How Does a Dental Night Guard Work?
Updated: August 2025
A dental night guard — also called an occlusal guard — is a custom-fitted oral appliance worn while you sleep to protect against bruxism (teeth grinding and clenching). According to the Mayo Clinic, untreated bruxism can lead to headaches, jaw disorders, and serious tooth damage — which is why prevention is so important.
Its main function is simple: create a barrier between your upper and lower teeth, reducing pressure on your jaw and preventing tooth damage.
👉 This article is part of our [Complete Guide to Custom Night Guards], where we cover costs, types, and what to expect.
The Core Functions of a Night Guard
1. Cushions Grinding Forces
When you clench or grind, the guard absorbs and redistributes that pressure, protecting your teeth, jaw, and surrounding muscles.
2. Prevents Tooth-on-Tooth Contact
The plastic barrier keeps enamel from wearing down, helping prevent chips, fractures, and sensitivity.
3. Supports Jaw Alignment
Custom guards are shaped to your bite, which can reduce strain on the temporomandibular joint (TMJ) and ease jaw pain or stiffness.
4. Promotes Muscle Relaxation
By separating the teeth, a guard interrupts the grinding reflex and allows jaw muscles to rest overnight.
Does Grinding on the Guard Still Damage Teeth?
No — the whole point of a night guard is to sacrifice itself instead of your enamel. The guard absorbs the force, which means over time it will show wear. That’s a good thing — it means your teeth are being protected. When your guard becomes cracked or worn, it’s time for a replacement, but your smile stays safe.
👉 Related: [How Long Do Dental Night Guards Last?]
Upper vs. Lower Night Guards
Both upper and lower guards prevent grinding damage, but the choice often comes down to comfort and preference:
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Upper Guard: Most commonly prescribed, stable fit, less likely to be chewed through.
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Lower Guard: Slimmer and less visible; good for those with a gag reflex or extensive dental work on upper teeth.
Either way, the protection is the same.
👉 Related: [Which Night Guard Type Should I Choose?]
What Night Guards Are Made From
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Soft EVA – flexible, cushioning; best for light grinders.
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Hard Copolyester – rigid, durable; for heavy grinding/TMJ.
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Dual Laminate – EVA inner + copolyester outer; balanced option for moderate grinders.
Ordering a Custom Night Guard Online
At Sentinel, the process is simple:
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Order your kit – choose thickness (1mm, 2mm, 3mm depending on grinding severity).
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Take your dental impression – quick, at-home kit included.
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Mail it back – prepaid shipping label included.
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Receive your guard – crafted in 3–4 business days at our U.S. lab.
FAQ's
❓ Do dental night guards work immediately?
Most people adjust to wearing a night guard within a few nights, and it begins protecting your teeth right away. However, relief from jaw pain, headaches, or TMJ tension can take a few weeks as your muscles adapt and the guard reduces strain on the joint. Consistent use is key to seeing full results.
❓ Can night guards stop teeth grinding?
No — night guards don’t stop the grinding or clenching habit itself. Instead, they act as a protective barrier, absorbing and redistributing pressure so your teeth, enamel, and jaw joints aren’t damaged by the grinding forces. Over time, this helps prevent chips, fractures, sensitivity, and costly dental repairs.
❓ How do I know if my night guard is working?
Signs your night guard is doing its job include:
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Fewer morning headaches or jaw aches.
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Reduced tooth sensitivity.
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Your guard showing visible wear or grooves — instead of your teeth.
If your symptoms don’t improve after consistent use, or if your guard feels uncomfortable, consult your dentist or consider a replacement.
Final Thoughts
A night guard doesn’t cure bruxism, but it prevents damage and reduces symptoms like jaw pain, headaches, and tooth wear. Think of it as an investment in protecting your teeth for the long run.
💚 Since 2012, Sentinel has crafted thousands of custom-fit night guards in our FDA-registered U.S. lab — at a fraction of the dentist’s price.