The difference between teeth grinding and teeth clenching

Sleep bruxism (or teeth grinding or clenching during sleep) is a common condition that affects approximately 1 in 10 adults. Since this is a subconscious behavior, people who do this in their sleep often have no idea if they grind or clench their teeth. However, there are distinct differences in symptoms between teeth clenching and teeth grinding.

Teeth grinding vs. teeth clenching – what’s the difference?

Teeth grinding and clenching are both manifestations of bruxism. The difference between the two lies in the chewing muscle movements that happen during the bruxism episode.

When researchers examined the jaw muscles during a bruxism episode, they found three distinct types of movements:

  1. Phasic (rhythmic teeth grinding)
  2. Tonic episodes (teeth clenching)
  3. Mixed episodes (a mix of phasic and tonic)

Teeth grinding produces a characteristic sound while teeth clenching tends to be silent.

In teeth grinding (phasic) episodes, the jaw muscles are moving your jaws and teeth side-to-side or front-to-back rhythmically. This causes your upper and lower teeth to grind against each other, producing the characteristic teeth grinding movement.

This is also often accompanied by the squeaky, cracking, crunching sound that is created when two hard objects (your teeth) rub against each other. Most teeth grinders have never heard this sound before as they are sound asleep when it happens. But their partners, or whomever is sleeping next to them, will hear these loud teeth grinding sounds. The strange noise can be quite unsettling, especially if they didn’t know where the sound came from.

On the other hand, in teeth clenching, your jaw muscles are contracted (tensed) and stay that way throughout the duration of the episode, which can be as short as 3 seconds, or can last up to a few minutes. The whole time you are clenching your teeth, your upper and lower teeth are pressed against each other with a force than can be up to 10x the force of chewing.

Despite the immense amount of force involved, teeth clenching does not produce the same sound characteristic as teeth grinding. They tend to be silent, and your partner probably won’t notice any sound while you’re sleeping. However, those who unconsciously clench their teeth in their sleep tend to report substantial muscle soreness, pain, and headaches in the morning. It has been hypothesized that these painful symptoms are a result of the muscles being in a tense, contracted position for a long period of time during the night.

Why does it matter?

It is believed that teeth grinding causes more damage to your teeth (visible tooth wear, chipped teeth, teeth sensitivities, early failures of implants, prosthesis etc.) than clenching as clenching causes more damage to the musculature and temporomandibular joints.

One study from Japan showed a significant correlation between teeth grinding frequency and duration (especially ones that produce teeth grinding sounds) with extreme tooth wear, to the point where the dentin layer is exposed. Simply put, those who frequently grind loudly – as reported by their partner or family member – are more likely to see significant wear to their teeth. This is especially concerning not only because of its cosmetic effect, but also because extreme tooth wear can cause teeth sensitivities, pain (if the nerve-rich layer of the teeth become exposed as a result), as well as long-term structural damage.

The same study also showed that study participants who experienced sore or painful jaw muscles in the morning tend to clench for longer periods of time. Other studies have seen similar results where extreme teeth grinders, despite having longer and more frequent bruxism episodes at night, do not experience any painful symptoms. On the other hand, those with shorter duration of teeth clenching complain of noticeable facial pain and headaches in the morning. This lends credence to the hypothesis that teeth grinding and clenching might result in different symptoms.

How do I know if I’m a grinder or a clencher?

Well, to be 100% sure, you have to undergo a sleep study in a sleep lab, or use a portable EMG device that can measure your jaw muscle movements.

But, you can also deduce if you’re a teeth grinder or a teeth clencher from your symptoms.

Teeth grinders are more likely to learn about their condition from their dentists, who might notice :

  • excessive tooth wear
  • increased tooth sensitivity
  • fractured or chipped teeth
  • early failures of prosthesis (implants, crowns, etc.)

In addition, teeth grinding is more likely to produce audible sound (grinding noise) compared to clenching. So if a bed partner or a family member / friend has heard teeth grinding sound while you are sleeping, it’s very likely that you are a teeth grinder and not a clencher.

One thing to note: tooth wear is accelerated by acidic diet. So if you know you’re a severe teeth grinder, you should probably also take a look at your diet. Try to avoid acidic food, drink plenty of water and rinse your mouth after eating.

The damage to teeth caused by teeth grinding or clenching
Source: Jonsgar C, Hordvik PA, Berge ME, Johansson AK, Svensson P, Johansson A. Sleep bruxism in individuals with and without attrition-type tooth wear: An exploratory matched case-control electromyographic study. J Dent. 2015;43(12):1504-1510.

Now, if your symptoms consist of muscle soreness, facial pain, earaches, and headaches that are worst in the morning, then you are most likely a clencher.

Clenchers tend to have the following symptoms:

  • Pain or fatigue of the jaw muscles
  • Tenderness while chewing
  • Headaches – usually in the temples
  • Tinnitus or ear aches
  • Sore neck

Now that you’ve learned the difference in symptoms between teeth grinding and teeth clenching, you should be able to identify which type you are.

Other relevant articles you might want to check out