The most common reason now for a tooth to be extracted is gum disease. Unfortunately, many dentists are not particularly interested in gums, and as such, gum disease often goes unnoticed until relatively advanced, and difficult to treat. Early signs are bleeding gums after brushing or flossing, and healthy gums SHOULD NOT BLEED! Treatment in early stages is thorough cleaning of the teeth by the dentist or hygienist (who is specifically trained for this purpose), followed by instruction in suitable maintenance techniques for homecare.
The main reason for bringing people back for 6, 9 or 12 month check-ups is to allow regular professional tooth cleaning to prevent gum disease and maintain optimum oral health, so if your dentist only ever cleans the back of the front 6 teeth and gives them a quick brush, CHANGE DENTIST NOW!! There is no excuse for ignoring gum disease anymore, and any dentist that does should not be allowed to get away with it. Be particularly aware if you are being seen under your PRSI, a medical card, or other third party scheme, as it is easy for the dentist to skip the proper cleaning and still get paid, and this should not happen.
Treatment of more advanced gum disease will cost you money, as there is no easy fix, and it will require time and effort on your part, and usually the intervention of a good hygienist or periodontist (gum treatment specialist). It is much easier to prevent than to treat gum disease.