What are Night Guards?
Night guards (also called occlusal guards, splints and bruxing appliances) are made of rigid or semi-rigid materials like laboratory-processed acrylic. They are generally made to be worn over the biting surfaces of either the upper or lower teeth, and are easily inserted and removed by the patient.
Night guards accomplish three main functions:
- Evenly distribute bite forces to protect the teeth from stresses that can crack or wear them abnormally
- Protect the temporomandibular joints (TMJs) from excessive bite stress that can produce pain, damage to the jaw joint components, and dysfunction
- Reduce the heavy forces generated by the jaw-closing muscles.
Night guards can prevent damage to teeth and dental restorations, saving the time, expense and potential discomfort of fixing problems that result from clenching the jaw muscles and grinding the teeth (bruxism). They can also be used to treat patients with temporomandibular joint (TMJ) dysfunction and pain (TMD); and people suffering from jaw/facial muscle discomfort and fatigue (myalgia). It is important to understand how night guards work, to decide whether you are a patient who might benefit from the use of night guards.
In the absence of TMJ problems (TMD) or jaw/facial muscle myalgia, is important to establish that a patient has a current bruxism or jaw clenching habit before prescribing a night guard. Patients who have undergone episodes of clenching or grinding their teeth in the past may have teeth that exhibit significant signs of wear. However, they may no longer have the habit. Prescribing a night guard for such a patient may not be helpful, incurring unnecessary cost for the patient and their dental plan.
What else causes tooth wear?
Bruxism isn’t the only cause of tooth wear (attrition). Malocclusion and factitious habits can also cause tooth wear.
Malocclusion is a term for teeth that are poorly aligned don’t mesh properly. Poorly aligned teeth can wear at an accelerated rate even under normal function. If you have this problem, ask your dentist if orthodontic treatment might be an option. Learn more about malocclusion on ToothIQ.com.
Factitious habits is a dental term for using your teeth for purposes other than chewing food. Repeatedly chewing on hard or abrasive objects, biting your nails, grinding sunflower seed husks and other habits like these can accelerate the formation of flattened planes (wear facets) and chips on your teeth. Night guards won’t help with this, but you may need the chipped or worn teeth repaired with bonding, fillings, or crowns. You should try to quit the habit to avoid the re-occurrence of the resulting dental problems.
The process of creating Night Guards
Here are the usual steps a dentist takes to create a night guard:
- The dentist will sometimes have you rest your front teeth on a tongue depressor for a few moments to de-program your jaw closing muscles and allow them to relax. He/she will be able to tell when the muscles are at rest, because it will be possible for the dentist to move your lower jaw for you.
- Once the dentist can manipulate your lower jaw, they will gently position it into a stable jaw joint position known as centric relation. In this position, they will use any of several materials (e.g. wax, silicone, etc.) to record the position. The selected material will record the position of the upper and lower teeth (interocclusal record), when your jaw is positioned in the centric relation position.
- Next, impressions will be made of your teeth, and a dental stone material resembling wet concrete is poured into them. When the dental stone hardens, it produces a very accurate replica of your upper and lower teeth, on which the night guard will be made.
- The stone casts of your teeth will be mounted onto a jaw simulation tool called an articulator, with the teeth positioned correctly using the interocclusal record.
- A lab technician will use wax to build the night guard on the stone casts. When complete, the wax model will be surrounded with plaster (investing) in such a way that a two-piece mold of the night guard is formed. The wax is then melted out, and a heat-processed acrylic is placed in the mold and allowed to harden.
- After trimming any sharp edges and polishing the night guard, it is ready to be delivered to the patient.
- The dentist will make any adjustments to the night guard that may be necessary, and will provide you with instructions on wearing and caring for the appliance. You may or may not require follow-up appointments to adjust the night guard further, depending on the goals of treatment and other factors.
Some advantages and benefits of Night Guards
Night guards protect the teeth by evenly distributing the bite forces, and by introducing a sacrificial element for absorption of the bite stress besides tooth structure. They protect the jaw joints (TMJs) from damage, and the jaw muscles from tenderness and pain by reducing the amount of force the closing muscles are able to generate.
How do night guards reduce muscle forces?
If your jaw joints don’t already hurt, and your front teeth are not heavily restored with fillings, crowns, etc., you can try this simple experiment:
Place a tongue depressor (sucker stick) between your upper front four (incisor) teeth. Make sure that only your four front upper and lower teeth (incisors) can touch the stick. Slowly and carefully, start to contract your jaw muscles to squeeze down on the stick. Stop immediately if you feel any pain. Now remove the stick and close your teeth fully together. Again begin to clench your jaw muscles. You should notice that you can develop a lot more muscle contraction force without the stick in between your front teeth than you can with it in there. It may help to place your fingers over the muscles at the corners of your jaws—you’ll be able to feel more of them contracting when your back teeth can touch.
What you have just observed is a phenomenon called proprioception (or nociception), a feedback mechanism from the nerves that surround your incisor teeth, to your brain, that tells your brain not to let your jaw muscles squeeze too hard. A similar feedback mechanism is what gives you the ability to stand up and maintain your balance, only that proprioception system involves your leg muscles and nerves.
Night guards help to reduce muscle contraction forces by placing the front teeth in function the way you just did.
Potential disadvantages and risks of Night Guards
- Night guards can be relatively expensive; however, they are usually less expensive than even one crown, and can protect teeth from fracturing or wearing excessively.
- Some people find it difficult to adjust to the bulk of an night guard in the mouth; however, they can usually be adjusted enough to make them comfortable.
- People who wear night guards during waking hours may notice alterations in speech while wearing the appliance, especially at first. If yours will be worn primarily while you’re awake, it may be a good idea to have one made that covers the lower teeth. That way, speaking sounds that involve the tongue will be less affected.
- Anterior bite plates (a type of night guard that only covers the front teeth) can produce pain in the jaw joints, and are contraindicated in patients already suffering from joint pain or dysfunction. Anterior bite plates are generally indicated only for reducing tenderness in the jaw closing muscles. Even in patients who find relief with anterior bite plates, the device should not be worn more than eight hours per day, or the unsupported back teeth in each jaw may begin to move toward each other (erupt). Then, when the bite plate is out, the front teeth may no longer touch.
- Night guards may temporarily increase saliva flow when they are first placed into the mouth. This is because your brain thinks they’re food, and initiates the digestive process. This process is generally short-lived, however, and should not impede the ability to wear the device.
- Pets (dogs in particular) are attracted to night guards, and will quickly destroy them if they get ahold of them.
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