How do i know it is bad gingivitis or periodontitis?

You don't: You can't make that determination. Only your dentist can accurately diagnosis this. If the gingivitis has been going on long enough it will lead to periodontitis. It is best to get it evaluated and treated so that it doesn't get worse.

Some signs: Some signs that you are overdue for a dental appointment due to "bad gingivitis and perodntitis" would be blood on your toothbrush, loose long teeth, bad breath and or pus around your teeth. Of course you shouldnt wait for those symptoms since its easier, cheaper and less painfull to prevent periodontal disease than to try to treat it. Its economical to be preventive.

Dental exam: You may notice a fetid odor or loosening teeth; but the only sure diagnosis is from a periodontal exam and x-rays with your dentist.

See dentist: Inflammation of the gums ( gingivitis) usually develop from poor oral hygiene , and if left untreated , it turns into periodontitis which is inflammation of the tissues surrounding the teeth from gums, ligaments and bone of the jaw