Assessment of Relationships Between Implant Insertion Torque and Cortical Shape of the Mandible Using Panoramic Radiography: Preliminary Study

Purpose: To assess the relationship between mandibular cortical bone status as determined with panoramic radiography and insertion torque (IT) in implant treatment. Materials and Methods: Using panoramic radiographs, two dental radiologists assessed patients' mandibular cortical bone status and classified them into two groups-normal or abnormal (mildly, moderately, or severely resorbed)-based on morphologic features of the mandibular cortical bone margins. Kappa coefficients between the two dental radiologists were calculated to determine interexaminer variability. Included patients underwent implant placement and surgery, during which IT was measured. Patients were classified into three groups based on these measurements: 15 Ncm or lower, between 15 and 35 Ncm, and 35 Ncm or higher. Correlations between mandibular cortical bone morphology and measured IT were assessed and analyzed statistically. Results: Ninety-six patients (34 men, 62 women; mean age 59.1 years) were included in this study; 73 (76.0%) displayed a normal cortex and 23 (24.0%) had an abnormal cortex. In patients with a normal cortex, 13 (8.6%) had IT measurements of 15 Ncm or lower, 42 (27.6%) between 15 and 35 Ncm, and 97 (63.8%) of 35 Ncm or higher. In patients with an abnormal cortex, 3 (4.9%) had IT of 15 Ncm or lower, 35 (57.4%) between 15 and 35 Ncm, and 23 (37.7%) of 35 Ncm or higher. IT values were significantly lower in patients with an abnormal cortex compared to those with a normal cortex. A significant correlation between morphology of the mandibular cortex and IT was observed. Conclusion: The mandibular cortical bone status assessed on panoramic radiographs correlates with implant IT, suggesting that panoramic radiographs may be used effectively to determine bone density before implant treatment. Keywords: bone mineral density, image evaluation, insertion torque, panoramic radiography, primary stability