes, as well as the introduction of colored units designed to match contemporary bathroom decors. But the basic principle of using the shear force created by water under pressure remains the same.

Adapting to modern lifestyles

Who doesn’t want whiter, brighter teeth? And who doesn’t appreciate efficiency, especially when the end result delivers an extra benefit or makes life easier? Water Pik has launched three new products over the past year that are taking oral irrigation into new, exciting areas. While each new product delivers a predictable irrigation outcome, the new designs offer a diverse range of features and benefits.

The Waterpik Whitening Water Flosser is the first irrigator to combine biofilm disruption with enhanced stain removal. The irrigator handle is fabricated so that a pulsating water stream flows over a special whitening tablet containing glycine, an amino acid. While glycine is relatively new to the North American market, it has a long, established history in Europe. Glycine powder is used in professional polishing to remove surface stains as well as disrupt subgingival biofilm. Oral irrigation is not the same as polishing, but initial reports indicate users feel their smiles are brighter and whiter, an outcome that certain patients will find very compelling. This is particularly important in preventing or removing extrinsic stains in hard-to-reach areas, such as interproximal spaces.

The Whitening Water Flosser has two modes—flossing and massage—10 pressure settings, and a built-in one-minute timer with a 30-second pacer. The handle is designed with a special compartment for the whitening tablet. The tips are specifically designed to fit this unique handle. The Classic Jet Tip is for general use. The Orthodontic Tip is perfect for cleaning around brackets, and the Plaque Seeker Tip is designed for use around implants, crowns, bridges, and retainers.

The Waterpik Sidekick is a dream machine for people who are on the go. The entire lightweight device fits neatly into a 4x7x2-inch pouch that can be tucked into a carry-on bag or suitcase. The unit is built in components that fit together like a puzzle. There is absolutely no wasted space, and the unit has global voltage settings.

Even though the unit itself weighs little more than one pound, it stays put on the countertop. A universal Classic Irrigation Tip is built into the handle, and the Sidekick has a five-setting sliding switch designed to deliver the full range of power. The Sidekick is perfect for a minimalist, a bathroom with limited counter space, or someone who does not like clutter. On top of being a very effective device, the esthetic design is sleek and modern.

The new hybrid Waterpik Sonic-Fusion unit melds creativity with solid design, combining sonic brushing and water flossing into a single brush head. The user can select both the activity and the sequencing. A multitasker may want to brush and water floss at the same time, while another may prefer to irrigate first and then brush, or vice versa. The Sonic-Fusion features replaceable brush heads and a two-minute timer with a 30-second pacer. The balanced handle detaches easily, quickly converting the brush to a portable, on-the-go device.

The design challenges were complex. The fluid irrigant flows directly from the tank into the brush handle via an irrigation hose. The handle features a 360-degree swivel, making it easy to access all areas of the mouth. The unit is built with global voltage. A fully charged toothbrush has enough battery power for 14 two-minute brushing sessions.

A recent study reported subjects using the Sonic-Fusion were more than twice as effective than the group using standard manual brushing and flossing techniques in reducing gingivitis, bleeding on probing, and an overall reduction of supragingival plaque biofilm deposits.23

An added bonus

Many people like using mouth rinses, and most products work well in water flossing units. A capful of mouth rinse added to the warm water in the tank is sufficient for most. If the mouth rinse is a prescription, it is recommended not to exceed a 1:1 ratio of rinse to warm water.

Flush the unit with water after using any mouth rinse/water preparation. A few products should not be used in the unit: povidone iodine, essential oils such as tea tree oil, and baking soda.

Embracing water flossing

Regular and thorough debridement of pathogens is key to helping the body’s immune system fight inflammation. Reducing the pathogen burden supports the growth of beneficial, healthy commensal microbes that populate a healthy, homeostatic subgingival environment.

Irrigators are easy to use, and they leave patients with a clean, fresh feeling. Even after using a power brush, it is amazing to see just how much debris is dislodged with water flossing. Even more startling is knowing that soft-plaque biofilm is being flushed away at the same time. But most importantly, patients like using oral irrigators. Over the last 50 years, oral irrigation has proven to be a very successful tool in improving and maintaining oral health, and the key is finding the right device that a patient will use on a regular basis. 


1. Lamont RJ, Koo H, Hajishengallis G. The oral microbiota: dynamic communities and host interactions. Nat Rev Microbiol. 2018;16(12):745-759. doi:10.1038/s41579-018-0089-x.

2. Hajishengallis G, Lamont RJ. Dancing with the stars: how choreographed bacterial interactions dictate nososymbiocity and give rise to keystone pathogens, accessory pathogens, and pathobionts. Trends Microbiol. 2016;24(6):477-489. doi:10.1016/j.tim.2016.02.010.

3. Hajishengallis G, Liang S, Payne MA, et al. Low-abundance biofilm species orchestrates inflammatory periodontal disease through the commensal microbiota and complement. Cell Host Microbe. 2011;10(5):497-506. doi:10.1016/j.chom.2011.10.006.

4. Hajishengallis G, Maekawa T, Abe T, Hajishengallis E, Lambris JD. Complement involvement in periodontitis: molecular mechanisms and rational therapeutic approaches. In: Lambris J, Ekdahl K, Ricklin D, Nilsson B., eds. Immune Responses to Biosurfaces. Advances in Experimental Medicine and Biology. Switzerland: Springer, Cham; 2015;865:57-74. doi:10.1007/978-3-319-18603-0_4.

5. Hajishengallis G, Abe T, Maekawa T, Hajishengallis E, Lambris JD. Role of complement in host-microbe homeostasis of the periodontium. Semin Immunol. 2013;25(1):65-72. doi:10.1016/j.smim.2013.04.004.

6. Olsen I, Lambris JD, Hajishengallis G. Porphyromonas gingivalis disturbs host-commensal homeostasis by changing complement function. J Oral Microbiol. 2017;9(1):1340085. doi:10.1080/20002297.2017.1340085.

7. Hajishengallis G, Lamont RJ. Breaking bad: manipulation of the host response by Porphyromonas gingivalis. Eur J Immunol. 2014;44(2):328-238. doi:10.1002/eji.201344202.

8. Lamont RJ, Hajishengallis G. Polymicrobial synergy and dysbiosis in inflammatory disease. Trends Mol Med. 2015;21(3):172-183. doi:10.1016/j.molmed.2014.11.004.

9. Roberts FA, Darveau RP. Microbial protection and virulence in periodontal tissue as a function of polymicrobial communities: symbiosis and dysbiosis. Periodontol 2000. 2015;69(1):18-27. doi:10.1111/prd.12087.

10. Singh A, Wyant T, Anaya-Bergman C, et al. The capsule of Porphyromonas gingivalis leads to a reduction in the host inflammatory response, evasion of phagocytosis, and increase in virulence. Infect Immun. 2011;79(11):4533-4542. doi:10.1128/IAI.05016-11.

11. Han YW. Fusobacterium nucleatum: a commensal-turned pathogen. Curr Opin Microbiol. 2015;23:141-147. doi: 10.1016/j.mib.2014.11.013.

12. Rodriguez Herrero E, Boon N, Pauwels M, et al. Necrotrophic growth of periodontopathogens is a novel virulence factor in oral biofilms. Sci Rep. 2017;7(1):1107. doi:10.1038/s41598-017-01239-9.

13. Barnes CM, Russell CM, Reinhardt RA, Payne JB, Lyle DM. Comparison of irrigation to floss as an adjunct to tooth brushing: effect on bleeding, gingivitis, and supragingival plaque. J Clin Dent. 2005;16(3):71-77.

14. Goyal CR, Lyle DM, Qaqish JG, Schuller R. The addition of a water flosser to power tooth brushing: effect on bleeding, gingivitis, and plaque. J Clin Dent. 2012;23(2):57-63.

15. Tawakoli PN, Sauer B, Becker K, Buchalla W, Attin T. Interproximal biofilm removal by intervallic use of a sonic toothbrush compared to an oral irrigation system. BMC Oral Health. 2015;15:91.

16. Goyal CR, Lyle DM, Qaqish JG, Schuller R. Evaluation of the plaque removal efficacy of a water flosser compared to string floss in adults after a single use. J Clin Dent. 2013;24(2):37-42.

17. Goyal CR, Lyle DM, Qaqish JG, Schuller R. Efficacy of two interdental cleaning devices on clinical signs of inflammation: a four-week randomized controlled trial. J Clin Dent. 2015;26(2):55-60.

18. Sharma NC, Lyle DM, Qaqish JG, Schuller R. Comparison of two power interdental cleaning devices on plaque removal. J Clin Dent. 2012;23(1):17-21.

19. Goyal CR, Lyle DM, Qaqish JG, Schuller R. Comparison of water flosser and interdental brush on reduction of gingival bleeding and plaque: a randomized controlled pilot study. J Clin Dent. 2016;27(2):61-65.

20. Ioannidis A, Thurnheer T, Hofer D, Sahrmann P, Guggenheim B, Schmidlin PR. Mechanical and hydrodynamic homecare devices to clean rough implant surfaces - an in vitro polyspecies biofilm study. Clin Oral Implants Res. 2015;26(5):523-528.

21. Richards D. The effectiveness of interproximal oral hygiene aids. Evid Based Dent. 2018;19(4):107-108. doi:10.1038/sj.ebd.6401341.

22. Kotsakis GA, Lian Q, Ioannou AL, Michalowicz BS, John MT, Chu H. A network meta-analysis of interproximal oral hygiene methods in the reduction of clinical indices of inflammation. J Periodontol. 2018;89(5):558-570. doi:10.1002/JPER.17-0368.

23. Goyal CR, Qaqish JG, Schuller R, Lyle DM. Comparison of a novel sonic toothbrush to a traditional sonic toothbrush and manual brushing and flossing on plaque, gingival bleeding and inflammation: a randomized controlled clinical trial. Compend Contin Educ Dent. 2018;39(suppl 2):14-22.