摘要BACKGROUND: To evaluate the diagnostic accuracy of clinical signs combined with the tongue blade test (TBT) to detect maxillary and mandibular fractures. METHODS: A cross-sectional study enrolled patients with maxillary and mandibular injuries in the emergency department. Physical examination and the TBT were performed, followed by radiological imaging (facial X-ray or computed tomography [CT]). The diagnostic accuracy was calculated for individuals and a combination of clinical findings at predicting maxillary and mandibular fractures. RESULTS: A total of 98 patients were identified, of whom 31.6％ had maxillary fractures and 9.2％ had mandibular fractures. The combination of malocclusion, tenderness on palpation and swelling with positive TBT had 100％ specificity to detect maxillary and mandibular fractures. In the absence of malocclusion, the combination of tenderness on palpation and swelling with positive TBT produced a specificity of 97.8％ for maxillary fracture and a specificity of 96.2％ for mandibular fracture. A clinical decision tool consisting of malocclusion, tenderness on palpation, swelling and TBT revealed a specificity of 100％ and a positive predictive value of 100％. CONCLUSION: The clinical decision tool is potentially useful to rule out mandibular fractures, thus preventing unnecessary radiation exposure.