Study Model-based Evaluation of Built-in Tip, Torque, and In-out Characteristics of a Third-generation Preadjusted...

The aim of the study was to evaluate the clinical effectiveness of MBT™ preadjusted edgewise appliance (PEA) in terms of achieving the optimal expression of its built-in characteristics of tip, torque, and in-out.

Pretreatment and posttreatment study models of 20 subjects who received full fixed appliance treatment involving four first premolar extractions using the MBT™ appliance were measured for tip, torque, and in-out using the method described by Andrews. Treatment changes were analyzed statistically, and the posttreatment measurements were compared with the MBT™ specifications as well as Andrews' values for the above-mentioned parameters.

Except for the maxillary canines and second premolars, the built-in tip of MBT™ appliance was nearly fully expressed, though there was some lack of correlation with Andrews' values. Despite the fact that the full amount of torque built into the MBT™ appliance was not expressed, torque measurements for all teeth except the maxillary second premolars and the first molars showed either no statistically significant difference or were significantly higher than Andrews' values for these teeth. In-out readings were lower than both MBT™ and Andrews' values, but the relative order of crown prominences was similar. Conclusion and clinical significance: The MBT™ appliance is thus effective in ensuring a successful treatment result, though individual adjustments may be necessary for optimal tooth positioning at the end of the treatment, as with any preadjusted appliance.