A night guard creates a physical barrier between your upper and lower teeth. When you grind or clench during sleep, instead of your enamel meeting your opposing enamel, the guard absorbs and redistributes that force. A night guard reduces jaw muscle tension by allowing the jaw joints to be separated just enough to be more relaxed. This mechanism works on either arch. The difference between the two comes down to anatomy, comfort, and individual circumstance.
The Case for an Upper Night Guard
Upper guards are the more commonly prescribed option. Upper night guards fit over the top teeth and are often recommended by dentists, since many people find upper guards more comfortable because they do not interfere with the tongue. Your tongue rests naturally on the floor of your mouth — the lower arch. A lower guard sits directly where your tongue wants to be, which for many people creates a persistent awareness of the appliance throughout the night. An upper guard sits on the palate side, where the tongue does not rest, and many wearers find they stop noticing it within a few weeks.
Upper night guards also tend to produce less salivary flow than lower guards. Wearing a night guard often increases salivary production, particularly when the guard is placed on the lower teeth, while upper night guards tend to reduce the extra saliva production. This is a minor consideration for most people but can be a meaningful comfort factor for those who find excessive salivation disruptive to sleep.
The Case for a Lower Night Guard
The primary advantage of a lower guard is gag reflex management. For individuals with a sensitive gag reflex, upper night guards are more likely to trigger the gag reflex. Lower teeth guards are often preferred by people who have a sensitive gag reflex because they sit on the lower arch with no contact with the palate.
Lower night guards generally provide better protection for the lower teeth, as they typically experience more wear from grinding. In lateral grinding — where the jaw moves side to side — the lower teeth often take the primary abrasive force. Lower guards are also often preferred by people who have existing restorations on their upper teeth. If you have dental work on your upper teeth such as crowns or bridges, a lower guard protects those restorations by placing the guard on the opposing arch.
The Four Factors That Should Drive Your Decision
1. Your Gag Reflex Sensitivity
This is the most practical deciding factor for many people. Most people can protect their teeth with either an upper or a lower night guard, but the best choice depends on your mouth anatomy, gag reflex sensitivity, and comfort preferences. If you have a sensitive gag reflex, start with a lower guard. If your gag reflex is not a concern, upper is typically the more comfortable starting point.
2. Where Your Existing Dental Work Is Located
If you have crowns, bridges, veneers, or implants concentrated on one arch, the guard should generally go on the opposite arch to avoid fitting over restorations and to protect them from grinding contact.
3. Where You Notice the Most Wear or Pain
The arch showing the most strain or vulnerability is prioritized. If one arch shows significantly more enamel wear, that information should guide the placement decision.
4. Which Feels More Comfortable to You
Comfort is not a secondary consideration. If you are uncomfortable wearing your night guard, you probably will not want to use it. A guard you do not wear does nothing for your teeth, jaw, or sleep. Consistent wear over years is what produces the protective benefit of a night guard, and that consistency depends entirely on whether you can sleep with it comfortably.
What You Should Not Do: Wearing Both Simultaneously
Some people reason that if one guard protects one arch, two guards must provide double protection. This is incorrect. The discomfort of wearing both upper and lower guards can force your jaw's alignment to shift, leading to an unnatural bite. This creates extra strain on the jaw muscles — instead of relieving the symptoms of bruxism, it could make them worse. A well-fitted single arch guard provides enough protection to keep the teeth from touching without the risks of dual guards.
How to Make a Decision Without a Dentist
Many dentists begin with an upper guard because it is common and often easier to adapt to. In the absence of a dentist recommendation, upper is a reasonable default for most people — with lower being the right choice for anyone with gag sensitivity, significant upper arch dental work, or a personal preference based on prior appliance experience.
At DentalNightGuard.com, both upper and lower arch guards are available across all four guard types — soft, hard, hybrid, and multicolor. You select your preferred arch at checkout. If you try one and want to switch, replacement guards start from $99.
Order your custom night guard — upper or lower — from $99 at DentalNightGuard.com
