The fixed lingual arches that are used for mandibular molar uprighting works in two dimensions, whereas the 3D lingual arch works in all the three dimensions. The 3D lingual arch was fabricated from a 0.028 "round S.S wire with parts consisting of an adaptor, activator, friction lock and extender. The friction lock was inserted into the vertical stubs welded on the molar bands of the lingually tipped molar. They provided greater stability and anchorage to the molars. Up righting of the lingually tipped mandibular molars was attained within one month after insertion of the Wilson's 3D lingual arch. Correction was attained in all three dimensions with a buccal crown torque and lingual root torque. Levelling and alignment of the anterior segment was also attained by this multipurpose modular appliance. The 3D lingual arch enabled the clinician to set up a more positive anchorage for a greater variety of treatment applications than earlier lingual arches. Quality treatment results were attained with less span of time and were cost effective.

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According to Bacetti (1998) tooth rotation is defined as observable mesiolingual or distolingual intra-alveolar displacement of the tooth around its longitudinal axis. 1 Tooth rotations cause difficulty in finishing fixed orthodontic treatment. In Begg's technique rotation springs are used to correct tooth rotations. These springs are engaged into the vertical slot of the bracket. In case of preadjusted edgewise technique and edgewise technique brackets doesn't have a vertical slot. So alternative methods are used to correct tooth rotations. 2 Various methods include engaging NiTi arch wire into the bracket slot, off centering the bracket, using rotation wedges, creating a couple on the rotated tooth, by using ligature ties. 3 The purpose of this case series is to discuss the biomechanics involved in rotation correction using bracket offsetting and couple.

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