A mouth guard is a protective oral appliance designed to cover the teeth and surrounding soft tissues to prevent or mitigate injury. This device functions as a barrier against external impacts, manages internal forces from clenching and grinding, and can even assist with respiratory function during sleep. The effectiveness of a mouth guard is tied to its design, which is engineered to address the unique forces associated with its intended use. While they all appear similar, their underlying mechanisms for shock absorption, force distribution, and airway management are distinct.
Protection Against Physical Trauma
Mouth guards used in athletics, often called sports guards, function primarily through shock absorption and force distribution. These devices are typically made from resilient thermoplastic materials, such as ethylene-vinyl acetate (EVA). When a blow is delivered to the face or jaw, the mouth guard acts as a cushion to absorb and dissipate the energy of the impact.
The material spreads the concentrated force of a direct strike over a much larger surface area of the dental arch and jawbone. This action prevents the force from being solely focused on a single tooth, which would otherwise lead to a fracture or displacement. The guard also provides a buffer between the upper and lower teeth, helping to stabilize the jaw and reduce the risk of fractures or temporomandibular joint damage. The device creates a soft barrier that prevents the teeth from lacerating the soft tissues of the mouth, minimizing injuries to the lips, cheeks, and tongue.
Mechanism for Preventing Teeth Grinding
Occlusal guards, or night guards, are specialized appliances used to manage bruxism (involuntary grinding or clenching of teeth). These guards work by creating a physical separation between the upper and lower teeth, eliminating destructive contact. The device, often constructed from hard acrylic or a combination of soft and hard materials, prevents the direct abrasion and wear of tooth enamel that can lead to chipping and cracking.
The guard’s surface distributes the intense biting forces generated during clenching evenly across the entire dental arch. By providing a uniform platform, the guard encourages the jaw muscles to relax, reducing the hyperactivity of the masticatory muscles. Some designs, such as those that cover only the front teeth, work by eliminating posterior contact, which can significantly reduce the force generated by the jaw muscles. This relaxation is beneficial for alleviating symptoms like jaw soreness, headaches, and pain in the temporomandibular joint.
Function in Treating Sleep Disorders
Mouth guards designed for sleep disorders, specifically Mandibular Advancement Devices (MADs), employ a mechanical action to keep the airway open. These devices are custom-fitted to cover both the upper and lower teeth and are connected by hinges or other mechanisms. Their function is to physically hold the lower jaw, or mandible, in a slightly forward position while the user sleeps.
Repositioning the jaw forward mechanically pulls the base of the tongue and the surrounding soft tissues away from the back of the throat. This action increases the cross-sectional area of the upper airway, preventing the soft tissues from collapsing and obstructing the flow of air. By maintaining an open airway, MADs reduce the vibrations that cause snoring and treat mild to moderate Obstructive Sleep Apnea (OSA). This stabilization of the airway allows for continuous, unobstructed breathing, which improves oxygen flow.
Selecting the Appropriate Guard
Choosing the correct mouth guard is linked to its functional effectiveness, as the precision of the fit impacts the device’s ability to execute its specific mechanism. The three general categories are stock, boil-and-bite, and custom-made guards, each offering a different level of fit and protection. Stock guards offer the least protection due to their loose fit, which can interfere with speech and breathing.
Boil-and-bite versions improve the fit by conforming to the teeth after being softened in hot water, but they lack the uniform thickness and retention necessary for optimal performance. Custom-made guards, which are created from a precise dental impression, offer the highest degree of protection and comfort. This tailored fit ensures maximum shock absorption in sports guards and precise force distribution in bruxism guards. For sleep disorders, a custom fit is necessary to achieve the precise mandibular advancement required to maintain an open airway.