AbstractThe changes in the mandible and in its relationship to surrounding soft tissue structures after loss of the teeth are described; the regular presence of deficiencies in the cortical bone along the line of the occlusal ridge is emphasized. Resection specimens of squamous carcinoma of the oral cavity not treated by radiotherapy were examined where there was mandibular involvement by tumor, and showed that the main route of tumor entry into the bone was through the occlusal ridge. Subsequent perineural spread along the inferior alveolar nerve has been found to be a regular occurrence.