Hello Sir, I Am Located At India. My Mother Is

Hello Sir, I am located at India.
My mother is diabetic for last 35 years. Her blood sugar level is under control now. She is now 66years and facing teeth problem. Her only one teeth is very sour while eating food and little pain while eating. Otherwise no trouble. We consulted dentist and he told that teeth is ok. Doctor gave Rabeprazole 20, and Rantidine150mg. But problem not solved. Previously Panlipase was given to her and that worked good. This sour teeth is the recurrence of the problem after two months... what medicine we would suggest to us..Please help...