Frequency of External Root Resorption in Mandibular Second Molars Associated With Mandibular Impacted Third Molars Using CBCT

Inclusion Criteria: * The patient should be older than 18 years old. * Having all teeth erupted except the third molar. Exclusion Criteria: * Completely erupted third molars. * Impacted third molars with pathologic lesions. * Third molars with evidence of root development which is less than two-thirds. * Any artifact demonstration that obscure the areas of interest. * Missing third molars. * Patients with developmental disorders like microdontia, presence of fourth molars, impacted second molars, supernumerary teeth, and odontomes.