Continuing Education Activity

Bruxism can be defined as the involuntary, unconscious, and excessive grinding of teeth. Bruxism may occur while awake, and it is then called wakeful or diurnal bruxism, and also during sleep, which is known as nocturnal bruxism. The main cause for bruxism has not been determined but is held to involve multiple factors. This activity reviews the cause, pathophysiology, presentation of bruxism and highlights the role of the interprofessional team in the managing these patients.

Objectives:

• Describe the pathophysiology of bruxism.

• Describe the presentation of a patient with bruxism.

• Summarize the treatment options for bruxism.

• Outline the importance of improving care coordination among interprofessional team members to improve outcomes for patients affected with bruxism.

Introduction

Bruxism can be defined as the involuntary, unconscious, and excessive grinding of teeth. During bruxism, there is forceful contact between the biting surfaces of maxillary and mandibular teeth. Bruxism may occur while awake, which is then called awake or diurnal bruxism, and during sleep, known as sleep or nocturnal bruxism. The main cause of bruxism has not yet been determined, but it is believed to be multifactorial.[1][2][3]. Researchers believe wakeful bruxism has different causes from nocturnal bruxism

Bruxism can be subclassified into primary and secondary, whereas primary bruxism is not related to any other medical condition; secondary bruxism is associated with neurological disorders or is considered an adverse effect of drugs.

The recommended approach to managing bruxism includes three angles. The use of an occlusal splint - preferably the hard acrylic-resin devices - works more as a protector of the teeth, preventing further damage. A behavioral approach to increase the patient’s awareness of the disorder, relaxation, lifestyle, and sleep hygiene instruction, and the use of drugs, which should be limited to short periods and severe cases where occlusal devices and psychological methods were ineffective.[4]

Anatomy and Physiology

The Current Definition of Bruxism

In 2013, a consensus was obtained by an international group of experts on a clear definition of bruxism as the repetitive masticatory muscle activity characterized by tooth clenching or grinding, or bracing or thrusting of the mandible, occurring during sleep (sleep bruxism) or wakefulness (awake bruxism).[5]

In the masticatory system, bracing refers to rigidly maintaining a mandibular position, and thrusting can be interpreted as moving the mandible in an anterior or lateral direction.[6] It is worth noting that these activities do not necessarily involve tooth contact,[6] correlating with the current hypothesis of the etiology of bruxism, believed to be regulated centrally and not peripherally.[6]

Sleep and awake bruxism should be considered different entities; therefore, they are defined separately.[6] Awake bruxism is a masticatory muscle activity (while awake) where repetitive or sustained tooth contact or mandibular bracing or thrusting occurs.[6] It is not considered a movement disorder in otherwise healthy patients.[6] Sleep bruxism is a masticatory muscle activity that happens during sleep and is characterized as rhythmic or non-rhythmic.[6] It is not considered a sleep or movement disorder in otherwise healthy patients.[6]

The phrase "in otherwise healthy individuals" is added to emphasize that bruxism is not a disorder in most individuals but could be a sign of a condition in some, e.g., epilepsy, obstructive sleep apnoea, and REM behavior disorder.[6]

Is Bruxism a Disorder?

Whereas a disorder is a condition that inherently causes harm and dysfunction in an individual,[6] a risk factor is a variable that increases the probability of disease. Raphael et al. suggested that bruxism (understood as increased masticatory muscle activity) should be considered a risk factor rather than a disorder.[7] Bruxism increase the risk of oral complications such as dental attrition and masticatory muscle and TMJ pain,[7] but such complications may or may not occur. Interestingly, some inconclusive evidence suggests that bruxism may even act as a protective response in some cases.[7] For example, it may prevent the collapse or restore the patency of the upper airway during sleep.[7]

Diagnosing Bruxism

Diagnosing bruxism may pose a challenge for the treating physician. In the clinical setting, the diagnosis of awake and sleep bruxism is usually based on patients' self reports (questionnaires and oral history) and clinical examination.[6] Self-reports are helpful in indicating possible bruxism activity and the frequency of the behaviour, but they do to provide information on the intensity and duration of masticatory muscle activity.[6]

The patients must be well informed about what clenching, bracing, and thrusting mean and asked to monitor the behavior during a specific period, e.g., one to two weeks.[6] The recollection of the bruxism history is more straightforward if the patient keeps a journal.[6] Furthermore, the patient’s partner or parents, in case of children, can also be interrogated to provide more information about the behavior.[6]

Electromyographic (EMG) recordings help determine both awake and sleep bruxism.[6] During sleep, EMG recordings may also be supplemented by other methods used in polysomnography, including audio and video recordings. For awake bruxism, using an app-based assessment that provides personal information about muscle activity while awake can offer more evidence of the behavior.[6]

Grading System

Lobbezoo et al.[5] suggested a grading system for diagnosing sleep and awake bruxism, which is divided into three categories: "possible," "probable," and "definite":

1- Sleep or awake bruxism is possible when is based on self-report only.2- Sleep or awake bruxism is probable when is based on self-report plus clinical examination.3- Sleep bruxism is definite when is based on self-reporting, clinical inspection, and polysomnographic recording, ideally accompanied by audio and video recordings.

Indications

It is still not clear when bruxism in otherwise healthy individuals requires intervention. Generally, the treatment of bruxism is indicated when there are negative consequences in the oral structures:

• Mechanical wear of the teeth, which results in loss of occlusal morphology and flattening of the occlusal surfaces
• Hypersensitive teeth
• Tooth fractures
• Restorations fractures, usually class I and class II restorations, fracture of crowns, and fixed partial prosthesis
• Dental implants failure
• Hypertrophy of masticatory muscles
• Tenderness and stiffness in jaw muscles
• When bruxism leads to limited mouth opening
• Temporomandibular pain
• Pain in the preauricular region
• Clicking and tenderness of the temporomandibular joint
• When headaches occur as a result of muscle tenderness associated with the temporalis muscle
• Unpleasant loud noises during sleep that cause sleep disturbances[4][8]

Technique or Treatment

To date, no management strategy has been found to cure bruxism; the treatment is directed at preventing further damage to the stomatognathic system.[9] The efficacy of the available treatment options in managing bruxism consequences varies significantly.[9]

Bruxism management relies on the recognition of the potential causative factors associated with the development of the condition. Diurnal bruxism can be managed by considering interventions such as habit modification, relaxation therapy, and biofeedback. In patients with sleep bruxism, which does not appear to be impacted by psychological or psychosocial factors,[10] appropriate intervention might include appliance therapy. In patients with medication or drug-induced bruxism, medication withdrawal or substitution should be considered. If recreational drugs are being used, intervention should include psychological counseling.[8][11][8]

Bruxism occurring in patients with neurogenic abnormalities such as dystonia may benefit from botox injection of the mastication muscles, which seems to decrease the frequency of parafunctional activity. Still, concerns have been raised regarding plausible adverse effects. Dietary counseling and management may be essential in some cases, such as excessive caffeine and tobacco use.[9]

Methods to Manage Bruxism

The available treatments can be classified into occlusal, behavioral, and pharmacological.

Occlusal Adjustments and Equilibration Therapy

Premature contacts or occlusal interferences have been associated with the development of bruxism in the past, and some dental clinicians still advocate performing occlusal adjustments to treat bruxism. However, there seems to be no basis in evidence for performing such irreversible procedures since the etiology of the disorder is now known to be mainly regulated centrally, not peripherally.[4][8]

The proposed idea that bruxism may be due to malocclusion makes orthodontic treatments viable options for managing the condition. But, this is still a controversy among dental clinicians and researchers, and there is no evidence to support it.[4]

Occlusal Splints

Occlusal splints are worn at night on the maxilla or mandible,[12] covering the occlusal surfaces of all the teeth. The exact mechanism of action of these appliances is still under debate. There is insufficient evidence to state that occlusal splints reduce sleep bruxism, but they show some benefit in protecting from tooth wear.[12] Occlusal splints are indicated to protect the teeth and restorations from traumatic loading and toothwear.[13]

Appliances vary in appearance and features. They may be constructed in the dental office or a laboratory and fabricated from hard or soft materials. Hard acrylic-resin stabilization splints are suggested to be more effective in reducing bruxism activity than soft splints. Soft-resin splints are more difficult to adjust than hard acrylic-resin devices and may increase the clenching behavior in some patients.[14] Studies show that some patients may have an increased electromyography (EMG) activity when they wear an occlusal splint during sleep, particularly the soft splints.[9]

Sleep Hygiene

It is recommended to counsel patients on sleep hygiene practices, including avoiding tobacco, coffee, or alcohol at night, limiting physical activity and mental stimulation before going to sleep, and sleeping in a quiet and dark room.[15] The indication of sleep hygiene seems reasonable and considered good practice, although its effectiveness in reducing bruxism activity is yet to be supported by evidence.[15]

Psychotherapy

Awake bruxism has been related to stress.[14] Psychotherapeutic approaches can be implemented to foster calmness. Patient counseling can lead to a decrease in tension and also create awareness of the habit.[14] This will increase voluntary control and thus reduce parafunctional movements.

Physical Therapy

Physical therapy may be recommended if bruxism is associated with muscle pain and stiffness.

Relaxation Training

In this method, the patient is trained to relax the muscle group voluntarily.

Biofeedback

This technique utilizes positive feedback to enable the patient to learn tension reduction. It is based on the concept that bruxers can unlearn their behavior.[4] It is accomplished by allowing the patient to view an electromyography (EMG) monitor while the mandible is postured with minimum activity. For nocturnal bruxism, auditory, vibratory, or taste stimuli may be used.[4]

Contingent electrical stimulation (CES) 

Contingent electrical stimulation (CES) intends to decrease the masticatory muscles activity by applying a low-level electrical stimulation when the muscles responsible for bruxism become active.[15] But, more studies are still needed to elucidate long-term results.

Medication

The use of drugs in treating bruxism should be limited to short periods and severe cases where occlusal devices and psychological approaches were ineffective.[4]

Pharmacological management includes the use of antianxiety agents, tranquilizers, sedatives, and muscle relaxants. Medications such as diazepam can be prescribed for a few days to alter the sleep disturbance and anxiety level. Low doses of tricyclic antidepressants may be used to inhibit the amount of rapid eye movement (REM) sleep.

Botulin Toxin

Botulin toxin, a neurotoxin synthesized by Clostridium botulinum,[16] is currently used to treat various medical conditions, including bruxism, and for cosmetic purposes. It works by impeding acetylcholine production and blocking calcium channels in nerve endings, temporarily inhibiting muscle contraction.[16]

Botulin toxin A injections in the masseter and temporal muscles have been demonstrated to improve the quality of life of patients with bruxism. Also, doses of <100UI carry a low chance of adverse effects.[16] This neurotoxin decreases the frequency of bruxism episodes, the severity of pain, and the intensity of the masticatory force.[16]

Complications

Complications of bruxism are wide-ranging. A stomatognathic breakdown will occur when occlusal forces of high intensity and duration overcome the body's adaptive capacity, and the consequences of bruxism will appear. To mentions some, tooth wear, tooth hypersensitivity, tooth mobility, pain in the temporomandibular joint (TMJ) or jaw musculature, temporal headache, and poor sleep. Indentation on the tongue's surface, the presence of linea alba along the biting plane of the buccal mucosa, and gingival recessions are also clinical signs of this habit.[17][18]

Bruxism may be associated with other parafunctional activities such as cheek biting or lip biting. There will be hypertrophy of masseter muscle accompanied by tenderness or fatigue of masticatory muscles. Tenderness of the TMJ may manifest as otalgia.

Clinical Significance

Bruxism has been linked to the development of temporomandibular disorders (TMD), tooth wear, dental mobility, changes in oral soft tissues and mandible, among others.[19] Bruxism is also associated with technical challenges when constructing and placing a dental prosthesis.[19]

Enhancing Healthcare Team Outcomes

Because bruxism is a multifactorial condition, an interprofessional team should work together to manage the disease better and improve patients' quality of life, including dentists, mental health nurses, pediatricians, primary caregivers, neurologists, and psychotherapists.

Bruxism management relies on the recognition of potential causative factors. Nocturnal bruxism is usually not cured by an intervention. The behavior possibly diminishes with age.

The outlook for most patients is guarded; despite treatment, in many cases, the condition recurs.[20] [Level V]