Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Nedicine - Department of Oral and Radiology Diagnosis

Aim To investigate the prevalence and risk factors of external root resorption (ERR) and distal caries in mandibular second molars adjacent to impacted third molars in a sample of Egyptian population. Methodology: CBCT scans involving 255 mandibular impacted third molars were included. Demographic factors (age and gender) and Radiographic factors (impaction angulation and impaction depth) were assessed. The presence of ERR and distal caries in mandibular second molar and their association with the demographic and radiographic data was analyzed. Statistical analysis was performed using IBM SPSS Statistics Version 2.0 for Windows. Results: The prevalence of ERR was 18.4% in mandibular second molars with higher occurrences in horizontal and mesioangular third molars classified as class B and C (P= 0.001, P=0.017). Besides, class C impaction increased the risk of ERR severity in second molars (P < 0.05). The prevalence of caries was 14.5%, with increased caries severity with class A impaction (P< 0.001).Conclusions: ERR and distal caries occurring in mandibular second molars adjacent to impacted third molars should not be neglected. ERR should be suspected with horizontal and mesioangular third molars classified as class B and C impaction depth

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