The present invention relates to a centering and guiding device (1) for a dental drill which comprises a body (10) including a guiding hole (15) for a dental drill and two arms (20, 30) pivotally coupled to the body (10). Each arm includes a respective free end (22, 32). Said arms (20,30) are capable of pivoting between a first open position, in which said respective free ends (22, 32) are mutually spaced apart to promote the movement of the device (1) from and towards an operating surface, and a second closed position, in which the free ends (22, 32) are approached to each other to match an operating surface. The device according to the invention also comprises an elastic element (40) to push the arms (20, 30) towards the closed position. According to the invention, each of said arms (20, 30) comprises a cylindrical end (27, 37), opposite to the corresponding free end (22, 32), accommodated in a corresponding seat (10A) defined by the body (10). Moreover, the cylindrical ends (27, 37) of said arms (20, 30) comprise respective toothed sectors (25, 35) mutually meshing each other to guide the rotation of said arms (20, 30) between said closed and open positions.