| Popis: |
Accurate bracket placement is essential for successful orthodontic treatment. The indirect bonding (IDB) technique was developed to overcome errors found in direct bonding. IDB provides advantages of minimized patient discomfort, improved visualization of teeth, and reduction of wire bending. Digital IDB techniques now include intra-oral scanning, 3D printing, and IDB software. Studies have repeatedly shown the high transfer accuracy of silicone IDB trays. 3D printed IDB trays are a time saving alternative with comparable accuracy to silicone trays. To utilize the benefits of both materials, a novel shape memory polymer (SMP) Tera Harz TC-85DAC has been proposed as a digital IDB material for this study. The objective of this study is to evaluate the bracket transfer accuracy of three distinct digital IDB techniques: 3D printed resin, CAD driven silicone, and 3D printed shape-memory polymer (SMP) trays. 15 maxillary and 15 mandibular intra-orally scanned arches of pre-existing University of Illinois Chicago (UIC) Orthodontic Department were used for the study. Brackets were semi-automatically placed on each arch following the digitally fabricated facial axis (FA) point. 30 IDB transfer trays were produced for each material: 3D printed resin (“bar”), CAD driven silicone (“silicone”), and 3D printed (“SMP”) for a total of 90 transfer trays. IDB was performed for each technique and bracketed models were scanned for superimposition to test accuracy in the linear (mesiodistal, occluso-gingival, and bucco-lingual) and angular (torque, rotation, and tip) dimensions. A one-sample t-test was conducted to assess for any significant error in bracket placement in the three materials. A repeated measures ANOVA, with Greenhouse-Geisser correction, was conducted to assess whether there were mean differences between the three techniques in the linear and angular dimension. The results of our study showed that the bar material had the greatest frequency of bracket placement errors. Premolars had the greatest frequency of bracket placement errors specifically with the bar technique. Overall, the SMP technique had the greatest accuracy in linear and angular dimensions when compared to the bar and silicone method. The standard for clinical acceptability was set to |
