Journal of Orofacial Sciences

ORIGINAL ARTICLE
Year
: 2022  |  Volume : 14  |  Issue : 1  |  Page : 21--27

Evaluation of the Association of Alveolar Bone Dimensions in Unilateral Palatally Impacted Canine: A Cone-Beam Computed Tomography Analysis


Amir Hooman Sadrhaghighi1, Sajad Farrokhi2, Maryam Rad3, Mahsa Eskandarinezhad4,  
1 Department of Orthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran
2 Kerman University of Medical Sciences, Kerman, Iran
3 Oral and Dental Diseases Research Center and Kerman Social Determinants on Oral Health Research Center, Kerman University of Medical Sciences, Kerman, Iran
4 Department of Endodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran

Correspondence Address:
Sajad Farrokhi
Resident in periodontics, Faculty of Dentistry, Kerman University of Medical Sciences, Kerman
Iran

Abstract

Introduction: Maxillary canine impaction is directly associated with changes in dentoalveolar dimensions and adjacent teeth displacement. This investigation aimed to perform skeletal and dentoalveolar measurements of unilateral palatally impacted canines and compare them with the unaffected contralateral side using cone-beam computed tomography (CBCT). Materials and Methods: This cross-sectional study examined unilaterally impacted canines of the maxilla in 46 CBCT scans. The lateral incisor angulations, nasal cavity width, alveolar bone height, bucco-palatal width, and arch perimeter were measured and compared on both impaction and unaffected sides. All statistical tests were two-sided and analyzed using the paired sample t test and the Kolmogorov-Smirnov test using SPSS 26.0. A P < 0.05 was deemed statistically meaningful. Results: On the impacted side, a significant decrease was observed in the width of the alveolar bone at the height of 2 mm (P = 0.001). Furthermore, at the height of 10 mm, the impacted side was significantly thicker (P = 0.001). There was a statistically significant difference between the maxillary arch width on the nonimpacted and impacted sides (P = 0.001); the distance of mid-palatine raphe to the first premolar and canine proximal bone on the non-impaction side was significantly lower (13.251 ± 1.75 mm) compared to the impacted side (14.334 ± 1.80 mm) (P = 0.01). The external angle of the lateral maxillary incisor on the impacted side (86.803 ± 8.425°) showed a significant decrease (P = 0.001) compared with the contralateral side (91.403 ± 6.791°). Conclusion: The lateral incisors’ lateral angulations, the inter-premolar width, and the alveolar bone thickness can be affected by palatally impacted canine teeth. However, the height of the alveolar bone and the width of the nasal cavity are not affected.



How to cite this article:
Sadrhaghighi AH, Farrokhi S, Rad M, Eskandarinezhad M. Evaluation of the Association of Alveolar Bone Dimensions in Unilateral Palatally Impacted Canine: A Cone-Beam Computed Tomography Analysis.J Orofac Sci 2022;14:21-27


How to cite this URL:
Sadrhaghighi AH, Farrokhi S, Rad M, Eskandarinezhad M. Evaluation of the Association of Alveolar Bone Dimensions in Unilateral Palatally Impacted Canine: A Cone-Beam Computed Tomography Analysis. J Orofac Sci [serial online] 2022 [cited 2022 Aug 10 ];14:21-27
Available from: https://www.jofs.in/text.asp?2022/14/1/21/353476


Full Text



 Introduction



Failure in permanent teeth eruption is a dental anomaly, and according to the study conducted by Fardi et al., any permanent tooth can remain impacted.[1] An unerupted tooth is considered impacted when the root is entirely developed, and the contralateral tooth has completely erupted.[2] The maxillary canine is the second most frequently impacted tooth in the oral cavity after the third molar.[3]-[5] The canine impaction is more common in the maxilla than in the mandible, and canine impactions are more often unilateral than bilateral.[5] According to Coulter’s study, this impaction occurs when canines deviate from their normal eruption pathway, which is 22 mm. This phenomenon can occur palatally or buccally.[6],[7] The prevalence of palatal impaction for canines is 0.8% to 3%.[8]

Impacted teeth can be associated with different dentoalveolar and dental arch dimensions.[2] For instance, an impacted canine can affect the space in the dental arch. Palatal impaction is associated with excessive space, while buccal impaction occurs in cases with insufficient space in the dental arch.[9] Another factor to be considered in canine impaction cases is arch width. McConnell claims that palatal impaction is associated with a small maxillary anterior width.[10] However, Langberg and Peck did not find any significant relationship between these two variables.[11]

In orthodontic diagnosis and treatment, the accurate localization of the impacted tooth and its effect on adjacent structures such as alveolar bone thickness and height, maxillary arch width and perimeter, and maxillary incisor root angle are essential factors to consider.[12] Radiographic images can be used to obtain this information. However, using conventional radiographic methods is not convenient due to the superimposition of the adjacent structures in the radiographic images.[13] Today, using CBCT has become prevalent due to the precise and reliable information it provides.[14]-[16]

Few studies have been conducted on the effect of unilateral palatal impaction on dentoalveolar variables, and the few that have been conducted have reached contradictory results.[17] Tadinada et al. compared the alveolar bone dimensions on the impacted maxillary canine side with those on the contralateral side.[2] They found that compared with the contralateral side, the height of the alveolar bone and the arch perimeter were significantly smaller on the impacted side.[2] In another study, Oleo-Aracena et al. did not observe any significant difference between the alveolar bone height of the impacted side and its contralateral side; however, lateral incisors presented a greater distal angulation in their study on the impacted side compared with the contralateral side.[17] In general, sample sizes of previous studies are small and results are contradictory regarding dentoalveolar variable correlations. Moreover, most studies have not employed CBCT to analyze the samples, which could affect the measurement accuracy; CBCT provides 3D images with higher accuracy compared with conventional methods.[18] This method can accurately reconstruct linear and angular measurements for research purposes without significant error.

Therefore, conducting a study with a larger sample size using CBCT 3D images to obtain more accurate results is necessary. The present study aimed to eliminate the limitations in previous studies. To this end, the study population was increased. The effect of maxillary canine impaction on adjacent teeth displacement and skeletal and dentoalveolar variables, including nasal cavity width, alveolar bone height, bucco-palatal width, and the arch perimeter, was evaluated and compared on both impaction and unaffected sides using CBCT imaging.

 Materials and Methods



The present study was a cross-sectional study in which CBCT images of patients with unilateral maxillary canine impaction referred to the radiology department in Tabriz University of Medical Sciences Faculty of Dentistry were analyzed. Ethical approval for this study (protocol No. IR.TBZMED.REC.1397.645) was provided by Tabriz University of Medical Sciences, Tabriz, Iran on 25 sept 2021.

In this study, 46 CBCTs of patients with unilateral maxillary canine impaction were gathered and analyzed after acquiring written informed consent from the participants. The inclusion criteria were unilateral palatal impaction of the maxillary canine and the complete eruption of the contralateral canine. Exclusion criteria included having pathologic conditions, such as supernumerary teeth, cysts, mesial tilting of the first premolar, systemic problems affecting the bone, or having received orthodontic treatment.

Using CBCTs produced by the NewTom VGi machine (Verona, Italy), six variables were determined to assess the association between dentoalveolar dimensions and the palatally impacted canine. Afterward, DICOM files were analyzed and measured by Planmeca Romexis software release 5.3.R.

The first and second variables to be analyzed were alveolar bone height and thickness. The criterion used to determine the alveolar bone height on both sides measured the line drawn from the alveolar crest to the nasal cavity floor [Figure 1]A and B. The alveolar bone height in the sagittal view of the impacted side in the hypothetical condition of edentulism, which is suitable for an impacted canine, was measured and compared with the contralateral side in which the canine had naturally erupted. This study measured the alveolar ridge bucco-palatal thickness in the sagittal views 2, 6, and 10 mm from the alveolar crest [Figure 1]C. The bucco-palatal thickness was measured in the center of the impacted side’s dentulous and edentulous sections.{Figure 1}

In the measurement of the third variable, the criterion for determining the arch width is the distance between the mid-palatine raphe to the proximal alveolar bone crest between the impacted canine and the first maxillary premolar at ½ bucco-palatal thickness of the proximal bone on the impacted side and the distance between the mid-palatine raphe to the proximal bone between the erupted canine and the first premolar at half bucco-palatal thickness of the non-impacted side proximal bone. This distance was measured in axial sections at the bone crest level [Figure 2]A.{Figure 2}

For measuring the fourth variable, the criterion for determining the arch perimeter on both sides in the tooth one-third cervical cut of CBCT image measured the line connecting the first maxillary molar’s distal to the mid-palatal suture on the nonimpacted and impacted sides [Figure 2]B.

In measuring the fifth variable, the criterion for determining the lateral incisor angulation on both sides was the external angle between the nasal horizontal axis and the lateral incisor’s longitudinal axis. The lateral incisor’s longitudinal axis external angle was measured according to the nasal floor’s tangent line on the impacted and nonimpacted sides [Figure 3]A.{Figure 3}

The criterion for determining the nasal cavity thickness on both sides was the distance between the nasal cavity’s lateral walls and the anterior nasal spine on the impacted and non-impacted sides in millimeters [Figure 3]B.

Sample size calculation

Using the results of Tadinada et al.’s[2] study and considering the arch perimeter means of 41.3 ± 2.49 and 43.54 ± 2.37 on the impacted and nonimpacted sides, respectively, with α = 0.05, 80% power, and 10% error, 46 samples were selected. Two examiners, who were completely capable of both evaluating the volume and manipulating the contrast and histogram, measured all CBCT scan parameters. If there was a disagreement between the two examiners, a third person (third radiologist) was consulted.

Statistical approach

The results were reported using descriptive statistic methods (mean ± standard deviation). The Kolmogorov-Smirnov test was used to analyze data normality. Based on data normality in this test, paired t test was used to assess the mean of alveolar bone height, bucco-palatal alveolar bone thickness at the three heights of 2, 6, and 10 mm, arch width and perimeter, lateral incisor angulation, and nasal cavity thickness on the nonimpacted and impacted sides. SPSS Ver. 26 was used for statistical analysis, and P < 0.05 was considered statistically significant. Moreover, the correlation between the researcher’s observations (the first examiner) and the radiologist’s (the second examiner) was measured using inter-rater and intra-rater agreement coefficients.

 Results



In the present study, 46 CBCT scans of patients with unilaterally impacted maxillary canines were analyzed.

Measurements of the arch perimeter, maxillary arch width, alveolar bone height, lateral incisor angulation, and nasal cavity thickness on the impacted and nonimpacted sides are presented in [Table 1] based on descriptive measures of mean, standard deviation, and minimum and maximum values. After a 2-week interval, all the parameters mentioned above were measured again by the researcher (the first examiner) and the results were recorded. An agreement coefficient greater than 0.80 shows acceptable reliability. Based on the results, all coefficients obtained were more than 0.88. Therefore, the inter-rater reliability coefficient between the researcher’s and the radiologist’s results and the intra-rater reliability coefficient between the researcher’s results in the two stages showed acceptable reliability.{Table 1}

Alveolar bone thickness at 2 mm was significantly smaller (P = 0.001) on the impacted side (6.822 ± 1.214 mm) compared with the nonimpacted side (7.852 ± 1.178 mm). At 10 mm, the thickness of the impacted side (9.489 ± 1.614 mm) was significantly greater than that of the nonimpacted side (8.43 ± 1.658 mm) (P = 0.001). Maxillary arch width was found to be significantly different on the impacted side (13.251 ± 1.75 mm) and the nonimpacted side (14.343 ± 1.80 mm) (P = 0.001). Moreover, the external angle of the impacted side lateral maxillary incisor (86.803 ± 8.425°) showed a significant decrease compared with the contralateral side (91.403 ± 6.791°) (P = 0.001). Other dentoalveolar variables did not present any significant difference in [Table 2].{Table 2}

The bucco-palatal alveolar bone thickness at 2, 6, and 10 mm, arch width, and lateral incisor angulation were measured by the researcher (the first examiner) and the radiologist (the second examiner) using CBCT scans and both recorded the results.

 Discussion



In the present study, the alveolar bone thickness (bucco-palatal width) was less at 2 mm height from the alveolar bone crest on the impacted side compared to the nonimpacted side. At 10 mm height from the alveolar bone crest, however, the thickness on the impacted side was greater than that of the nonimpacted side. Nonetheless, no significant results were obtained for these measurements at 6 mm. In fact, the thickness patterns of the bone on the two sides were inverse. In this study, the alveolar bone thickness was measured in the canine region. Tadinada et al. reported similar results for measurements at 2 mm but did not find significant results for 6 and 10 mm.[2] The alveolar process develops following the tooth root elongation and tooth eruption. The teeth morphology, their axis, and inclination affect the thickness and height of the alveolar process.[2] As a matter of fact, local alveolar ridge resorption occurs in the absence (for instance, extraction and impaction) of a tooth. The less thickness of the alveolar bone on the impacted side at 2 mm could be due to the canine’s absence at this height because of impaction. On the other hand, due to the presence of impacted canine bud at 10 mm, the impacted side’s bone thickness was greater than the nonimpacted side’s. However, the contradictory results of the studies necessitate the need for further evaluations.

Maxillary arch width showed a significant decrease compared with the nonimpacted side. In other words, the distance of the mid-palatine raphe to the first premolar and canine proximal bone on the non-impaction side was significantly lower (13.251 ± 1.75 mm) compared to the impacted side (14.334 ± 1.80 mm). Arboleda-Ariza, D Oleo-Aracena, McConnel, Schindel, Al-Khateeb, and Saiar’s results were in line with those of the present study.[10],[17],[19]-[22] In agreement, Yan et al. reported a reduced maxillary width in patients with buccally displaced canines using CBCT.[14] This decrease in width on the impacted side was probably due to the incomplete development on the impacted side compared with the nonimpacted side with a normally erupted canine. This finding might indicate that smaller maxillary transverse dimensions lead to a canine impaction probability. Al-Nimri and Gharaibeh reported a larger maxillary arch width on the impacted side.[23] However, maxillary arch width was measured using the patient’s dental cast, which would have had lower accuracy than the CBCT scans. CBCT scans are currently the gold standard because they provide highly accurate 3D images. CBCT scans were used to localize the canine and analyze dentoalveolar dimensions in the present study. Besides, the differences above could have occurred due to the samples’ ethnic differences.

The lateral incisor longitudinal axis external angle on the impacted side showed a significant decrease compared with the contralateral side. Oleo-Aracena and Hanke also reported similar results.[17],[24] In the study of Dekel et al., the lateral incisors showed significant mesiobuccal rotation in the palatally impacted canine group.[25] It seems that the pressure the lateral incisor root was subjected to due to the impacted canine bud on the same side resulted in mesial tipping of the root and distal tipping of the crown in the lateral incisor, decreasing the longitudinal axis external angle of lateral incisors on the impacted side. No significant relationship was found between the alveolar bone heights on the impacted and nonimpacted sides. This result was in line with Oleo-Aracena’s study.[17] However, the impacted side alveolar bone height was smaller in Tadinada’s study.[2] They explained that this had occurred because adjacent bones had developed with the tooth’s eruption, leading to a larger bone height on that side than on the impacted side.[2] This difference in results could have occurred because of smaller sample size or measurement errors.

No significant relationship was found between the arch perimeters on the impacted and nonimpacted sides in the present study. According to Jacoby, an acceptable arch perimeter can be observed in 85% of patients with palatal impactions.[26] Stellzig et al. stated that 82% of palatal canine impactions are seen in patients with a normal arch perimeter.[27] Therefore, it should be noted that arch perimeter deficiency is not necessarily observed on the impacted side. Contrary to this finding, Tadinada’s results showed that due to the posterior teeth’s mesial movement and earlier deciduous tooth loss on the impacted side, a smaller arch perimeter was seen on the impacted side compared to the nonimpacted side.[2] However, according to this study’s exclusion criteria, patients with the mesial movement of premolars were excluded. Therefore, the reason mentioned above seemed contradictory, and there is a need for further studies and more comprehensive analyses of this subject. Another reason for the arch perimeter deficiency mentioned in this study was the small maxillary lateral incisor mesiodistal dimensions.[2] In another study conducted by Becker et al., the mesiodistal and bucco-palatal widths of all teeth of the 58 patients with impacted canines were measured. This study reported that the only tooth with a significant decrease in mesiodistal and bucco-palatal dimensions was the lateral incisor.[28] Peck et al. reported that 16% of palatal canine impactions are associated with lateral incisor agenesis, peg-shaped lateral incisors, and arch perimeter deficiency.[29] Peck and Tadinada stated that arch perimeter deficiency is related to small mesiodistal dimensions of lateral incisors. Peck has also reported that only 16% of palatally impacted canines are associated with lateral incisor problems and arch perimeter deficiency. Therefore, a comprehensive study to precisely analyze the relationship between arch perimeter and lateral incisor shape is necessary.[2],[29]

According to the genetic theory, the maxillary canine position is determined by the jaw’s deciduous tooth bud position. Generally, the maxillary canine bud is located in the nasal cavity’s outer part and is higher than other teeth buds.[26],[30] Therefore, we expected that the impaction would affect the nasal cavity thickness and that thickness would be less on the impacted side. However, the results did not confirm our expectations. There was no significant relationship between the nasal cavity thicknesses on the impacted and the nonimpacted sides in the present study.

Consequently, nasal cavity thickness can affect the canine tooth bud position, but we cannot state that the palatally impacted canine can affect nasal cavity thickness. In Kim et al.’s and D Oleo-Aracena’s study, no significant relationship was found between this variable and the maxillary canine.[9],[17] Therefore, it would seem that maxillary canine impaction does not have any association with nasal structure and nasal cavity thickness. Some of the parameters measured in this study had been analyzed in previous studies.[19],[20],[23],[31] The most comprehensive study conducted in the field is Tadinada’s study, in which some parameters such as nasal cavity thickness and arch width were not measured.[2] However, these parameters were measured in the present study. The present study aimed to review the previous studies and address their limitations. One of the issues seen in previous studies is the sample size. Based on the inclusion and exclusion criteria, this study had a limited sample; however, we tried to have a larger sample size than similar studies. There were 39 and 28 samples in Tadinada’s and Oleo-Aracena’s studies, respectively, while the present study analyzed 46 CBCT scans.[2],[17]

One of the challenges in this type of study is the sample size. Owing to the strict inclusion and exclusion criteria, we faced a sample size limitation. However, we have tried to have more samples than similar studies. It is suggested that studies be conducted with different methods, for example, evaluating the correlation of impaction and non-impaction with respect to sella turcica, nasal floor, and maxillary sinus floor to find causal factors and further increase the sample sizes for future studies. Also, to prove the effect of canine tooth impaction on maxillary bone dimensions, the measured parameters in patients with unilateral palatal impaction can be compared with patients with bilateral canine impaction.

 Conclusion



The results of the CBCT measurements yielded the following findings:Palatal impaction of the maxillary canine tooth did not affect the alveolar bone height.The bone thickness patterns were inverse on the nonimpacted and impacted sides.Palatal impaction of maxillary canine tooth decreased the maxillary arch width.Palatal impaction of maxillary canine decreased the external angle of lateral incisors.The maxillary canine tooth’s palatal impaction did not affect the nasal cavity thickness and arch perimeter.

This study evaluated dentoalveolar variables as predisposing factors leading to greater canine impaction probability. These findings are of paramount significance for early diagnosis in order to develop the most appropriate interdisciplinary treatment plan.

Consequently, we should correct bilateral symmetry in the orthodontic treatment of unilateral palatal impaction of the maxillary canine and balance the maxillary arch width in the premolar area on the two sides. Nevertheless, owing to the lateral incisor’s distal angulation, we need to be aware of this tooth’s possible interference when moving the impacted canine to return it to the dental arch.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Fardi A, Kondylidou-Sidira A, Bachour Z, Parisis N, Tsirlis A. Incidence of impacted and supernumerary teeth-a radiographic study in a North Greek population. Med Oral Patol Oral Cir Bucal 2011;16:e56–61.
2Tadinada A, Mahdian M, Vishwanath M, Allareddy V, Upadhyay M, Yadav S. Evaluation of alveolar bone dimensions in unilateral palatally impacted canine: a cone-beam computed tomographic analyses. Eur J Orthod 2015;37:596–602.
3Lai 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;35:529–38.
4Oberoi 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;113:260–7.
5Alyami B, Braimah R, Alharieth S. Prevalence and pattern of impacted canines in Najran, South Western Saudi Arabian population. The Saudi Dental Journal 2020;326:300–5.
6Coulter J, Richardson A. Normal eruption of the maxillary canine quantified in three dimensions. Eur J Orthod 1997;19:171–83.
7Chaushu S, Bongart M, Aksoy A, Ben-Bassat Y, Becker A. Buccal ectopia of maxillary canines with no crowding. Am J Orthod Dentofacial Orthop 2009;136:218–23.
8Peck S, Peck L, Kataja M. The palatally displaced canine as a dental anomaly of genetic origin. Angle Orthod 1994;64:249–56.
9Kim Y, Hyun HK, Jang KT. Interrelationship between the position of impacted maxillary canines and the morphology of the maxilla. Am J Orthod Dentofacial Orthop 2012;141:556–62.
10McConnell TL, Hoffman DL, Forbes DP, Janzen EK, Weintraub NH. Maxillary canine impaction in patients with transverse maxillary deficiency. ASDC J Dent Child 1996;63:190–5.
11Langberg BJ, Peck S. Tooth-size reduction associated with occurrence of palatal displacement of canines. Angle Orthod 2000;70:126–8.
12Almuhtaseb E, Mao J, Mahony D, Bader R, Zhang ZX. Three-dimensional localization of impacted canines and root resorption assessment using cone beam computed tomography. J Huazhong Univ Sci Technolog Med Sci 2014;34:425–30.
13Elefteriadis JN, Athanasiou AE. Evaluation of impacted canines by means of computerized tomography. Int J Adult Orthodon Orthognath Surg 1996;11:257–64.
14Yan 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;143:527–34.
15Cook VC, Timock AM, Crowe JJ, Wang M, Covell DA, Jr. Accuracy of alveolar bone measurements from cone beam computed tomography acquired using varying settings. Orthod Craniofac Res 2015;18 Suppl 1:127–36.
16Alhummayani FM, Mustafa ZA. A new guide using CBCT to identify the severity of maxillary canine impaction and predict the best method of intervention. J Orthod Sci 2021;10:3.
17D'Oleo-Aracena MF, Arriola-Guillén LE, Rodríguez-Cárdenas YA, Ruíz-Mora GA. Skeletal and dentoalveolar bilateral dimensions in unilateral palatally impacted canine using cone beam computed tomography. Progress in orthodontics 2017;181:7.
18Haney E, Gansky SA, Lee JS et al., Comparative analysis of traditional radiographs and cone-beam computed tomography volumetric images in the diagnosis and treatment planning of maxillary impacted canines. Am J Orthod Dentofacial Orthop 2010;137:590–7.
19Saiar M, Rebellato J, Sheats RD. Palatal displacement of canines and maxillary skeletal width. Am J Orthod Dentofacial Orthop 2006;129:511–9.
20Verma P, Dinesh SPS. Maxillary transverse dimensions in subjects with and without impacted canines in South Indian population: a comparative cone-beam computed tomography study. Orthodontic Waves 2021;801:9–16.
21Schindel RH, Duffy SL. Maxillary transverse discrepancies and potentially impacted maxillary canines in mixed-dentition patients. Angle Orthod 2007;77:430–5.
22Arboleda-Ariza N, Schilling J, Arriola-Guillén LE, Ruíz-Mora GA, Rodríguez-Cárdenas YA, Aliaga-Del Castillo A. Maxillary transverse dimensions in subjects with and without impacted canines: a comparative cone-beam computed tomography study. Am J Orthod Dentofacial Orthop 2018;154:495–503.
23Al-Nimri K, Gharaibeh T. Space conditions and dental and occlusal features in patients with palatally impacted maxillary canines: an aetiological study. Eur J Orthod 2005;27:461–5.
24Hanke S, Hirschfelder U, Keller T, Hofmann E. 3D CT based rating of unilateral impacted canines. J Craniomaxillofac Surg 2012;40:e268–76.
25Dekel E, Nucci L, Weill T et al., Impaction of maxillary canines and its effect on the position of adjacent teeth and canine development: a cone-beam computed tomography study. Am J Orthod Dentofacial Orthop 2021;159:e135–e47.
26Jacoby H. The etiology of maxillary canine impactions. Am J Orthod 1983;84:125–32.
27Stellzig A, Basdra EK, Komposch G. [The etiology of canine tooth impaction--a space analysis]. Fortschr Kieferorthop 1994;55:97–103.
28Becker A, Sharabi S, Chaushu S. Maxillary tooth size variation in dentitions with palatal canine displacement. Eur J Orthod 2002;24:313–8.
29Peck S, Peck L, Kataja M. Prevalence of tooth agenesis and peg-shaped maxillary lateral incisor associated with palatally displaced canine (PDC) anomaly. Am J Orthod Dentofacial Orthop 1996;110:441–3.
30McBride LJ. Traction--a surgical/orthodontic procedure. Am J Orthod 1979;76:287–99.
31Anic-Milosevic S, Varga S, Mestrovic S, Lapter-Varga M, Slaj M. Dental and occlusal features in patients with palatally displaced maxillary canines. Eur J Orthod 2009;31:367–73.