Night guard materials explained
Updated September 1, 2026 to clarify the materials used in modern night guards and separate material composition from broader safety, allergy and microplastics questions.
Pick up three different night guards and they may look remarkably similar: clear, smooth and shaped around the teeth. What you cannot see as easily is that they may be made from very different materials.
Some guards are soft and flexible. Others are rigid. Some combine multiple layers, while others are milled or 3D printed from entirely different dental polymers.
Night guards can be made from several types of dental polymers. Common examples include EVA thermoplastic, rigid copolyester, acrylic materials such as PMMA, and specialized photopolymer resins used in 3D printing. The material affects how a guard feels, flexes, wears and is manufactured—but there is no single material used for every night guard.
What are night guards usually made of?
Materials used for mouth guards and dental splints have evolved considerably.
Thermoformed appliances may use flexible or rigid thermoplastics. Traditional rigid occlusal splints have also been fabricated from acrylic-based materials, while newer digital workflows may use milled polymers or light-cured 3D-printing resins.
That means asking “What are night guards made of?” does not have a one-word answer.
EVA — ethylene-vinyl acetate
EVA is a flexible thermoplastic widely associated with mouth guards. It softens with heat, which makes it useful for thermoforming.
Depending on its formulation and thickness, EVA can be used in athletic mouth guards, soft night guards and layered appliances.
Copolyester
Copolyester can be manufactured as a clear, stiff thermoforming sheet and used for rigid dental splints and related appliances.
It behaves very differently from EVA: rather than providing a soft, compressible feel, it creates a comparatively rigid appliance.
Acrylic and PMMA
Acrylic materials have a long history in dentistry. PMMA—polymethyl methacrylate—is one well-established material used in rigid occlusal splints.
Acrylic splints may be fabricated using conventional processing methods or produced from pre-polymerized material using digital milling.
3D-printing resins
Some modern dental splints are fabricated from specialized light-cured photopolymer resins using technologies such as SLA or DLP printing.
These are not one universal material. Formulations, mechanical properties, intended uses and required post-processing vary by product.
What is EVA in a mouth guard?
EVA stands for ethylene-vinyl acetate.
It is a thermoplastic polymer valued for flexibility and its ability to be shaped with heat. The American Dental Association notes that EVA is commonly used in mouthguards, including heat-adapted boil-and-bite designs and custom athletic mouthguards.
In a night guard, EVA is particularly useful when a softer or more flexible construction is desired.
Thickness matters too. Two guards made from the same general polymer can feel and perform differently when their thickness, density, shape and design differ.
What is copolyester in a night guard?
Copolyester is another type of thermoplastic polymer, but its physical behavior can be quite different from soft EVA.
Clear copolyester sheets can be thermoformed over a dental model or printed model to create a rigid appliance. Keystone Industries' Pro-Form Splint material, for example, is identified in its safety documentation as a copolyester and is intended for applications including hard splints and retainers.
A rigid copolyester guard therefore should not be described simply as “hard plastic” or “acrylic-like” without identifying what it actually is.
Copolyester and acrylic are not the same material family.
Are hard night guards always acrylic?
No.
“Hard” describes a physical characteristic of the finished appliance—not a single chemical composition.
A rigid guard might be made from:
- A thermoformed rigid copolyester
- A conventional acrylic or PMMA-based material
- A milled dental polymer
- A specialized 3D-printed splint resin
That distinction is especially important when comparing products. If a manufacturer only says “hard night guard,” you still do not necessarily know what polymer was used.
What is acrylic or PMMA?
PMMA stands for polymethyl methacrylate, a rigid acrylic polymer with a long history in dental applications.
Contemporary occlusal splints can be made from conventionally processed PMMA or milled from pre-manufactured PMMA blocks or discs. Research comparing splint materials shows that material properties vary not only by chemistry but also by fabrication method.
For that broader discussion, see our Complete Guide to Night Guard Safety .
What are 3D-printed night guards made from?
A 3D-printed dental splint is generally produced from a photopolymer formulation designed to harden when exposed to a specific wavelength of light.
But “3D-printing resin” is a manufacturing category—not one standardized chemical recipe.
Different dental resins can contain different monomers, oligomers, photoinitiators and other formulation components. Their performance also depends on factors such as printing orientation, printer compatibility, washing and post-curing.
That is why it is more useful to identify the specific resin and its intended dental use than to make a blanket statement about all printed splints.
Material vs. manufacturing method
Thermoformed, milled and 3D printed are not materials
These words describe how the appliance is produced.
Thermoformed
A sheet of thermoplastic material is heated and formed over a physical or printed model of the teeth. EVA and copolyester are examples of materials that may be used in thermoforming.
Milled
A digital design is carved from a pre-manufactured block or disc. PMMA is one material that can be used in milled splints.
3D printed
The appliance is built layer by layer from a compatible dental photopolymer.
So two appliances can both be “custom night guards” while using entirely different materials and manufacturing workflows.
What is a dual-laminate night guard made from?
“Dual laminate” describes a layered construction, not a single polymer.
One material can be used on the tooth-facing side while another creates the exterior biting surface. The exact combination depends on the manufacturer.
Sentinel's current Hybrid Guard uses a soft EVA inner layer paired with a rigid copolyester outer layer.
This is different from a guard made from two layers of the same soft material and different again from an acrylic or printed appliance.
Soft vs. hard night guard materials
Flexible under pressure
Soft night guards commonly use flexible thermoplastics such as EVA.
The feel of the finished appliance depends on its formulation, thickness and design.
Maintains a firm biting surface
Hard night guards may use copolyester, PMMA/acrylic materials or certain dental resins.
“Hard” therefore tells you how the guard behaves, but not necessarily what it is made from.
If you're deciding between the two rather than researching the chemistry itself, see: Soft vs. Hard Night Guard Materials: How to Choose .
Night guard materials compared
| Material | Typical feel | How it may be made | Common use |
|---|---|---|---|
| EVA | Soft to flexible | Thermoformed | Soft guards, athletic mouthguards, layered appliances |
| Copolyester | Rigid / firm | Thermoformed | Hard splints, rigid guards, retainers and layered appliances |
| PMMA / acrylic | Rigid | Conventionally processed or milled | Occlusal splints and other removable dental appliances |
| Dental photopolymer resin | Varies by formulation | 3D printed and post-cured | Digitally manufactured splints and night guards |
This table is intentionally descriptive rather than ranking one material as universally “best.” Within each category, formulation and device design can vary substantially.
Are boil-and-bite guards made from different material than custom guards?
Not necessarily.
This is one of the biggest misconceptions in the old “custom vs. store-bought” comparison.
Many boil-and-bite mouthguards use heat-softening thermoplastics such as EVA. Custom appliances can also use EVA.
The difference between an over-the-counter appliance and a custom appliance may involve:
- How the guard is fitted
- Its dimensions and thickness
- The specific polymer formulation
- How the biting surface is designed
- How the appliance is fabricated and finished
So it is not accurate to assume that “EVA” means store-bought or that “custom” automatically identifies a particular polymer.
What about PVC, latex, BPA and phthalates?
Those are important composition and exposure questions, but they are different from the basic question of what material families are used to manufacture night guards.
A consumer should not assume that a mouth guard contains PVC, natural rubber latex, BPA, phthalates—or any other specific substance—simply because it is inexpensive, soft, hard, imported or sold over the counter.
The useful approach is to look for manufacturer-specific material disclosure.
For a closer look at BPA, BPS, phthalates, acrylics and other broader concerns, read: Are Night Guards Safe? What to Know About Materials and Long-Term Use .
Inside the Sentinel lab
What materials does Sentinel use?
Sentinel's current thermoformed night guard line uses EVA and copolyester in different combinations and thicknesses depending on the appliance.
Flexible EVA construction.
Rigid clear copolyester construction.
Approximately 1 mm EVA inner layer with a 1 mm copolyester outer layer.
Thicker rigid copolyester construction.
Sentinel's current hard guards are not acrylic night guards, and our current night guard line is not fabricated from 3D-printing resin.
For current manufacturer information and our material disclosures, visit: Sentinel Materials & Safety .
Which night guard material is best?
There is no universal winner for every person.
Material selection can depend on factors such as:
- Whether a softer or firmer feel is preferred
- The thickness of the appliance
- The design of the biting surface
- The amount and pattern of wear the appliance experiences
- How the appliance is manufactured
- Known material sensitivities
- The recommendation of the treating dentist or provider
Material is important, but it should be considered alongside fit and appliance design rather than treated as the only indicator of quality.
Different question?
Follow the part of the materials conversation you actually need
BPA, BPS, phthalates, acrylics and broader exposure questions belong in our safety guide.
Read the safety guide →Burning, itching, redness or soreness is a different question from material composition.
Read the allergy & irritation guide →We review particle release and the current evidence separately.
Read the microplastics guide →Frequently asked questions about night guard materials
What are night guards made of?
Night guards can be made from several dental polymers, including flexible thermoplastics such as EVA, rigid thermoformed materials such as copolyester, acrylic materials including PMMA, and specialized resins used to 3D print dental splints.
What is EVA material in a night guard?
EVA stands for ethylene-vinyl acetate. It is a flexible thermoplastic that can be shaped with heat and is widely used in mouthguards and other protective dental appliances.
Are hard night guards made from acrylic?
Some are, but not all. Hard guards may be made from acrylic or PMMA, rigid thermoformed copolyester, milled dental polymers or specialized 3D-printing resins. “Hard” describes the appliance's rigidity rather than identifying one material.
Is copolyester the same as acrylic?
No. Copolyester is a thermoplastic polyester material, while common dental acrylics such as PMMA belong to a different polymer family.
Are boil-and-bite mouthguards made from EVA?
Many are made from heat-softening thermoplastics such as EVA, but formulations vary by manufacturer. EVA is also used in some professionally fabricated custom mouthguards, so it is not exclusive to over-the-counter products.
Are 3D-printed night guards made from resin?
3D-printed dental splints are generally fabricated from light-cured photopolymer resin formulations designed for compatible dental printing systems. The exact chemistry and required processing vary by product.
Is there a plastic-free night guard?
Most modern night guards and occlusal splints are polymer-based appliances. If a product is marketed as “plastic-free” or “natural,” check the manufacturer's exact material disclosure rather than assuming what the label means.
What is the best night guard material?
There is no single material that is best for everyone. The right choice depends on the desired rigidity, thickness, appliance design, wear pattern, fit, individual sensitivities and professional recommendations.
What are Sentinel night guards made from?
Sentinel's current night guard line uses EVA, rigid copolyester or a layered combination of the two depending on the model. Our current hard night guards are not conventional acrylic splints.
The bottom line
Night guards are not made from one universal material.
EVA is commonly used when flexibility is desired. Copolyester can create a rigid thermoformed appliance. PMMA and other acrylic materials have a long history in rigid dental splints. And specialized photopolymer resins have expanded the options available through digital 3D-printing workflows.
The important question is not simply whether a guard is “plastic,” “soft,” “hard,” “custom” or “store-bought.” It is what specific material was used, how the appliance was manufactured, and whether that combination is appropriate for its intended use.
This article is for educational purposes only. Material selection for an individual dental appliance should take into account the specific product, its intended use, individual dental needs and guidance from a qualified dental professional when appropriate.