Canker sores appear as erythematous erosion of borders and whitish center, 3 to 5 mm. diameter at the inside of the cheeks and lips, soft palate, floor of the mouth or tongue edges.

These self-healing between 7 and 10 days, keep in mind they are very painful in the acute phase of three or four days, which interferes with feeding or speech.

We leave the ratings of thrush:

Aphthous minor:

Ulcers of a size between 1 to 10 mm, about 5 mm.
Are given in number of 1 to 5.
They exhibit a halo of erythema around it.
Lasts between 7 to 10 days.
They are not very painful.
Displayed on the nonkeratinized oral mucosa, lips, cheeks and tongue area.
Present in 80% of cases.

Aphthous stomatitis more:

More than 10 mm, but can be smaller.
They appear in number 1 or 2.
Erythema peri ulcerar variable.
Last 2 weeks to several months.
Occur at the edge of the tongue, mouth or soft palate
They are very painful, making it difficult for food.
Leaving scar heal.
They occur in 10-12% of cases.

Aphthous stomatitis herpetiformis:

Size from 0.5 to 3 mm.
Appear being 5-100.
They are round, but take irregular shapes.
They last from 1 week to 2 months.
Are presented in the inner lip and the underside of the tongue.
They can be very painful.