What are Canker SoresCanker sores, also known as aphthous ulcers, are small, open wounds found inside your mouth. They can appear on any of the soft tissues of your mouth including the tongue, roof of your mouth, inside of your cheeks, and even along the gum line. Canker sores can be painful and can make eating, drinking, and talking uncomfortable at times. Fortunately, most canker sores disappear on their own without treatment and are not contagious.


There are three general types of canker sores:

  • Minor canker sores – Minor canker sores are the most common type of canker sores. They are small, often oval-shaped lesions with a red border. They are typically less than 1 centimeter in diameter and usually heal within a week without any scarring.
  • Major canker sores – Major canker sores are less common than minor canker sores and are generally larger and deeper in size. They are often round in shape with undefined borders. These can be painful and last a few weeks. Scarring is common with this type of canker sore.
  • canker sores – Herpetiform canker sores, despite the name, do not develop due to an infection of the herpes virus. These canker sores are rare and often appear in older patients. They are pinpoint in size and have irregular edges. They can appear in clusters ranging from 10-100 but may merge into one large sore. These sores can be extremely painful but heal within several weeks without scarring.

Canker Sore vs. Cold Sore

Though similar in appearance at times, canker sores and cold sores are not the same. Cold sores are fluid-filled blisters caused by the herpes virus and generally appear on the outside of the mouth. Cold sores are also highly contagious, unlike canker sores.

When trying to determine at home whether you have a canker or cold sore, check the location. If it is inside your mouth it is most likely a canker sore, while a sore outside of the mouth is most likely a cold sore.


The precise cause of canker sores remains unknown, though research suggests that a combination of factors may contribute to outbreaks. Some possible causes of canker sores include the following:

  • Fatigue
  • Food sensitivities
  • Hormonal shifts
  • Irritation from orthodontic appliances such as braces, retainers, or dentures rubbing against soft tissue
  • Stress
  • Trauma to the mouth

Those with underlying health conditions that can result in a weakened immune system, nutritional deficiencies, or gastrointestinal conditions may be at an increased risk of developing canker sores regularly.


Most canker sores are formed in the mouth, are round or oval-shaped, have a white or yellowish center, and typically have a red border. Before they appear you may notice a tingling or burning sensation. They can become inflamed and painful when irritated. In severe cases fever, fatigue, and swollen lymph nodes may also be possible signs of a canker sore.


Typically, no testing is needed to diagnose canker sores as your dentist or doctor can easily confirm with a quick visual exam. As mentioned above, canker sores typically resolve on their own without treatment. However, please contact your dentist if you notice:

  • An unusually large sore
  • Extreme pain and sensitivity
  • High fever
  • A sore that persists longer than three weeks
  • Spreading of sores

If your canker sore is larger, persistent, or extremely painful, several treatment options exist. Your dentist may prescribe a medicated mouth rinse to reduce pain and inflammation. If your case is severe and does not respond to other forms of treatment, oral prescription medication can be given to relieve symptoms. Cautery through dental lasers can also help to eliminate any source of pain or discomfort.

Home Remedies

Home treatments are beneficial in speeding up the healing process and alleviating symptoms. Common home treatments for canker sores include:

  • Applying milk of magnesia onto the sore
  • Avoiding abrasive, acidic, or spicy foods that can cause further irritation
  • Rinsing your mouth with salt and warm water
  • Topical over-the-counter products such as medicated gels, creams, and liquids that can be applied to the canker sore

Though there is no cure for canker sores and they can be recurring, there are some ways to reduce your risk. We recommend avoiding foods that may irritate your mouth such as citrus fruits, acidic vegetables, and spicy dishes. Brushing your teeth with a soft-bristled brush after meals and maintaining good flossing habits can help to keep your mouth free of foods that may trigger a sore. Lowering your stress levels by learning better stress management skills may also help to reduce your risk.

For more information on canker sores or to schedule an appointment, please contact Tooth + Tusk Pediatric Dentistry & Orthodontics today.

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Beaverton, OR 97006

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