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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.

This paper demonstrates the biomechanics used in orthodontics for the labial movement of a lingually blocked out tooth. Alignment of a lingually blocked out tooth with proper expression of labial root torque is often challenging as creation of a moment to force ratio of higher than 10:1 is difficult in the oral environment. This high moment to force ratio is needed to move the root of the tooth ahead of the crown. Here, we demonstrate a very simple spring that can torque the root ahead of crown and align the teeth to the remaining dentition by maintaining the moment to force ratio in a more than 10:1 value. This will move the root ahead of crown into the medullary area and the crown follows the root into a good alignment.