Proximity of upper central incisors to incisive canal among subjects with maxillary dentoalveolar protrusion in various facial growth patterns

Radiologic study of the distance between the maxillary central incisor root and the incisive canal according to skeletal malocclusion classification

The aim of this study was to evaluate the distance between the maxillary central incisor root and the incisive canal based on skeletal malocclusion classification and to analyze the morphology of the incisive canal using cone-beam computed tomography (CBCT). Skeletal malocclusion was categorized into Class I, II, and III using lateral cephalometric analysis. Measurements of the distance between the maxillary central incisor root and the incisive canal were taken at two levels: 2 mm (L1) and 4 mm (L2) superior to the labial cementoenamel junction of the maxillary central incisor. At L1, the distance was found to be closer in the Class II group compared to the Class I or Class III groups. Similarly, at L2, the Class II group exhibited a closer distance than the Class III group. Interestingly, females showed a closer distance compared to males at both L1 and L2. Further analysis revealed a significant gender difference in the Class I and III groups, but not in the Class II group. These findings emphasize the significance of evaluating the distance between the maxillary central incisor root and the incisive canal in patients with skeletal Class II malocclusion, regardless of gender.

The Assessment of the Rank of Torque Control during Incisor Retraction and Its Impact on the Resorption of Maxillary Central Incisor Roots According to Incisive Canal Anatomy-Systematic Review

BACKGROUND

Root resorption is one of the complications of orthodontic treatment, and has a varied and unclear aetiology.

OBJECTIVE

To evaluate the relationship between upper incisor resorption and contact with the incisive canal and the risk of resorption during orthodontic treatment associated with upper incisor retraction and torque control.

SEARCH METHODS

According to PRISMA guidelines, the main research question was defined in PICO. Scientific databases MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were searched for linking keywords: Resorption of roots incisive canal, Resorption of roots nasopalatine canal, Incisive canal retraction and Nasopalatine canal retraction.

SELECTION CRITERIA

No time filters were applied due to the significantly limited number of studies. Publications in the English language were selected. Based on the information provided in the abstracts, articles were selected according to the following criteria: controlled clinical prospective trials and case reports. No randomised clinical trials (RCTs) or controlled clinical prospective trials (CCTs) were found. Articles unrelated to the topic of the planned study were excluded. The literature was reviewed, and the following journals were searched: American Journal of Orthodontics and Dentofacial Orthopedics, International Orthodontics, Journal of Clinical Orthodontics, Angle Orthodontist, Progress in Orthodontics, Orthodontics and Craniofacial Research, Journal of Orofacial Orthopedics, European Journal of Orthodontics and Korean Journal of Orthodontics.

DATA COLLECTION AND ANALYSIS

The articles were subjected to risk of bias and quality assessment using the ROBINS-I tool.

RESULTS

Four articles with a total of 164 participants were selected. In all studies, differences in root length were observed after contact with the incisive canal, which was statistically significant.

CONCLUSIONS AND IMPLICATIONS

The contact of incisor roots with the incisive canal increases the risk of resorption of these roots. IC anatomy should be considered in orthodontic diagnosis using 3D imaging. The risk of resorption complications can be reduced by appropriate planning of the movement and extent of the incisor roots (torque control) and the possible use of incisor brackets with built-in greater angulation. Registration CRD42022354125.

Tridimensional Analysis of Incisive Canal and Upper Central Incisor Approximation

OBJECTIVE

The present study aimed to estimate the location of the incisive canal (IC) concerning the upper central incisor roots (U1) in order to explore the amount of incisor retraction as per the envelope of discrepancy amongst Chinese patients with different vertical facial growth patterns.

METHODS

This is a cross-sectional study that used a total of 207 pretreatment cone-beam computed tomography (CBCT) scans of adults with a skeletal class I relationship. Sixty-nine cases were included in each of the normodivergent, hypodivergent, and hyperdivergent facial groups. The IC volume was measured using Mimics 21 software. The IC width and IC-U1 proximity were measured using in vivo 6 software. Linear measurements were conducted at 3 vertical levels.

RESULTS

The IC has shown a larger volume in the hyperdivergent group and male patients. Overall, the IC has recorded linear width greater than the inter-root distance of U1 in 59.1%, 66%, and 68.8% amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively, and in 58.3% of males and 70.8% of females. The overall sagittal distances between the U1 and IC were 4.00 ± 0.82 mm, 4.60 ± 0.83 mm, and 3.60 ± 0.80 mm amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively.

CONCLUSIONS

The maximum sagittal distances between U1 and IC were 4.8 mm, 5.4 mm, and 4.4 mm amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively. Thereby, our findings have revised the retraction aspect of the envelope of discrepancy as per the different vertical facial growth patterns, which could serve a reference for the clinical practice involved considerable incisors movement, especially among Chinese patients.