Is it a good idea to treat tooth decay at home?

Decay: If you mean preventing decay -yes there are lots of things you can do - sealants, fluoride, brushing and flossing and using an electric toothbrush.

Tooth decay: You can prevent but not treat tooth decay on your own! my suggestion would be to start by seeing your own dentist for a clinical exam, appropriate x-rays, periodontal exam and cancer screening. At that point you can discuss with your own dentist what treatment, if any, is needed, as well as how best to prevent both dental caries and gum disease, and have a healthy mouth for the rest of your life.

Not even with degree: You should not treat tooth decay at home not even if you are good working back wards in the mirror and have a dental degree. Decay does not get better by itself (well rarely). You need professional help immediately.