All On Four is a new concept in implantology, where we can replace all the teeth with fixed prosthesis with the help of FOUR implants in each jaw. this is particularly used in the patients with severe bone loss and where conventional implants can not be placed. Conventional way of placing implants in these kind of patients was to do bone regeneration inside the sinus by doing a surgery called SINUS LIFT, putting bone substitutes and waiting period of one to one and half year till you get final teeth/prosthesis. second disadvantage is cost as more number of implants are used and bone substitute and extra surgeries are involved.