A night guard (occlusal splint) is a dental appliance worn primarily at night to cover the biting surfaces of the teeth. Its main purpose is to manage symptoms of bruxism (involuntary clenching or grinding) and alleviate discomfort associated with temporomandibular joint (TMJ) disorders. By creating a protective barrier, the guard prevents excessive tooth wear and distributes clenching forces evenly across the jaw. A common concern is whether this device, meant for protection, can inadvertently lead to a permanent alteration of dental alignment or bite.
Custom vs. Over-the-Counter Devices
The risk of an unwanted bite change depends heavily on the type of night guard used. Custom-made occlusal splints, provided by a dentist, fit the user’s dental arch precisely. The construction involves taking a detailed impression or digital scan, which ensures the appliance maintains the existing, stable relationship between the upper and lower jaws. This precise, full-coverage design protects the teeth without forcing the jaw into an unnatural position.
Over-the-counter (OTC) options, such as boil-and-bite or one-size-fits-all guards, carry a significantly higher risk of causing dental shifts. These generic appliances are not based on unique dental anatomy, resulting in an imprecise fit. An ill-fitting guard may create uneven pressure points or inadvertently guide the lower jaw into an unstable position. This lack of customization is the primary factor that can initiate unwanted muscular or tooth movement.
A custom guard ensures balanced contact across all teeth, which is essential for maintaining the current bite. Without this even distribution, the appliance can act like a low-grade orthodontic device, applying pressure that slowly moves teeth out of position. Choosing a professionally fabricated device, though more costly, helps mitigate the potential for long-term occlusal changes.
The Mechanism of Unwanted Occlusal Shifts
An improper night guard can alter the bite through two main processes: dental eruption and mandibular repositioning. Dental eruption (supra-eruption) occurs when a tooth lacks the normal opposing contact to hold it in place. If a night guard only covers a partial section of one dental arch, the opposing teeth may slowly migrate out of their socket over time, attempting to find a new point of contact. This unintended movement can lead to an open bite, where the front or back teeth no longer meet when the jaw is closed.
The second mechanism involves the muscles and ligaments controlling jaw movement. An appliance that forces the lower jaw into a position different from its natural resting point can cause the jaw system to adapt to that new alignment. This is often seen with ill-fitting or poorly designed appliances that have a thick or uneven biting surface. The constant, subtle strain on the temporomandibular joint and associated muscles can result in chronic misalignment when the guard is removed.
Even a full-coverage guard can cause issues if its surface is not perfectly adjusted to allow for simultaneous, even contact across all teeth. Uneven contacts can lead to localized, intrusive forces on some teeth while allowing others to slightly over-erupt. Since the bone surrounding teeth is constantly remodeling, even minor, consistent pressure from an appliance can cause slow, subtle, and sometimes permanent changes to the bite.
Monitoring Usage and Mitigating Risk
To safely use a night guard, professional monitoring is necessary, even with a custom appliance. Regular check-ups ensure the guard maintains its proper fit and that the bite remains stable. The dentist can assess the appliance for signs of wear and make small adjustments to the biting surface to prevent uneven pressure points. Any new night guard, even a custom one, often requires follow-up appointments for fine-tuning the occlusion.
Users should be vigilant for specific warning signs suggesting a bite change is occurring. These include persistent jaw pain, difficulty closing the mouth completely after removing the guard, or a sensation that the teeth no longer fit together. New or recurring headaches can also indicate the appliance is causing muscle strain rather than relief. If the teeth feel “different” or if there is a newly developed lisp, the guard should be evaluated promptly.
In most cases, early changes to the bite are reversible simply by discontinuing the use of the improper appliance, as the teeth and jaw muscles can return to their original position. If an improper guard is worn regularly for many months or years without professional supervision, however, the resulting occlusal shifts can become permanent. Addressing these signs quickly allows a dentist to adjust or replace the guard before the damage requires more extensive treatments, such as orthodontics.