Canker Sore FAQs

Dr. Kyle Hornby

I see patients commonly at my Kitchener Dental Office about cold sores, and if you suffer with them, you know just how painful they can be. Canker sores are a very common oral condition and affect the majority of the population from time to time. For some individuals, the frequency of developing canker sores is very high and affects their quality of life.

Today, I will answer the most frequently asked questions about Canker Sores. I hope the information provided below can help you to minimize or eliminate Canker Sore relapses.

What does a Canker Sore look like?

A canker sore is a whitish-yellow circular break in the mucosa inside your mouth. Mucosa is the fancy word for the reddish pink, thin tissue on your cheeks and inner lips.

This whitish-yellow break in the mucosa will have a red halo or border around it.

What causes Canker Sores?

Canker sores are thought to have a number of different causes. Generally, the frequency increases when your are under great stress, not eating well, and/or lacking sleep. If you suffer from frequent canker sores, the best thing you can do is to maintain a good diet, sleep well, and try to manage stress with regular relaxation and decompression exercises.

Other causes include:

  • Vitamin and mineral deficiencies. Commonly B Vitamins but may result from deficiencies in Zinc or Iron.
  • Trigger Foods. These can include foods that are highly acidic or sugary. Some food allergies may manifest as aphthous ulcers.
  • Mechanical Irritation. If you develop a single canker sore in the same area repeatedly, see your Dentist in Kitchener as they may be able to locate a sharp tooth edge or rough piece on a denture leading to the recurrent sore.
  • SLS-containing Toothpastes. Many studies have showed that Sodium Lauryl Sulfate (SLS) has a damaging effect on oral mucosa. Moreover, several studies have shown a significant decrease in Canker Sore number and frequency in patients following a switch to SLS-free toothpaste.

How long does it take for Aphthous Ulcers to heal?

Typical Canker Sores take 7-12 days to heal. Some interventions can speed healing such as rinsing with high salt solutions.

Can Canker Sores spread?

No. Canker Sores cannot spread and are not contagious. They are a mechanical disruption or break in the oral tissues and they are not related to viral infection.

Some people who suffer from Recurrent Aphthous Ulceration (RAU) can develop multiple Canker Sores at once but this is not the result of spread from one site to another.

Do Canker Sores bleed?

Canker sores do not bleed. If you traumatize a canker sore (i.e. by scraping it) then you can certainly make it bleed. However, these sores do not bleed on their own.

Can Canker Sores cause headaches? Can canker sores cause jaw pain?

Canker sores cause very localized, stinging pain. They do not typically cause referred pain to other sites. As such, these sores do not cause headaches or jaw pain.

How can you treat or heal Canker Sores?

The Canker Sore, or Aphthous Ulcer, will heal on it's own within 7-12 days. There's really no "magic bullet" for ridding yourself of a canker sore immediately.

You can, however, help speed healing by:

  • Avoiding sharp, acidic or sugary foods
  • Rinse 3-4 times daily with a good quality Himalayan salt water (dilute 1 tsbp or 15mL of salt in 1 cup or 250mL of water)
  • Discontinue use of your SLS-containing toothpaste (this will continue to strip layers of mucosa)
  • Make sure to brush slowly and gently in the area of the sore

What's the best way to relieve pain from an Aphthous Ulcer?

There are many chemical ointments and gels out there for Aphthous Ulcer pain relief. I try to discourage use of potentially harmful chemicals, especially in the mouth. One thing that can provide transient relief for 20-30 minutes at a time is a topical anesthetic like Orajel. I would discourage using this more than 2-3 times per day. Importantly, less is more with Orajel - you only need a very thin layer over the ulceration.

Laser treatment can also diminish nerve pain around the Canker Sore. If pain is severe, you can call your Kitchener Dentist to request laser treatment.

How can you tell the difference between a Canker Sore and a Cold Sore?

A canker sore occurs inside the mouth. It appears as a whitish-yellow circular break in the reddish-pink mucosa of the cheek or inner lip.

A Cold Sore (or herpes labialis) occurs on the border of your lip, outside of the mouth. It goes through phases, starting as a raised red area, eventually forming blisters that break, dry out and crust over.

By Dr. Kyle Hornby, Dentist in Kitchener, ON

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This article is meant to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Accordingly, always seek the advice of your Kitchener Dentist or other healthcare provider regarding a dental condition or treatment.

Enjoy a fresh start.
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