Mandibular involvement in oral cancer. It is difficult to predict the tumour invasion into the mandible by oral cancer pre-operatively, and consequently the decision to preserve or sacrifice the mandible is largely individualistic. The present study of 44 cases analyses the reliability of pre-operative parameters to assess mandibular involvement. Clinical, radiological and scintigraphic features have been compared with the detailed histology of the bone. This study confirms the usefulness of superior marginal resections in lesions which are close to but not involving the mandible, as well as for superficial lesions which are actually seen to involve the mandible but their CT and bone scans are negative for tumour invasion. 