I have xexcellent dental health. At my 6 month checkup, the dental probe foud a cavity at the base of my 5 year old lower molar crown. Xrays did not show anything. One dentist wants to remove and replace the crown; another says he can fill the cavity without removing the crown. The dentist who wants to replace the crown says if not, he will be "working in the dark" and if he does not get the whole cavity, it could lead to nerve damage, a root canal, a post and then a crown but he will do it if I want.I'm 61 with all of my teeth and no root canals. your opioinion please?