Infection at teethroot. The best option?

Hello sir my mother has reported recently that she has been suffering from toothpain at the end of right lower jaw. We consulted a local doctor and got the x-ray report at the infected area. He said that the root of the teeth has infection and the initial treatment will be through mdicines and oitment.... if there is no sign of cure then rootcanal surgery will be done. Sir my questions are as follows : 1) why would ones teeth get infection at the roots? 2) What are best treatments available till date that avoids surgery? 3) What are the further measures to be taken? 4) If my mother wants her teeth replaced... is ceramic tooth the best option? Need some suggestions regarding tooth replacement. Please do the needful.