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

Aim of this study: is to compare the chairside time and bond failure of fixed mandibular retainers when bonded using the conventional direct technique and the 3D printed positioning tray immediately and after the first 6 month of placement. Materials and methods: A randomized controlled trial was performed using the two techniques to directly and indirectly bond the fixed lingual retainers.20 subjects who were in need of fixed retainers showing no signs of enamel defects or signs of gingival inflammation were recruited in this study. 20 retainers were bonded to the lower anterior teeth. Group I was the intervention group (3D printed positioning tray technique) and Group II was the comparative (the direct technique). In the intervention group, lower impression was taken and the cast produced was scanned using desktop scanner to produce the digital model on which the virtual retainer was placed using the OrthoAnalyzer software. The tray was designed by using Appliance Designer software and printed with rigid resin to allow ease of insertion and removal.The wire was placed inside the 3D printed positioning tray and then transferred inside the patients mouth the chairside time was recorded and number of detached composite was recorded for the bond failure measurements immediately and after 6 month. In the comparative group, same steps where done as intervention group, but with the exception of the bonding technique where the retainer was placed directly inside the patient{u2019}s mouth. Results and conclusion: The chairside time difference between the two bonding techniques was statistically significant, with the 3D printed positioning tray technique taking less chairside time than direct technique

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