PDF: Roth versus MBT: Does bracket prescription have an effect on the subjective outcome of pre-adjusted edgewise treatment?

The aim was to determine if bracket prescription has any effect on the subjective outcome of pre-adjusted edgewise treatment as judged by professionals.

Since the introduction of the Straight Wire Appliance™ in the 1970s, there have been many suggested modifications to the tip and torque values used in preadjusted edgewise appliances.

Many of these changes involve alterations of a few degrees, even though it is known that torque expression in particular is affected by the amount of play between the archwire and the slot, differences in the tolerance size of manufactured brackets and archwires, the method of ligation, the initial inclination of the teeth, additional widening and notching of the bracket slot when placing the larger archwires, and even variations in the shape of the labial surface of teeth.

This retrospective observational assessment study was undertaken in the Orthodontic Department of the Charles Clifford Dental Hospital, Sheffi eld, UK. Forty sets of post-treatment study models from patients treated using a pre-adjusted edgewise appliance (20 Roth and 20 MBT) were selected.

The models were masked and shown in a random order to nine experienced orthodontic clinicians, who were asked to assess the quality of the outcome, using a pre-piloted questionnaire.

The aim of this study was to investigate the bracket manufacturers claims that when a patient is treated to a reasonable occlusal outcome, then small changes in bracket prescription can lead to visually detectable differences in tooth positions.

The null hypotheses were that there are no differences in the subjective aesthetic judg e ments of orthodontists as to the appearance of torque of the maxillary and mandibular incisors and the tip of the maxillary canines between cases treated using a pre-adjusted edgewise appliance with a Roth or MBT prescription.