Throughout the medical field, a biopsy is simply the removal of a tissue sample to determine if it is diseases. In dentistry, teeth and gums are sent for biopsy. The role of a biopsy in the dental industry is to diagnose oral cancer. In these instances, a brush biopsy is used to identify oral lesions that warrant further attention. If you have unexplained lesions in your mouth, they need to be examined by a dentist. They may or may not be cancerous, but they need medical attention nonetheless.