Bruxism is the involuntary clenching or grinding of teeth, a repetitive jaw-muscle activity classified as an oral parafunctional activity that serves no normal function like chewing or speaking.
Unmanaged bruxism can lead to dental damage, including worn enamel, chipped teeth, and fractured restorations.
Common physical symptoms include dull headaches, soreness in the jaw muscles, and pain similar to an earache.
While stress, anxiety, and sleep disorders are frequent causes, many cases are now recognized as an adverse reaction to prescription medications.
Neurochemical Causes of Teeth Grinding
Medications induce bruxism by affecting neurotransmitters that govern mood and motor control, primarily serotonin and dopamine. The balance between these two chemicals is a factor in the development of drug-induced jaw clenching and grinding.
When medications increase serotonin concentration, it can inhibit dopamine release. Since dopamine controls muscle movement, this imbalance can lead to movement disorders that manifest as bruxism in the jaw muscles.
This drug-induced movement is categorized as dyskinesia, referring to abnormal, involuntary muscle movements. In the context of the face and jaw, these movements are sometimes referred to as orobuccolingual dyskinesias.
These symptoms often emerge quickly, sometimes within weeks of starting a new medication or adjusting the dosage. The jaw and face are susceptible because they are part of the extrapyramidal system, which regulates automatic motor functions.
Furthermore, some medications directly interfere with dopamine receptors, causing movement irregularities. This lack of proper motor regulation leads to hyperactivity or spasticity in the muscles responsible for chewing and jaw movement.
Specific Drug Classes That Trigger Bruxism
The most commonly reported culprits are drugs that modulate serotonin levels, particularly Selective Serotonin Reuptake Inhibitors (SSRIs). Specific SSRIs associated with jaw clenching and grinding include:
- Fluoxetine (Prozac)
- Sertraline (Zoloft)
- Paroxetine (Paxil)
- Citalopram (Celexa)
- Escitalopram (Lexapro)
Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs), such as venlafaxine (Effexor) and duloxetine (Cymbalta), also frequently appear in case reports. For many patients, bruxism symptoms may occur around three to four weeks after initiating treatment or increasing the dose.
Stimulants prescribed for conditions like Attention-Deficit/Hyperactivity Disorder (ADHD) are also known to trigger or exacerbate bruxism. These drugs, such as methylphenidate and amphetamine-based medications, increase alertness and focus by acting on the central nervous system. This action can promote muscle tension and jaw clenching, leading to the repetitive motor activity of grinding.
Antipsychotic medications, especially older generations, are linked to bruxism due to their strong inhibitory effects on dopamine receptors. This mechanism leads to extrapyramidal symptoms, including orofacial movements like jaw clenching. Even atypical antipsychotics, such as aripiprazole, have been cited as a potential cause. The movement disorder associated with these drugs can sometimes appear after medium- to long-term treatment.
Other neurological and pain medications have been linked to bruxism through varied mechanisms. This includes levodopa, used to treat Parkinson’s disease by increasing dopamine levels. Any drug that significantly alters the central regulation of motor pathways carries the potential risk of inducing teeth grinding.
Strategies for Managing Medication-Induced Bruxism
Patients who suspect their medication is causing teeth grinding should consult their prescribing physician. Management involves manipulating the dosage or switching the medication. A physician may first lower the dose of the causative drug to the minimum effective level.
If dose reduction is ineffective, the next step is often switching the patient to an alternative medication within the same class that has a lower reported incidence of bruxism.
If the drug must be continued, the physician may add a secondary medication to counteract the bruxism. Buspirone, a 5-HT1A partial agonist, is a documented successful intervention when added to an antidepressant regimen, as it helps restore the balance of dopamine and serotonin.
Other pharmacological options include short-term use of muscle relaxants before bedtime to reduce nocturnal clenching. For stimulant-induced bruxism, clonidine has shown success in alleviating symptoms. In severe cases, small injections of botulinum toxin into the masseter and temporalis muscles can reduce the grinding force.
Protective dental interventions are essential to prevent irreversible damage. A dentist can fabricate a custom-fitted occlusal splint or mouthguard, which acts as a physical barrier between the upper and lower teeth. Wearing this device protects the tooth surfaces from wear and absorbs the forces generated by clenching.