Effect of Force Magnitude on Canine Retraction and Gingival Crevicular Fluid Proteome

This study aims to examine the effect of force levels in orthodontic treatment during canine retraction. Force levels refer to the pressure applied by the orthodontic devices to move teeth. Data collection will include gingival fluid, dental molds from a digital scanner, and x-rays of the upper canine region on both sides of the mouth during treatment. The null hypothesis to be tested is that there is no significant difference in the rate of canine movement between the light force and the heavy force levels.

Patients' participation in the study at the first visit (T0) Timepoint 0, will be started at the stage of canine retraction. At this appointment, 0.019 x 0.025-inch stainless steel archwire will be placed; power arms will be fabricated from 17x25-inch stainless steel on the maxillary first molars and canines. The height of the power arm will be matched with the center of resistance of both canines and molars based on the root length measured on the periapical radiographs. The archwire will be engaged in the canine bracket using stainless steel ligature wire. At the T0 appointment, before applying the retraction force, periapical radiographs of canines (with coronal and apical reference wires for calibration and magnification correction) and GCF (gingival crevicular fluid) samples of each canine will be collected. Gingival sulcus of mesial and distal to canine (bilaterally) will be chosen as sites for GCF sample collection. The study coordinator will take a digital scan using iTero® Element™ in the clinic as the baseline (T0). As the split-mouth design will be applied in this study, right and left sides will be assigned randomly for either 150gm (light force) or 400gm force (heavy force) for each subject. NiTi coil spring calibrated for force magnitude at oral temperature will be used to deliver the assigned force will be engaged from the first molars to the canine power arms. IRB-approved written instructions will also be provided to all the participants. Follow-up visits will be scheduled. After applying the force, follow-up visits will be scheduled at (T1) 1-2 weeks, (T2) 4-5 weeks, (T3) 8-9 weeks, (T4)12-13 weeks, and (T5)16-17 weeks. A new digital scan will be taken at each study appointment (T0 - T5). These digital scans will be used for tooth movement measurements. GCF samples (mesial and distal to canines bilaterally) will be collected only for the first 3 appointments (T0 - T2) for the first 10 participants only in this study. Periapical radiographs for canines on both sides will be obtained on (T0) Timepoint 0, and (T3) 8-9 weeks and (T5) 16-17 weeks of the study for each participant and analyzed to measure the EARR (external apical root resorption). Following the last study visit, all subjects' treatment will continue as recommended by the primary orthodontic care provider. No new data will be reviewed or collected after (T5).