IOSR Journal of Dental and Medical Sciences (IOSR-JDMS) e-ISSN: 2279-0853, p-ISSN: 2279-0861.Volume 20, Issue 1 Ser.9 (January. 2021), PP 10-18 www.iosrjournals.org DOI: 10.9790/0853-2001091018 www.iosrjournal.org 10 | Page Case Report: Compensatory Orthodontic Treatment of a Patient with Skeletal Class II Malocclusion Using the 3D Maxillary Bimetric Distalizing Arch Josué E. Villegas, Rubén D. Pérez, José L. Pérez, David Barajas, Daniel Cerrillo, Alicia Percevault Abstract: The selection of the treatment protocol for a patient with class II malocclusion will depend on many factors, the age and degree of skeletal discrepancy being relevant. Case Report: A 10-year and 10-month of age female patient is taken by her parents to the orthodontic department at the Autonomous University of Baja California (UABC), Mexico, requesting orthodontic treatment. Taking into account the results of the different analysis performed, a class II division I skeletal pattern was found due to a maxillary protrusion and a mandibular retrusion, presenting a deep bite and mixed dentition. Since the patient is growing up, a dentoalveolar compensation is chosen, using a 3D Maxillary Bimetric Distalizing Arch (3D-MBDA). Obtaining as a result the correction of molar and canine relationships to class I and better facial harmony were achieved. Conclusion: 3D-MBDA can be effectively used as an aid in compensatory orthodontic treatment of CII malocclusion. Key Word: Orthodontics; Class II malocclusion; 3-D Maxillary Bimetric Distalizing Arch; Dentoalveolar compensation; Molar distalization. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 02-01-2021 Date of Acceptance: 15-01-2021 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Class II division I malocclusion "is one in which the lower first molars occlude distally in their normal relationship with the upper first molars in extension of more than one half of the width of a cusp on each side, presenting protruded incisors" (1) . Throughout history, various procedures have been described for the correction of this type of malocclusion, which are selected depending on their etiology, either due to excessive maxillary growth, mandibular growth deficiency, a combination of both or simply a dentoalveolar alteration. Among these procedures we can mention myofunctional devices and mandibular propulsor, for example, twin-block, Andersen device, Herbst, etc. In addition, there are maxillary distalizers, some require the cooperation of the patient, such as the headgear and the maxillary bimetric distalizing arch, on the other hand, the following devices do not require patient activation, such as the Hilgers pendulum appliance, the Jones Jig device, Distal Jet and the temporary anchoring devices (TAD's). It should be mentioned that there is also the option of extractions to obtain a dentoalveolar camouflage, as well as resorting to an orthognathic surgical approach in case the previous procedures are not viable (2,3) . William L. Wilson and Robert C. Wilson (4–7) introduced the Modular Orthodontic System in the late 70s and early 80s, which proposed, for the correction of class II malocclusions, the use of a device called 3D Maxillary Bimetric Distalizing Arch (3D-MBDA) in combination with a lingual arch. The objective of the 3D lingual arch is to reduce side effects and serve as an anchor for the use of class II intermaxillary elastics. The Lip Bumper can also be used to maintain stability in the mandibular arch; this device has some extra advantages such as the uprighting of the lower molars and the elimination of the mandibular anterior crowding, if it’s present in the patient (3) . The 3D-BMDA arch consists of a round anterior section with a thickness of 0.022" and a posterior one of 0.040", the hooks for the elastics are welded at the anterior end in the section of 0.040" at the level of the cusp of the canine and presents an adjustable omega loop at the level of the first molar and the second premolar, which will remain closed when starting treatment. Activation is performed by placing an open stainless steel coil of 0.010” X 0.045” and 5 mm in length between the closed omega loop and the mesial portion of the accessory tube of the first molar, only 2 mm being compressed. As the molars rapidly distalize, space will be created between the loop and the accessory tube, which will require opening the omega loop to keep the coil activated. To avoid any effect on the anterior area and that the coil force is directed only towards the molars, two 5/16” 3 oz (85 gr.) elastics are used for 24 hours, the first 10 days after the adjustment, afterwards only one elastic is used until the day of the adjustment, in cases of extractions, it is suggested 1/4”