Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Orthodontics

Aim: The aim of this study was to assess the root parallelism between maxillary canines and second premolars in adolescent versus adult group of patients following maxillary first premolar extraction and space closure (Primary outcome), and to compare the incidence of associated post treatment root resorption (Secondary outcome). Methodology: The sample of this study comprised post treatment panoramic radiographs (OPGs) of cases having extracted maxillary first premolar from the record archives of the outpatient{u2019}s clinic, Orthodontic Department, Cairo University. A sample of 180 panoramic radiographs were enrolled in this study after fulfilling the eligibility criteria and were divided into two groups, 96 Adult Patients (mean age 23.7 years old ± 6.7), and 84 Adolescent patients (mean age 14.3 years old ± 3.9). All included radiographs were digitized, the long axes of canines and second premolars were traced. The angulation between the long axes of canines and 2nd premolars in the same quadrant was measured and categorized accordingly into either good, acceptable, poor or over-treated parallelism. Furthermore, canines and 2nd premolars{u2019} mesiodistal angulation were additionally assessed in relation to a true horizontal reference plane passing through infraorbital rim. Meanwhile, digital assessment of root resorption on OPGs was done by calculating the difference between the pre and post treatment root length after proper calibration and standardization. Results: the frequency of good root parallelism was statistically higher in adolescent group (60.11%) than the adult group (41.6%).The amount of root resorption in adult group was significantly greater than adolescent group (P<0.05) in both central and lateral incisors. The highest mean of root resorption in adolescent group was in left lateral incisor (1.14 mm ± 0.26), while in adult group the highest mean of root resorption was in right lateral incisor (1.5 mm ± 0.3)

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