Relevant papers were identified by using Medline–PubMed and the Cochrane Central Register of Controlled Trials.
Papers were assessed for inclusion independently by two reviewers and only those published in the English language were chosen. Randomised controlled clinical trials (RCT) or controlled clinical trials (CCT) conducted in adults with good general health were selected.
Evaluation parameters included changes in dental plaque, gingival bleeding/ inflammation and probing pocket depth. Study quality was assessed based upon study design, evaluation period, profiles of subjects, method of randomisation, blindness of examiners and completeness of followup assessment.
Data extraction and synthesis
Data were extracted by three reviewers. As the selected studies showed considerable heterogeneity in the study designs, characteristics, outcome variables and results, a descriptive review of the data was presented instead of performing a meta-analysis.
Seven papers (four RCT and three CCT) were included. Mean values and standard deviations were collected from the data. Data showed that oral irrigation does not reduce plaque scores more than toothbrushing or regular oral hygiene measures.
This systematic review suggests that oral irrigation as an adjunct to toothbrushing does not have a beneficial effect in reducing dental plaque, but it may improve gingival health.
It has been estimated that at least 1014 species of commensal microbes reside on the surfaces of skin, teeth, dentures, dental restorations, prosthetic implants, and the mucosal epithelia of the linings of respiratory, gastrointestinal, urinary tracts and oral cavity.1 The human oral cavity contains approximately 6×109 microbes, representing 500–700 species. These micro-organisms are present in the form of biofilms, matrix-enclosed bacterial populations that both adhere organisms together and to surfaces or interfaces.2 The evolution of the biofilm permits survival of a whole microbiological community, allowing various species to grow, with increased metabolic efficiency, enhanced virulence and the ability to evade host defence mechanisms, and better resist stress and antibiotics.
A bacterial biofilm is the common cause of a number of human diseases, including the two most common oral ones, caries and periodontal disease.3 Periodontal disease is the most commonly occurring yet curious infection in humans because of the unique anatomical features of dento-gingival structures and the nature of pathogenic plaque biofilm infection. Plaque biofilm constantly forms on the non-shedding tooth surface allowing micro-organisms to remain continuously in immediate proximity to periodontal tissues, and rendering host defences and antimicrobial therapy less effective.4 From the clinical point of view, a pathogenic plaque biofilm is extraordinarily persistent and difficult to control without appropriate professional care and effective daily plaque control regimes.
Toothbrushing is of course the most common means of removing plaque biofilm at home but it is usually not possible to get access to interproximal areas between the adjacent teeth without using adjunctive interdental cleaning aids such as dental floss. Effective plaque control at interproximal areas remains a great challenge for most individuals and their dental professionals, with the common problems of patient motivation and compliance, and limited dexterity.
The oral irrigator is one of the oral hygiene aids developed to enhance the effectiveness of plaque control and bring benefits for gingival health. Its exact clinical efficacy and usefulness remain unclear. The work reported here, conducted by Husseini and colleagues, systematically reviewed the literature on the adjunctive effect of the oral irrigator in addition to toothbrushing on controlling plaque and bleeding index gingival inflammation and pocket probing depth. Notably, two internet databases, namely Medline–PubMed and the Cochrane Central Register of Controlled Trials from 1965 to January 2008, were extensively searched and analysed. The authors independently screened the relevant abstracts of 809 PubMed and 105 Cochrane papers, and subsequently identified a total of seven well-conducted studies that fulfilled the defined criteria. Unfortunately, the selected studies could not generate sufficient data to perform a meta-analysis. Despite these limitations, this systematic review suggests that the oral irrigator, as an adjunct to toothbrushing, does not have a beneficial effect in reducing visible plaque, although it may improve gingival health more than regular oral hygiene measures or toothbrushing alone.
Currently, the exact mechanisms of action accounting for these observations remain unclear. Several possible factors may be considered and are worthy of further study. Although oral irrigation does not generate a beneficial effect by reducing visible plaque, it may flush away only loosely adhered plaque and thus interfere with maturation of the plaque biofilm every day; it may also, to some extent, modify the microbial components of plaque and its virulence factors. Another possible effect is the mechanical action of a jet stream of water and its pulsations, which might reduce the levels of inflammatory mediators in the gingival crevice/ pocket, and alter the gingival response to microbial challenge, thereby contributing to gingival homeostasis and health.
It should be noted that the plaque indices used in the studies selected are an insensitive measure of plaque level, limited by making measurements on an ordinal scale. It is conceivable that any benefit of the oral irrigator in reducing dental plaque may be undetectable clinically or not measurable statistically. Further well-designed RCT are warranted to research the effectiveness of the oral irrigator as an adjunct to regular oral hygiene measures for controlling plaque biofilm and long-term maintenance of gingival health, and to explore the mechanisms involved.
The oral irrigator is a safe oral hygiene aid for healthy individuals
Oral irrigation as an adjunct to toothbrushing may be beneficial to gingival health in addition to regular oral hygiene measures
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Address for correspondence: Fridus Van der Weijden, Academic Centre for Dentistry Amsterdam, Department of Periodontology, Louwesweg 1, 1066 EA Amsterdam, The Netherlands. E-mail: email@example.com
Husseini A, Slot DE, Van der Weijden GA. The efficacy of oral irrigation in addition to a toothbrush on plaque and the clinical parameters of periodontal inflammation: a systematic review. Int J Dent Hygiene 2008; 6: 304–314
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Jin, L. Is oral irrigation beneficial to gingival health as an adjunct to toothbrushing?. Evid Based Dent 10, 40–41 (2009). https://doi.org/10.1038/sj.ebd.6400644