الفهرس 
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Abstract
Evaluation of the amount of mandibular molars movement and type of tooth movement using 3D printed customized retro-molar plate. CBCT and intra-oral scans were used for assessment of mandibular distalization.
Eight participants were recruited in this study who required mandibular distalization selected from the outpatients clinic of the Orthodontic department Faculty of Dentistry, Ain shams University. Out of the 8 participants six participants completed the study and two patients dropped out. All candidates were treated by unilateral mandibular distalization.
Panoramic x-ray and lateral cephalometric x-ray were investigated prior to intra-oral scanning and CBCT to check for the availability of bone in the retromolar area enough for the mandibular molars distalization both buccolingual and mesiodistal.
Molar Bands were selected for the first and second molars and an impression was taken for the fabrication of the intra-oral appliance. The intra-oral appliance was fabricated using a rigid stainless steel wire 1 mm thickness soldered from buccal and lingual site to connect the two molar bands and soldered to the connector wire form labial and buccal side a rigid power arm extending vestibular till the level of the molar bifurcation.
The plate was designed using solid works software after importing the STL file converted from the CBCT DICOM file. The plate was designed so that it fits the retro-molar area giving enough space for mandibular distalization and to be secured in place using standard surgical fixation screw. The plate was designed to have two arms extending vestibular buccally and lingually to the level of the power arms.
Placement of plates was done in the Department of Oral and Maxillofacial surgery, Faculty of Dentistry, British university in Egypt. Plates were placed under local anaesthesia using a split thickness flap and copious irrigation with saline during drilling. No sutures were needed, and the flap was left to heal with secondary intention.
Loading was started two weeks after plate placement using a closed NiTi coil was secured the power arms and the arms of the plat to generate from 250 to 350 grams per side with an average total of 600 grams. The participants were followed up every 2 weeks for reactivation of the NiTi coil to ensure the least amount of force decay. The participants were followed up for six month.
CBCT with the same machine used and the same specs for the preoperative x-rays were taken to evaluate the amount of distalization of the first and second mandibular molars and the type of tooth movement after the desired distalization have been achieved.
The amount distalization was evaluated in mm for each cusp in reference to frontal plane on the sagittal plane also the mesiodistal angulation was measured in relation to mandibular plane on sagittal plane, the buccolingual inclination was measured in relation to mandibular plane on coronal plane in addition to the occlusogingival movement of each cusp in reference to horizontal plane on axial plane.
Results showed a statistically significant increase in the amount of mesiobuccal cusp and mesial lingual cusp distalization of the mandibular first molars with a mean of 5.67 mm and 5.7 mm respectively. Distal molar tipping was minimum after distalization and the mean tipping was 2.6 degrees. Most of the distalized molars showed minimum mesiobuccal rotations and buccal crown tipping after distalization.