RESULTS	The use of chlorhexidine rinses following implant placement resulted in a slight improvement ( 2.5 % ) in survival in non-Type 2 patients and a greater improvement in Type 2 patients ( 9.1 % ) ; the use of preoperative antibiotics improved survival by 4.5 % in non-Type 2 patients and 10.5 % in Type 2 patients .\