The inferior dental artery suffers from a marked collagenosis of its wall some 15 years before arterial disease usually appears in the remainder of the carotid arterial tree. It is suggested that this is due to abnormal stress factors being exerted within the wall and as a result, from middle age onwards, the blood supply to the mandible is mainly from the subperiosteal plexus of vessels. The clinical significance of this is discussed in relation to surgery, the treatment of fractures and radiotherapy to the jaws.