Objectives: The objective of this paper is to evaluate the predictability of preoperative tumour bone invasion of the mandible by squamous cell carcinoma of the oral cavity using CT, cone-beam CT and bone scintigraphy with SPECT. Material and methods: Eighty-four patients who had received CT, SPECT or cone-beam computed tomography (CBCT), as well as a further 48 patients who undergone all these investigations for preoperative evaluation of bone invasion were included in the study. A case-control analysis and the receiver operating characteristics were performed. Histological results of bone specimens served as the gold standard for assessment of bone invasion. Results: CBCT and SPECT showed a comparable sensitivity for bone invasion (93 % [CI 0.816-0.972] and 96 % [CI 0.867-0.990], respectively) which was significantly higher than that of CT (63 % [CI 0.488-0.752]). Further, CBCT obtained higher specificity than SPECT (62 % [CI 0.478-0.743] and 48 % [CI 0.342-0.614], respectively), whereas CT showed the best specificity among the investigation methods (81 % [CI 0.677-0.896]). Conclusions: CT scan provides by its high specificity and positive predictive value a precise imaging technique for clinical routine. However, CBCT shows a much higher sensitivity for cortical bone invasion and a better negative predictive value. With a significantly lower exposure dose it can rule out this invasion effectively and prevent overtreatment. Clinical relevance: Considering the high-resolution images delivered by CBCT along with minimized artefacts in the mandible it provides an alternative imaging technique, which could be combined and accomplished with another soft-tissue imaging modality like MRI to obtain optimal hard and soft-tissue visualisation in patients with squamous cell carcinoma of the oral cavity.