Abstract
Background
The aim of this study was to investigate the effect of impacted maxillary canines on root resorption and periodontal tissues of adjacent central, lateral, and premolar teeth across different age groups using Cone Beam Computed Tomography (CBCT) imaging.
Methods
CBCT images of 203 impacted maxillary canines from patients of varying ages were retrospectively evaluated. Parameters included eruption stage, localization (right/left and palatal/buccal/central), dental follicle characteristics (shape and width), contact with adjacent teeth, periodontal contour integrity, and degree and location of root resorption. Statistical analyses assessed the relationships between these variables.
Results
A total of 203 impacted maxillary canines, including 123 on the right and 80 on the left side, were assessed. Impacted canines were most commonly affected with lateral teeth (57.6%). Root resorption occurred in 33.3% of these lateral teeth, with 14.5% showing severe resorption. Mild resorption was most frequently observed in central incisors and first premolars (16.7% and 12.5%, respectively). Root resorption was significantly more frequent when impacted maxillary canines were in contact with adjacent teeth (p = 0.005 for central incisors, p < 0.001 for lateral incisors, and p = 0.012 for premolars). No significant difference was found between genders in terms of root resorption (p > 0.05). Impacted canines were most commonly located in the palatal position (73.4%), but no statistically significant difference was found in root resorption rates between palatal, buccal, and central positions (p = 0.490). Canine follicle shape, width, and eruption stage did not significantly affect root resorption (p > 0.05).
Conclusion
Palatal position and contact of impacted maxillary canines with adjacent teeth increase root resorption frequency, especially affecting lateral incisors. CBCT provides accurate diagnostic information that supports clinical decision-making for impacted canine cases.
Keywords: Adjacent teeth, Cone-Beam computed tomography, Impacted canine, Maxillary canine, Root resorption
Introductıon
Impacted teeth are defined as the inability of the teeth to erupt in their proper place during the normal growth period [1]. Third molars in both maxilla and mandible are frequently reported as the most commonly impacted teeth in the literature [1, 2]. Permanent maxillary canines have the second-highest rate of impaction after third molars [3]. Maxillary canines are reported to be 20 times more likely to be impacted than mandibular canines [4]. Impacted maxillary canines are more commonly observed in the palatal position (85%) and unilateral (92%) and occur twice as frequently in females as males [5, 6].
Several factors have played a role in impacted maxillary canine teeth, including a long eruption path, malocclusion, lack of resorption of the primary canine root, trauma, soft tissue pathologies, heredity, and disruption of periodontal ligament continuity [7–10]. Impacted maxillary canines often remain asymptomatic for many years but may increase the risk of infection, cause cysts, root resorption in adjacent teeth, and shorten arch length [11].
Resorption is defined as the destruction of dental hard tissues such as cementum and dentin by cellular activity [12]. Systemic factors, chronological age, gender, genetics, dentition, malocclusion type, orthodontic treatment, and ectopic eruption have been among the causes of external root resorption [13]. Maxillary canines most commonly affect the roots of lateral teeth [14]. It has been reported in various studies that, in addition to the roots of lateral teeth, it also causes resorption in the roots of central and premolar teeth [15–17].
Root resorption can cause serious complications for teeth. The most commonly used imaging technique to detect resorption in teeth has been periapical radiographs. However, these images have been insufficient for adequate evaluation of root resorption caused by the impacted canine tooth [18, 19]. When impacted canines are positioned palatally or buccally, they superpose on the roots of adjacent incisors, and root resorption cannot be detected. Artifacts such as magnification, distortion, and superposition in two-dimensional X-rays have caused the positions of impacted canines to be incorrectly determined [19–21]. Since two-dimensional radiographs are insufficient for diagnosis, computed tomography has been recommended and shown to increase detection of root resorption by 50% [18, 22].
Compared to two-dimensional radiographs, CBCT provides superior features; it allows examination in the axial, sagittal, and coronal planes, and facilitates detailed evaluation of the tooth’s morphological structures, such as the crown and root, its relationship with surrounding anatomical features, and the amount of bone surrounding each tooth [23, 24].
These advantages have enabled its frequent use in impacted teeth as well as in many dental diagnoses. The literature contains numerous studies on this subject [1, 5, 15, 21], but studies evaluating the root resorption of adjacent lateral, canine, and premolar teeth of impacted canines using CBCT in the Turkish population have been limited [25, 26].
Although several studies have reported an association between impacted canines and root resorption, the extent and consistency of these effects remain unclear. This ambiguity justifies the need for further investigation.
Therefore, this study aimed to evaluate the effects of impacted maxillary canines on root resorption and periodontal structures of adjacent central incisors, lateral incisors, and first premolars using Cone Beam Computed Tomography (CBCT) across different age groups. In addition to assessing the prevalence and severity of root resorption, the study investigated the influence of canine localization (buccal, palatal, or central), eruption stage, follicle morphology and width, and contact with adjacent teeth. The impact of demographic variables such as age and gender on resorption was also examined. It was hypothesized (H0) that impacted maxillary canines had no significant effect on the root resorption or periodontal tissues of adjacent teeth.
Materials and methods
This retrospective research involved the use of images from patients who underwent CBCT scans at the Bolu Abant İzzet Baysal University Oral, Dental, and Maxillofacial Radiology Department between 2017 and 2021. The study protocol was approved by the local ethics committee of Bolu Abant İzzet Baysal University on 22.02.2022 (Protocol No: 44/2022).
Sagittal, coronal, and axial slices of the CBCT images, as well as multiplanar images showing all three slices, were carefully analyzed. The field of view (FOV) of the images was 16 × 6 cm², 16 × 8 cm², and 16 × 10 cm². Scanning was performed using an i-Cat imaging system (Model 17–19, Imaging Sciences International, Hatfield, PA, USA) at 120 kVp and 15 mA settings, with a voxel size of 0.3 mm and an exposure time of 4.8 s. Images were analyzed with i-CAT Vision Q imaging software. All CBCT images were independently evaluated by two experts, a maxillofacial radiologist (N.T.) and a periodontologist (E.A.Y.), both with four years of experience. Each expert independently assessed the images based on predefined radiographic parameters. In cases of disagreement between the two evaluators, consensus was reached through joint discussion. Due to this consensus-based approach, formal interobserver reliability measures such as Cohen’s kappa were not calculated.
In this study, CBCT images of 203 individuals with maxillary impacted canine teeth were analyzed. The age and gender information of the patients were recorded, and all personal identifiers, including patient names, were anonymized to ensure confidentiality. The age of the patients was determined as over 13 years, taking into account the eruption time of the canine tooth. Patients aged 13 years and older with images of sufficient resolution showing the entire impacted canine, including the lower margins of the nasal cavity and maxillary sinus, were included in the study. Images showing incomplete examination area, images with artifacts in the examination area, images of patients undergoing orthodontic treatment, cleft lip and palate, orthognathic surgery, and images of patients with fractures or pathology in the maxilla, partial eruption of impacted canine teeth, and congenital canine tooth deficiency were excluded from the study.
Radiographic evaluation parameters of images
Localization of the maxillary impacted canine
According to the crown position of the impacted tooth, classified as palatal, buccal, or central.
Eruption direction of the maxillary impacted canine: impacted canines were classified as following the eruption path (normal) and not following the eruption path (ectopic).
Effect on adjacent teeth: The adjacent teeth affected by the impacted canine tooth (central, lateral, 1 st premolar tooth) were recorded.
Status and degree of resorption in adjacent teeth
Examined in 4 categories [22];
No resorption: intact root surface, cement loss possible.
Slight resorption: Root resorption that extends towards the pulp up to half the dentin thickness. (Fig. 1A)
Fig. 1.
A Slight resorption of the lateral tooth on the sagittal section of CBCT, B Severe resorption of the central tooth on the sagittal section of CBCT
Moderate resorption: Root resorption extending halfway or more toward the pulp without exposing the pulp.
Severe resorption: Root resorption in which the pulp is exposed. (Fig. 1B)
Root resorption location
If there is root resorption on the adjacent tooth, it is examined in four categories according to its location in the root. These were classified as cervical, middle, apical, and combined. Resorptions involving more than one location on the root surface (usually the apical and middle third) were evaluated combined.
Periodontal contours of adjacent teeth
It was examined in three categories [15].
Unbroken Contours: Intact Lamina Dura and periodontal ligament space.
Broken contours, no root resorption: Destruction of the lamina dura on adjacent teeth, but no resorption.
Broken contours with root resorption: Destroyed periodontal contours and the presence of resorption.
Contact relationship between the canines and adjacent teeth
The contact relationship between the adjacent teeth and canines was examined in two categories [15].
No contact: In cases where the distance between the canine tooth and the adjacent tooth is more than 1 mm.
Contact: In cases where the distance between the canine tooth and the adjacent tooth is less than 1 mm.
Canine dental follicle shape
It was examined in two categories [27].
Symmetric: Round or spherical-shaped follicle surrounding the impacted canine. (Fig. 2A)
Fig. 2.
Symmetric (A) and asymmetric (B) shape of the dental follicle of the canine in CBCT axial section
Asymmetric: Irregularly shaped; in combination with the crown of a buccal, mesial, distal, palatal, or impacted canine. (Fig. 2B)
Canine dental follicle width
Every canine follicle’s width was determined as the greatest distance from the crown of the impacted canine to the periphery of the follicle, on axial scans, and divided into two categories: less than 3 mm and 3 mm or greater [28].
Eruption stage of the canine tooth
According to the cortical lining of the alveolar bone, the eruption pathway of the impacted maxillary canine is categorized in two ways [29].
Unbroken: The impacted canine follicle is within the alveolar cortical bone and encircled by a complete compact bone lining.
Broken: The impacted canine follicle is not completely covered by compact bone and has emerged from the alveolar bone.
Statistical analysis
The statistical analyses were conducted using IBM SPSS Statistics software version 14.0 (Chicago, IL, USA). The Kolmogorov-Smirnov test was employed to assess the age distribution. For the comparison of ages between genders, the Mann-Whitney U test was utilized. Categorical data were represented through frequencies and percentages. For cases with infrequent data, the chi-square test or Fisher’s exact test was used to examine associations between two categorical variables.
All statistical tests were carried out using a two-sided approach, with a p-value of less than 0.05 deemed statistically significant.
Results
The study evaluated CBCT images of 203 patients, including 149 females and 54 males. The study examined the effects of 123 right-impacted maxillary canines and 80 left-impacted maxillary canines on the periodontal contours and root resorption of the adjacent central, lateral, and first premolar teeth. The mean (± SD) age of female participants was 22.4 (± 10.7) years, and the mean (± SD) age of male participants was 23.2 (± 13.3) years.
No statistically significant difference in age was observed between genders (p = 0.645). There was no statistically significant relationship between gender and the presence of root resorption (p = 0.604). 60.6% of the impacted maxillary canine teeth were on the right side, and 39.4% were on the left. 74.9% of the impacted canine teeth had a symmetrical follicle shape, while 25.1% had an asymmetric shape. 88.7% of the examined impacted canine teeth had follicle widths less than or equal to 3 mm, and 11.3% had widths greater than 3 mm. The majority of the impacted canine teeth were in the palatal position 73.4%, and 92.1% were in the normal eruption path. 39.4% of the impacted canine teeth had unbroken cortical bone lining, while 60.6% had broken cortical bone lining.
The majority of impacted canines (70.9%) were in contact with adjacent teeth. Among these, lateral teeth were the most affected (57.6%), followed by central (26.6%) and premolar teeth (15.8%). A broken periodontal contour was observed in 53.7% of the adjacent teeth affected by the impacted maxillary canine teeth. Regarding root resorption, no root resorption was observed in 70% of the teeth adjacent to the impacted maxillary canine teeth, while slight, moderate, and severe root resorption was observed in 14.3%, 4.4%, and 11.3% of the cases, respectively. The location of root resorption was most frequently observed as combined in 12.8% of the cases. (Table 1)
Table 1.
Distribution of radiographic variables related to impacted canines according to gender
| Variables | Female (n) | Male (n) | Total N(%) |
|---|---|---|---|
| Impacted canine | |||
| 13 | 93 | 30 | 123 (60.6) |
| 23 | 56 | 24 | 80 (39.4) |
| Shape of dental follicle of canine | |||
| Symmetric | 111 | 41 | 152(74.9) |
| Asymmetric | 38 | 13 | 51(25.1) |
| Width of dental follicle of canine | |||
| ≤ 3 mm | 134 | 46 | 180(88.7) |
| > 3 mm | 15 | 8 | 23(11.3) |
| Localization of impacted canine | |||
| Palatal | 110 | 39 | 149(73.4) |
| Buccal | 23 | 7 | 30(14.8) |
| Central | 16 | 8 | 24(11.8) |
| Eruption direction of impacted canine | |||
| Normal | 141 | 46 | 187(92.1) |
| Ectopic | 8 | 8 | 16(7.9) |
| Cortical lining of the alveolar bone | |||
| Unbroken | 56 | 24 | 80(39.4) |
| Broken | 93 | 30 | 123(60.6) |
| Effected adjacent teeth | |||
| Central incisor | 40 | 14 | 54(26.6) |
| Lateral incisor | 87 | 30 | 117(57.6) |
| First Premolar | 22 | 10 | 32(15.8) |
| Contact relationship with adjacent teeth | |||
| No contact | 40 | 19 | 59(29.1) |
| Contact | 109 | 35 | 144(70.9) |
| Periodontal contours of adjacent teeth | |||
| Unbroken contours | 23 | 13 | 36(17.7) |
| Broken contours no root resorption | 86 | 23 | 109(53.7) |
| Broken contours with root resorption | 40 | 18 | 58(28.6) |
| Resorption of adjacent teeth | |||
| Absent | 106 | 36 | 142(70.0) |
| Present | 43 | 18 | 61(30.0) |
| Severity of root resorption of adjacent teeth | |||
| No resorption | 106 | 36 | 142(70.0) |
| Slight resorption | 23 | 6 | 29(14.3) |
| Moderate resorption | 5 | 4 | 9(4.4) |
| Severe resorption | 15 | 8 | 23(11.3) |
| Localization of root resorption of adjacent teeth | |||
| No resorption | 106 | 36 | 142(70.0) |
| Cervical third | 8 | 4 | 12(5.9) |
| Middle third | 7 | 1 | 8(3.9) |
| Apical third | 12 | 3 | 15(7.4) |
| Combined | 16 | 10 | 26(12.8) |
Data are shown as number of cases (n) and percentages (%). No statistically significant gender differences were found in any parameter (Chi-square and Fisher’s Exact test; p > 0.05 for all)
*This table presents the distribution of all evaluated radiographic parameters related to impacted canines according to patient gender
The study found that root resorption occurred in 26% of the central incisors affected by impacted canines, 33.3% of the lateral incisors, and 25% of the first premolar teeth (p = 0.490) (Table 2). When root resorption did occur, severe resorption was most frequently observed in the lateral teeth (14.5%), while slight resorption was most commonly observed in the central (16.7%) and first premolar teeth (12.5%) (p = 0.197) (Table 3). The effect of impacted canines on the periodontium of all adjacent teeth was most frequently seen as broken contours with no root resorption (p = 0.829) (Table 4).
Table 2.
Distribution of root resorption in teeth adjacent to impacted canines
| Adjacent teeth | No resorption | Resorption | Total |
|---|---|---|---|
| Central incisor | 40 | 14 | 54 |
| 74% | 26% | 100.0% | |
| Lateral incisor | 78 | 39 | 117 |
| 66.7% | 33.3% | 100.0% | |
| first premolar | 24 | 8 | 32 |
| 75.0% | 25.0% | 100.0% |
*No significant difference was found in the prevalence of root resorption among the different adjacent tooth types (central incisor, lateral incisor, first premolar) (Chi-square test; p = 0.490)
Table 3.
Severity of root resorption in teeth adjacent to impacted canines
| Adjacent teeth | Resorption degree | Total | |||
|---|---|---|---|---|---|
| No resorption | Slight resorption resorption | Moderate | Severe | ||
| Central incisor | 40a | 9a | 1a | 4a | 54 |
| 74% | 16.7% | 1.9% | 7.4% | 100.0% | |
| Lateral incisor | 78a | 16a | 6a | 17a | 117 |
| 66.7% | 13.7% | 5.1% | 14.5% | 100.0% | |
| First premolar | 24a. b | 4a. b | 2a. b | 2b | 32 |
| 75.0% | 12.5% | 6.25% | 6.25% | 100.0% | |
*Distribution of root resorption severity (no, slight, moderate, severe) in teeth adjacent to impacted canines. No significant differences in severity among tooth types (Chi-square test; p = 0.197). Each subscript letter indicates groups of resorption categories whose proportions do not differ significantly at the 0.05 level
Table 4.
Periodontal contours of teeth adjacent to impacted canines
| Adjacent teeth | Periodontal contours of adjacent teeth | Total | ||
|---|---|---|---|---|
| Unbroken contours | Broken contours no root resorption | Broken contours with root resorption | ||
| Central incisor | 8a | 32a | 14a | 54 |
| 14.8% | 59.3% | 25.9% | 100.0% | |
| Lateral incisor | 21a | 60a | 36a | 117 |
| 17.9% | 51.3% | 30.8% | 100.0% | |
| first premolar | 7a | 17a | 8a | 32 |
| 21.9% | 53.1% | 25.0% | 100.0% | |
*Distribution of periodontal contour status (unbroken, broken without root resorption, broken with root resorption) in central incisors, lateral incisors, and first premolars adjacent to impacted canines. No significant differences were found among tooth types (Chi-square test; p = 0.829). Each subscript letter indicates groups with no significant difference in proportions at the 0.05 level
The study found that when the impacted maxillary canine teeth were in contact with the adjacent teeth, root resorption was observed in all adjacent teeth, while no resorption was found when there was no contact (p = 0.005 for central incisors, p < 0.001 for lateral incisors, and p = 0.012 for first premolars; Table 5).
Table 5.
Relationship between contact with adjacent teeth and root resorption
| Adjacent teeth | Resorption of adjacent teeth | Contact relationship with adjacent teeth | ||
|---|---|---|---|---|
| No contact | Contact | p | ||
| Central incisor | No resorption | 15a | 25b | 0.005* |
| 37.50% | 62.50% | |||
| Resorption | 0a | 14b | ||
| 0.00% | 100.00% | |||
| Lateral incisor | No resorption | 32a | 46b | < 0.001* |
| 41.00% | 59.00% | |||
| Resorption | 0a | 39b | ||
| 0.00% | 100.00% | |||
| First premolar | No resorption | 12a | 12b | 0.012* |
| 50.00% | 50.00% | |||
| Resorption | 0a | 8b | ||
| 0.00% | 100.00% | |||
*Relationship between contact with adjacent teeth and root resorption in central incisors, lateral incisors, and first premolars adjacent to impacted canines. Significant associations were found for all tooth types (Chi-square test; p < 0.05). Each subscript letter indicates groups with significantly different proportions
Impacted canines were most frequently located in the palatal position (73.4%), followed by buccal (14.8%) and central (11.8%) positions (Table 1). When impacted canines were located palatally, they caused root resorption in 85.7% of affected central incisors, 78.6% of lateral incisors, and 25.0% of first premolars. Buccally positioned canines caused resorption in 7.7% of lateral incisors and 50.0% of first premolars, while centrally positioned canines led to resorption in 14.3% of central incisors, 13.7% of lateral incisors, and 25.0% of first premolars. However, no statistically significant association was found between the localization of the impacted canine and root resorption in any of the adjacent teeth (p = 0.064 for central incisors, p = 0.338 for lateral incisors, and p = 0.544 for first premolars; Table 6).
Table 6.
Relationship between localization of impacted canine and root resorption in adjacent teeth
| Localization of impacted canine | |||||
|---|---|---|---|---|---|
| Palatal | Buccal | Central | p | ||
| Central incisor | No resorption | 40 | - | 0 | 0.064 |
| 100.00% | - | 0.00% | |||
| Resorption | 12 | - | 2 | ||
| 85.70% | - | 14.30% | |||
| Lateral incisor | No resorption | 63 | 4 | 11 | 0.338 |
| 80.80% | 5.10% | 14.10% | |||
| Resorption | 29 | 5 | 5 | ||
| 78.60% | 7.70% | 13.70% | |||
| First premolar | No resorption | 3 | 17 | 4 | 0.544 |
| 12.50% | 70.80% | 16.70% | |||
| Resorption | 2 | 4 | 2 | ||
| 25.00% | 50.00% | 25.00% | |||
*No statistically significant relationship was found between the localization of impacted canines and root resorption in adjacent teeth (Chi-square test; p > 0.05 for all comparisons)
Canines with symmetric dental follicles tended to be associated with more frequent resorption in adjacent teeth compared to asymmetric follicles, and follicles ≤ 3 mm in width showed slightly higher resorption rates than those > 3 mm. However, neither the shape nor the width of the dental follicle showed statistically significant associations with root resorption in any adjacent tooth group (for central incisors: p = 0.129 and p = 0.173; for lateral incisors: p = 0.235 and p = 0.750; for first premolars: p = 0.691 and p = 1.000; Table 7).
Table 7.
Relationship between shape and width of canine dental follicles and root resorption in adjacent teeth
| Width of dental follicle of canine | Shape of dental follicle of canine | ||||||
|---|---|---|---|---|---|---|---|
| ≤ 3 mm | > 3 mm | p | Symmetric | Asymmetric | p | ||
| Central incisor | No resorption | 37a | 3a | 0.173 | 34a | 6a | 0.129 |
| 92.50% | 7.50% | 85.00% | 15.00% | ||||
| Resorption | 11a | 3a | 9a | 5a | |||
| 78.60% | 21.40% | 64.30% | 35.70% | ||||
| Lateral incisor | No resorption | 70a | 8a | 0.750 | 64a | 14a | 0.235 |
| 89.70% | 10.30% | 82.10% | 17.90% | ||||
| Resorption | 36a | 3a | 28a | 11a | |||
| 92.30% | 7.70% | 71.80% | 28.20% | ||||
| First premolar | No resorption | 19a | 5a | 1.000 | 12a | 12a | 0.691 |
| 79.20% | 20.80% | 50.00% | 50.00% | ||||
| Resorption | 7a | 1a | 5a | 3a | |||
| 87.50% | 12.50% | 62.50% | 37.50% | ||||
*No statistically significant association was found between the shape or width of the dental follicle and root resorption in adjacent teeth (Chi-square test; p > 0.05)
Regarding cortical bone integrity, root resorption was more frequently observed in central incisors when the alveolar cortical lining was unbroken (57.1%). In comparison, resorption was more common in lateral incisors (76.9%) and first premolars (62.5%) when the cortical lining was broken. However, none of these associations were statistically significant (p = 0.757 for central incisors, p = 0.098 for lateral incisors, and p = 1.000 for first premolars; Table 8).
Table 8.
Relationship between cortical bone integrity (Eruption Stage) of impacted canines and root resorption in adjacent teeth
| Cortical lining of the alveolar bone | ||||
|---|---|---|---|---|
| Unbroken | Broken | p | ||
| Central incisor | No resorption | 19a | 21a | 0.757 |
| 47.50% | 52.50% | |||
| Resorption | 8a | 6a | ||
| 57.10% | 42.90% | |||
| Lateral incisor | No resorption | 31a | 47a | 0.098 |
| 39.70% | 60.30% | |||
| Resorption | 9a | 30a | ||
| 23.10% | 76.90% | |||
| First premolar | No resorption | 10a | 14a | 1.000 |
| 41.70% | 58.30% | |||
| Resorption | 3a | 5a | ||
| 37.50% | 62.50% | |||
*Association between cortical lining status of the alveolar bone (unbroken vs. broken) and root resorption in adjacent teeth. No significant differences were observed (Chi-square test; p > 0.05)
Discussion
In this study, the null hypothesis (H0) assumed that impacted canine teeth have no significant effect on root resorption in adjacent teeth. However, the findings of this study indicate that this hypothesis is rejected, primarily due to the significant association between contact of impacted canines with adjacent roots and the occurrence of root resorption. Therefore, early identification of root resorption risk in adjacent teeth, especially incisors and premolars, is crucial for effective orthodontic treatment planning. Root resorption can arise from the physical proximity of impacted canines or as a consequence of orthodontic forces during alignment. Radiographic monitoring, particularly with CBCT, remains the gold standard for early detection and prevention of irreversible damage to adjacent teeth [28]. In the present study, root resorption was observed in 26% of central incisors, 33.3% of lateral incisors, and 25% of first premolars adjacent to impacted maxillary canines. These results are broadly consistent with previous CBCT-based studies. For example, Liu et al. [24] reported resorption in 27.2% of lateral incisors and 23.4% of central incisors, while Simić et al. [16] observed root resorption in 36.3% of lateral incisors, 23.8% of central incisors, and 6.3% of premolars. Variations in prevalence across studies can be attributed to differences in imaging modalities, population characteristics, and diagnostic criteria [15, 17, 22, 24, 30, 31].
Among the evaluated variables, contact between the impacted canine and adjacent teeth emerged as the most significant factor associated with root resorption. The simultaneous evaluation of multiple radiographic parameters in this study underscores the value of CBCT as a comprehensive diagnostic tool, enabling early identification of risk factors such as root contact before irreversible damage occurs. In our sample, 70.9% of impacted canines were in contact with adjacent roots, and in all cases with resorption, contact was present (p < 0.05). Notably, no root resorption was observed in cases without contact, emphasizing the clinical importance of identifying such contact in the early stages of treatment planning. This finding aligns with those of Akkuc et al. [32], who observed contact in 88.2% of resorbed lateral incisors, and Lai et al. [28], who also reported a significant association between contact and resorption. The presence of cytokines and resorptive enzymes in the follicle may also contribute to this process [15, 22].
Root resorption was most commonly located in the middle and apical thirds of the root, observed in 12.8% of cases. This pattern is consistent with Ericson and Kurol [22], who reported that 60% of resorption cases involved these areas, and Rimes et al. [33], who found combined resorption in 60% of incisors. These findings emphasize the need to assess the full length of the root in multiple planes.
In the present study, slight resorption was more frequently observed in central incisors (16.7%) and premolars (12.5%), whereas severe resorption was more prevalent in lateral incisors (14.5%). Similar findings were reported by Strbac et al. [15] and Lai et al. [28] who also found severe resorption more frequently in lateral teeth, likely due to their anatomical proximity to the canine.
Periodontal contour integrity was evaluated as an additional parameter in this study. Broken periodontal contours were observed in 53.7% of adjacent teeth, including cases without root resorption. This indicates that disruption of the periodontal contour does not necessarily imply the presence of root resorption, highlighting the importance of assessing this parameter alongside other diagnostic factors. These findings support those of Strbac et al. [15], who reported disrupted contours in 41% of central incisors and 79.7% of lateral incisors. Ericson et al. [27] also found a significant association between the proximity of the canine follicle and breakdown of periodontal contours. Even in cases without root resorption, impacted canines frequently caused alterations in the periodontal contours of adjacent teeth. Therefore, disruption of periodontal contour alone should not be interpreted as definitive evidence of root resorption.
Although palatal impaction was the most prevalent in our study (73.4%), there was no significant association between impaction location and resorption severity (p >0.05). Similar findings were reported in other studies [15, 28, 30]. Nonetheless, anatomical differences between populations may influence impaction patterns, with palatal impactions more common in European populations and labial/central impactions in Asian populations [34]. Previous studies have shown that racial and etiological factors also influence the position of impacted canines in different populations [35, 36].
The higher resorption rates observed in cases with symmetrical follicles, although not statistically significant, may suggest that follicle symmetry influences the directional distribution of eruptive pressure on adjacent roots, potentially increasing localized risk. This trend aligns with the findings of Strbac et al. [15], who also reported greater resorption in cases with symmetrical follicles. On the other hand, Ericson et al. [27] noted a higher resorption rate in asymmetrical follicles, although this difference was similarly not statistically significant. These conflicting results may stem from variations in measurement criteria, sample demographics, or the inherent subjectivity in defining follicle morphology. Taken together, the findings highlight the potential diagnostic value of follicular shape, warranting further investigation in standardized, prospective studies.
Follicle width greater than 3 mm did not significantly impact resorption in our study. Similar conclusions were drawn in previous studies [15, 27, 32], while Dağsuyu et al. [37] suggested that larger follicles may be associated with more severe resorption. These discrepancies may reflect methodological differences, including voxel size and sample heterogeneity.
The continuity of the cortical lining around the impacted canine also showed a non-significant trend: resorption was more frequently observed in adjacent central incisors when the cortical lining was intact, and in lateral and premolar teeth when it was disrupted. Strbac et al. [15] similarly reported more frequent resorption in cases with disrupted cortical integrity, albeit without statistical significance. In contrast, Lai et al. [28] found a higher prevalence of resorption when the cortical lining remained intact. These contradictory findings underscore the complexity of interpreting cortical changes in CBCT imaging and suggest that cortical integrity alone may not serve as a reliable predictor of resorption risk. Differences in CBCT protocols, including voxel size, field of view, and image interpretation criteria, may partly account for these inconsistencies among studies. Instead, it should be assessed in conjunction with other radiographic parameters such as root proximity and follicle morphology. Although these parameters did not reach statistical significance, their potential contribution to root resorption risk warrants further investigation.
Although root resorption was numerically more common in female patients in our study, the difference was not statistically significant, aligning with prior findings that gender does not significantly influence the incidence or severity of root resorption [15, 24].
This study offers a comprehensive assessment by simultaneously evaluating follicle morphology, contact relationships, cortical continuity, and periodontal contour in a substantial CBCT dataset. Importantly, it provides valuable data from a Turkish population, which is underrepresented in the literature, thereby contributing to a broader understanding of impacted canine-related root resorption across different populations. Unlike many previous studies that focused on isolated parameters, our approach sheds light on the multifactorial etiology of root resorption.
Nonetheless, several limitations must be acknowledged. The retrospective design precluded the inclusion of clinical parameters such as tooth vitality and mobility. The sample was geographically limited, and the predominance of palatal impactions restricted subgroup analyses. Additionally, the voxel size of 0.3 mm may not capture subtle resorptive changes compared to higher-resolution scans. Future studies with prospective design, multi-center sampling, and higher-resolution CBCT protocols are needed to validate and expand upon these findings. These findings demonstrate that CBCT is an indispensable tool for the early detection of root resorption risk in orthodontic treatment planning. Therefore orthodontists should prioritize careful evaluation of contact between impacted canines and adjacent teeth to prevent irreversible root damage and optimize treatment outcomes.
Conclusions
The presence of root contact in impacted maxillary canines should be regarded not as an incidental anatomical finding but as a primary diagnostic risk factor. This study underscores the necessity of incorporating CBCT assessments into the early stages of orthodontic treatment planning to facilitate timely intervention against the risk of root resorption. Rather than focusing solely on the location of impaction (e.g., palatal or labial), clinicians are advised to adopt three-dimensional evaluation strategies based on root proximity and follicular morphology. These findings support the adoption of personalized, imaging-guided orthodontic protocols that minimize irreversible root damage and enhance long-term treatment outcomes.
Acknowledgements
Not applicable.
Authors’ contributions
NT: Methodology, Validation, Investigation, Visualization, Writing - Original Draft, Writing-Reviewing, and Editing. EAY: Methodology, Investigation, Writing - Original Draft, Writing-Reviewing, and Editing DGB: Formal analysis, Data curation GU: Conceptualization.
Funding
The authors did not receive any funding from any organizations.
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
Declarations
Ethics approval and consent to participate
The ethics committee of Bolu Abant İzzet Baysal University approved the study (protocol no: 2022/44). The exemption from informed consent was approved by the ethics committee of Bolu Abant İzzet Baysal University. All methods were performed in accordance with the relevant guidelines and regulations.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
- 1.Alqerban A, Jacobs R, Lambrechts P, Loozen G, Willems G. Root resorption of the maxillary lateral incisor caused by impacted canine: a literature review. Clin Oral Investig. 2009;13(3):247–55. [DOI] [PubMed] [Google Scholar]
- 2.Cosola S, Kim YS, Park YM, Giammarinaro E, Covani U. Coronectomy of mandibular third molar: four years of follow-up of 130 cases. Medicina (B Aires). 2020;56(12):654. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Tymofiyeva O, Rottner K, Jakob PM, Richter EJ, Proff P. Three-dimensional localization of impacted teeth using magnetic resonance imaging. Clin Oral Investig. 2010;14(2):169–76. [DOI] [PubMed] [Google Scholar]
- 4.Cakir Karabas H, Ozcan I, Erturk AF, Guray B, Unsal G, Senel SN. Cone-beam computed tomography evaluation of impacted and transmigrated mandibular canines: a retrospective study. Oral Radiol. 2021;37(3):403–11. [DOI] [PubMed] [Google Scholar]
- 5.Oberoi S, Knueppel S. Three-dimensional assessment of impacted canines and root resorption using cone beam computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;113(2):260–7. [DOI] [PubMed] [Google Scholar]
- 6.Bedoya MM, Park JH. A review of the diagnosis and management of impacted maxillary canines. J Am Dent Assoc. 2009;140(12):1485–93. [DOI] [PubMed] [Google Scholar]
- 7.Noorollahian S, Shirban F. Chair time saving method for treatment of an impacted maxillary central incisor with 15-month follow-up. Dent Res J (Isfahan). 2018;15(2):150–4. [PMC free article] [PubMed] [Google Scholar]
- 8.Crincoli V, Tettamanti L, Lucchina AG, et al. Correlation between maxillary canine impaction and facial biotype. J Craniofac Surg. 2019;30(4):1044–8. [DOI] [PubMed] [Google Scholar]
- 9.Evren AD, Nevzatoğlu Ş, Arun T, Acar A. Periodontal status of ectopic canines after orthodontic treatment. Angle Orthod. 2014;84(1):18–23. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Bayram M, Ozer M, Sener I. Maxillary canine impactions related to impacted central incisors: two case reports. J Contemp Dent Pract. 2007;8(6):72–81. [PubMed] [Google Scholar]
- 11.Mazinis E, Zafeiriadis A, Karathanasis A, Lambrianidis T. Transmigration of impacted canines: prevalence, management and implications on tooth structure and pulp vitality of adjacent teeth. Clin Oral Investig. 2012;16(2):625–32. [DOI] [PubMed] [Google Scholar]
- 12.Mohammadi Z, Cehreli C, Shalavi Z, Giardino S, Palazzi L, Asgary F. Management of root resorption using chemical agents: a review. Iran Endod J. 2016;11(1):1–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Vlaskalic V, Boyd RL, Baumrind S. Etiology and sequelae of root resorption. Semin Orthod. 1998;4(2):124–31. [DOI] [PubMed] [Google Scholar]
- 14.Simić S, Nikolić P, Stanišić Zindović J, et al. Root resorptions on adjacent teeth associated with impacted maxillary canines. Diagnostics. 2022;12(2):380. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Strbac GD, Foltin A, Gahleitner A, Bantleon HP, Watzek G, Bernhart T. The prevalence of root resorption of maxillary incisors caused by impacted maxillary canines. Clin Oral Investig. 2013;17(2):553–64. [DOI] [PubMed] [Google Scholar]
- 16.Simić S, Nikolić PV, Pavlović J, Vukićević V, Vujačić A. Root resorption of adjacent teeth due to maxillary impacted canines–comparative analysis of the findings on cone beam computed tomography and panoramic imaging. Vojnosanit Pregl. 2023;80(2):136–42. [Google Scholar]
- 17.Sosars P, Jakobsone G, Neimane L, Mukans M. Comparative analysis of panoramic radiography and cone-beam computed tomography in treatment planning of palatally displaced canines. Am J Orthod Dentofacial Orthop. 2020;157(5):719–27. [DOI] [PubMed] [Google Scholar]
- 18.Ericson S, Kurol J. Incisor root resorptions due to ectopic maxillary canines imaged by computerized tomography: a comparative study in extracted teeth. Angle Orthod. 2000;70(4):276–83. [DOI] [PubMed] [Google Scholar]
- 19.Ericson S, Kurol J. Incisor resorption caused by maxillary cuspids. A radiographic study. Angle Orthod. 1987;57(4):332–46. [DOI] [PubMed] [Google Scholar]
- 20.Tsao DH, Kazanoglu A, McCasland JP. Measurability of radiographic images. Am J Orthod. 1983;84(3):212–6. [DOI] [PubMed] [Google Scholar]
- 21.Ericson S, Kurol J. CT diagnosis of ectopically erupting maxillary canines–a case report. Eur J Orthod. 1988;10(2):115–21. [DOI] [PubMed] [Google Scholar]
- 22.Ericson S, Kurol PJ. Resorption of incisors after ectopic eruption of maxillary canines: a CT study. Angle Orthod. 2000;70(6):415–23. [DOI] [PubMed] [Google Scholar]
- 23.Botticelli S, Verna C, Cattaneo PM, Heidmann J, Melsen B. Two- versus three-dimensional imaging in subjects with unerupted maxillary canines. Eur J Orthod. 2011;33(4):344–9. [DOI] [PubMed] [Google Scholar]
- 24.Liu DG, Zhang WL, Zhang ZY, Wu YT, Ma XC. Localization of impacted maxillary canines and observation of adjacent incisor resorption with cone-beam computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;105(1):91–8. [DOI] [PubMed] [Google Scholar]
- 25.Köse E, Canger EM. Evaluation of maxillary impacted teeth and their relationship with adjacent teeth and anatomic structures with cone beam computed tomography. J Dent Indones. 2020;27(3):131–8. [Google Scholar]
- 26.Dağsuyu İM, Okşayan R, Kahraman F, Aydın M, Bayrakdar İŞ, Uğurlu M. The relationship between dental follicle width and maxillary impacted canines’ descriptive and resorptive features using cone-beam computed tomography. BioMed Res Int. 2017;2017:2938691. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Ericson S, Bjerklin K, Falahat B. Does the canine dental follicle cause resorption of permanent incisor roots? A computed tomographic study of erupting maxillary canines. Angle Orthod. 2002;72(2):95–104. [DOI] [PubMed] [Google Scholar]
- 28.Lai CS, Bornstein MM, Mock L, Heuberger BM, Dietrich T, Katsaros C. Impacted maxillary canines and root resorptions of neighbouring teeth: a radiographic analysis using cone-beam computed tomography. Eur J Orthod. 2013;35(4):529–38. [DOI] [PubMed] [Google Scholar]
- 29.Ericson S, Bjerklin K. The dental follicle in normally and ectopically erupting maxillary canines: a computed tomography study. Angle Orthod. 2001;71(5):333–42. [DOI] [PubMed] [Google Scholar]
- 30.Walker L, Enciso R, Mah J. Three-dimensional localization of maxillary canines with cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2005;128(4):418–23. [DOI] [PubMed] [Google Scholar]
- 31.Alqerban A, Jacobs R, Fieuws S, Willems G. Comparison of two cone beam computed tomographic systems versus panoramic imaging for localization of impacted maxillary canines and detection of root resorption. Eur J Orthod. 2011;33(1):93–102. [DOI] [PubMed] [Google Scholar]
- 32.Akkuc S, Duruk G, Duman S. Evaluation of impacted canines’ localization and adjacent lateral incisors’ root resorption with orthopantomography and cone-beam computed tomography. Oral Radiol. 2021;37(3):476–86. [DOI] [PubMed] [Google Scholar]
- 33.Rimes RJ, Mitchell CN, Willmot DR. Maxillary incisor root resorption in relation to the ectopic canine: a review of 26 patients. Eur J Orthod. 1997;19(1):79–84. [DOI] [PubMed] [Google Scholar]
- 34.Peck S, Peck L, Kataja M. The palatally displaced canine as a dental anomaly of genetic origin. Angle Orthod. 1994;64(4):249–56. [DOI] [PubMed] [Google Scholar]
- 35.Yan B, Sun Z, Fields H, Wang L, Luo L. Etiologic factors for buccal and palatal maxillary canine impaction: a perspective based on cone-beam computed tomography analyses. Am J Orthod Dentofacial Orthop. 2013;143(4):527–34. [DOI] [PubMed] [Google Scholar]
- 36.Gudelevičiūtė I, Spaičytė N, Smailienė D. Skeletal and dental maxillary morphological characteristics in patients with impacted canines: systematic review and meta-analysis. Eur J Orthod. 2023;45(6):832–41. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Dağsuyu İM, Kahraman F, Okşayan R. Three-dimensional evaluation of angular, linear, and resorption features of maxillary impacted canines on cone-beam computed tomography. Oral Radiol. 2018;34(1):66–72. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.