A night guard, often referred to by dentists as an occlusal splint, is a custom-fitted medical device worn over the teeth, typically during sleep. Its primary function is to prevent damage caused by bruxism (involuntary teeth clenching or grinding) by creating a physical barrier between the upper and lower dental arches. These appliances are crafted from specialized dental-grade polymers, selected for long-term effectiveness and patient safety. The specific materials used determine the guard’s physical properties, such as its hardness, flexibility, and overall durability.
Core Materials Used in Custom Night Guards
Custom night guards primarily use two categories of polymers: thermosetting and thermoplastic. Thermosetting materials, such as various acrylic resins, are chemically cured during manufacturing, resulting in a permanent, rigid structure. These resins are often based on methyl methacrylate polymers, creating a strong, durable, and rigid plastic ideal for hard appliances.
In contrast, thermoplastic materials become soft and malleable when heated and then solidify into a stable shape upon cooling. Ethylene-Vinyl Acetate (EVA) is a common thermoplastic used for night guards, offering a flexible, rubber-like quality. Another material is Polyethylene Terephthalate Glycol (PETG), a strong, clear, and durable thermoplastic often incorporated into hybrid designs.
Material Hardness and Appliance Function
Hardness is a primary factor determining the night guard’s function and suitability. Soft night guards, typically made from flexible EVA, provide a comfortable, cushioned layer between the teeth. They are recommended for individuals with mild clenching habits or those new to wearing an appliance, as the pliable material offers greater initial comfort.
Hard night guards are fabricated from rigid acrylic resins and are designed for severe bruxism where intense grinding forces are present. This material is more durable, offering superior resistance to wear and providing occlusal stability to manage jaw joint issues. The rigidity of the hard acrylic prevents the patient from biting through the material and helps prevent further tooth damage.
For a balance of comfort and durability, a dual-laminate or hybrid guard is often prescribed, featuring a two-layer construction. This design combines a soft polymer on the interior surface, which rests against the teeth, with a hard, protective acrylic shell on the exterior. The soft inner layer promotes patient compliance, while the hard outer layer provides the necessary strength to withstand moderate to severe grinding forces.
Safety and Allergen Concerns
Material safety is a significant concern since night guards spend many hours in the mouth. Bisphenol A (BPA) is a chemical used to harden certain plastics. Reputable manufacturers have transitioned to using BPA-free materials to eliminate potential health risks associated with the chemical.
Phthalates, sometimes called plasticizers, are used to make plastics more flexible. Most professional dental materials are manufactured to be phthalate-free or use specific types deemed safe for intraoral use. Patients with known sensitivities should inquire about latex, although most custom night guards are made with latex-free polymers. Methyl methacrylate, used to create hard acrylic, is safe in the final cured appliance, as the chemical process eliminates the risk of toxic exposure.