The power of disinfection

Dec. 1, 2006
Not many RDH readers, especially those younger than 30, will remember Mercurochrome.

Not many RDH readers, especially those younger than 30, will remember Mercurochrome. I recall learning to ride my two-wheeler bicycle back in the 1960s. My dad walked my bike and me to the end of the street to make my initial attempt. All I can remember is feeling secure as he steadied me by holding the handlebars and seat as I got on the bike. He gave me a push and off I went ... a distance of about 20 feet before I landed on both knees on a street paved with crushed stone. OUCH!

My mom was home when we got back to our house, so she gently cleaned the wounds, applied Mercurochrome, and covered my knees with a gauze bandage.

Mercurochrome was a common antiseptic agent used in most American homes back then. It was bright orange-red in color. We dabbed it on wounds with a special applicator and allowed it to dry. American moms and dads were very disappointed when the U.S. Food and Drug Administration declared Mercurochrome unsafe because it contained mercury.

Like my wonderful mom, hygienists also clean wounds (pockets) and make decisions about disinfecting them. We perform scrupulous initial tooth “cleanings” in gingivitis patients and work hard to help them adopt new oral health habits. While treating patients with periodontal disease, we also “clean” pockets during scaling and root planing. Here’s the question for this month’s column: In treating periodontal diseases nonsurgically, is cleaning and disinfecting better than cleaning alone?

In diagnosing periodontal infections, we must get into the habit of performing some type of risk assessment, and we must give a name to our diagnosis based on the current classification system of periodontal diseases. For example, a patient with periodontitis who also has type 2 diabetes, smokes, and has poor glycemic control is going to have severe destruction of the periodontium. If we assess this type of patient by merely probing to record periodontal pockets, we do him or her a disservice.

This type of patient needs a comprehensive periodontal exam that includes probing depths, clinical attachment loss, bleeding on probing, mobility, and furcation involvement. Even more important, we must ask the appropriate questions to determine the patient’s glycemic control. We need to explore the patient’s medical history and ask the appropriate questions about his or her systemic health. Not all periodontal diseases were created equal, and treatment plans will differ depending on the type of infection diagnosed.

Let’s look at cleaning and disinfection and discuss the best available evidence, which guides us but is not gospel. Sometimes the evidence we have is not good enough and we need to dig deeper to find the truth. So relax, sit back, sip a soothing beverage, maintain an open mind, and get ready for challenge.

There is strong evidence that a professional prophylaxis does indeed have tremendous value (We already knew that, a no-brainer!) In a prophylaxis or debridement procedure, bacteria are removed nonspecifically and in proportion to their original numbers. Max Goodson from the Forsyth Institute concluded in 2004, “Regular plaque removal appears necessary to prevent the consequences of early gingivitis.”1

If we agree that nonsurgical periodontal therapy (the debridement portion with mechanized and hand instrumentation) results in a profound reduction in the subgingival microflora, we also know that these results are temporary, especially in deep pockets where certain bacteria, including spirochetes, recolonize. The rate of recolonization depends on an individual’s level of oral hygiene, the removal of subgingival calculus, residual probing depths, and immuno/inflammatory response.

In one study that included untreated periodontitis patients with deep, bleeding pockets greater than 5 mm, researchers discovered that subgingival mechanical cleaning alone has a limited effect in removing bacteria. However (and this is the important part), once the subgingival biofilm was removed, the nonadhering bacteria that were sandwiched between the biofilms on the tooth and pocket side had a tough time surviving. 2 Perhaps the sudden disappearance of their friendly neighbors resulted in traumatic shock. Just kidding! Let me reword that. The researchers guessed that the remaining pathogens could be more easily phagocytosed by PMNs in the pocket (eaten alive).

So, if it is difficult for bacteria to survive in a cleaned pocket, why disinfect too? Are there any benefits to disinfection following cleaning? Answering this is relatively easy if we look at the research on systemic antibiotics that can be used for more aggressive and refractory cases of peridontitis. Yes, indeed, a round of an appropriate systemic antibiotic does provide an added benefit to SRP alone.3 In looking at benefits obtained by local delivery antimicrobials (LDAs), I’d like to focus on some important observations by periodontal researchers in Belgium.

To begin, I need to point out that the beneficial effects of one-stage, full-mouth disinfection as opposed to quadrant scaling remain controversial in scientific literature.4 The purpose of the study in Belgium was to evaluate the role of antiseptics and the timing of one-stage, full-mouth disinfection. The research protocol that was developed included full-mouth disinfection with and without antiseptics. The results of this particular study may surprise you.

The 71 subjects were assigned to one of the following groups:

Group 1: SRP by quadrant with two-week intervals between quadrants; no local delivery antimicrobials (LDAs)

Group 2: Full-mouth SRP (in two consecutive days); no LDAs

Group 3: Full-mouth SRP (in two consecutive days). This group was divided into three smaller groups that used different antiseptic mouth rinses in various ways. Besides receiving mechanical debridement, the antimicrobial protocol included: irrigation with 1 percent chlorhexidine gel (three times repeated in 10 minutes); tongue brushing with the same gel for one minute; and mouth rinsing twice for one minute using a 0.2 percent chlorhexidine solution. This antimicrobial regimen was also used at the one-week follow-up visit. Patients in these groups also applied chlorhexidine at home for two months.

Note: Keep in mind that the 1 percent chlorhexidine gel and the 0.2 percent chlorhexidine rinse are not commercially available in the United States.

Oral hygiene instructions were very detailed and included interdental brushes or toothpicks, tooth brushing, and tongue brushing. The research design was also very detailed, and here I will emphasize the discussion section of the report.

The full-mouth SRP approach, which included the use of chlorhexidine to all oral habitats where periopathogens reside, both chairside and at home for a period of two months, resulted in statistically significant clinical improvements when compared to the conventional quadrant-by-quadrant approach. The strong antiseptic (chlorhexidine) played an important role, as did good oral hygiene home care. The good news from this study and previous studies that found significant advantages to a full-mouth approach over a two-day period is the immediate reduction in microbial load. Adding an antiseptic or some other sustained or controlled-release local delivery agent also has a beneficial effect. The only missing piece of the cleaning/disinfecting puzzle is a consensus on which LDAs are the most efficient and cost-effective for the patient.

So, to all of you “disinfection divas” out there: get creative. Individualize your treatment plans for nonsurgical periodontal therapy to include LDAs as needed, and you’ll have another reason not to be described as the office “cleaning lady.” RDH


1 Goodson JM, et al. Microbiological changes associated with dental prophylaxis. JADA 2004; 135:1559-1564.

2 Rhemrev GE, et al. Immediate effect of instrumentation on the subgingival microflora in deep inflamed pockets under strict plaque control. J Clin Periodontol 2006; 33:42-48.

3 Haffajee AD, Socransky SS, Gunsolley JC. Systemic anti-infective periodontal therapy. A systematic review. Annals of Periodontol 2003; 8(1):115-181.

4 Quirynen M, et al. Benefit of one stage full-mouth disenfection and root planing within 24 hours: a randomized controlled trial. J Clin Periodontol 2006; 33:639-647.

Lynne H. Slim, RDH, BSDH, MSDH, is a practicing hygienist/periodontal therapist who has more than 20 years experience in both clinical and educational settings. She is also President of Perio C Dent Inc. (Perio-Centered Dentistry), a practice management consulting firm. Lynne is a member of the Speaking and Consulting Network (SCN) and has won two first place journalism awards from ADHA. Lynne is also owner/moderator of a periodontal therapist group: She can be contacted at [email protected].