Treatment of Halitosis: Comparison
Please note this is a comparison between Version 1 by Catarina Izidoro and Version 2 by Catherine Yang.

Halitosis, or bad breath, is an oral health problem characterized by an unpleasant malodor emanating from the oral cavity. This condition can have different origins and causes a negative burden in social interactions, communication and quality of life, and can in uncommon cases be indicative of underlying non-oral non-communicable diseases.

  • halitosis
  • periodontal disease
  • periodontitis
  • tongue coating

1. Treatments for Intra-Oral Causes

The course of treatment for halitosis is determined after a thorough oral clinical examination, including the dentition, soft tissue, and periodontal health status. All active caries, secondary caries, pulp pathology, oral pathologies such as chronic ulcerative conditions, oral candidiasis and xerostomia, must be identified, diagnosed and treated appropriately. Moreover, the diagnosis of periodontal diseases such as gingivitis, periodontitis or necrotizing periodontal diseases, should be performed and adequately treated, since these pathologies are a major contributor to the levels of oral VSC [1][79].The treatment of intra-oral halitosis include four phases: (1) mechanical reduction of nutrients and intraoral microorganisms; (2) chemical reduction of microorganisms; (3) inversion of volatile gases into non-volatile components (chemical neutralization of VSC) or (4) masking the malodor [2][91].

1.1. Mechanical Reduction

Bearing in mind that microorganisms and their metabolites are involved in halitosis etiopathogenesis, mechanical removal of biofilm and microorganisms is the first step in halitosis control [3][92]. Tongue coating is the main causal factor of intraoral halitosis, hence the importance of extensive cleaning of the tongue. Scraping the dorsum of the tongue reduces both available nutrients and available microorganisms, leading to improved odor [4][93]. All patients should receive clear instructions on the most appropriate oral hygiene care for their case, as well as an explanation of tongue cleaning. The patient should gently brush the dorsum of the tongue with a soft bristle brush and a toothpaste in 5 to 15 movements. The area that tends to accumulate bacterial deposits and keratin and food debris, contributing to physiological halitosis is terminal sulcus, is the division between the posterior and middle thirds of the tongue. Removal of these materials decreases the release of VSCs.
There are two ways to do daily tongue cleaning: using a regular toothbrush or using atongue scraper [5][94]. It was described in a systematic review published by Van der Sleen et al. that tongue brushing or tongue scraping allows the reduction of tongue coating and improvement of halitosis. According to these authors, tongue scrapers are suitable for the anatomy of the tongue and reduce 75% of VSCs compared to 45% when a toothbrush is used [6][95].
On the other hand, in a Cochrane review in 2006, which compared randomized controlled trials for different tongue cleaning methods, concluded that there was a weak, but statistically significant, difference in the reduction of VSC levels when scrapers or cleaners were used instead of toothbrushes [7][96]. More studies are needed for clearer conclusions.
Since periodontitis is a major cause of oral malodor, treating periodontitis will also improve halitosis.
One-stage full-mouth disinfection can be performed, as described by Bollenet et al. [8][97], combining scaling and root planing with the use of chlorhexidine. There is a significant microbiological reduction up to 2 months, with reduced organoleptic scores [9][98].
The accumulation of bacterial plaque due to lack of interproximal cleaning leads to a high incidence of malodor, so it is essential to use dental floss/interproximal brush to control bacterial plaque and oral microorganisms [10][99].
The oral health professional should dedicate time from their consultation to the motivation and instruction of oral hygiene care to patients. This is the only way to achieve good treatment adherence results [11][100].

1.2. Chemical Reduction

Antibacterial agents for mouthwashes include chlorhexidine (CHX), cetylpyridinium chloride (CPC), and triclosan. Its mechanism acts on bacteria capable of producing volatile sulfur compounds [12][29].
Mouthwashes containing CHX and CPC can inhibit the production of VSCs, while mouthwashes containing chlorine and zinc dioxide have a neutralizing action on sulfur compounds that produce halitosis, according to a Cochrane review [13][101].
Rinsing is a common practice in the management of oral malodor. The most used rinse components are:
  • Chlorhexidine (CHX): considered the gold standard mouth rinse for halitosis treatment [14][102]. Its use at a concentration of 0.2% causes a 43% reduction in VSCs and a 50% reduction in organoleptic scores throughout the day [10][99]. CHX in combination with CPC produce greater reductions in VSCs level, and both aerobic and anaerobic bacterial counts showed the lowest percentage of survival in a randomized, double-blind, cross-over study design [14][102]. Combined effects of zinc and CHX were studied in a study conducted in 10 participants, Zinc (0.3%) and CHX (0.025%) in low concentration led to 0.16% drop in H2S levels after 1 h, 0.4% drop after 2 h and 0.75% drop after 3 h showing a synergistic effect of the two [15][103]. However, patients may be reluctant to use CHX long-term as it has an unpleasant taste and can cause (reversible) staining of the teeth [16][104].
  • Essential oils: these products give only a short-term and restricted effect (25% reduction) for 3 h. Furthermore, the reduction in odor-producing bacteria is limited [17][105]. Usage of Listerine containing essential oils resulted in significant reduction in halitosis-producing bacteria in healthy subjects [18][106].
  • Chlordioxide: It is a strong oxidant that can reduce halitosis by oxidizing H2S, CH3SH, cysteine and methionine. A 29% reduction in odor was reported after 4 h [19][107].
  • Triclosan, is a widely used antimicrobial agent with good results in reducing dental plaque, gingivitis and halitosis [20][108]. Its use in toothpastes in combination with a tongue scraper and toothbrush revealed a significant reduction in organoleptic scores and sulfur levels in the mouth air [20][108].
  • A formulation of triclosan/copolymer/sodium fluoride in 3 weeks randomized double blind trial by Hu et al. seemed to be particularly effective in reducing VSC, oral bacteria, and halitosis [21][109].
Toothpastes containing stannous fluoride, zinc or triclosan have a beneficial effect on reducing oral malodor for a limited period of time [22][23][24][110,111,112].
In a recent Cochrane review by Fedorowicz, with five randomized controlled trials involving 293 participants, 0.05% chlorhexidine + 0.05% cetylpyridinium chloride + 0.14% zinc lactate was compared to placebo. With the use of this mouthwash, there was a significant reduction in organoleptic scores, but also a more significant presence of stains on the tongue and teeth. A meta-analysis of the data was not possible due to clinical heterogeneity between trials [13][101].
It is concluded that this mouthrinse (0.05% chlorhexidine + 0.05% cetylpyridinium chloride + 0.14% zinc lactate)plays an important role in reducing the levels of halitosis producing bacteria on the tongue and can be effective in neutralization of odoriferous sulfur compounds. However, well-designed, randomized controlled trials with larger sample size, a longer intervention and follow-up period are still needed to confirm these results.

1.3. Probiotics

Several studies have shown that probiotic bacterial strains, originating from the indigenous oral microbiota of healthy humans, may have potential application as adjuvants for the prevention and treatment of halitosis [25][113]. The aim is to prevent the re-establishment of unwanted bacteria and thus limit the recurrence of oral malodor for an extended period. Recently, several studies have been carried out to replace the bacteria responsible for halitosis with probiotics such as Streptococcus salivarius (K12), Lactobacillus salivarius or Weissellacibaria.
Oral administration of probiotic lactobacilli has shown good results in the treatment of physiological halitosis, as well as improved bleeding on probing of periodontal pockets [26][114].
Furthermore, in vivo and in vitro studies revealed that Weisellacibaria isolates have the ability to inhibit the production of VSC, demonstrating that they have potential for the development of new probiotics for use in the oral cavity [27][115]. The use of a suspension of living non-pathogenic Escherichia coli bacteria also seems to have good results in the treatment of gut-caused halitosis [28][116].

1.4. Transformation of Volatile Sulfur Components

Products containing chlorite anion and chlorine dioxide have been shown to be effective in oxidizing and inactivating the oral VSC demonstrating long-lasting effects [29][30][117,118]. Positively charged metal ions such as zinc, mercury and copper bind to sulfur radicals inhibiting the expression of VSCs [31][32][119,120]. For this reason, the combination of zinc and CHX appears to have a synergistic effect on the elimination of VSCs. According to the authors Young et al., a commercial rinse (containing 0.005% CHX, 0.05% cetylpyridinium chloride (CPC) and 0.14% zinc lactate) appears to be much more efficient than CHX alone, due to the zinc effect [31][119].

1.5. Masking Effect

Rinsing products, sprays, mint tablet, chewing gum increase the saliva production, thereby retaining more soluble sulfur components for a short period of time, having only a short-term masking effect [33][121].

2. Treatments for Extra-Oral Causes

Bearing in mind that halitosis presents a multifactorial complexity, treatment should be individualized and directed to each patient, rather than generalized [34][1].
Diagnosis and treatment involve a multidisciplinary team: primary healthcare clinician, dentist, otolaryngologist, nutritionist, gastroenterologist and clinical psychologist [35][122].
After a detailed clinical oral examination and anamnesis, that excludes intra-oral causes for halitosis, patients with signs or symptoms of systemic diseases that may be the cause of oral malodor, should be referred to the appropriate medical specialty (ENT, pulmonologist, endocrinologist or gastroenterologist). Patients with pseudohalitosis or halitophobia should be counseled appropriately and referred for psychologic evaluation and treatment.
In the clinical approach to halitosis, a relationship of trust and empathy between the patient and a general practitioner is extremely important. In this reliable medical approach, the patient will feel comfortable to communicate their complaints and the doctor will be able to encourage the patient to undergo treatment, improving the quality of life of the patient as a whole, and improving their interactions and social relationships [16][104].

2.1. Halitophobia

Imagined halitosis is poorly documented in the psychiatric literature [36][123]. Many of the cases with imagined halitosis described in the literature resemble the psychiatric syndrome of social phobia [37][124]. Generally, these patients believe that their oral malodor is related to social rejection or avoidance behaviors of the people with whom they interact [38][125]. Patients with halitophobia require referral for clinical psychology investigation and treatment for mental assessment and appropriate treatment [16][35][104,122].
The ‘treatment’ of these patients is impossible, as they are not within the arguments presented by a physician. Mostly, these patients hop from clinic/specialist to clinic/specialist to find an argument for their self-reported problem.

2.2. Dry Mouth/Xerostomia

It is important to accurately describe and differentiate dry mouth problems. The subjective feeling of dry mouth is defined as xerostomia, while hyposalivation is the objective finding of decreased salivary production [39][126].
The treatment of hyposalivation or dry mouth will also contribute to the treatment of halitosis. The dry mouth symptom can be treated with hydration and sialogogues or with artificial saliva substitutes [39][126].
When the cause of dry mouth is medication, it becomes important to find other pharmacological alternatives without compromising the patient’s health.
The patient should be encouraged to increase water intake and avoid drinking caffeinated beverages.
When there is a complaint of dry mouth sensation—Xerostomia—for salivary stimulation, we can resort to the use of sugar-free candies or gums and also the use of an artificial salivary substitute, which is usually composed of carboxymethylcellulose.
In severe cases of dry mouth, e.g., patients with Sjögren’s syndrome or patients undergoing radiotherapy, therapy with a cholinergic agonist is prescribed. The most frequently used has been pilocarpine at a dosage of 5 to 10 mg/day [34][1], and more recently cevimeline hydrochloride (Evoxac), 30 mg three times a day, also with good results in the treatment of dry mouth [39][40][126,127].
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