Squamous cell carcinoma is the most common cancer within the oral cavity. Bone invasion involving the maxilla or mandible is reported in up to 50% of tumors on initial presentation. Although conflicting data exist, true bone invasion is thought to negatively affect risk of recurrence and long-term prognosis. The ultimate goal is to accurately identify bone invasion preoperatively and intraoperatively, because it affects the treatment plan. This article focuses on methods of evaluation of the bone margin in the preoperative and intraoperative setting, discussing the implications for prognostic, staging, and reconstructive methods.