Wearing of enamel is physiological, that naturally happens with time. However there are some other causes of loss of enamel, could be attributed to diet (nepalese tend to chew bone and eat hard stuff like durukho, supari, chiura what not), parafunctional habits like grinding, aggresive toothbrushing etc. Zalim singh you better go see a dentist ! Fluoride does help in remineralization along with the physiologically saturated calcium and phosphate to some extent and rebuilding of enamel is not yet scientifically feasible in the patient level.