A radiographic study on the prevalence of knife-edge residual alveolar ridge at proposed dental implant sites

Dental implants are widely used in restoration of completely or partially edentulous dental arches. Before placement of endosseous implants in the jaws, both the quantity and quality of the residual ridge must be assessed radiographically. Remodeling activity after tooth extraction is localized primarily at the crestal area of the residual ridges, resulting in reduction of the height of bone and creation of various three-dimensional shapes of the residual ridges. When bone resorption at the lingual and buccal aspects is greater than that at the crestal area, a knife-edge type of residual ridge develops.OBJECTIVE: The aim of this study was to evaluate the prevalence of the knife-edge morphology of the residual alveolar bone at proposed implant sites in partially or completely edentulous patients. MATERIAL AND METHODS: Computed tomography (CT) cross-sectional images of the upper and lower jaws were assessed at the proposed sites before implant placement. Images of 258 proposed implant sites belonging to 30 patients were assessed radiographically. RESULTS: In 120 proposed implant sites out of 258 (46.5%), the residual alveolar ridge had a knife-edge configuration, the majoritybelonging to completely edentulous patients who lost their teeth more than ten years previously. CONCLUSION: High prevalence of knife-edge ridge was found, therefore, replacement of missing teeth by immediate implant is recommended to prevent atrophy or knife-edge morphology of the residual ridge.