Inferior alveolar nerve paresthesia in impacted lower third molars extractions’ postoperative period and tomography assessment of the distance between these dental elements and the mandibular canal cortical bone

Objectives: assess the incidence of paresthesia in the inferior alveolar nerve (IAN) after extractions of impacted lower third molars and observe, through cone beam computed tomography (CBCT), the distance between these dental elements and the mandibular canal (MC) cortical bone. Methodology: for the study, 29 patients were selected that presented both lower third molars impacted (corresponding to a sample with 58 teeth) and met other qualification criteria. They initially underwent clinical examination and the standard protocol for evaluation of nerve injury, according to University of Illinois Chicago, College of Dentistry, Department of Oral & Maxillofacial Surgery (Chicago, Illinois, USA), for assessment of pre-operative sensory condition. The patients then underwent CBCT and extraction of third molars. The surgical procedures were conducted by residents from the Oral and Maxillofacial Surgery Residency Program from the Western Paraná State University. On the seventh postoperative day, the patients were again subjected to the indicated sensory analysis protocol for verification of possible presence of paresthesia in IAN after the extraction. With regard to measurements made in the CBCT, the distance between the MC cortical bone and the tooth was determined by the arithmetic mean of the closest measurement of these two structures in each of the tomography three sections (axial, coronal and sagittal). Results: only one patient presented unilateral paresthesia in the IAN, corresponding to 1.72% incidence. Besides, according to CBCT analysis, 57 third molars were in close contact with the MC, while one element presented distance superior to 2 mm and inferior to 3 mm. Conclusions: CBCT played an important role in the surgical planning and it is believed that the use of this imaging exam contributed to the considerably low IAN paresthesia rate of the present study