Mouth Sores and Canker Sores: When Should You See a Dentist?

Small sores that appear inside the mouth from time to time are very common, and they can make eating, talking or brushing uncomfortable. Most of them are harmless and clear up on their own. Some, however, do need to be looked at by a dentist. In this article we cover canker sores, sores caused by irritation, how they differ from cold sores, and why any sore that lasts longer than two weeks should be examined.

What Is a Canker Sore?

A canker sore (recurrent aphthous stomatitis) is a round or oval ulcer with a whitish-yellow centre and a red border. It typically appears on the inside of the cheek, the inner lip, the side of the tongue or the floor of the mouth, and it tends to come back. It usually starts with a burning sensation and, in most cases, heals without a trace within 7 to 14 days.

The exact cause is not fully understood, but several factors are known to act as triggers:

• Stress and fatigue
• Minor injuries inside the mouth
• Certain vitamin and mineral deficiencies
• Hormonal changes
• Sensitivity to certain foods
• A family tendency

Sores Caused by Irritation

Many mouth sores are the result of mechanical irritation: accidentally biting the cheek or tongue, very hot food or brushing too hard. A poorly fitting denture, orthodontic brackets or the sharp edge of a broken tooth can also rub repeatedly against the same spot and create a sore. Cracked or broken teeth are easy to overlook in this respect. Once the source of irritation is removed, these sores generally begin to settle within a few days.

Canker Sores vs Cold Sores

A cold sore is caused by a virus and usually starts as a cluster of small fluid-filled blisters on or around the outer lip. The blisters burst and form a crust. Canker sores, by contrast, appear on the soft lining inside the mouth and are not contagious. Because cold sores can spread, it is advisable to avoid close contact and shared items while one is active.

Care at Home

While a sore heals, it helps not to irritate it further. Avoiding spicy, acidic and hard foods for a while, using a soft-bristled toothbrush and keeping up good oral hygiene all support healing. If the discomfort is significant, your dentist may suggest a soothing treatment where appropriate; it is better to be examined first than to self-medicate.

Why a Sore Lasting Over Two Weeks Matters

The vast majority of mouth sores are harmless. Even so, a sore that has not healed after two weeks, feels firm, bleeds easily or appears for no obvious reason should always be shown to a dentist. Although it is uncommon, such a sore can occasionally be an early sign of a serious condition such as oral cancer. Changes spotted early are far easier to assess, which is why people who use tobacco or drink alcohol regularly are advised to keep a closer eye on the inside of their mouth. The effects of smoking on oral health are relevant here too.

Part of Every Check-Up: Soft Tissue Examination

A dental examination is not limited to the teeth. The cheeks, tongue, palate, floor of the mouth and gums are also inspected and felt. Having the soft tissues assessed during regular check-ups and scale and polish appointments helps changes that might otherwise go unnoticed to be picked up early.

When Should You Seek Care?

• A sore that has not healed for more than two weeks
• Canker sores that recur very often or are unusually large
• A sore accompanied by fever, fatigue or swelling in the neck
• A white or red patch, a hard area or numbness inside the mouth
• A denture or brace that keeps causing a sore in the same place

Summary

Most mouth sores are canker sores or the result of minor irritation, and they heal on their own. Cold sores are a separate, virus-related condition seen around the lips. Sores that last beyond two weeks, become firm or keep coming back should be assessed by a dentist. Regular check-ups allow changes in the soft tissues to be noticed early.

This article is intended for general information purposes. A clinical examination is required to determine the right treatment plan for you.