OBJECTIVES:–

To evaluate and compare the vertical changes in non–growing class I subjects treated with all first premolars extraction and non–extraction using pre adjusted edgewise appliance.

METHOD:–

The pretreatment and post treatment lateral cephalograms of 28 patients out of which 14 patients were treated by all first premolars extraction and 14 with no extraction pre adjusted edgewise appliance therapy were used. Intragroup and intergroup comparison was done by using paired t–test and unpaired t–test respectively.

RESULTS:–

Both the treatment modalities caused an increase in lower anterior facial height along with an increase in mandibular plane angle due to general extrusive nature of the mechanotherapy. However, this backward rotation of the mandible was found to be more in non extraction group.

CONCLUSION:–

 Thus, the wedge hypothesis suggesting decrease in vertical dimension following all first premolars extraction stands invalid.