Abstract
Smell and odours play a vital role in social interaction. Halitosis is a social problem that affects one third of the population, causing a negative impact on the quality of life. There is little knowledge on the prevalence and management of halitosis in multiple sclerosis (MS) patients. The present study aims to evaluate the presence of halitosis in patients with MS when compared to a control group, and also evaluate treatment of the problem with antimicrobial photodynamic therapy (aPDT). This is a case-control clinical study in which 60 patients were evaluated: 30 MS patients in treatment at the Specialties Clinic School of Medicine, and 30 healthy patients, matched in age and gender for the control group. Data was collected on the duration of the disease as well as the degree of disability and medication use in the MS group. For all patients, halitosis was assessed with Oral Chroma™. Individuals with halitosis underwent treatment with tongue scraping and aPDT. The photosensitizer was methylene blue (0.005%) and a THERAPY XT-EC® laser (660 nm, 9 J, 100 mW for 90 s per point, 320 J cm−2, 3537 mW cm−2) was used. Six points 1 cm apart from each other were irradiated in the tongue dorsum. There was a positive correlation between the disability and disease duration. No parameter was correlated with halitosis. Patients with MS have higher levels of SH2 compounds when compared to the control group (p = 0.003, Mann–Whitney), but after aPDT both groups significantly reduced the levels to under the halitosis threshold. The aPDT scraping treatment was effective in the immediate reduction of halitosis in both groups.
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Introduction
Multiple sclerosis (MS) is a chronic, immune-mediated, neurodegenerative disease for which there is no cure [1, 2]. It affects the central nervous system, impairing the transmission of nerve impulses. It occurs every 69.1 per 100 000 person-years in the world, most predominantly in females and young adults [2–4].
MS treatment aims to reduce the relapse rate of the disease, being undertaken mainly with the use of immunosuppressants or immunomodulators [5, 6]. The most common oral side effect related to these drugs is xerostomia, followed by dysgeusia, dysphagia, mouth ulceration and sinusitis [7].
Despite there being several studies on the oral condition of MS patients [8–10], there is a gap in the literature about the prevalence and management of halitosis and whether there is a relation to the type of medication used for MS or the expanded disability status scale (EDSS) score (degree of neurological disability, which is measured on a scale of 0 to 10, 0.5 by 0.5, and in which the higher the number, the higher the inability is).
Halitosis represents a serious social problem. It is mainly caused by microbial metabolism on the tongue dorsum and periodontium, being modulated by low salivary flow at certain times during the day, food impaction, improper dental restoration, unclean dentures and diet [11].
Volatile sulfur compounds (VSCs) (e.g. hydrogen sulfide, methylmercaptan) are responsible for the bad odors originating in the oral cavity. Other compounds, such as indoles, scatoles, amines and organic acids (e.g. butyric acid) are also involved in the process. Oral malodor can be measured using organoleptic measurements or gas chromatography analysis [12]. The gold standard for objectively measuring bad breath is to evaluate quantitatively the VSCs produced by the oral flora using an Oral Chroma™ (Abilit Corp., Osaka, Japan) device [13]. After identification of the compounds, with proper diagnosis, identification of the etiology and timely referrals, certain steps can be taken to create a successful individualized therapeutic approach for each halitosis patient.
Mechanical and chemical removal of the biofilm using tongue scrapers, toothbrushes and mouth rinses constitutes the current control of halitosis. Unfortunately, there is very limited evidence of the potential effect of diet modification, use of sugar-free chewing gum, tongue cleaning by brushing, scraping the tongue or the use of zinc-containing toothpaste for treating oral malodour [11, 14, 15].
A treatment that has been increasingly used for microorganism-related diseases is antimicrobial photodynamic therapy (aPDT) [16, 17]. A photosensitizing (PS) substance binds to cells and is activated by light of a suitable wavelength. Free radicals of oxygen are formed, leading to necrosis or apoptosis of these cells [18–20]. aPDT represents an alternative to conventional antibacterial treatments because it neither causes any resistance to the development of microbes, nor is it affected by existing drug resistance status [17]. In aPDT, the photosensitizers used are methylene blue and toluidine blue , associated with red lasers [21]. aPDT can also be used for the treatment of halitosis, in accordance with the satisfactory results obtained by Lopes et al [22].
Because of the social impact of halitosis, it is important to assess its presence in patients with multiple sclerosis and the effectiveness of aPDT as a new form of treatment for the problem. The objectives of this study are to evaluate the presence of halitosis in patients with MS and to verify whether treatment with aPDT is effective against it.
Methods
This study was approved by the ethics committee of the Nove de Julho University with the number 42605615.0.0000.5511. We selected 30 patients with multiple sclerosis in treatment at the Specialties Clinic School of Medicine, Universidade Metropolitana de Santos (UNIMES). We also selected thirty patients, matched in age and gender with the MS group, as a control group, at Universidade Nove de Julho (UNINOVE). The patients or their guardians signed a consent form. We used the protocol that was registered with clinical trials number NCT02007993. The patients were selected while awaiting consultation (convenience sample), and came back for a return, in which a complete evaluation was carried out (figure 1). We collected data on the duration of the disease, the medication used at the time and the degree of disability (EDSS—expanded disability status scale) in the MS group.
Figure 1. Activity flowchart.
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Standard image High-resolution imageThe study included patients of both sexes, and to perform the aPDT we included patients diagnosed with halitosis, presenting the Oral Chroma™ results (with cysteine challenge) SH2 ≥ 112 ppb. The study excluded patients with dentofacial abnormalities (such as cleft lip and cleft palate), in orthodontic and/or orthopedic treatment, possessing spasms, seizures or repetitive involuntary muscle movement, patients who were undergoing cancer treatment, who had diabetes mellitus, periodontal diseases, caries, those in treatment with antibiotics up to 1 month before the survey and those who were pregnant. Smoking was not an exclusion factor.
Breath evaluation
The collection of breath followed the manufacturer's guidelines (Oral Chroma™ manual instructions) [23]. The participant was instructed to rinse with cysteine (10 mM) for 1 min, with the aim of selecting the gases produced by bacteria. A syringe of the same manufacturer was introduced into the patient's mouth to collect the oral air. The patient remained with his/her mouth closed for 1 min, breathing through the nose, without touching the syringe with the tongue. The plunger was pulled out, emptied into the patient's mouth and we pulled back the plunger to fill the syringe with the breath sample. The gas injection needle was placed on the syringe and the plunger was set to 0.5 ml. The gases were injected into the machine with a single movement. Oral Chroma™ measures the VSC thresholds accurately after 8 min. The measured VSCs are:
- —Sulfhydride: originating mainly from bacteria at the back of the tongue; values above 112 ppb are halitosis indicators.
- —Methylmercaptan: predominantly higher in periodontal pockets; values up to 26 ppb are considered normal.
- —Dimethylsulfide: can either be from periodontal disease or have a systemic origin; the dimethylsulfide perception threshold is the lowest at 8 ppb.
Participants were instructed to follow the following guidelines: 48 h before evaluation, avoid eating foods with garlic, onions and strong spices, avoid alcohol consumption and the use of mouthwash. On the assessment day, in the morning, they were allowed to eat up to a maximum of 2 h before the test, but had to refrain from candy, chewing gum, oral and personal care products with scent (aftershave, deodorant, perfume, creams and/or tonics) and had to brush their teeth with a minimal amount of toothpaste.
Antimicrobial photodynamic therapy (aPDT) against halitosis
As the proposed treatment was intended to eliminate bacteria from the tongue coating—the main cause of bad breath—we selected those patients whose sulfhydride was greater than 112 ppb for the treatment. Firstly, we performed the scraping process with a plastic tongue scraper (Halicare®). The technique described by Lopes et al [15] for photodynamic therapy was used. The device we used was the THERAPY XT-EC® (DMC ABC Medical Equipment and Dental, SP, BR) with red laser emission (660 nm), a tapered tip for use in dentistry and a diameter of 0.094 cm2.
One aPDT session was performed with methylene blue manipulated at a concentration of 0.005% (165 mM) (Formula and Ação®) as the photosensitizer (PS) applied in an amount which covered the middle third and dorsum of the tongue for 5 min incubation. The excess was removed with an aspirator in order to keep the surface wet with the PS itself, without the use of water. We irradiated six points which were 1 cm apart, considering the scattering halo of light and the effectiveness of aPDT. The instrument was calibrated with a wavelength of 660 nm, an energy of 9 J and a power of 100 mW for 90 s per point, a fluence of 320 J cm−2 and an irradiance of 3537 mW cm−2. The punctual application method was used, in direct contact with the tongue.
Statistical analysis
The data was analyzed with respect to its distribution by using the Shapiro–Wilk test. Since all data was presented in a non-parametrical distribution, the inferential analysis was performed by using the Mann–Whitney and Wilcoxon test for the independent and paired data, respectively. For the correlation of numerical variables the Spearman coefficient was used, and to verify the association of the type of drug used (immunosuppressant or immunomodulatory) and halitosis, we used the chi-square test, followed by the G Williams test. The significant level is set at α = 0.05.
Results
In table 1, we can see a description of the study population. Briefly, it was composed mostly of women (76%) with a mean age of 39 years. The median EDSS is relatively low (2), showing us that the population studied was in good condition when it came to disability, and were functional when it came to neurological conditions. The female patient majority is consistent with the literature; there were two smokers in each group.
Table 1. Descriptive statistics of both groups.
| Control group | MS group | |
|---|---|---|
| Gender | Male: 24% | Male: 24% |
| Female: 76% | Female: 76% | |
| Age (mean) | 37 (19–66) | 39 (18–64) |
| Drug in use for MS | — | Glatiramer acetate: 30% |
| Interferon beta: 28% | ||
| Natalizumab: 18% | ||
| Fingolimod: 16% | ||
| Teriflunomide: 2% | ||
| None: 6% | ||
| Duration of disease (years) | — | 5 (1–15) |
| Disability: EDSS (mean) | — | 2 |
Halitosis and aPDT treatment
The halitosis diagnosis was set when the SH2 levels were higher than 112 ppb. Based on this criteria, 93% (n = 28) of the control and 86% (n = 26) of the MS patients had halitosis present, with no statistical difference (p = 0.38, Mann–Whitney test) between the groups. The accurate evaluation of this data shows that the median of SH2 was higher in the MS group (1226 ± 140.9) when compared to the control group (398.7 ± 184.9) (p = 0.003, Mann–Whitney), and eight patients from the MS group (26.6%) presented SH2 higher than 2000 against only one in the control group (3.3%) (figure 2).
Figure 2. A comparison of the initial SH2 levels between the MS and control groups.
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Standard image High-resolution imageAfter the photodynamic therapy, both groups significantly reduced their levels to under the halitosis threshold (p = <0.0001 for both groups, Wilcoxon); figure 3 shows the boxplot of the data.
Figure 3. SH2 levels before and after treatment in both groups.
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Standard image High-resolution image
The methylmercaptan and dimethylsulfide data was collected. Most of the patients did not have VSC present, and aPDT did not reduce the levels of the compounds in a significant manner (p = 0.21).
Correlations and associations
In order to fully appreciate our data and provide a better evaluation of the population studied, we checked whether there were any correlations or associations between the information collected in the MS group. There was no correlation between the degree of disability (EDSS) or the initial halitosis (p = 0.82) or between the type of drug (immunosuppressant or immunomodulator) the patient used at the time and the initial halitosis (p = 0.79). There was only a correlation between the EDSS and the duration of the disease (p < 0.001).
Discussion
This study is unprecedented, since it is the first to evaluate the presence of halitosis in MS patients showing higher levels of SH2, which is the volatile sulfur compound related to halitosis originating in the tongue coating in MS individuals, when compared to the pair-matched control group. Furthermore, we proposed the use of a new treatment (aPDT) for immediate and effective reduction of halitosis.
Bad breath affects approximately 2.4% to 57.9% of the samples when evaluated by the organoleptic method or gas chromatography [24]. Due to its ability to distinguish between VSCs, the Oral Chroma™ device is the most appropriate way of determining halitosis in scientific research [25]. In our study, the levels of halitosis were higher in the MS group when compared to the control group, suggesting that patients with MS may experience more halitosis than the general population. We hypothesized that the presence of halitosis in patients with MS could be due to the continuous use of immunomodulators/immunosuppressants, which could lead to alterations in the saliva, and consequently more bacteria in the mouth. We also considered that patients with a greater degree of disability would have more halitosis, as it may be more difficult for them to have proper hygiene. Even though there was no correlation between the medication in use, or disability and the presence of halitosis, it would be important to conduct more studies in this area.
The forms of treatment for halitosis that are more evident in the literature are the use of tongue scrapers and mouthwashes [14]. Tongue scrapers are presented as the most effective conventional method for mechanical removal of the tongue coating. When combined with conventional treatments, aPDT has had satisfactory results in the treatment of bacterial infections. Bacteria do not show bacterial resistance to this treatment and there are no side effects [21, 26]. Two controlled trials showed that the combination of a scraper with aPDT was more effective in the immediate reduction of oral malodor when compared to the separate use of a scraper and aPDT [27, 28]. The results of these studies corroborate with our results, in which the combination of tongue scraping with aPDT proved effective in reducing oral malodor in patients with MS.
As study limitations, we can cite the limited number of patients who were able to come back for a full evaluation. Moreover, the queries for data collection were long and some patients experienced discomfort during the tongue scraping and laser application.
MS patients seem to have a higher prevalence of SH2 compounds when compared to a paired-matched control group. Among the factors evaluated, there was only a correlation between the EDSS and disease duration. Treatment with a tongue scraper associated with aPDT was effective in the immediate reduction of halitosis in both groups.
Acknowledgments
This research received no specific grant from any funding agency. The authors declare no conflicts of interest.