Thanks for writing,
To be frank the hygiene of the mouth is to be graded as poor. This requires an immediate visit to the dentist
. Full mouth clinical examination and X-rays have to be taken.
First, i want you to know, that teeth can be saved even if they are decayed. There are many procedures which you will be guided to, by your dentist.
Second, the infections arising from teeth are immediate concern and have to be treated by a course of antibiotics which your dentist will prescribe. They can even lead to major complications if not looked after on time.
Third, as you told in your history some teeth never grew back, they might have been impacted in the bone. If teeth dont erupt on their own, they have to be surgically removed. If not, in some cases they might cause other complications and even develop cysts around themselves.
Finally i would like to tell you that an early visit to the dentist can restore the whole dentition for the patient. Present teeth can be saved and crowned, infections cured and missing teeth replaced, to give a whole new set of shining white teeth. Its never too late.
Dr. Tarush Thakur