[header] How to avoid getting canker sores [title] Use toothpaste that does not contain sodium lauryl sulfate. [step] Sodium lauryl sulfate (sls) can be found in some commercial toothpastes and mouthwashes. Sls is often used as a cheap filler to help toothpaste thicken and foam up. 
But this additive has been shown to increase the likelihood of developing canker sores in your mouth. [substeps] Read the labels on toothpastes and mouthwashes to make sure they are free of sls before you use them or search online for brands that specifically do not contain sls.