Teeth decaying from the gum base line can easily be taken care of. Of course the ones the have decayed and formed cavities or if the enamel has eroded away and is noticeable to the little finger nail can be ground and filled up with the commonly called plastic. It all depends on the dentist. If your dentist is experienced he will very carefully grind the cavity/ or the decayed part and fill it up to last for 5 to 15 years depending on the expertise of filling and hygiene you maintain. It is not uncommon for smokers and those who drink for acid accumulation at the base of the teeth and that is what causes the corrosion on the enamel. You DO NOT HAVE TO HAVE THEM EXTRACTED. They can be saved. Extraction of one tooth leaves a gap for the adjoining teeth to go without support and in due course of time they also start getting loose. So save your teeth, and a good dentist will always go all out trying to save your teeth. As an added measure you must rinse your mouth with listerine at least morning and night. Best would be after every meal. If you find it harsh you may dilute it with water. Two parts of listerine and one part of water. Even that will help you. Flossing after meals is a great help. Vitamin C 500 mg twice a day helps in dentene (enamel) strength and of course take fat free vit. d milk two glasses a day. Your tooth teeth life will be increased at 20 times. Now that is a lot. A word to add. Never have a heavy night meal nor have any juices or snacks at at or atleast three hours before going to bed. Your teeth will be healthy and so would you. Best wishes.