Studies performed on the “killing” of biofilms have revealed some interesting results. While a “free floating” bacterial cell (planktonic) can be incredibly easy to kill, bacteria that have formed a biofilm can be incredibly resistant to antibacterials/antibiotics, etc.[1] Further observations using microscopy have revealed that the longer a bacterial biofilm population resides, the more ordered the biofilm structure becomes; and as the cells in the biofilm become more ordered and tightly packed, the biofilm becomes harder and harder to penetrate. Studies have shown that once bacteria cooperate and form a biofilm, packing tightly together, and establishing themselves, they further enhance their survival.[2] There are only three ways to remove or kill an established biofilm: complete mechanical debridement (which is impossible in the mouth), heat in excess of 400°F (which would destroy tooth structure), and a very strong oxidizing agent capable of penetrating a biofilm.[3] For this reason, a broad spectrum oxidizing antibacterial agent capable of penetrating a biofilm, such as sodium hypochlorite, should be considered as part of a treatment strategy. 

A broad-spectrum oxidizing antibacterial agent capable of penetrating a biofilm, such a sodium hypochlorite, should be considered as part of a treatment strategy.

The medical management of dental caries has historically included fluoride in different delivery agents and antimicrobial or antibacterial therapy. Numerous antibacterial agents have been used, including ethyl alcohol, essential oils, chlorhexidine, and povidone-iodine. While ethyl alcohol can be an effective antibacterial agent, it has obvious issues and has also been linked to oral cancer.[4, 5, 6] Essential oils have been used for years as an antibacterial agent, but most commonly for the treatment of gum disease. 

A standard antibacterial agent for dental caries has been chlorhexidine gluconate 0.12% rinse. There is a large body of evidence supporting the use of chlorhexidine as an antiplaque agent. The chlorhexidine molecule attaches to the bacterial cell wall and, after a prolonged period of contact, weakens the cell wall and eventually disrupts it. Chlorhexidine has a broad spectrum of action and has a significant effect against Mutans streptococci but has little effect on Lactobacillus. Clinicians recommending chlorhexidine rinse identified reduction of MS but also a coincident increase of Lactobacillus by bacterial culture of the saliva.

Povidone-iodine 10%, or Betadine, has also been used as a dental caries antibacterial agent in limited applications. Povidone-iodine is a strong and broad-spectrum antibacterial agent that kills gram-positive and gram-negative bacteria, fungi, mycobacteria, viruses, and protozoans on contact. Povidone-iodine is effective against both MS and Lactobacillus in children when applied topically. Results from trials in adults demonstrated no anticaries effect. Problems associated with povidone-iodine as a rinse include taste and the limitation of using it only once a month because of the danger of iodine exposure, and it cannot be used by people with iodine or shellfish allergies. Aside from compliance issues, it also permanently stains clothing and countertops in the dental operatory.

Because dental caries is a biofilm disease, and biofilm diseases are best treated with a strong oxidizing agent, sodium hypochlorite has been introduced as an antibacterial agent. Sodium hypochlorite 0.2% oral rinse is bactericidal to all bacteria on contact. Limitations are alteration of taste and a recommendation to use it on patients aged 6 and older. As with all antibacterial agents, it should first be determined whether the patient has a bacterial biofilm load issue and would benefit from antibacterial therapy. The FDA considers oral rinse solutions with less than 0.3% concentration of sodium hypochlorite safe for daily use. (An example would be CTx4 Treatment Rinse.)

In another clinical trial, the authors examined the potential of 0.2% sodium hypochlorite rinse with a pH of 11 as an effective anticaries antibacterial agent. In the study, 5 high-caries-risk patients were instructed to rinse with the 0.2% sodium hypochlorite solution 2 times per day for a period of 30 days. Mixed samples of their plaque were taken prior and after the 30-day period. The plaque samples from each individual were then checker-boarded using PCR and 16Sgene sequencing DNA identification to identify the individual bacteria and the changes in the bacterial species and concentration based on the antibacterial strategy. The plaque samples revealed an elimination of caries-causing bacteria like Streptococcus mutans/sobrinus, a reduction of Lactobacillus, and a concurrent growth of healthy bacteria including Capnocytophaga, Prevotella, Campylobacter, Neisseria, Megasphaera, Veillonella, Eubacterium, Gemella, Granulicatella, Leptotrichia, Synergistes, and Actinomyces spp (See Figure 15). These results demonstrate that it is possible to eliminate/reduce the cariogenic microbes from the oral biofilm while replacing them with healthy organisms by short-term therapy with a high pH antibacterial 0.2% sodium hypochlorite rinse strategy.

Sodium hypochlorite 0.2% oral rinse is also being prescribed for oral conditions other than caries. Clinicians have reported excellent results when prescribed for periodontal disease (biofilm imbalance below the gumline) as well as mouth ulcers (canker sores). Many patients who are undergoing dental treatment such as root canals, orthodontics, crown work or bridgework, and implants are provided 0.2% sodium hypochlorite oral rinse for home use to reduce the bioburden during restorative or cosmetic treatment plans.

  1. P. L. Phillips, R. D. Wolcott, J. Fletcher, and G.S. Schultz, “BiofilmsMade Easy,” Wnds Intl 1, no. 3 (May 2010).
  2. H. Cho, H. Jönsson, K. Campbell, P. Melke, J. W. Williams, B.Jedynak, et al., “,” PLoS Biology 5, no. 11 (2007): e302 EP.
  4. D. M. Winn, W. J. Blot, J. K. McLaughlin, et al., “Mouthwash Use and Oral Conditions in the Risk of Oral and Pharyngeal Cancer,” CancerResearch 51 (1991): 3044–3047.
  5. C . W. Werner and R. A. Seymour, “Are Alcohol ContainingMouthwashes Safe?” British Dental Journal 207 (2009): E19.
  6. M. J. McCullough and C. S. Farah, “The Role of Alcohol in OralCarcinogenesis with Particular Reference to Alcohol-ContainingMouthwashes,” Aust Dent J 53 (2008): 302–305.