Bruxism | Why Do We Grind Our Teeth at Night and How Can We Stop It?

Sleep bruxism is a sleep-related movement disorder characterized by the involuntary clenching or grinding of teeth during sleep. It is not a dental problem at its core, but rather a neurological one. The activity originates from the central nervous system (CNS) and is often associated with sleep arousals, which are brief awakenings that naturally occur throughout the night. During these arousals, the brain sends signals that cause the rhythmic activation of the masticatory (chewing) muscles, leading to forceful contact between the teeth. The precise mechanism is complex, but it involves neurotransmitters—the chemical messengers that transmit signals between nerve cells. An imbalance in specific neurotransmitters, particularly dopamine, is thought to play a significant role in triggering these muscle contractions. Therefore, bruxism is understood as a centrally mediated phenomenon, where the brain, not the teeth or jaw, is the command center for the grinding activity.

Several factors can increase the likelihood and severity of sleep bruxism. Psychological stress and anxiety are primary contributors, as they heighten the body's overall state of arousal and muscle tension, which persists during sleep. Lifestyle choices also play a critical role; stimulants such as caffeine and alcohol are known to disrupt normal sleep architecture, leading to more frequent sleep arousals and a higher probability of bruxism episodes. Furthermore, there is a strong association between sleep bruxism and obstructive sleep apnea (OSA), a condition where breathing repeatedly stops and starts during sleep. In individuals with OSA, teeth grinding may be a subconscious response to an airway collapse, acting as a mechanism to tighten the upper airway muscles and restore airflow. Certain medications, particularly selective serotonin reuptake inhibitors (SSRIs) used to treat depression, can also induce or worsen bruxism as a side effect.

Diagnosing sleep bruxism involves a combination of clinical evaluation and, in some cases, objective measurement. A dentist is often the first to suspect the condition by observing characteristic signs of excessive tooth wear, flattened biting surfaces, and fractures in the enamel. Patients may also report symptoms like morning jaw pain, facial muscle fatigue, or tension headaches. A definitive diagnosis, however, is established through an overnight sleep study called polysomnography (PSG). During a PSG, sensors are placed on the head and jaw to record brain wave activity (EEG) and muscle activity (EMG). This allows clinicians to directly observe the rhythmic masticatory muscle activity characteristic of bruxism and correlate it with sleep stages and arousals, distinguishing it from other sleep disorders.

If left unmanaged, chronic sleep bruxism can lead to significant and irreversible consequences. The most direct impact is severe dental damage, including worn-down enamel, chipped or fractured teeth, and damage to dental restorations. This increases tooth sensitivity and the risk of decay. The persistent strain on the jaw muscles and temporomandibular joint (TMJ) can result in a painful condition known as temporomandibular disorder (TMD), characterized by jaw clicking, locking, and chronic facial pain. This discomfort can radiate to the neck and shoulders, and frequent tension-type headaches, especially upon waking, are a common complaint. The quality of sleep for both the individual and their bed partner can also be significantly diminished.

The primary and most widely recommended treatment for managing the consequences of sleep bruxism is the use of a custom-fitted occlusal splint, also known as a mouthguard or night guard. Fabricated by a dentist from a precise impression of the patient's teeth, this device is typically made of a hard acrylic material and is worn over the upper or lower teeth during sleep. The splint does not stop the grinding behavior itself; instead, it functions as a protective barrier. It absorbs the immense forces generated during clenching and grinding, preventing direct tooth-on-tooth contact and thereby protecting the enamel from wear and fracture. Additionally, by providing an ideal biting surface, the splint can help to deprogram the jaw muscles, reducing the intensity of contractions and alleviating muscle strain and pain. A custom-fit is essential for comfort, stability, and effectiveness, unlike over-the-counter options which can be ill-fitting.