Evaluation Of External Apical Root Resorption Associated With Canine Retraction With Two Different Amounts Of Orthodontic Loads: A CBCT Split Mouth Design Study.

•       This will be a split mouth in-vivo study. 19 patients (age group between 16 years and 30 years) undergoing orthodontic treatment requiring extraction of 1st premolar as a part of orthodontic treatment will be selected for the study. The maxillary teeth will be well aligned, before retraction of canine. Each participant will be treated with fixed pre-adjusted appliance. The system used will be metal 0.022 x 0.028” slot MBT bracket system. The timeframe of the study will be between 4 months to 7 months as according to research, this much time is generally needed for canine retraction. Minimum 19 samples will be included in this study. Participants will be allocated into 2 sides using lottery method: one side of the maxillary region will be delivered with 100gm of orthodontic load and the other side of maxillary region will be delivered with 200gm of force. This force will be measured by standardized Dontrix Gauge.

•       All CBCT scans will be performed by the same standardized CBCT machine (Vera view Pox R-200) The scans of each subject will be taken immediately before and after the canine retraction. The same setting will be used for all scans. The EARR will be quantified by using the CBCT scans obtained immediately before and after canine retraction. The CBCT images will be processed with soft view CBCT software (idixel by Jmonita Japan).

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•       Before the study, the right and left first premolars will be extracted, and the maxillary dental arch will be leveled and aligned upto 0.019 * 0.025-in stainless steel arch wire engaged in 0.022 * 0.028-in slot brackets. The maxillary second molars may be included in the arch wire and colligated to the maxillary second premolar and first molar with a 0.010-in stainless steel wire on each side that served as anchorage. The bilateral first molars are used for anchorage reinforcement. All individual canine retraction will be done by sliding mechanics using round stainless-steel wire (0.018 inch)

•       The canine will be segmented first, and the tooth length will be easily measured by using the 3-dimensional (3D) length measuring function in idixel software. The tooth length will be defined as the distance between crown tip and root tip.  The length reduction measured from the pretreatment and posttreatment scans will be used to quantify EARR

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SCORING CRITERIA:

Grade

Defintion

|Grade 0

No evidence of Root Resorption

|Grade 1

Irregular Root Contour

|Grade 2

Apical Root Resorption Less than 2mm

|Grade 3

Apical Root Resorption >2mm and <13rd of its original length

|Grade 4

Root Resorption exceeding 1/3rd of its original length

Grade

Defintion

|