there is supposedly some kind of tolerence testing one can have done but i just couldnt afford it. i asked my friendly mercury free biologic dentist which material had the greatest percentage of acceptance in people and he said diamond lite. thats what i got. it is by no means a panacea. it has a rough finish and if i dont keep oil pulling and cleaning and waterpik at least daily, it smells like rot. at least i have good hygeine. i will forever have problems with my teeth until i have them pulled. or i can grow new ones!