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Bacteria Management

Preprocedural mouthrinsing reduces the number of transmissible microorganisms in dental aerosols—possibly decreasing infection risk.

The oral cavity contains a host of transmissible  bacteria and viruses, including bacterial strains Streptococcus, Actinomyces, Lactobacillus, Staphylococcus, and Candida. The hepatitis B, hepatitis C, and human immunodeficiency viruses and tuberculosis can also be found in the oral cavity, as well as in the nose, throat, and respiratory tract. Secretions from the oronasal pharynx may contain pathogenic microorganisms, such as cold, influenza, or herpes viruses.1 These bacteria and viruses can be transmitted via the dental aerosols produced during ultrasonic instrumentation and polishing. Aerosols are characterized as the cloud of mist emanating from ultrasonic scalers and air abrasive polishing devices. The aerosol particles are as small as 10 ?, (equal to 0.01 mm) and have the potential to penetrate and lodge in the narrow passages of the lungs.1

Although the United States Centers for Disease Control and Prevention considers the risk of infection from airborne pathogens “minimal” for oral health professionals, clinicians must adhere to stringent infection control protocols.2 The use of preprocedural mouthrinses prior to delivering care may reduce the risk of infection for both clinicians and patients.


The use of antimicrobial mouthrinses by patients before the provision of dental care is designed to decrease the number of microorganisms emitted within the dental aerosols produced during power instrumentation and polishing. These aerosols and spatter are potential sources of contamination.2

Any antimicrobial mouthrinse may be used during preprocedural rinsing. Research has demonstrated the efficacy of chlorhexidine gluconate (CHX) mouthrinse, which is available by prescription only.Over-the-counter rinses containing antimicrobials, such as essential oils4 and cetylpyridinium chloride (CPC),5 are also effective, and can be found in almost every operatory. The antimicrobial rinse must be swished around the oral cavity for at least 30 seconds immediately prior to beginning treatment in order to be effective. Since the 1990s, studies on the benefits of preprocedural mouthrinses that contain CHX6 and essential oils7 have been compared to the effects of rinsing with water alone. These studies found that CHX and essential oil mouthrinses were more effective than water in reducing bacterial loads, while rinsing with water reduced the load better than not rinsing at all.6,7


Although the evidence does not demonstrate that preprocedural mouthrinsing prevents infection in patients or clinicians, studies do show that rinsing with an antimicrobial mouthrinse reduces the number of bacteria generated during dental procedures.7–9 The typical study design compared the number of bacterial colony-forming units by placing collection plates or filters in various areas of the dental operatory. This study design is most effective when collecting spatter-sized particles—large particles visible with the naked eye that travel quickly from the point of origin to the place of rest.

The results of studies utilizing this collection technique vary, though all share three common themes: rinsing with an antimicrobial mouthrinse reduced particles more than rinsing with water; rinsing for a period of 30 seconds to 60 seconds was as effective as rinsing for 120 seconds; and rinsing with water reduced more particles than no prerinse prior to treatment.6,7,9 To determine if one active ingredient was most effective in reducing aerosolized particles, Feres et al compared preprocedural

mouthrinses among four patient groups, including: rinsing with CPC; rinsing with CHX; rinsing with water; and no rinsing.5 The results indicated that CPC and CHX equally reduced bacteria from the spatter-sized particles, while water reduced bacteria presence  more than no prerinse.5 A similar study design determined the effectiveness of preprocedural rinsing on aerosol contamination during ultrasonic instrumentation. This study compared CHX with an herbal mouthrinse and water. The results of this study found the CHX prerinse was most effective, and the herbal mouthrinse reduced more particles than water prerinse.10 Other studies yielded similar results, demonstrating that prerinsing with an antimicrobial rinse was more effective than prerinsing with water.1,7 Temperature control for CHX was evaluated by Reddy et al,11 who found that warming the rinse to 140° increased its antimicrobial effect. These studies looked at the effect of preprocedural mouthrinse against free-floating bacteria in the oral cavity. A potentially greater risk, however, comes from subgingival biofilm, which is protected from the rinsing action.


Current disease transmission theories teach a three-stage cycle to spread infection: an infection source; a mode of transmitting the infection; and a susceptible host. To block the spread of infection, a break in this cycle must occur. Unfortunately, no single method of protection is foolproof, and the true nature of potential threats—with new viruses discovered often—remains unknown.

Incorporating the use of preprocedural mouthrinsing before treatment is one facet of the layered approach to preventing infection via dental aerosols, which includes the use of personal protective equipment and high volume evacuation. In addition, careful consideration should be given to the amount of bacterial biofilm present during ultrasonic instrumentation. Future study is needed on the effects of basic plaque removal (brushing, flossing, or polishing) prior to ultrasonic instrumentation.



  1. Harrel SK, Molinari J. Aerosol and splatter in dentistry: a brief reviewof the literature and infection control implications. J Am Dent Assoc.2004;135:429–437.
  2. Cole EC, Cook CE. Characterization of infectious aerosols in health carefacilities: an aid to effective engineering controls and preventive strategies.Am J Infect Control. 1998;26:453–464.
  3. Moshrefi A. Chlorhexidine. J West Soc Periodontol Periodontal Abstr.2002;50:5–9.
  4. Baqui AA, Kelley JI, Jabra-Rizk MA, Depaola LG, Falkler WA, Meiller TF. Invitro effect of oral antiseptics on human immunodeficiency virus-1 andherpes simplex virus type 1. J Clin Periodontol. 2001;28:610–616.
  5. Feres M, Figueiredo LC, Faveri M, Stewart B, de Vizio W. The effectivenessof preprocedural mouthrinse containing cetylpyridinium chloride inreducing bacteria in the dental office. J Am Dent Assoc. 2010;141:415–422.
  6. Logothetis DD, Martinez-Welles JM. Reducing bacterial aerosolcontamination with a chlorhexidine gluconate pre-rinse. J Am Dent Assoc.1995;126:1634–1639.
  7. Fine DH, Mendieta C, Barnett ML, et al. Efficacy of preproceduralrinsing with an antiseptic in reducing viable bacteria in dentalaerosols. J Periodontol. 1992;63:821–824.
  8. Centers for Disease Control and Prevention. Infection Control, FrequentlyAsked Questions, Preprocedural Mouth Rinse. Available at: Accessed

    October 18, 2013.

  9. DePaola LG, Minah GE, Overholser CD, et al. Effect of an antisepticmouthrinse on salivary microbiota. Am J Dent. 1996;9:93–95.
  10. Gupta DG, Mitra DD, K P DA, et al. Comparison of efficacy of preproceduralmouth rinsing in reducing aerosol contamination produced byultrasonic scaler: a pilot study. J Periodontol. 2013:1–12.
  11. Reddy S, Prasad MG, Kaul S, Satish K, Kakarala S, Bhowmik N. Efficacyof 0.2% tempered chlorhexidine as a pre-procedural mouth rinse: A clinicalstudy. J Indian Soc Periodontol. 2012;16:213–217.

From Dimensions of Dental Hygiene. November 2013;11(11):46,48.

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