Why It Can Hurt to Open Your Mouth After a Filling

Every now and then, we get a phone call from a patient who we saw a couple of days earlier. It goes something like this:

I had a filling done on my last tooth on the lower left three days ago. The filling and tooth feel fine, but it hurts to open my mouth, especially if I try to open wide.

We then go on to explain to our patient WHY this is the case and how it is normal.

So why is there pain with opening? There are two major factors.

Dental Injections for Lower Molars

In many cases, the pain while opening is from the injection. For lower molars, most dentists will do a nerve block, which involves a very long needle. See the photo below.

Dental shot for a lower tooth can cause pain while opening

A dental injection used to anesthetize a lower right molar. The needle in this photo is 1 and 1/4 inches long.

As can be seen in the above photo, a needle is inserted into the muscle in the back of the mouth. In most cases, for this injection, the needle goes in nearly to the hub, which would mean approximately 1 and 1/4 inches.

Here’s an analogy: feel your biceps and press it hard enough so you can feel the bone underneath. Then, imagine taking a needle, and inserting it through the biceps, approximately 1 inch, until the needle hits bone. Then, imagine doing that a second time. Don’t you think that moving the arm and using that muscle over the next several days would hurt?

The biceps analogy is very effective. Everyone understands that their arm would be sore. So, if you get an injection back there, or in some cases two, using that muscle in opening and closing can frequently result in pain for several days afterwards.

Your TMJ (Temporomandibular Joint)

The second source of pain while opening after a filling can be from the actual jaw joint, known as the TMJ (temporomandibular joint). This is the area at which your lower jaw bone connects to the base of the skull.

Your jaw joint was made for all of your daily activities – talking, smiling, eating normal foods, etc. The joint was not designed for “abnormal” tasks such as gum chewing, chewing on ice, or holding your mouth open for your dentist or hygienist to work.

photo of TMJ in a skull which can have pain after opening

The temporomandibular (TMJ) joint. Pain in this joint as well as the muscles and ligaments associated with the joint can occur after a dental visit.

Here’s another analogy: imagine standing on the tips of your toes. Now do this for 5 minute intervals several times, with perhaps 30 second breaks in between. Do this for approximately 45 minutes. Don’t you think that the next day, moving that muscle and the joints would be sore? This assumes you are not a ballet dancer.

A cleaning or a filling of moderate duration will be a lot like the above. Lots of straining to keep your mouth open, which can lead to fatigue and soreness in the muscles and joint. This can then result in pain and soreness on opening for several days.

Some Assumptions

We find that one or both of these reasons are responsible for the pain and soreness approximately 99% of the time. There are other circumstances which can include:

  • Infection of either a tooth or an infection at the injection site.
  • Pain after a surgical procedure such as a lower wisdom tooth extraction.
  • Aphthous ulcers (cold sores) in the back of the throat.
  • Upper respiratory infections, etc.
  • And many others.

Of course there can be other explanations. But for the vast majority of the time, the pain is either from the actual injection or in joint after being open for a prolonged period of time.

Connecticut Residents Grind Their Teeth Too!

A recent article in the Washington Post discussed teeth grinding and gave numbers suggesting that nearly half of the adult population in the Washington DC area either grind or clench their teeth.

The reporter apparently has never visited the stressed out state of Connecticut! Our experience in Orange treating thousands of patients has shown us that many Connecticut residents grind or clench too.

Teeth Grinding Photo on a Patient from Orange, CT

teeth grinding photo showing cracks and craze lines on front teeth

Craze lines or cracks on front teeth on one of our patients. This was from years of clenching at night.

The above photo is from a long time female patient in our office. She freely admits she is stressed – commuting into Manhattan a couple of days a week – as well as travelling across the U.S. for work. She has been grinding her teeth for many years. Even though we had recommended a nightguard, she did not follow our recommendation until she developed these cracks on her front teeth!

Bruxism (also known as teeth grinding)

Bruxism is defined as the involuntary grinding of your teeth, occurring most frequently while sleeping. According to the American Academy of Sleep Medicine, bruxism frequently occurs in highly determined people. And the research clearly shows that teeth grinding in adults is caused by and exacerbated by stress.

If untreated, bruxism can lead to:

cracked tooth from bruxism and grinding that needs a crown

A cracked tooth from years of nocturnal bruxism on our patient from Woodbridge. This tooth required a crown.

  • Visble wear on both the front and back teeth.
  • Broken or lost fillings.
  • Cracks so deep that the teeth require crowns and/or root canals. The photo to the right shows a crack that caused a tooth to need a crown.
  • Fractures leading to loss of one or more teeth so that dental implants are required.
  • Pain and/or dysfunction of the jaw muscles and temporomandibular joint (TMJ). These are collectively known as TMD (temporomandibular joint disorders).

In our office in Orange, we’ve seen it all – including all 5 findings in one patient!

wear of teeth from grinding and bruxism photo

Another Connecticut resident who grinds his teeth!

Treatment for Bruxism

Before we can even begin treatment, we need to establish that the clenching or grinding is still occurring. Many times patients will grind or clench their teeth for a period of time and then stop. But in most cases, the activity continues, especially for stressed out Connecticut residents.

NTI nightguard appliance for stressed Connecticut bruxers

NIT bruxism appliance for one of our patients.

The most common treatment option is a nightguard. As the name implies, a nightguard is custom fit protection for your teeth.

The nightguard to the left is one of many types we make. This is called an NTI.

One of the key mishaps that can occur is a “one size fits all” approach. There are many types of nightguards available, each for specific purposes. We spend a great deal of time analyzing our patient’s problems so that we make the correct type of appliance. Making the wrong type of nightguard can actually make things worse!

Once the appropriate appliance is made and used by the patient, the TMD symptoms will typically resolve, and the teeth are far less likely to break or fracture.

So, it doesn’t matter if you live in Connecticut or Washington DC. If you’re grinding or clenching, you need a nightguard. We are always available to discuss your symptoms and recommend the most appropriate solution.