A bone reamer used in the internal sinus lifting procedure of dental implantation is disclosed. A working end of the bone reamer includes a reamer body having a cutting edge, and a front end protrusion at the front end of the reamer body with a smooth, round and blunt surface. The diameter of the front end protrusion is smaller than that of the reamer body. During the internal sinus lifting procedure, a pilot drill is used to penetrate the bone lamella at the maxillary sinus floor, continued with the bone reamer of the present invention to enlarge a hole of implantation. As the front end surface of the bone reamer is smooth, round and blunt, the mucous membrane is blocked without being scratched and damaged. The front end protrusion also guides the bone reamer not to shift from a pathway grinded by the pilot drill, for the guiding purpose.
