Comparison of Maxillary Canine Retraction Rate With and Without Power Arm

Researchers will compare a power arm placed in the vertical slot of the canine bracket with elastomeric chain to a mini-screw (experimental/PAS) against a conventional elastomeric chain from the canine bracket directly to a mini-screw (control/DS) during canine retraction phase.

Participants will:

• undergo bilateral maxillary first premolar extractions, followed by placement of a titanium mini-screw or TAD (Vector TAS, 1.4×8.0 mm) between second premolar and first molar on each side for anchorage.
• receive fixed orthodontic treatment using a pre-adjusted edgewise appliance system (Roth, 0.018-inch slot).
• have levelling and alignment carried out using a graduated arch-wire sequence (0.014-inch, 0.016-inch, 0.016×0.016-inch, 0.016×0.022-inch, and 0.017×0.025-inch), with angulation corrections addressed at this stage.
• have bilateral canine retraction initiated three months post-extraction on a 0.016×0.022-inch stainless steel arch-wire, with an elastomeric chain attaching from the power arm to the mini-screw on the experimental (PAS) side and directly from the canine bracket to the mini-screw on the control (DS) side, under a standardized force of 150g reactivated every 21 days.
• be evaluated via CBCT at baseline (T0) and at 3 and 6 months (T1, T2) to measure canine retraction rate and angulation change on both sides

Inclusion criteria

• Participant with Angle's class I and class II malocclusion who required both maxillary bilateral premolar extraction for orthodontic treatment.
• Participants who required maximum anchorage.
• Participants with good general health condition and oral hygiene status.
• Age range of the participants will be 18 to 25 years.
• Sex of the participants will be both male and female.
• Participants with full permanent dentition present (excluding 3 rd molar).
• Participants who have completed the levelling and alignment phase before the start of canine retraction.
• Participants with no caries, fracture, periapical lesion, root resorption, morphological variation or other pathology involving the maxillary canine.

Exclusion criteria

• Participants with systemic conditions affecting bone metabolism or orthodontic tooth movement (e.g., diabetes mellitus, osteoporosis).
• Participants with impacted or displaced maxillary canines.
• Participants with retained deciduous canines.
• Participants with dental anomalies affecting canine retraction.
• Participants with previous orthodontic treatment.
• Participants with cleft lip/palate, craniofacial syndromes, or facial asymmetry.
• Participants requiring surgical orthodontic treatment.
• Pregnant women.
• Participants with poor cooperation, missed appointments, or frequent appliance breakage.
• Habit of smoking.