Dentist or doctor, i want to know what cause blisters in the mouth?

A few possibilities:: There are a number of conditions that can cause blisters in the mouth, including thermal injury, viral infection, and a range of "vesiculo-bullous" disorders. Persistent oral blistering should be assessed by a clinical oral pathologist. If you're located in the United States, you can find contact information for an oral pathologist at: http://www.Aaomp.Org/find-an-omp/clinical-services.Php?Php.