The Effect of Chlorhexidine Varnish on Root Caries: A Systematic Review

Objective: The aim of this study was to systematically review the present literature on the effect of chlorhexidine varnish (CHX-V) on root caries. Materials and Methods: The MEDLINE-PubMed, the Cochrane-CENTRAL and EMBASE databases were searched through December 2010 to identify any appropriate studies. Root caries incidence and root caries activity were selected as outcome variables. Results: An independent screening of the unique titles and abstracts of 24 MEDLINE-PubMed, 14 Cochrane-CENTRAL and 18 EMBASE papers resulted in 6 publications that met the eligibility criteria. Data extraction provided no conclusive evidence that the application of CHX-V is effective in patients when regular professional oral prophylaxis is performed. If effective, the 40% CHX-V was found to provide a benefit over a control or fluoride varnish. CHX-V at lower concentrations (1 and 10%) may provide protection against root caries in high-risk patients (such as geriatric and xerostomia patients) in the absence of regular professional oral prophylaxis. Conclusion: Within the limitations of this review, it may be concluded Received: January 5, 2011 Accepted: March 11, 2011 Published online: April 27, 2011 Dagmar Else Slot, Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and VU University Amsterdam Department of Periodontology, Gustav Mahlerlaan 3004 NL–1081 LA Amsterdam (The Netherlands) Tel. +31 205 980 179/307, E-Mail d.slot @ acta.nl © 2011 S. Karger AG, Basel 0008–6568/11/0452–0162$38.00/0 Accessible online at: www.karger.com/cre D ow nl oa de d by : 54 .7 0. 40 .1 1 10 /6 /2 01 7 6: 35 :2 3 A M Chlorhexidine Varnish and Root Caries Caries Res 2011;45:162–173 163 to medication are particularly at high risk for root surface caries [Banting et al., 2000]. Chlorhexidine (CHX) has been studied for over 30 years as an antimicrobial agent for the chemical control of plaque formation and for the prevention of caries. CHX is a strong base and it acts bacteriostatically when administered at low concentrations. At higher concentrations, CHX acts bactericidally. Its antibacterial spectrum covers Gram-positive and Gram-negative bacteria (the latter to a lesser extent), fungi and yeast. It is not a virucide, nor is it effective against acidand alcohol-resistant bacilli [Emilson, 1977]. In general, the efficacy of CHX is related to its concentration and the frequency of application [Junco and Baca, 2005]. The vehicles most often used to administer CHX are mouth rinses, sprays, gels and varnishes. The inhibition of Streptococcus mutans was found to be the most persistent with CHX varnishes (CHX-V), followed by gels and mouthwashes [Emilson, 1994]. However, the higher effect on a surrogate outcome, i.e. inhibition of S. mutans, does not necessarily imply that CHX-V has a stronger caries-inhibiting effect than CHX gels or mouthwashes [Hujoel, 2004]. Balanyk and Sandham [1985] first reported on the in vitro use of CHX-V against S. mutans, and in 1988, Sandham et al. [1988] published the first report of the use of CHX-V in humans. CHX-V has advantages compared to other methods, since it is easily applied and does not result in the discoloration of teeth. One disadvantage of CHX-V is the unpleasant flavor that can temporarily alter one’s sense of taste [Matthijs and Adriaens, 2002]. The first systematic review on the effect of the antibacterial approach to prevent and control caries with special reference to the use of CHX-V concluded that the evidence was inconclusive for the use of CHX-V for caries prevention in risk groups [Twetman, 2004]. A more recent systematic review on the reduction of caries with CHX-V showed a moderate caries-inhibitory effect in children, adolescents and young adults when applied every 3–4 months [Zhang et al., 2006]. The most recent systematic review on the effectiveness of CHX-V for preventing dental caries in children and adolescents concluded that the evidence regarding the effectiveness of CHX-V compared to fluoride varnish (FV) for preventing caries is inconclusive [James et al., 2010]. However, a systematic quantitative evaluation of the effect of CHXV, particularly on root surface caries, has not yet been performed. Therefore, this paper aimed to systematically evaluate the current literature to determine the effect of the use of CHX-V on root caries incidence and activity. Materials and Methods This systematic review was conducted in accordance with the guidelines of Transparent Reporting of Systematic Reviews and Meta-Analyses [PRISMA statement; Moher et al., 2009]. The question being focused on was as follows: what is the effect of CHX-V on root caries, in a patient with gingival recessions? Search Strategy Three Internet sources were used to search for appropriate papers that satisfied the study purpose. These included the National Library of Medicine, Washington, D.C. (MEDLINE-PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL) and EMBASE (Excerpta Medical Database by Elsevier). The databases were searched for studies conducted in the period up to and including December 23, 2010. The structured search strategy was designed to include any published paper that evaluated the effect of CHX-V on root caries (for details on the used search terms, see tables 1 and 2 ). The following eligibility criteria were used: • randomized controlled clinical trials (RCTs) or controlled clinical trials; • papers written in English; • conducted in humans; • subjects 6 18 years of age; • intervention: CHX-V; • control: placebo OR control treatment OR FV; • clinical parameters: root caries incidence and/or root caries activity. Screening and Selection Two reviewers (D.E.S. and N.C.V.) independently screened titles and abstracts for eligible papers. If information relevant to the eligibility criteria was not available in the abstract, or if the title was relevant but the abstract was not available, the paper was selected for a full reading of the text. Next, full-text papers that fulfilled the eligibility criteria were identified and included into this study. The two reviewers hand-searched the reference lists of all of the selected studies for additional published papers that could possibly meet the eligibility criteria of this study. Papers that fulfilled all of the selection criteria were processed for data extraction. The heterogeneity across the studies was detailed according to the following factors: • type of varnish and comparison; • application regimen and procedure; • funding source; • clinical indices. Quality Assessment Two reviewers (N.C.V. and D.E.S.) scored the methodological quality of the included studies. An assessment of the methodological study quality was performed as proposed by the RCT checklist of the Dutch Cochrane Center [2009] and was completed with quality criteria that were obtained from the CONSORT statement 2001 [CONSORT Group, 2009], Moher et al. [2001a, b, c], Needleman et al. [2005], the Jadad scale [Jadad et al., 1996] and the Delphi List [Verhagen et al., 1998]. Criteria were designated to each domain of internal validity, external validity, and statistical methods. D ow nl oa de d by : 54 .7 0. 40 .1 1 10 /6 /2 01 7 6: 35 :2 3 A M Slot et al. Caries Res 2011;45:162–173 164 Each aspect of the score list was given a ‘+’ sign for an informative description of the item at issue and a study design meeting the quality standard, a ‘–’ sign for an informative description, but a study design not meeting the quality standard, and a ‘?’ for lacking or insufficient information. If random allocation, defined eligibility criteria, blinding to patient and examiner, balanced experimental groups, an identical treatment between groups except for intervention and report of follow-up were present, the study was classified as having a low risk of bias. If 1 of these 6 criteria was missing, the study was considered to have a moderate potential risk of bias. If 2 or more of these criteria were missing, the study was considered to have a high potential risk of bias, as proposed by Van der Weijden et al. [2010]. In addition, the Centre for Evidence-Based Medicine levels of evidence [Centre for Evidence-Based Medicine, 2009] were used to assess the methodological quality. Score 1a is given to individual RCTs with a narrow confidence interval and 1b– to individual RCTs with a wide confidence interval. Score 2b is given to individual cohort studies, including low-quality RCTs (e.g. ! 80% followup). Data Extraction Data from the papers that met the selection criteria were processed for analysis. Data were extracted with regard to the effect of CHX-V in comparison to a placebo, a control treatment, or an FV. For studies that presented intermediate assessments, the baseline and final evaluations were used for this review. Mean values and standard deviations were extracted by D.E.S. and N.C.V. Data Analysis After a preliminary evaluation of the selected papers, it was found that considerable heterogeneity was present in the study designs, characteristics, outcome variables, and results. Where appropriate, a meta-analysis was performed and weighted mean differences were calculated by means of the Review Manager 4.2 software using a ‘random effect’ model (RevMan version 4.2 for Windows, Copenhagen, The Nordic Cochrane Centre, The Cochrane Collaboration, 2003). Only a few studies could be included to perform a valid quantitative analysis of the total body of evidence. Therefore, as a summary, also a descriptive manner of data presentation was used. Any disagreement between the two reviewers (D.E.S. and N.C.V.) was resolved after additional discussion. If a disagreement persisted, the judgment of a third reviewer (G.A.W.) was decisive. Grading the ‘Body of Evidence’ The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system as proposed by the GRADE working group was used for grading evidence emerging from this review [Guyatt et al., 2008; GRADE working group]. Two reviewers (D.E.S. and G.A.W.) rated the quality of the evidence and strength of recommendations on the following aspects: risk of bias of the individual studies, consistency and precision among the study outcomes, directness of the study results and the detection of publication bias. Any disagreement between the two reviewers was resolved after additional discussion; if a disagreement persisted, the judgment of a third reviewer (C.V.L.) was decisive. Table 1. The following terms were used in the search strategy: Pubmed-MEDLINE and Cochrane-CENTRAL search Intervention {<(chlorhexidine [MeSH] OR chlorhexidine OR chlorhexidine phosphanilate OR chlorhexidine di-gluconate OR chlorhexidine gluconate OR Zinc-chlorhexidine OR chlorhexidine gluconate lidocaine hydrochloride OR CHX OR CHX formulations [textwords])