Abstract
Introduction
Halitosis can be caused by oral disease, or by respiratory tract conditions such as sinusitis, tonsillitis, and bronchiectasis, but an estimated 40% of affected individuals have no underlying organic disease.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments in people with physiological halitosis? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2008 (Clinical evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
Results
We found five systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
Conclusions
In this systematic review we present information relating to the effectiveness and safety of the following interventions: artificial saliva; cleaning, brushing, or scraping the tongue; diet modification; regular or single use of mouthwash; sugar-free chewing gums; and zinc toothpastes.
Key Points
Halitosis can be caused by oral disease, or by respiratory tract conditions such as sinusitis, tonsillitis, and bronchiectasis, but an estimated 40% of affected people have no underlying organic disease.
The main chemicals causing the odour seem to be volatile sulphur compounds, but little is known about the cause of physiological halitosis.
Regular use of a mouthwash may reduce breath odour compared with placebo, but single-use mouthwash may have only a short-term benefit.
We don't know whether tongue cleaning, sugar-free chewing gums, zinc toothpastes, artificial saliva, or dietary modification reduce halitosis, as no studies of adequate quality have been found.
About this condition
Definition
Halitosis is an unpleasant odour emitted from the mouth. It may be caused by oral conditions, including poor oral hygiene, and periodontal disease, or by respiratory tract conditions, such as chronic sinusitis, tonsillitis, and bronchiectasis. In this review, we deal only with physiological halitosis (i.e. confirmed persistent bad breath in the absence of systemic, oral, or periodontal disease). We have excluded halitosis caused by underlying systemic disease that would require disease-specific treatment, pseudo-halitosis (in people who believe they have bad breath but whose breath is not considered malodourous by others), and artificially induced halitosis (e.g. in studies requiring people to stop brushing their teeth). This review is only applicable, therefore, to people in whom such underlying causes have been ruled out, and in whom pseudo-halitosis has been excluded. There is no consensus regarding duration of bad breath for the diagnosis of halitosis, although the standard organoleptic test for bad breath involves smelling the breath on at least two or three different days.
Incidence/ Prevalence
We found no reliable estimate of prevalence, although several studies report the population prevalence of halitosis (physiological or because of underlying disease) to be about 50%. One cross-sectional study of 491 people found that about 5% of people with halitosis have pseudo-halitosis and about 40% have physiological bad breath not caused by underlying disease. We found no reliable data about age or sex distribution of physiological halitosis.
Aetiology/ Risk factors
We found no reliable data about risk factors for physiological bad breath. Mass spectrometric and gas chromatographic analysis of expelled air from the mouths of people with any type of halitosis have shown that the principal malodorants are volatile sulphur compounds, including hydrogen sulphide, methyl mercaptan, and dimethyl sulphide.
Prognosis
We found no evidence on the prognosis of halitosis.
Aims of intervention
To improve social functioning; to reduce embarrassment; to reduce odour, with minimum adverse effects.
Outcomes
Breath odor, measured by organoleptic test scores or other odour scales; quality of life including embarrassment and social functioning; adverse effects. We excluded non-clinical outcomes such as gas chromatography and spectroscopy results, and concentrations of compounds in exhaled air.
Methods
Clinical Evidence search and appraisal July 2008. The following databases were used to identify studies for this systematic review: Medline 1966 to July 2008, Embase 1980 to July 2008, and The Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Clinical Trials 2008, Issue 2 (1966 to date of issue). An additional search was carried out of the NHS Centre for Reviews and Dissemination (CRD) — for Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA). We also searched for retractions of studies included in the review. Abstracts of the studies retrieved from the initial search were assessed by an information specialist. Selected studies were then sent to the contributor for additional assessment, using predetermined criteria to identify relevant studies. Study design criteria for inclusion in this review were: published systematic reviews of RCTs and RCTs in any language, and containing more than 20 individuals of whom more than 80% were followed up. There was no minimum length of follow-up required to include studies. We excluded all studies described as "open", "open label", or not blinded unless blinding was impossible. We included systematic reviews of RCTs and RCTs where harms of an included intervention were studied, applying the same study design criteria for inclusion as we did for benefits. In addition, we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the reviews as required. We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).
Table.
GRADE Evaluation of interventions for Halitosis.
| Important outcomes | Breath odour, Quality of life | ||||||||
| Studies (Participants) | Outcome | Comparison | Type of evidence | Quality | Consistency | Directness | Effect size | GRADE | Comment |
| What are the effects of treatments in people with physiological halitosis? | |||||||||
| 3 (187) | Breath odour | Regular-use mouthwash versus placebo | 4 | –2 | 0 | 0 | NA | Low | Quality points deducted for sparse data and methodological flaws |
| 2 (less than 147 people) | Breath odour | Regular-use mouthwashes versus each other | 4 | –2 | 0 | 0 | 0 | Low | Quality points deducted for sparse data and methodological flaws |
| 3 (142) | Breath odour | Single-use mouthwash versus placebo | 4 | –2 | –1 | 0 | NA | Very low | Quality points deducted for sparse data and incomplete presentation of data. Consistency point deducted for conflicting results |
| 1 (less than 99 people) | Breath odour | Single-use mouthwashes versus each other | 4 | –2 | 0 | 0 | NA | Low | Quality points deducted for sparse data and incomplete presentation of data |
We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.
Glossary
- Low-quality evidence
Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
- Organoleptic test scores
These are assigned by one or more examiners who sniff the person's exhaled breath on two or three different days. People having this examination should not have had antibiotics in the previous 3 weeks, and should have refrained from eating garlic, onions, and spicy foods for 48 hours, and should have refrained from usual oral hygiene and smoking for the previous 12 hours. Scoring systems vary among studies.
- Very low-quality evidence
Any estimate of effect is very uncertain.
Disclaimer
The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients.To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.
Contributor Information
Crispian Scully, UCL - Eastman Dental Institute, London, UK.
Stephen Porter, UCL - Eastman Dental Institute, London, UK.
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