Commentary

Chlorhexidine is a broad-spectrum antiseptic that was first introduced in the 1950s, and mouthwashes/rinses containing chlorhexidine have been extensively marketed. Typically, chlorhexidine is available in concentrations of 0.1%, 0.12% or 0.2% chlorhexidine digluconate as well as in low concentration (≤ 0.06%) rinse, and its antimicrobial properties reduce microbial biofilm, potentially reducing inflammation. The aim of this review was to assess the effectiveness of chlorhexidine mouthwash as an adjunct to mechanical oral hygiene procedures for controlling plaque and gingivitis. While toothbrushing and interdental cleaning are common methods of removing and or disrupting the biofilm many find it difficult to achieve and maintain effective plaque control, and mouthwashes are seen as a potential adjunct.

This review has been conducted following the Cochrane Collaboration's robust methodological approach. A large number of trials have been included, although almost all of them are considered to be at high risk of bias. This is largely due to concerns regarding blinding of participants, personnel and outcome assessors, because of the well known propensity of chlorhexidine to stain both teeth and oral tissues, successful blinding was considered to be unlikely. However, despite this the authors did not downgrade the GRADE assessment which was high for both gingival index and plaque at four to six weeks. Nineteen of the included studies acknowledged the manufacturers' support with 17 providing no indication of funding or support.

The review considered that there was high quality evidence for a reduction in gingivitis in patients with mild to moderate disease although the level of reduction achieved was not considered to be clinically important. There was also a reduction in plaque levels at four to six weeks and six months. Most of the studies in the meta-analysis used a twice daily rinsing frequency and no evidence that one concentration of chlorhexidine rinse was more effective than another in reducing gingivitis and plaque was found.

There was moderate quality evidence that the use of chlorhexidine rinse for four weeks or more caused extrinsic tooth staining, an adverse effect that is well-known. Twenty-one out of the 51 studies, (43%), also reported at least one other adverse effect. Several other reviews1,2,3,4 have considered this topic and they are discussed in this review. Despite methodological variations their findings are broadly similar and demonstrate a positive effect of chlorhexidine mouthwash on plaque and gingivitis. Consequently, chlorhexidine rinse is considered to be indicated for particular clinical situations for short-term use. Longer-term use in particular patient groups needs to be carefully balanced with the recognised adverse effects.

While chlorhexidine rinse is often considered to be a ‘first choice’ mouthwash, essential oil mouthwashes have also been shown to have a statistically significant impact on plaque and gingival indices, and a recent review of these agents by Haas et al.5 is considered on page 39–40 of this issue.