Bruxism

# Overview
Bruxism is defined as repeated involuntary grinding and clenching of teeth which can occur either diurnal or nocturnally. In 1907, Marie Pielkiewics coined the French term 'La Bruxomanie" for bruxism. Bruxism can be classified into awake bruxism and sleep bruxism based on the physiological sleep status of the individual. The etiology of bruxism can be categorized into three groups:psychosocial factors, peripheral factors, and pathophysiological factors. Multifactorial etiology causes involving brain neurotransmitters or basal ganglia. Bruxism affects men and women equally. Factors associated with an increased risk of bruxism include obstructive sleep apnea, alcohol abuse, caffeine intake, smoking, and anxiety. The symptoms of bruxism usually develop in the first decade of life, and start with the appearance of the first primary upper and lower anterior teeth. Common complications of bruxism are tooth wear, and tooth hypersensitivity. Bruxism is primarily diagnosed based on the clinical presentation. History of complaints of disturbance from the clicking or grating sound by the accompanied partners. The most common symptoms of bruxism include involuntary rhythmic contractions of the masticator muscles during sleep. Removal of any offending agent responsible for bruxism is the primary step in the management. Surgery is the mainstay of treatment in the management of bruxism.

# Historical Perspective
- In 1907, Marie Pielkiewics coined the French term 'La Bruxomanie"  for bruxism. 
- In 1931, Frohman first coined the English term bruxism.

# Classification
Bruxism can be classified into awake bruxism and sleep bruxism based on the physiological sleep status of the individual.

# Causes
The etiology of bruxism can be categorized into three groups: psychosocial factors, peripheral factors, and pathophysiological factors.

# Pathophysiology
- Bruxism is caused by the activation of reflexive chewing activity
- Chewing is a neuromuscular activity that is controlled by the reflex nerve pathways.
- During sleep, the reflex part is active while the higher control is inactive, resulting in bruxism.
- As stated, bruxism is considered to have multifactorial etiology. Multifactorial etiology causes involving brain neurotransmitters or basal ganglia.
- Pathophysiological Factors
As bruxism often occurs during sleep, the physiology of sleep has been studied extensively, especially the arousal response, in search of possible causes of a disorder.
Arousal response is a sudden change in the depth of the sleep during which the individual either arrives in the lighter sleep stage or actually wakes up.
Such a response is accompanied by gross body movements, increased heart rate, respiratory changes, and increased muscle activity.
It is derived that disturbances in the central neurotransmitter system may be involved in the etiology of bruxism.
It is hypothesized that the direct and indirect pathways of the basal ganglion, a group of five subcortical nuclei that are involved in the coordination of movements, is disturbed in bruxer.
The direct output pathway goes directly from the stratum to the thalamus from where afferent signals project to the cerebral cortex. The indirect pathway, on the other hand, passes by several other nuclei before reaching it to the thalamus.
If there is an imbalance between the pathways, movement disorder results like Parkinsons disease.
The imbalance occurs with the disturbances in the dopamine-mediated transmission of an action potential. In the case of bruxism there may be an imbalance in both pathways.
Acute use of dopamine precursors like L-dopa inhibits bruxism activity and chronic long-term use of l-dopa results in increased bruxism activity. SSRTs (serotonin reuptake inhibitors), which exert an indirect influence on the dopaminergic system, may cause bruxism after long-term use.
Amphetamine, which increases the dopamine concentration by facilitating its release has been observed to increase bruxism.
Nicotine stimulates central dopaminergic activities, which might explain the finding that cigarette smokers report bruxism two times more than the nonsmokers.
- As bruxism often occurs during sleep, the physiology of sleep has been studied extensively, especially the arousal response, in search of possible causes of a disorder.
- Arousal response is a sudden change in the depth of the sleep during which the individual either arrives in the lighter sleep stage or actually wakes up.
- Such a response is accompanied by gross body movements, increased heart rate, respiratory changes, and increased muscle activity.
- It is derived that disturbances in the central neurotransmitter system may be involved in the etiology of bruxism.
- It is hypothesized that the direct and indirect pathways of the basal ganglion, a group of five subcortical nuclei that are involved in the coordination of movements, is disturbed in bruxer.
- The direct output pathway goes directly from the stratum to the thalamus from where afferent signals project to the cerebral cortex. The indirect pathway, on the other hand, passes by several other nuclei before reaching it to the thalamus.
- If there is an imbalance between the pathways, movement disorder results like Parkinsons disease.
- The imbalance occurs with the disturbances in the dopamine-mediated transmission of an action potential. In the case of bruxism there may be an imbalance in both pathways.
- Acute use of dopamine precursors like L-dopa inhibits bruxism activity and chronic long-term use of l-dopa results in increased bruxism activity. SSRTs (serotonin reuptake inhibitors), which exert an indirect influence on the dopaminergic system, may cause bruxism after long-term use.
- Amphetamine, which increases the dopamine concentration by facilitating its release has been observed to increase bruxism.
- Nicotine stimulates central dopaminergic activities, which might explain the finding that cigarette smokers report bruxism two times more than the nonsmokers.
- Psychosocial Factors
There is no proper description of conclusive nature of psychological factors role in bruxism because of the absence of large scale longitudinal trials.
- There is no proper description of conclusive nature of psychological factors role in bruxism because of the absence of large scale longitudinal trials.

## Associated Factors
- Disturbed sleep pattern/other sleep disorders (obstructive sleep apnea, snoring, moderate daytime sleepiness)
- Malocclusion, in which the upper and lower teeth fit together in a dysfunctional way, typically through lateral asymmetry and dysocclusion of the front teeth through premature contact of back teeth.
- Relatively high levels of consumption of caffeinated drinks and foods, such as coffee, colas, and chocolate
- High levels of alcohol consumption
- Smoking
- High levels of anxiety and/or stress
- SSRIs
- Digestive problems
- Hypersensitivity of the dopamine receptors in the brain.
- Consumption of stimulant drugs and medications, such as those of the amphetamine-based family, such as MDMA
- Excessive use of (i.e., frequent redosing and dependency on) GHB and similar GABA-inducing analogues such as Phenibut 
- Disorders such as Huntington's and Parkinson's diseases 

# Epidemiology and Demographics
Bruxism often occurs during sleep and can even occur during short naps. Bruxism is one of the most common sleep disorders: 30 to 40 million Americans grind their teeth during sleep.

### Gender
- Bruxism affects men and women equally.

### Age
- Bruxism commonly affects individuals younger than 6 years of age and its incidence declines as age increases.

# Screening
There is insufficient evidence to recommend routine screening for bruxism.

# Risk Factors
Factors associated with an increased risk of bruxism include:
- Obstructive sleep apnea
- Alcohol abuse
- Caffeine intake
- Smoking
- Anxiety

# Natural History, Complications and Prognosis

## Natural History
- The symptoms of bruxism, usually develop in the first decade of life, and start with symptoms such as appearance of the first primary upper and lower anterior teeth.
- The symptoms of bruxism typically develop in childhood and may persist into adult due to presence of other risk factors.
- Usually bruxism follows a benign course.
- If left untreated, bruxism can lead to hypertrophy of masseter muscle accompanied by tenderness of TMJ, which  manifests as otalgia.

## Complications
Common complications of bruxism are:
- Tooth wear
- Tooth hypersensitivity
- Tooth mobility
- Pain in the temporomandibular joint (TMJ) or jaw musculature
- Temporal headache,
- Poor sleep
- Signs of this parafunctional habit
Indentation on the tongue
Presence of linea alba along the biting plane of the buccal mucosa
Gingival recessions
- Indentation on the tongue
- Presence of linea alba along the biting plane of the buccal mucosa
- Gingival recessions

# Diagnosis

## Diagnostic study of choice
Bruxism is primarily diagnosed based on the clinical presentation.
- History of tooth grinding during sleep
- Confirmation by parents or bed partners.

## History
- History of complaints of disturbance from the clicking or grating sound by the accompanied partners.

## Symptoms
The most common symptoms of bruxism include:
- Involuntary rhythmic contractions of the masticator muscles during sleep.
- Secondary symptoms may develop due to forceful grinding in some  patients which include:
Morning headaches
Jaw pain
Clicking in the temporomandibular joints
- Morning headaches
- Jaw pain
- Clicking in the temporomandibular joints
- Dental deformities may be seen, however not disease specific, and not limited to:
Thermal sensitivity in the teeth
Hypermobility
Need for dental restorations
Tooth wear  on tooth surfaces that contact during biting or chewing
Lateral grinding forces in particular can be particularly destructive.
- Thermal sensitivity in the teeth
- Hypermobility
- Need for dental restorations
- Tooth wear  on tooth surfaces that contact during biting or chewing
- Lateral grinding forces in particular can be particularly destructive.
- Severe cases of bruxism do present with:
Injury to soft tissues of the mouth
Dental fractures
Difficulty with chewing
Temporomandibular joint pain and dysfunction
Head and neck pain
- Injury to soft tissues of the mouth
- Dental fractures
- Difficulty with chewing
- Temporomandibular joint pain and dysfunction
- Head and neck pain

## Physical Examination
Patients with  bruxism usually appear normal.

## Laboratory Findings
There are no diagnostic laboratory findings associated with  bruxism.

## Electrocardiogram
There are no ECGfindings associated with bruxism.

## X-ray
There are no x-ray findings associated with bruxism.

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound findings associated with bruxism .

## CT scan
There are no CT scan findings associated with bruxism.

## MRI
There are no MRI findings associated with bruxism.

## Other Imaging Findings
There are no other imaging findings associated with bruxism.

## Other Diagnostic Studies
There are no other diagnostic studies associated with bruxism.

# Treatment

## Medical Therapy
- Removal of any offending agent responsible for bruxism is the primary step in management.
- The wait-and-see approach is recommended in cases with medically induced bruxism, as spontaneous remission is ensured with the cessation of the offending agent.
- Pharmacotherapy mainly concentrated to alleviate symptoms
- Buspirone and Gabapentin are the two recommended medications to manage bruxism
Preferred regimen 1 : Buspirone 15 to 20 mg/day  PO q12.
Preferred regimen 2: Gabapentin 100 to 300 mg PO q24
- Preferred regimen 1 : Buspirone 15 to 20 mg/day  PO q12.
- Preferred regimen 2: Gabapentin 100 to 300 mg PO q24

## Surgery
Surgery is the mainstay of treatment in the management of bruxism.

### Indications
The treatment of bruxism is indicated when there are any of these possible consequences:
- Mechanical wear of the teeth, which results in loss of occlusal morphology and flattening of the occlusal surfaces
- Hypersensitive teeth
- Loss of periodontal support
- Tooth fractures
- Restorations fractures, usually class I and class II restorations, fracture of crowns, and fixed partial prosthesis
- Restorations or dental implants failure
- Hypertrophy of masticatory muscles
- Tenderness and stiffness in jaw muscles
- When bruxism leads to limited mouth opening
- Temporomandibularpain
- Pain in the preauricular region