Evaluation of Proximity Between Incisive Canal and Maxillary Central Incisor After Anterior Retraction: A CBCT Study

**AIM:**To analyze the effect of upper anterior teeth retraction on the root proximity to the incisive canal (IC).

**OBJE****CTIVES:.1.**To evaluate the effects of retraction on the proximity of incisive canal and roots of anterior teeth using CBCT

2.To assess the changes in the incisive canal (IC) and its relationship with the upper first incisor (U1) by measuring IC height, IC width, and U1-IC distances at multiple levels.

3.To explore the risk factors for contact between the incisive canal (IC) and upper central incisors (U1) and to evaluate the relationship between contact and root resorption.

4.To ensure consistency and accuracy in measurements by using a standardized method of evaluating CBCT data, with pre-retraction and post-retraction data compared for each patient, accounting for factors such as head position and anatomical landmarks (e.g., ANS, PNS).

Methodology

CBCT scan will be obtained for maxillary anteriors including canine at 8x8 cm field of view, 90 KV, 8 MVA, 11.4 second scan time and 200 micron voxel size Veraview X 800 model  machine. They will be taken at two time periods

a) before treatment

b) after retraction

Further which will be analyzed using i- Dixel software, ensuring the standardization of head position.Axial and sagittal sections are collected from each sample. Axial sections will be aligned parallel to the Frankfort plane, while sagittal sections will be made vertical to the axial plane and parallel to the connection between the anterior nasal spine (ANS) and posterior nasal spine (PNS). Coronal sections will then be made perpendicular to both the axial and sagittal sections

Several measurements will be conducted using the 3D measurement function of i-Dixel software:

 Incisive Canal (IC) Height: Will be defined as the vertical distance between the incisive foramen plane and the cemento-enamel junction (CEJ). The incisive foramen plane will be the horizontal plane passing through the lowest point of the buccal wall of the IC

IC Width: Will be defined as the transverse distance parallel to coronal sections between the most distal points of the IC. IC width will be measured at three horizontal levels in the sagittal view, ensuring consistency by recording the vertical distance between each level and the horizontal line passing through the ANS in pre-retraction images and transferring these levels to post-retraction images. The average of these three levels will be calculated for each patient.

U1-IC Distances: These will be measured at the same three horizontal levels and will be defined as the anteroposterior distance from the most mesial point of the upper first incisor (U1) to the cortical plate of the IC. Measurements will be recorded separately for the left and right sides.

U1-IC Decrease: Will be defined as the difference between the pre-treatment and post-treatment U1-IC distances. If the root comes into contact with or invades the IC, the distance will be recorded as 0 mm.

Root Length Measurement: The root length of both left and right U1 before and after retraction will be measured in the sagittal view.

Inclination change: Measurements of the inclination  of U1   before and after retraction will bemeasured in the sagittal view.inclination will be measured between tooth axis and H line

**Horizontal retraction distance:**horizontal retraction distance (HRD) of  U1 ,  the perpendicular distance between the maxillary incisor edge and V-line

**Vertical dental position:**vertical position of tooth is  the perpendicular distance between the maxillary incisor edgeand the H-line