Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Orthodontics

Objectives: The aim of this study was to evaluate the impact of LLLT on the rate of en-masse retraction in adult females having bimaxillary dentoalveolar protrusion as well as its effect on anchorage, root resorption. Materials and methods: Thirty two adult females having bimaxillary dentoalveolar protrusion were enrolled in the study (mean age of 20.65 years). Patients were randomly allocated into one of two intervention groups. Both groups received fixed orthodontic treatment with pre-adjusted edgewise brackets ROTH prescription slot 0.022ʺ till 0.019ʺ{u00D7}0.022ʺ st.st archwire was reached. Direct skeletal anchorage was implemented by inserting 2 buccal MSI between upper 2nd premolars and 1st molars, then 1st premolars extraction and en-masse retraction was done using NiTi closed coil springs with a retraction force of 200gm/side. 2Group A3 received LLLT during retraction while 2Group B3 was the comparator with no LLLT application. Assessment of rate of en-masse retraction as well as 1st molars rotation was done on 3D digital model scans captured from poured models taken for each patient of both groups every month starting from the day of extraction until the end of retraction. Anchorage loss, tip of anterior and posterior teeth, torque of anterior teeth and root resorption were measured by captured CBCT scans before extraction and after the end of retraction. Results: Patients undergoing ُn-masse retraction with LLLT showed less root resorption in comparison to the comparator group. The maxillary right lateral incisors, left canines and left lateral incisors showed relatively increased root resorption compared to other teeth. Upper anterior teeth showed greater palatal crown torque in 2group B3 than 2group A3. Conclusion: LLLT with the parameters used showed a significant increase in the rate of en-masse retraction with a marked shorter overall treatment duration

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