Evaluation Of the Effects of Location, Angulation, Follicular Status and Proximity of Impacted Maxillary Canines on Root Resorption of Adjacent Teeth Using Cone Beam Computed Tomography – A Cross-Sectional Study

Background

Previous studies in the literature have shown that the impacted maxillary canines may result in several complications like root resorption of adjacent teeth, cystic degeneration, various infections, shortening of dental arch, midline deviation or combination of these factors. This study assesses the effects of location, various angular and linear parameters, follicular width and proximity of impacted maxillary canines with adjacent tooth and associated complications in terms of root resorption of adjacent tooth.

Novelty

Root resorption of the adjacent tooth is a consistent feature with impacted maxillary canines, as noted in previous literature findings. But there are very few studies considering all the available parameters associated with impacted maxillary canine and its significance with respect to root resorption of the adjacent tooth.

PRIMARY OBJECTIVES

1.      To determine association between location, angular and linear parameters and follicular width of impacted maxillary canine and root resorption of adjacent teeth.

Therefore, the purpose of this study is to evaluate location, various angular and linear parameters, follicular status of impacted maxillary canines and its proximity with adjacent tooth, and its correlation to root resorption of adjacent teeth.

SECONDARY OBJECTIVES

1.     To determine the degree of root resorption of adjacent tooth caused by impacted         maxillary canines.

2.     To determine the association between proximity of impacted maxillary canine with adjacent tooth and associated root resorption.

3.     To determine any association between age of the patient and root resorption of adjacent tooth in patients with impacted maxillary canines.

STUDY DESIGN

A cross-sectional study

STUDY SETTING

Study will be conducted in the Department of Orthodontics and Department of Oral Medicine and Radiology at MES Dental College, Perinthalmanna.

STUDY PERIOD

10th February 2024 to 31st July 2025

STUDY POPULATION

Patients in the age group between 15 to 30 years with unilateral or bilateral maxillary impacted canines reporting for fixed orthodontic treatment to the Department of Orthodontics and Dentofacial Orthopaedics at MES Dental College, Perinthalmanna.

DATA COLLECTION METHODS

The impacted maxillary canines shall be identified by clinical examination and OPG, and supplemented with CBCT.

The patients will be scanned while in standing position using CMOS 9600 3D Face Scan (Carestream Dental). To keep the radiation dose to a minimum, all CBCT images will be taken using a limited dentoalveolar Field Of View (FOV:5*5, 8*8, 8*5). The exposure parameters will be 140KHz, 15mA, and 16 seconds. The CBCT images will be assessed in all 3D (axial, sagittal, coronal) on a flat screen monitor using the CS 3D imaging software (Carestream Dental).

The following analysis and measurements will be performed for every included subject:

Three-dimensional localization of the impacted maxillary canine:

a)     Sagittal: Location of the crown of the impacted maxillary canine in relation to the neighbouring teeth , classified as labial, mid-alveolar, or palatal position, will be assessed using sagittal and/or coronal CBCT scans.

Vertical (h): To measure the height of the impacted canine (h), the vertical distance from the canine cusp tip to the occlusal plane will be measured. The occlusal plane for left and right sides will be determined independently based on a tangent to a)     the incisal edge of the maxillary central incisor and the occlusal surface of the maxillary first permanent molar.

Transverse: Measurement of the cusp tip in relation to the midline based on the linear measurement methods will be taken. The maxillary midline is defined from the following reference points depicted on the CBCT: midpalatal suture, anterior nasal spine, and nasal septum. The shortest distance between the tip of the impacted canine and the midline will be measured perpendicularly in mm on respective axial CBCT scans

Mesio distal Position of canine:

The mesio-distal position of the maxillary impacted canine will be determined using modified Sector classification by Lindauer et al

Sector 1

Area distal to line tangent to distal heights of contour of lateral incisor crown and root

|Sector 2

Mesial to Sector 1, area from the tangent on the distal surface to a midline bisector of the lateral incisor tooth

|Sector 3

Mesial to Sector 2, area from the midline bisector to a tangent to the mesial surface of lateral incisor crown and root.

|Sector 4

All areas mesial to Sector 3

Angulation of the canine:(alpha and beta angles):

The angulation of the long axis of impacted maxillary canine with the arch midline (alpha angle) and the angle between the long axis of the impacted canine with the long axis of the adjacent lateral incisor (beta angle) will be analysed using CBCT. (Fig 4) The association between angulation and location of impacted canine measured in CBCT will be compared with the degree of root resorption of adjacent tooth.

Follicular size:

Follicle size measurement at the widest area of the follicle perpendicular to the crown of the impacted canine on coronal and axial CBCT slices will be measured. Distances greater than 3 mm will be considered to be an enlarged follicle.

Proximity with adjacent tooth:

Proximity and/or direct contact of the impacted maxillary canine with incisors or premolars will be determined (yes/no) . Proximity is defined by ≤0.5 mm distance between the two teeth. If yes: then location of the contact in relation to the long axis of the involved tooth is determined and is classified as the cervical, middle, or apical third of the root.

Root resorption of incisors or other teeth (premolars and incisors):

Location of the root resorption in relation to the long axis of the involved tooth, classified as the cervical, middle, or apical third of the root. Resorption was graded based on the criteria suggested by Ericson and Kurol

Grade 1

No Resorption

Intact root surface, the cementum layer may have been lost

|Grade 2

Slight Resorption

Resorption up to half of the dentine thickness

|Grade 3

Moderate Resorption

Resorption of the dentine midway to the pulp or more, the pulp lining being unbroken.

|Grade 4

Severe Resorption

Resorption reaches the pulp

EXPECTED OUTCOME

Primary outcome will be the association between location, angular, linear parameters and follicular width of impacted maxillary canine and root resorption of adjacent teeth. The secondary outcome will be the association between proximity of impacted maxillary canine with adjacent tooth and associated root resorption as well as the degree of root resorption of adjacent tooth caused by impacted maxillary canines.

BENEFITS FROM OUTCOME

As canine impaction is a routinely encountered problem, outcome can be utilised in reducing the rapid progression of root resorption.