Aligner therapy in treating bimaxillary dentoalveolar protrusion

Bimaxillary dentoalveolar protrusion is challenging to treat with aligners. Such patients have not only dental protrusion problems, but often a combination with skeletal protrusion problems. This article presents different bimaxillary protrusion case types, including treatment by extraction of the four first premolars, and non-extraction treatment. In the non-extraction case, temporary anchorage devices were used as anchorage to achieve molar distalisation and to prevent a 'rowboat' effect during the treatment. A special movement called the 'caterpillar motion design' is also described, which according to the authors helps to prevent the bowing effect in extraction space closure treatments. All described treatments were performed using the Invisalign System; extraction treatments are possible with aligner systems but require a profound knowledge of the biomechanics and forces of aligner orthodontics. Several possible approaches are presented. Keywords: aligner orthodontics, bimaxillary dentoalveolar protrusion, dental occlusion, protrusion, temporary anchorage device (TAD), tooth extraction