Can methadone treatment cause tooth decay?

Yes.: Methadone is an opioid and this class of drugs will cause a reduction in salive resulting in a dry mouth. Saliva has antibodies which help to fight the bacteria causing decay. If you are keeping your mouth wet by drinking sweetened beverages, particularly sodas, you've got a 2-pronged attack on the teeth. See a dentist for dietary counseling and proper home care routine to alleviate this problem.

Indirectly, yes.: If this will be ongoing, you will want to work with your dentist to manage the increased risk of tooth decay. An ounce of prevention is often worth more than the pound of cure ;).

Yes: You need to have a very good oral hygiene care as well as periodic visits to your dentist, probably three times or more a year to follow progression of decay , and give you Fluoride treatments to prevent further decay.

Yes: Methadone can cause dry mouth (xerostomia) which caused tooth decay.