Do the proper pre-anesthetic testing. Repeat your supportive periodontal therapy as needed with isoflurane. With communication and education, your clients will let you use isoflurane. To do this, you must re-educate yourself in the importance of correctly performed periodontal prophylaxis procedures. Have your own dentist's hygienist help you understand the methodology of root planing or even better, take a veterinary dentistry wet lab in periodontal care.
Plaque control is a daily project.
That means you should perform a periodontal grading of the patient under isoflurane anesthesia followed by the creation of a specific treatment plan for that patient. Don't convince yourself that your clients will not provide daily homecare. Some clients will and some won't. Give them the option and let them know that without daily homecare, professional prophylaxis appointments under isoflurane anesthesia will be more frequent the rest of their pet's life. This must be communicated with a detailed discussion and definition of the stage of periodontal disease existing in their pet.