Morphologic evaluation of the incisive canal and its proximity to the maxillary central incisors using computed tomography images

Assessment of variations in the nasopalatine canal on CBCT: considerations from an anatomical point of view

PURPOSE

The nasopalatine canal (NPC) is one of the most significant anatomical markers in the anterior maxillary region. Its location is quite important, especially for implant placement. Therefore, the purpose of this study was to use cone-beam computed tomography (CBCT) to evaluate the morphology, size, and anatomic variations of the NPC.

METHODS

A total of 150 individual CBCT images were assessed in various sections to evaluate the dimensions, morphology, and extent of the NPC. Reformatted sagittal images were chosen to classify the shape and course of the canal. The Student's t-test, the χ² test, and Pearson correlation coefficients were used.

RESULTS

The NPC was longer in males than in females, and the mediolateral diameter of the canal was greater in older adults. In sagittal sections, the canal predominantly exhibits a cylindrical shape, while a spindle shape is the least common. In coronal sections, a single shape is most frequently observed, with a Y-shape being the least common. Regarding the orientation of the canal, slanted canals are more prevalent, whereas vertically curved canals are rare. Typically, 2 canal openings are observed, with 4 openings being the least common.

CONCLUSION

The current study highlights the challenges associated with identifying the anatomical appearance and variations of the NPC. Consequently, possessing a thorough understanding of this anatomy is essential before undertaking any surgical procedures, such as implant placement. This knowledge helps prevent complications such as nerve injury-related loss of sensation, bleeding due to blood vessel injury, and the development of a nasopalatine duct cyst following trauma to the canal during surgery.

Cone-Beam Computed Tomography Study of Incisive Canal and Maxillary Central Incisors in Dravidian Population

INTRODUCTION

 En-masse maxillary anterior retraction is necessary to attain an esthetic profile in Angle's class I bimaxillary dentoalveolar protrusion and Angle's class II division 1 malocclusion. The objective of this study was to evaluate configurational relationships between maxillary incisors and incisive canal in Angle's class I bialveolar protrusion and Angle's class II division 1 malocclusion by cone-beam computed tomography (CBCT).

METHODS

A total of 108 adult CBCT scans of 54-skeletal class I bialveolar protrusion and 54-skeletal class II division 1 malocclusions were retrospectively analyzed. Angles between palatal plane and axis of maxillary alveolar border (θ1), incisive canal (θ2), and maxillary right central incisor (θ3) were measured in relation to the midsagittal plane. Linear measurements such as incisive canal width (IC-IC), medial inter-root distance (Rm-Rm), posterior inter-root distance (Rp-Rp), anteroposterior distance from Rm to tangent of right central incisor (11 Rm-Cat), and left central incisor (21 Rm-Cat) corresponding to three vertical levels (L1, L2, and L3) were assessed in axial cross-sectional plane. Association among angular measurements was examined by Spearman correlation coefficient analysis. Mann-Whitney U test compared variables of linear measurements at three vertical levels.

RESULTS

 Estimated distance from incisor root to incisive canal was 5-6 mm in both groups slightly influenced by skeletal class and vertical levels but not gender. Mann-Whitney test demonstrated significant differences between groups at three vertical levels (p<0.05). Only θ2 revealed a significant difference (p<0.05) between malocclusions compared to θ1 and θ3. The angular measurements for both malocclusions were positively correlated (p<0.05).

CONCLUSION

 Sagittal root-canal cortical plate distance varied significantly in both malocclusions (5-6 mm). Inter-root distance (Rp-Rp) was greater than incisive canal width (IC-IC) at all three vertical levels indicating a reduced possibility of canal invasion after maximum retraction at posterior levels.

Cone-Beam Computerized Tomography Evaluation of the Relationship between Orthodontic Vertical Direction Parameters and the Distance from the Apex of the Upper Central Tooth to the Nasal Floor and Anterior Nasal Spine

The aim of this study was to examine the relationship between the vertical cephalometric values and the distance from the apex tip of the upper central tooth (U1A) to the anterior nasal spine (ANS) and nasal floor (NF) using cone-beam computerized tomography (CBCT). One hundred and twenty-two patients who applied to the Department of Orthodontics between January 2011 and June 2019 were included. The distances between the U1A and the NF and ANS were measured using CBCT. Statistical significance was considered as p < 0.05. Of the 122 individuals, 73.8% (n = 90) were female and 26.2% (n = 32) were male, with a mean age of 22.8 ± 3.3 years. A statistically significant moderate positive correlation was found between the mean NF-U1A values and the N-Me, ANS-Me, ANS-Gn, S-Go, and N-ANS measurements (p < 0.01). A statistically significant positive correlation was found between the mean ANS-U1A values and the Ar-Go-Me, total posterior angles, N-Me, SN/GoGn and Y-axis angle, ANS-Me, and ANS-Gn measurements (p < 0.01). The distance from the U1A to the ANS and NF was related to the orthodontic vertical direction parameters. The ANS-U1A and NF-U1A distances can serve as reference points for identifying the orthodontic vertical growth pattern from CBCT scans.

Morphological Assessment of Nasopalatine Canal Using Cone Beam Computed Tomography: A Retrospective Study of 124 Consecutive Patients

This study aimed to assess and analyze the morphology and dimensions of the nasopalatine canal (NPC), as well as the adjacent buccal osseous plate (BOP), and to investigate the effect of gender, edentulism, NPC types, absence of maxillary central incisors (ACI) and age on the NPC and BOP, using cone beam computed tomography (CBCT). A total of 124 CBCT examinations (67 female and 57 male patients) were retrospectively included and evaluated. The assessment of the dimensions of the NPC, as well as the dimensions of the adjacent BOP, was performed by three Oral and Maxillofacial Radiologists on reconstructed sagittal and coronal CBCT sections under standardized conditions. Regarding the dimensions of the NPC and the adjacent BOP, the mean values were significantly higher among males than females. Furthermore, edentulous patients showed a significant reduction in BOP dimensions. Additionally, NPC types showed a significant effect on the length of the NPC, and the ACI had a significant effect on reducing BOP dimensions. Age had a significant effect on the diameter of the incisive foramen, with the mean values generally increasing with an increasing age. CBCT imaging of this anatomical structure contributes significantly to its full assessment.

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.

Are morphological and morphometric characteristics of maxillary anterior region and nasopalatine canal related to each other?

OBJECTIVES

The main purpose of this article was to clarify the relationship of anterior bone and tooth morphology with NPC. The anatomical features of the NPC region in three dimensions from coronal, axial, and sagittal directions were analyzed using CBCT and the effects of age, gender, sagittal root positions (SRPs) of central teeth, anterior overbite depth (AOD), central incisor (CI)/palatal plane (PP) angle, NPC/PP angle, and collum angles (CA) on NPC were evaluated in a group of the Turkish population.

MATERIALS AND METHODS

In this retrospective study, CBCTs of a total of 330 individuals between the ages of 17 and 82 were evaluated. The effects of SRP, AOD, CI/PP angle, NPC/PP angle and CA on the anatomical features of NPC were examined on the basis of age and gender. Descriptive statistics, Kolmogorov-Smirnov, Chi-square, Wilcoxon, Mann-Whitney-U, Kruskal-Wallis, and Spearman correlation tests were used. p values of < 0.05 were accepted as statistically significant.

RESULTS

While the SRPs, CI/PP angle, NPC/PP angle, CA, and age did not differ statistically according to NPC shape (p > 0.05), NPC shape varied according to gender and AOD (p < 0.05). It was found that cylindrical NPC (32.8%) was more common in females, while conical-shaped NPC (30.7%) was more common in males (p < 0.01). While most conical NPC was detected in individuals with Class I overbite depth, cylindrical NPCs were found in Class II and III individuals (p < 0.01).

CONCLUSIONS

The results showed that gender and AOD are influential factors on NPC shape. While conical-shaped NPC is more common in individuals with bite depth incisal, cylindrical-shaped NPC is more likely to be seen in individuals with middle and cervical thirds.

Morphometric and volumetric analysis of the proximity between the incisive canal and maxillary central incisors during anterior retraction: a retrospective cone-beam computed tomography study

OBJECTIVES

To elucidate the relationships and factors affecting the proximity between the incisive canal (IC) and maxillary central incisors and to predict the probable outcomes after anterior tooth retraction using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

Retrospective CBCT data taken before and after maxillary anterior retraction in 36 patients were used in this study. The incisive canal length (ICL), maxillary central incisor length (TL), angles between the palatal plane and axes of the maxillary alveolar border (θ1), IC (θ2), and maxillary central incisor (θ3), retraction distance (TDE), distance from the maxillary central incisors to the IC (D), cross-sectional area of the IC (CSA), and volume of the IC were evaluated. Comparison of the parameters between contact and noncontact groups were examined. Logistic regression was performed to analyze the probable outcome prediction.

RESULTS

All parameters significantly decreased after anterior retraction, except for the ICL. Eighteen roots in 12 patients contacted the IC. The θ1, θ2, θ3, and D values at all levels were significantly lower, whereas the TDE, midlevel and oral opening CSA, and volume were significantly higher in the contact group compared with the noncontact group. The larger the pretreatment θ1 and θ3 were, the higher was the chance of incisors not contacting the IC.

CONCLUSIONS

Maxillary central incisors not contacting the IC after anterior retraction was positively associated with larger degrees of pretreatment maxillary alveolar bone angle and maxillary central incisor angle.

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.

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

OBJECTIVE

To investigate the position of the upper central incisor roots (U1) relative to the incisive canal (IC) among subjects with maxillary dentoalveolar protrusion in various facial growth patterns.

MATERIALS AND METHODS

240 cone beam computed tomography images of skeletal Class I and II maxillary or bimaxillary protrusive subjects with a mean age of 23.74 ± 3.73 years were enrolled according to their facial growth pattern. The IC volume was measured using Mimics 21 software (Materialise, Leuven, Belgium). The U1 inter-root distance, width of IC, and their proximity were estimated using Invivo6 software (Anatomage, San Jose, CA).

RESULTS

The IC volume was slightly greater among the high angle facial group and female patients than the other groups. Overall, the IC width was greater than the U1 inter-root distance in 55.65%, 57.6%, and 65% among the average, low, and high angle facial groups, respectively, and in 56.5% and 62.9% of males and females, respectively. The overall anteroposterior (sagittal) distances between the U1 roots and IC were 4.36 ± 1.18, 4.78 ± 1.17, and 3.83 ± 0.90 mm among the average, low, and high angle facial groups, respectively.

CONCLUSIONS

The high angle facial group and female patients showed slightly greater IC dimensions than the other groups. The overall maximum sagittal distances between the U1 and IC were around 5.5, 6, and 4.7 mm among the average, low, and high angle facial groups, respectively. The low angle facial group and male patients tended to have greater sagittal distances. Therefore, the present findings could serve as a guideline when a considerable amount of upper incisor retraction is planned for Class I or II maxillary or bimaxillary dentoalveolar protrusion patients.

The Role of Morphometric Characteristics of Anterior Maxilla in Planning the Interventions Accompanied by Orthodontic Teeth Movement – An Overview

The anterior maxilla or premaxilla is part of the upper jaw and the most significant content of this region, from the aspect of orthodontic therapy, are the incisor teeth. The frequency of complications during orthodontic movement of the upper incisors refers to a more detailed evaluation of the anatomical structures of the premaxilla. The aim of this study was to investigate morphological and morphometric characteristics of the anterior maxilla by cone beam computed tomography, which could be of interest for planning orthodontic teeth movement. By reviewing the available literature, we compared the values of the alveolar bone height, the distance between the alveolar crest and enamel – cement boundary, total alveolar bone width, the thickness of the buccal, and palatal plate, nasopalatine canal, and accessory canals of the anterior maxilla. The results of our study show changes in the labial and palatal aspects of the alveolar bone height during orthodontic interventions. Different results of the alveolar bone width are in correlation with gender, age, and type of orthodontic tooth movement. Distance between the nasopalatine canal and maxillary central incisors was estimated at the value from 4 to 6 mm, which is below the recommended value for maximum incisal retraction by Proffit. Research results show variations in shape, length, and diameter of the nasopalatine canal, which indicates individual varieties detected on cone beam computed tomography. Other anatomical structures and measures show an insignificant correlation with orthodontic teeth movement. According to the contradictory results of the available articles, it is required to achieve an individual approach to orthodontic interventions in the area of the anterior maxilla.

The Shape of Nasopalatine Canal as a Determining Factor in Therapeutic Approach for Orthodontic Teeth Movement-A CBCT Study

The aim of this study was to evaluate the impact of the nasopalatine canal (NPC) shape and its morphometric characteristics on expected teeth movement by assessing the distance to maxillary central incisors (MCIs) according to NPC type. The retrospective study was performed on 133 CBCT images. The following parameters were obtained: the antero-posterior diameter (A-P) of the nasal foramen (NF), canal length, A-P and mediolateral diameter (M-L) of the incisive foramen (IF), and the distance between NPC and MCIs. With the exception of being hourglass-shaped, each NPC shape showed specific impacts of NPC shape on the relationship between NPC diameters at different sections and distances to MCIs. In banana-shaped NPC, a significant correlation was observed for A-P NF diameter, while in cylindrical-shaped NPC, a significant correlation was observed for NPC length. The increase in M-L IF, A-P IF, A-P NF, and NPC length in funnel-shaped NPC may be a risk factor for interventions that could result in teeth movement. According to the results, it seems that the proposed methodological approach for analysis of CBCT slices in the anterior maxilla may offer detailed information that could be an additional tool in planning the procedures that result in expected teeth movement.

The Shape of Nasopalatine Canal as a Determining Factor in Therapeutic Approach for Orthodontic Teeth Movement—A CBCT Study

The aim of this study was to evaluate the impact of the nasopalatine canal (NPC) shape and its morphometric characteristics on expected teeth movement by assessing the distance to maxillary central incisors (MCIs) according to NPC type. The retrospective study was performed on 133 CBCT images. The following parameters were obtained: the antero-posterior diameter (A-P) of the nasal foramen (NF), canal length, A-P and mediolateral diameter (M-L) of the incisive foramen (IF), and the distance between NPC and MCIs. With the exception of being hourglass-shaped, each NPC shape showed specific impacts of NPC shape on the relationship between NPC diameters at different sections and distances to MCIs. In banana-shaped NPC, a significant correlation was observed for A-P NF diameter, while in cylindrical-shaped NPC, a significant correlation was observed for NPC length. The increase in M-L IF, A-P IF, A-P NF, and NPC length in funnel-shaped NPC may be a risk factor for interventions that could result in teeth movement. According to the results, it seems that the proposed methodological approach for analysis of CBCT slices in the anterior maxilla may offer detailed information that could be an additional tool in planning the procedures that result in expected teeth movement.

Morphologic changes of the incisive canal and its proximity to maxillary incisor roots after anterior tooth movement

INTRODUCTION

The objectives were to evaluate the morphologic changes of the incisive canal (IC) and the influence of IC proximity to apical root resorption of maxillary central incisors after anterior tooth movement.

METHODS

Pretreatment and posttreatment cone-beam computed tomography images of adults (aged 18-47 years) were retrospectively evaluated. Subjects were divided into control group with minimal incisor movement (n = 32; maxillary incisor tip movement <2 mm) and maximum retraction group (n = 35; maxillary incisor tip movement >4 mm). The shape, direction, morphologic changes of the IC, the proximity of the central incisor root to IC, and the amount of apical root resorption associated with the proximity after orthodontic treatment were compared.

RESULTS

Changes in the shape of the IC were not observed in both control and retraction groups. However, 11.4% (4 of 35 subjects) in the retraction group indicated changes in the direction of the IC from slanted-straight to slanted-curved type after the direction of anterior retraction. The thickness of the cortical bone surrounding the IC and the distance between the incisor root and IC significantly decreased after orthodontic treatment in both groups (P <0.05). However, these changes were significantly greater in the retraction group than in control (P <0.0001). Contact or invasion of the incisor root to the IC was more prominent in the retraction group (42.8%-54.3%) than the control (10.9%-12.5%) (P <0.0001). The amount of root resorption indicated a tendency to increase in the order of separation, approximation, contact, and invasion in relation to IC.

CONCLUSIONS

Although remodeling of IC was evident in some patients, contact or invasion of the maxillary central incisor roots to IC was fairly high after maximum anterior retraction.

Comparison of distance of upper central incisor root and incisive canal in different sagittal and vertical skeletal patterns and sex: A retrospective CBCT study

INTRODUCTION

To evaluate the influence of sagittal and vertical skeletal patterns (skeletal classes and facial profiles), and sex on the distance between upper central incisors roots and incisive canal.

MATERIAL AND METHODS

Cone-beam computed tomography exams of 172 patients were classified into skeletal classes I, II, and III and according to the facial profile into mesofacial, brachyfacial, and dolichofacial. In sagittal reconstructions, linear measurements were done between central incisors roots and incisive canal at three levels: incisive foramen opening, intermediate region, and the region close to the apex of upper central incisors. In axial reconstructions, measurements of incisive canal width and distance between the roots were obtained. Analysis of Variance (three-way ANOVA) was used to evaluate measurement differences in relation to skeletal classes, facial profiles, and sex.

RESULTS

The distance between upper central incisors roots and incisive canal anterior region was little influenced by sagittal and vertical skeletal patterns and sex. Men had significantly greater incisive canal (mean=2.85mm; SD=1.18) width compared to women (mean=2.40mm; SD=1.04), regardless of skeletal class and facial profile (P<0.05). In general, inter-root distance between medial points of central incisors roots and incisive canal opening was greater in the region close to upper central incisors apex (mean=3.84mm; SD=1.44) than in incisive foramen opening (2.44mm; SD=1.04), (P<0.05).

CONCLUSIONS

The distance between upper central incisors roots and incisive canal is little influenced by sagittal and vertical skeletal patterns and sex.

Incisive canal remodelling following maximum anterior retraction reduces apical root resorption

INTRODUCTION

The objectives were to visualize the incisive canal (IC) remodelling following maximum incisor retraction and to evaluate its impact on canal-invasion-associated apical root resorption.

METHODS

Pre- and post-treatment CBCT images of 34 adult orthodontic patients (age 18-47 years) with a large amount of maxillary incisor retraction (>4 mm) using temporary anchorage devices (TADs) were retrospectively evaluated. Maxillary regional superimpositions and 3D models of the IC along with central incisors were used to measure the changes in IC dimension, IC invasion by the roots and IC remodelling. In addition, the association of the amount of apical root resorption with the root-IC relationship and IC remodelling were evaluated.

RESULTS

IC invasion by the incisor roots following maximum retraction was seen in 53% (18 out of 34) of the cases. IC with larger volume and area showed more invasions compared with those with smaller volume and area (P < .01). The amount of root resorption was significantly higher with IC invasion than without invasion (2.39 mm vs 0.82 mm, P < .0001). IC remodelling following maximum retraction was seen in 24% of the subjects. IC remodelling group demonstrated less apical root resorption than the non-remodelling group (0.98 mm vs 3.27 mm, P < .0001).

CONCLUSION

IC with larger volume and surface area before treatment were more likely to show canal invasion by the incisor roots after maximum retraction. IC invasion resulted in apical root resorption. However, approximately one-fourth of cases showed remodelling of the IC, which reduced the amount of root resorption.

Unilateral maxillary central incisor root resorption after orthodontic treatment for Angle Class II, division 1 malocclusion with significant maxillary midline deviation: A possible correlation with root proximity to the incisive canal

Root resorption can be caused by several factors, including contact with the cortical bone. Here we report a case involving a 21-year-old female with Angle Class II, division 1 malocclusion who exhibited significant root resorption in the maxillary right central incisor after orthodontic treatment. The patient presented with significant left-sided deviation of the maxillary incisors due to lingual dislocation of the left lateral incisor and a Class II molar relationship. Cephalometric analysis demonstrated a Class I skeletal relationship (A point-nasion-B point, 2.5°) and proclined maxillary anterior teeth (upper incisor to sella-nasion plane angle, 113.4°). The primary treatment objectives were the achievement of stable occlusion with midline agreement between the maxillary and mandibular dentitions and appropriate maxillary anterior tooth axes and molar relationship. A panoramic radiograph obtained after active treatment showed significant root resorption in the maxillary right central incisor; therefore, we performed cone-beam computed tomography, which confirmed root resorption along the cortical bone around the incisive canal. The findings from this case, where different degrees of root resorption were observed despite comparable degrees of orthodontic movement in the bilateral maxillary central incisors, suggest that the incisive canal could be an inducing factor for root resorption. However, further investigation is necessary to confirm this assumption.

Contact of the incisive canal and upper central incisors causing root resorption after retraction with orthodontic mini-implants: A CBCT study

OBJECTIVES

To explore risk factors for contact between the incisive canal (IC) and upper central incisors (U1) and to evaluate the relationship between contact and root resorption using cone-beam computer tomography (CBCT).

MATERIALS AND METHODS

This retrospective study used CBCT data of 33 patients treated by a senior orthodontist. Anterior teeth were retracted with mini-implants, and CBCT scans were taken before and after retraction. IC height and width, U1 lingual movement, and U1-IC distance and root length decrease were compared between contact and noncontact groups.

RESULTS

Sixteen U1 roots in 11 patients touched the IC. The contact group had lower positioned ICs (2.86 ± 1.10 mm) than the noncontact group (4.07 ± 1.72 mm). The middle of the U1 roots showed more lingual movement to ICs in the contact group (2.30 ± 1.20 mm) than in the noncontact group (1.07 ± 1.16 mm). Right central incisors were closer to the IC than were the left. Root length decreased significantly more in the contact group (2.63 ± 0.93 mm) than in the noncontact group (1.14 ± 0.83 mm).

CONCLUSIONS

There is a risk for the U1 root to contact the IC during anterior retraction when the IC is lower positioned. This contact might cause external apical root resorption.

The Incisive Canal: A Comprehensive Review

The incisive canal, also known as the nasopalatine canal, is an interosseous conduit through the anterior maxilla connecting the oral and nasal cavities. Within this canal lies the nasopalatine nerve and the vascular anastomosis between the greater palatine and sphenopalatine arteries. The embryology of the canal has led to interesting theories explaining its function. Efforts have been made to describe the morphometrics of the incisive canal by radiologic evaluation across sex and ethnicities. This paper aims to review the current literature on the embryology, anatomy, and clinical relevance of the incisive canal.

Quantitative analysis of the relationship between maxillary incisors and the incisive canal by cone-beam computed tomography in an adult Japanese population

Background

In setting goals for orthodontic treatment, determining the morphologies of the alveolar bone and maxillary incisor root is important for avoiding root resorption, dehiscence, and fenestration. This study aimed to analyze the configurational relationships among maxillary incisors, the alveolar border, and the incisive canal by cone-beam computed tomography (CBCT).

Methods

Cone-beam CT images of 93 orthodontic patients were evaluated for length of the incisive canal (L); angles between the palatal plane and the maxillary alveolar border (θ1), the incisive canal (θ2), and maxillary incisor (θ3); distance from the left maxillary incisor to the incisive canal (D); and cross-sectional areas of the incisive canal (CSAs) at three vertical levels. Comparison of variables between male and female patients was performed with the two-sample t test. Correlations between parameters were examined by Pearson’s correlation analysis and Bonferroni correction for multiple comparisons.

Results

Male patients exhibited significantly greater values of L than female patients. There were significant positive correlations between θ1 and θ2, θ2 and θ3, and θ3 and θ1. While the value of D was the lowest at the oral opening, that of the cross-sectional area of the incisive canal (CSA) was the greatest at the incisal root apex.

Conclusions

This study demonstrated that the incisive canal had large inter-individual variability, and the proximity between the incisive canal and the incisal root could not be precisely predicted by the conventional cephalograms. Therefore, pre-treatment CBCT examination should be recommended when a large amount of maxillary anterior retraction and/or intrusion is planned in orthodontic diagnosis.