Thanks ChristineB, Penners, and Anne-Marie for your responses and advice... I greatly appreciate it!

The dentist office said it could take anywhere from 48 hours to a week to get the test results back. He had a brush biopsy done. I have decided that, even if the results come back normal, that he should have a brush biopsy done at every check up. Reading about oral cancer, I had no idea how it can go undetected for so long...