A night guard is a protective dental appliance, typically worn during sleep, but it cannot straighten your teeth. Unlike orthodontic devices, a night guard is designed to stabilize the existing position of your teeth and jaw, not to apply the continuous, directional forces required to change their alignment. The appliance acts as a barrier, cushioning the dental arches from damaging forces.
The Primary Function of a Night Guard
The primary purpose of a night guard, also known as an occlusal guard or splint, is to manage the effects of bruxism, which is the involuntary clenching or grinding of the teeth. This nocturnal habit exerts tremendous pressure on the teeth, jaw joints, and surrounding muscles, leading to painful symptoms and dental damage. The guard functions by creating a physical barrier between the upper and lower teeth, preventing direct tooth-on-tooth contact.
By creating this cushion, the appliance absorbs and redistributes the intense forces generated by grinding and clenching, protecting the enamel from excessive wear, chipping, and fractures. This protective action is important for preserving existing dental restorations, such as crowns and fillings. A custom-fitted guard also helps stabilize the jaw and reduce strain on the temporomandibular joint (TMJ), alleviating associated symptoms like jaw pain, muscle soreness, and headaches. The goal of a night guard is protective and stabilizing, aiming to mitigate damage from parafunctional habits.
Orthodontic Movement and Stabilization
Correcting misaligned teeth requires a complex biological process known as alveolar bone remodeling, which a night guard is not designed to achieve. Tooth movement occurs when a continuous, light force is applied using devices like braces or clear aligners. This consistent pressure stimulates a response in the periodontal ligament (PDL), the tissue that anchors the tooth to the jawbone.
On the side of the tooth where pressure is applied, specialized cells called osteoclasts break down the alveolar bone tissue (resorption). Simultaneously, on the opposite side where tension is created, osteoblasts build new bone tissue (formation). This controlled cycle of bone breakdown and rebuild allows the tooth to safely move through the jawbone into a new position. Orthodontic appliances are engineered to apply precise force systems to regulate the speed and direction of tooth movement.
A night guard is fundamentally a passive appliance that covers the chewing surfaces of the teeth to distribute forces broadly and evenly, promoting stability rather than directional movement. The material and design are not intended to generate the sustained, controlled pressure necessary to initiate the cellular activity required for bone remodeling. Therefore, while an orthodontic appliance is an active device for repositioning teeth, a night guard is a passive one for protection and stabilization.
Can Night Guards Cause Unintended Tooth Movement?
While night guards cannot straighten teeth, they can cause unintended tooth movement if they are ill-fitting or improperly designed. When a guard does not fit correctly, it may place uneven, localized pressure on certain teeth rather than distributing the force uniformly across the dental arch. This non-uniform stress can act as an unintended orthodontic force, gradually pushing teeth out of alignment over time.
Over-the-counter (OTC) night guards, particularly “boil-and-bite” models, are prone to poor fit because they are not tailored to the individual contours of a person’s mouth. An appliance that is too bulky, warped, or worn down can create gaps or leverage points that encourage shifting or alter the bite relationship. This uneven pressure can lead to orthodontic relapse, where previously straightened teeth begin to move back toward their original positions.
To prevent this negative outcome, it is recommended to use a custom-fitted night guard made from a professional impression of your teeth. A guard designed by a dental professional ensures a snug, secure fit that distributes bite forces evenly, minimizing the risk of unwanted shifting and maintaining the stability of your existing alignment. Regular dental check-ups are also important to monitor the fit of the guard and ensure it functions purely as a protective barrier.