Another thought, if the dog is experiencing pain/discomfort/infection also known as periodontal disease. I would go to a specialist, example:
“The Dentistry Specialty Service at Angell Animal Medical Center has been proud to provide quality oral health care to pets and education to clients and veterinarians since 1998.”
“We are an experienced, dentistry-dedicated technical staff, with experience treating high-anesthesia-risk patients.” excerpt from https://www.mspca.org/angell_services/dentistry-service/
