The Mystery of Burning Mouth Syndrome

Burning Mouth Syndrome is a diagnosis of exclusion with no definitive treatments and significantly impacts the patient's quality of life
Burning mouth syndrome is defined as an intra-oral burning sensation for which no medical or dental cause can be found. (Wikimedia Commons)
Burning mouth syndrome is defined as an intra-oral burning sensation for which no medical or dental cause can be found. (Wikimedia Commons)

Imagine living with a chronic burning sensation trapped agonizingly inside the mouth. This is the reality for people with Burning Mouth Syndrome (BMS), a puzzling condition that affects between 0.7% to 5% of individuals.

Definition of Burning Mouth Syndrome

Burning Mouth Syndrome (BMS) is defined as chronic orofacial pain with an intraoral burning or dysesthetic sensation that recurs for more than two hours per day on 50 % of the days over more than three months, without evident causative lesions on clinical investigation and examination (WHO). According to the International Headache Society, it is defined as an intra-oral burning sensation for which no medical or dental cause can be found.

It manifests in more than one oral site of the oral mucous membrane - tongue, lips, buccal mucosa, and floor of the mouth. The most frequently involved sites are the anterior two-thirds of the tongue, the anterior hard palate, and the mucosa of the lower lips.

Risk factors of Burning Mouth Syndrome

BMS shows a higher prevalence in women compared to men, with a ratio of 7:1, particularly among middle-aged and older women during peri and postmenopausal stages. BMS often begins spontaneously but can also develop gradually. Certain factors may increase your risk of developing burning mouth syndrome, including:

  • Recent illness

  • Previous dental work

  • Allergic reactions to food

  • Certain medicines

  • Traumatic life events

  • Anxiety, depression

  • Smoking

Types of Burning Mouth Syndrome

There are two classification systems for BMS. The first classification is based on the underlying cause of BMS. It includes

  • Primary BMS - isn’t caused by an underlying medical condition

  • Secondary BMS - caused by an underlying condition

Secondary BMS contradicts the established definition of BMS, which typically states that no identifiable cause can be determined.

The other classification is based on the clinical presentations of BMS. They are as follows:

  • Type 1 - Symptoms present every day, but not upon waking. Occurs during the day which then increases throughout the day, deepening in the evening

  • Type 2 - Symptoms present every day upon waking and throughout the day

  • Type 3 - Symptoms present only a few days, no regular pattern, and located in unusual regions like neck

Burning mouth syndrome is defined as an intra-oral burning sensation for which no medical or dental cause can be found. (Wikimedia Commons)
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Causes of Burning Mouth Syndrome

The origin of this condition is likely multifactorial and often idiopathic. Several theories for the etiopathogenesis of BMS have been proposed with varying degrees of evidence. It can be caused by local factors (chronic low-grade trauma from parafunctional habits such as rubbing the tongue against the teeth or pressing it against the palate) and systemic factors with endocrinological (estrogen or progesterone deficit), psychosocial (depression and anxiety), or neuropathic (peripheral and central neuropathy disorders) components in many patients.

Apart from BMS itself, some of the causes of an oral burning sensation can be misdiagnosed as BMS.

Other oral conditions that can cause symptoms similar to Burning Mouth Syndrome are Sjogren’s syndrome, acid reflux, dry mouth (xerostomia), depression mouth infections and nutritional deficiencies.

Dr. Sadia Afrin Zumu, BDS, MS, General Dentist and Researcher, Tainan, Taiwan

Some studies state that where there is an identifiable cause for a burning sensation, it is secondary BMS and should be distinguished from primary BMS.

Symptoms of Burning Mouth Syndrome

The main symptoms present in patients with BMS:

1) The presence of the triad consisted of:

  • Pain in the oral mucosa: sensations like burning, scalding, tingling, numb feeling, swelling, stinging;

  • Dysgeusia: persistence of a certain taste/ altered taste perception

  • Xerostomia: dry mouth.

The pain is constant throughout the day in some while it comes and goes in others. It usually improves during sleep. However, the the cycle begins again the next day.

2) Additional associated symptoms: thirst, headache, tenderness/pain in the temporomandibular joint (TMJ), masticatory, neck, shoulder, and suprahyoid muscles.

The main symptoms of BMS present as a triad : pain in the oral mucosa, dry mouth (in picture) and altered taste perception. (Wikimedia Commons)
The main symptoms of BMS present as a triad : pain in the oral mucosa, dry mouth (in picture) and altered taste perception. (Wikimedia Commons)

Diagnosis of Burning Mouth Syndrome

BMS diagnosis is a clinical challenge, relying on the exclusion of other systemic or local disorders causing the burning sensation of the oral cavity. Initially, clinicians gather comprehensive medical history and conduct a thorough clinical examination. The psychological and sleep profiles are also evaluated.

From a dentist's perspective, some key questions we ask patients to diagnose Burning Mouth Syndrome are: "Do you have pain or any sensation in your mouth?", "Do you feel dryness in your mouth?", "Do you have altered taste in your mouth?", and "Do you feel numbness in your mouth?"

Dr. Sadia Afrin Zumu, BDS, MS, General Dentist and Researcher, Tainan, Taiwan

In many cases, local clinical examination does not yield observable changes, though minor variations like cracked tongue, exfoliative glossitis, geographic tongue, or white/coated tongue might be detected. The absence of clinically evident lesions in the oral mucosa leads to the consideration of intraoral burning as a potential indicator of systemic disorders.

A correct diagnosis should include a wide range of tests like

  • Complete blood cell counts (CBC)

  • Sedimentation rate (ESR)

  • Serum iron and serum ferritin concentration

  • Iron binding capacity

  • The concentration of circulating folic acid, vitamin B12, zinc, etc.

  • Blood glucose level

  • Serum estradiol levels in women

  • Sialometry

  • Patch test for allergens (dental materials, food etc.)

  • Fungal culture (for Candida species from oral mucosa)

  • Tissue biopsy

  • Imaging

  • Specific investigations of systemic diseases

Management of Burning Mouth Syndrome

Managing BMS poses significant challenges for clinicians due to the absence of definitive treatment options, often leading to frustration for patients. Open conversation between clinicians and patients is crucial, where treatment objectives, and realistic expectations are clearly outlined. The treatment approach for BMS involves counseling to educate patients about the condition and to help alleviate stress, aiming to reduce symptoms. If underlying secondary factors are identified in causing the burning sensation, they should be treated first. The major therapies used in the management of BMS are listed below.

Lower-level laser therapy, transcranial magnetic stimulation, oral appliances (tongue protector), cognitive behavioral therapy and acupuncture have also been used for managing BMS. The complete spontaneous remission is rare.

Lifestyle modifications include drinking plenty of water, avoiding spicy food, smoking, alcohol, betel nut chewing, and ensuring adequate intake of Vitamin B12 and zinc.

Dr. Sadia Afrin Zumu, BDS, MS, General Dentist and Researcher, Tainan, Taiwan

Apart from medical intervention, alleviating burning mouth symptoms requires lifestyle adjustments and self-care practices. These include staying hydrated, sucking on ice chips, avoiding acidic foods and beverages, coffee, abstaining from alcohol and spicy foods, avoiding tobacco, refraining from using products with cinnamon or mint, and opting for flavorless toothpaste. Additionally, efforts to manage stress and promote relaxation can contribute to symptom relief. There's no known way to prevent burning mouth syndrome. But it is possible to reduce the discomfort.

Lifestyle modifications to reduce BMS symptoms include drinking plenty of water and avoiding alcohol, tobacco, spicy food. (Representational image : Unsplash)
Lifestyle modifications to reduce BMS symptoms include drinking plenty of water and avoiding alcohol, tobacco, spicy food. (Representational image : Unsplash)

Prognosis of Burning Mouth Syndrome

BMS may either spontaneously remit, show moderate improvement, or worsen over time. While certain instances may be temporary and improve with symptomatic care and time, symptoms can endure for months to years, or even persist indefinitely. Achieving full spontaneous remission from BMS is uncommon.

To sum up, Burning Mouth Syndrome (BMS) persists as a condition marked by significant complexity and challenges in management with debilitating effects on patients. With the psychological aspects further complicating, clinicians must prioritize patient reassurance and education. While its etiology remains elusive and treatment outcomes vary, collaborative efforts among clinicians offer hope for better understanding and addressing this condition. Continued research and multidisciplinary approaches are essential to improve the quality of life for individuals affected by burning mouth syndrome.

References

  • WHO. Burning Mouth Syndrome [Internet]. 2018 [cited 2024 April 13]. Available from:  https://icd.who.int/browse11/lm/en#/http://id.who.int/icd/entity/618998878

  • Reyad AA, Mishriky R, Girgis E. Pharmacological and non-pharmacological management of burning mouth syndrome: A systematic review. Dent Med Probl. 2020; 57(3):295–304.

  • https://www.mayoclinic.org/diseases-conditions/burning-mouth-syndrome/symptoms-causes/syc-20350911

  • https://my.clevelandclinic.org/health/diseases/14463-burning-mouth-syndrome

  • https://www.nidcr.nih.gov/health-info/burning-mouth

  • Coculescu EC, Radu A, Coculescu BI. Burning mouth syndrome: a review on diagnosis and treatment. J Med Life. 2014 Oct-Dec;7(4):512-5. PMID: 25713611; PMCID: PMC4316128.

  • Tan HL, Smith JG, Hoffmann J, Renton T. A systematic review of treatment for patients with burning mouth syndrome. Cephalalgia. 2022 Feb;42(2):128-161. doi: 10.1177/03331024211036152. Epub 2021 Aug 18. PMID: 34404247; PMCID: PMC8793318.

  • Bookout GP, Ladd M, Short RE. Burning Mouth Syndrome. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Apr 16]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK519529/.

(By Dr. Nirainila Joseph)

Burning mouth syndrome is defined as an intra-oral burning sensation for which no medical or dental cause can be found. (Wikimedia Commons)
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