Three dimensional superimposition assessment of miniscrew supported two different canine retractiontechnique

The aim of this split-mouth study was to compare power arm sliding (PAS) and direct sliding (DS) canine retraction mechanics in terms of speed, rotation, angulation, and anchorage loss. Thirty-six (20 females, 16 males; mean age, 16.94 ± 3.23) Class II Division 1 patients requiring upper first premolar extraction were included in the study. The mini-screws were used as anchorage units and a retraction force of 150 gr was applied from the power arm on one side and from the bracket on opposide side by using elastomeric chains. Randomization was achieved by block randomization with a 1:1 allocation ratio to either right or left with allocations concealed in opaque, sealed envelopes. Digital models were acquired using an intraoral scanner at the beginning of retraction (T0), first month (T1), second month (T2), and third month (T3). Before the scans, the archwire was removed and the custom metal jigs were inserted into the vertical slot of the canine brackets to evaluate the canine angulation. The digital models of each patient were superimposed with the local best-fit algorithm separately and the retraction rate, angulation, rotation, and anchorage loss were measured. The digital measurements were performed using Geomagic Control X software. The DS technique's total retraction rate was higher than the PAS technique (2.09 and 1.57, respectively, P=.002). There was, however, no significant difference between the two techniques in terms of angulation, rotation, and anchorage loss. The negative correlation observed between retraction rate and age, but it was not statistically significant. No significant difference was seen between the retraction rate of female and male participants in both retraction techniques. For both orthodontists and patients, the DS technique is simpler and more convenient so that can be a preferential method for canine retraction