An alveolar ridge distractor for distracting a bone fragment (2) with respect to a maxillary bone (1) separated by an osteotomy line (11) the distractor is comprised of a threaded rod (5) with an upper piece (3) and a lower piece (4). The threaded rod (5) is formed by a top part (7) where the thread has a specific rotation direction and a bottom part (8) where the rotation direction of the thread is opposite to that of the top part of the rod (7) the upper piece (3) is located at the top of the rod (7) and the lower piece (4) is located at the bottom part of the rod (8) both bodies (3 and 4) have an end part (16) with no external thread, generating a free ring (12) in the area in which both bodies are joined, with no thread. That free ring (12) which is not threaded, is positioned to coincide with the osteotomy line (11).
