A mouthguard is a removable dental device designed to cover the teeth and surrounding tissues, serving as a protective barrier against impact or the forces of involuntary grinding and clenching. While custom-fitted versions are generally provided by a dental professional, stock and “boil-and-bite” appliances are also widely available. The primary concern is whether wearing a mouthguard, such as a night guard or a sports guard, can permanently alter occlusion, or bite. When properly designed and monitored, a mouthguard should not cause a lasting change to how the upper and lower teeth meet. Permanent structural changes are typically the result of improper use or an ill-fitting appliance.
Understanding Temporary vs. Permanent Bite Shifts
The feeling that your bite is “off” immediately after removing a night guard is a common, temporary phenomenon. This sensation relates to proprioception, the body’s sense of its own position, including the jaw. Jaw muscles and ligaments temporarily adjust to the appliance’s thickness, which separates the upper and lower teeth.
When the guard is removed, it takes a short period for the muscles to relax and for the jaw to return to its natural resting position, often within minutes to a couple of hours. This is an expected, harmless response where the muscle memory of the jaw system is simply resetting. A true permanent bite change, known as malocclusion, involves an actual movement or shifting of the teeth or a remodeling of the jaw joint.
One specific type of permanent change that can occur is a posterior open bite, where the back teeth no longer touch when the mouth is closed. This structural shift happens because the teeth are dynamic and can erupt or shift out of the bone if they are not consistently in contact with an opposing force. This kind of change represents a true alteration of the patient’s dental structure and requires dental intervention to correct.
Factors That Lead to Unintended Bite Changes
The most frequent cause of an unintended bite alteration is the use of a poorly fitted or generic dental appliance. Over-the-counter guards, such as stock or boil-and-bite versions, often lack the precision to distribute force evenly. These ill-fitting devices can exert uneven pressure, which, over an extended period, can physically push teeth and lead to misalignment or shifting.
The duration of use is also a significant factor in the risk of permanent changes, especially for individuals using a guard long-term without professional oversight. When a guard is worn beyond the prescribed time, the constant separation of the teeth can encourage them to move into a new position. Routine dental check-ups are necessary to ensure the appliance continues to fit correctly and is not causing any unwanted tooth movement.
Another risk is associated with certain materials, particularly softer, non-rigid guards used for bruxism therapy over many years. If the back teeth are not consistently loaded with biting forces, they may attempt to erupt out of the jawbone. This phenomenon, called supra-eruption, can ultimately lead to a posterior open bite. Using a guard that only covers the front teeth and separates the back teeth poses a similar risk, as the unopposed back teeth can shift out of position.
Different Mouthguard Types and Their Intended Effects
Mouthguards are categorized based on their intended function, and their effect on the bite varies significantly by type. Sports guards are thick, resilient appliances designed for short-term wear during athletic activities to absorb impact and prevent dental trauma. Since they are used only briefly, they pose minimal risk of causing a permanent bite change, provided they are not worn for extended periods or overnight.
Night guards, also known as occlusal splints, are designed to protect the teeth, muscles, and jaw joint from the damaging forces of clenching and grinding (bruxism). Custom-fitted night guards stabilize the bite and reduce muscle strain. While they can lead to temporary changes, they are stable and safe for long-term use when monitored. Even a custom splint must be regularly checked because the jaw and teeth naturally change over time.
Orthodontic appliances are explicitly designed to change the bite permanently. Retainers, for example, hold the teeth in a new, corrected position following orthodontic treatment, maintaining a specific bite. Other appliances actively move the teeth or reposition the lower jaw to treat conditions like temporomandibular joint disorders or sleep apnea. In these cases, a controlled, permanent bite change is the primary goal.
When to Consult a Dental Professional
If you suspect that your bite has changed while using a mouthguard, seek a professional evaluation promptly. Warning signs include chronic discomfort when chewing or biting down. Difficulty bringing your upper and lower front teeth together, or feeling like only your back teeth are making contact, may signal the onset of an open bite.
Persistent jaw pain, headaches upon waking, or a sense that your bite feels uneven also indicate the appliance may be causing unintended changes. The dentist will assess the fit of your mouthguard, check for signs of uneven pressure, and monitor the stability of your occlusion. A professional can adjust the current guard or recommend a new, properly fabricated custom appliance.