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Canker Sores | Mouth Ulcers
and Treatment

I don’t have to tell a denture wearer just how painful a canker sore or mouth ulcer can be.

Man with Canker Sore or Mouth Ulcer from Denture by Dr Dean Lloyd

First up, what is a canker sore or mouth ulcer?

Well, the easiest way to describe such a lesion is to say that a canker sore or mouth ulcer is the irritation, swelling, eruption and eventual dying of the oral mucosa traumatized by either:

1. A denture that moves, chaffs, or rubs against the tissue for a prolonged period of time. (Fig. 1)

Canker Sore or Mouth Ulcer by Dr Dean Lloyd

Fig. 1:  Mouth Ulcers are extremely sore when consistently irritated by a denture base

2. Or, it's due to incorrectly set false teeth and, as a result, the patient consistently bites their cheek! (Fig. 2 & 3)

Cheek-biting caused by incorrectly made dentures - by Dr Dean Lloyd

Fig. 2:  Most of us have bitten our cheeks before. But when denture teeth consistently "nip" your cheek - it becomes very annoying.

Your dentist may be able to fix your  Denture cheek biting within around 4 minutes! 

Here is a brief explanation of maybe why your denture teeth bite your cheeks.


The teeth of the upper denture are set "on top of" or "directly in line with" those of the lower teeth. (See fig. 3) As can be seen, by the image, your cheek is caught between the upper and lower denture teeth as you chew.

You can see, in fig. 4, how your upper denture's teeth push your cheek out of the way as your mouth chews up and down. This is the correct setting for teeth. 

Incorrectly Set Denture Teeth by Dr Dean Lloyd

Fig. 3 Incorrectly set teeth can cause cheek biting 

Correctly Set Denture Teeth by Dr Dean Lloyd

Fig. 4 Correctly set teeth push the cheek out of the way like a curtain

There are many reasons why your dentures rub, chaff, or cause this type of Canker sore or Ulceration.

  • In the case of cheek biting, the good news is that your Dentist should know how to fix this annoyance within around 4 minutes!

  • In the case of a loose denture, a reline is your best solution. 

  • And, in the case of rubbing or chaffing, perhaps an ease (reduction of the plastic base) may do the job.


There are three things you can do to help your canker sore or mouth ulcer situation.


Firstly, and if possible, remove your dentures immediately. DO NOT Persevere! "I know, I know. Your Dental Practitioner may have told you to persevere but think about this. If you want to get rid of those denture-related ulcers, you will have to remove the Cause." 

Secondly, your next step is to mix a teaspoon or two of salt in a glass of water, then rinse your mouth two to three times per day. This will start the repair process. There are, of course, other topical medications that will relieve the pain, but in this case, you may have to speak to your GP, as these ointments may interfere with other medications you are taking. Over the years I have found that the salt rinse works quite well so, definitely give that a try. 

Thirdly, immediately make an appointment with your local dentist. He or she will test your denture plate to find what's causing the rubbing, and then they may ease your denture plate in the area that is too high.     

It is critically important to fix the chaffing, rubbing, or loose denture, which is causing the canker sore or mouth ulcer in the first place. This may be a simple easing of the acrylic, a reline to tighten the denture, or even a more complicated procedure of re-arranging the teeth into the correct position. 

In the case of a Partial Denture, your dentist may need to adjust the retaining clasps or remove a section of the base plate.

Either way, we are not living in the stone age. There are many modern techniques to accomplish a nice, neat, natural-looking, comfortable, denture for you.

Author: Dr Dean Lloyd

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