If they are going to charge $800, it sounds like you need scaling and root planing, which means you have been diagnosed with gum disease. They are probably right in that the treatment will almost certainly fix the problem. Without treatment, no amount of brushing and flossing will help. Maybe you need to seek out some less costly alternatives. Is there a dental school nearby? Most schools will do treatment at 1/3 to 1/2 the cost of private practice. Also, check the web for dental insurances. Dental insurance unlike medical is usually very affordable. Try ehealthinsurance.com. Good luck!