Characteristic findings on panoramic radiography and cone-beam CT to predict paresthesia after extraction of impacted third molar.

The purpose of this study was to compare findings on the relationship between impacted molar roots and the mandibular canal in panoramic and three-dimensional cone-beam CT (CBCT) images to identify those that indicated risk of postoperative paresthesia. The relationship between impacted molars and the mandibular canal was first classified using panoramic images. Only patients in whom the molar roots were either in contact with or superimposed on the canal were evaluated using CBCT. Of 466 patients examined using both panoramic and CBCT images, 280 underwent surgical extraction of an impacted molar, and 15 of these (5%) reported postoperative paresthesia. The spatial relationship between the impacted third molar root and the mandibular canal was determined by examining para-sagittal sections (lingual, buccal, inter-radicular, inferior, and combinations) obtained from the canal to the molar root and establishing the proximity of the canal to the molar root (in contact with or without loss of the cortical border and separate). The results revealed that darkening of the roots with interruption of the mandibular canal on panoramic radiographs and the inter-radicular position of the canal in CBCT images were characteristic findings indicative of risk of postoperative paresthesia. These results suggest that careful surgical intervention is required in patients with the above characteristics.

Relationships between third-molar juxta-apical radiolucencies and mandibular canals in panoramic and cone beam computed tomography images.

OBJECTIVE: This study aimed to determine the relationship between third-molar juxta-apical radiolucencies and mandibular canals on panoramic and cone beam computed tomography (CBCT) images. STUDY DESIGN: Forty-two patients were included in this retrospective study. The root apices and the relationships of the juxta-apical radiolucencies to the mandibular canals were evaluated on both panoramic and CBCT images. The McNemar test (P < .05) was used to compare panoramic with CBCT findings. RESULTS: Root apices were visualized clearly with CBCT in most cases for which the apices were not seen clearly on panoramic images. Similarly, juxta-apical radiolucencies were separate from the mandibular canals with CBCT in most cases. CONCLUSIONS: The present study found that there is no consistent intimate relationship between juxta-apical radiolucencies and the mandibular canals. Similar studies with larger sample sizes are required to further confirm these findings.