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Year : 2018  |  Volume : 21  |  Issue : 3  |  Page : 301-305

Health of periodontal tissues and resorption status after orthodontic treatment of impacted maxillary canines

Department of Orthodontics, Faculty of Dentistry, Ondokuz Mayıs University, Atakum/Samsun, Turkey

Date of Acceptance28-Apr-2017
Date of Web Publication09-Mar-2018

Correspondence Address:
Dr. A Z Oz
Department of Orthodontics, Faculty of Dentistry, Ondokuz Mayis University, Atakum/Samsun
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njcp.njcp_419_16

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Objective: The aim of the present study was to evaluate the changes of incisor root resorption associated with impacted maxillary canines and health of periodontal tissues around maxillary canines erupted with orthodontic treatment. Materials and Methods: Twenty patients with a unilateral palatally impacted maxillary canine were included in the study. Cone-beam computed tomography images taken before and after orthodontic treatment were compared with the contralateral canines serving as control teeth. Results: Root resorption was present in 10% of central and 40% of lateral incisors before treatment. After treatment, the incidence of resorption decreased. The thickness of the buccal bone surrounding the impacted canines was similar to that surrounding the contralateral canines, except in the apical area. Periodontal pocket depth and alveolar bone loss were greater for the impacted canine teeth than for the contralateral canines. Conclusions: Incisor root resorption associated with impacted canine teeth showed signs of repair after orthodontic treatment. Slight differences related to periodontal health were found between the previously impacted teeth and contralateral canine teeth.

Keywords: Cone-beam computerized tomography, impacted maxillary canines, periodontal health, root resorption

How to cite this article:
Oz A Z, Ciger S. Health of periodontal tissues and resorption status after orthodontic treatment of impacted maxillary canines. Niger J Clin Pract 2018;21:301-5

How to cite this URL:
Oz A Z, Ciger S. Health of periodontal tissues and resorption status after orthodontic treatment of impacted maxillary canines. Niger J Clin Pract [serial online] 2018 [cited 2022 May 18];21:301-5. Available from:

   Introduction Top

Impacted teeth are a commonly encountered clinical problem in orthodontic practice. The maxillary canine is the most frequently impacted tooth after the third molar, with a prevalence of about approximately 1%–3%.[1],[2] In addition, the incidence of palatal impaction is greater than that of labial impaction by a ratio of at least 2:1 or 3:1.[3]

Impacted maxillary canines can cause esthetic and functional problems. Furthermore, migration of the neighboring teeth, loss of arch length, cystic lesions, infection, and most importantly, root resorption of the adjacent lateral and central incisors are frequent secondary problems.[4],[5] Therefore, early diagnosis and appropriate treatment to manage impacted maxillary canines are vital. Treatment options are selected according to canine position and the relationship of adjacent teeth and surrounding tissues. To assist in treatment planning, several radiographic diagnostic techniques have been used.[6],[7] However, two-dimensional (2D) imaging techniques can mask the presence and severity of resorption, as well as any bone destruction located on the mesiopalatal and distopalatal surfaces of roots adjacent to the impacted canine. For these reasons, computed tomography (CT) has been used to obtain more precise visualization without blurring or overlapping of adjacent teeth.[8],[9],[10] Despite its advantages, CT use has been restricted because of its high radiation dose and cost.[11] In recent years, cone-beam CT (CBCT) units have been developed and used to localize tooth impaction and assess resorption.[12]

The recommended treatment strategy for an impacted maxillary canine is orthodontic traction after surgical exposure of the tooth.[13],[14],[15] Open or closed surgical exposure may be undertaken; however, regardless of the technique used, the treatment of impacted maxillary canines can lead to varying amounts of periodontal damage.[15],[16],[17],[18]

The aim of the present study was to evaluate the periodontal status of impacted canines, thickness of the adjacent buccal bone, and incidence of root resorption of the adjacent incisors.

   Materials and Methods Top

The study included 20 patients (9 female and 11 male) between 13.1 and 17.4 years of age (mean 15.3 ± 1.5 years) who were referred to Hacettepe University, Department of Orthodontics. The selected patients had a unilateral palatally impacted maxillary canine, good oral hygiene, only minor crowding (if present), and no sagittal discrepancy. All patients signed informed consent form. The experimental protocol used in this study was approved by the Hacettepe University Scientific Research Review Committee.

Two sets of CBCT images were made for each patient. The first (T0) was taken before the start of orthodontic treatment, and the second (T1) after 3 weeks of retention. CBCT images were acquired with an Iluma CBCT Scanner (3M Imtec, Ardmore, OK, USA). The images of the impacted canines were compared with those of the normally positioned contralateral canines in the same patient.

Resorption of the incisors was assessed according to the severity method described by Ericson and Kurol.[19] No resorption: intact root surfaces; slight resorption: resorption midway to the pulp or more, the pulp lining being unbroken; moderate resorption: the pulp is exposed by the resorption, and the involved length of the root is less than one-third of the entire root; severe resorption: the pulp is exposed by the resorption, and the involved length is more than one-third of the root. Buccal bone thickness was measured at three locations on the coronal views of the impacted and contralateral canines.

Periodontal pocket depth (PD) was measured from the gingival margin. Six sites per tooth were probed and the mean values were recorded. Alveolar bone loss (ABL) was measured on the buccal, palatal, mesial, and distal surfaces of previously impacted and contralateral canines on the CBCT images. All measurements were made twice, and the mean values were recorded.

Statistical analysis

Statistical analyses were performed with SPSS software (version 15.0, SPSS Inc., Chicago, IL, USA). The Shapiro–Wilk test was used to assess the assumption of normality of the obtained data. Differences in nonnormally distributed variables between groups were compared with the Wilcoxon test; for normally distributed variables, paired t-test was used. For all analyses, P ≤ 0.05 was considered statistically significant. Incisor root resorption was analyzed with Chi-square test to evaluate the association between resorption and canine contact.

   Results Top

The severity of the root resorptions and contact relationship are shown in [Table 1]. Totally ten incisors were resorbed. Four lateral incisors had slight resorption and four had mild resorption, resulting in a total resorption incidence of 40% [Table 1]. Only two central incisors showed resorption. There is no severe root resorption associated with impacted maxillary canines. After orthodontic treatment, areas with previous slight resorption were scored as “no resorption” and those with mild resorption were scored as “slight resorption” [Figure 1] and [Figure 2]. There was a significant correlation between contact and resorption before treatment (χ2 = 11,214, P < 0.05). Most of the resorbed lateral incisors were close to impacted maxillary canines.
Table 1: Root resorption of incisors

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Figure 1: Series of cone-beam computed tomography reconstruction views. Moderate resorption of the left lateral incisor is seen in sagittal (a and b) and axial (c and d) views

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Figure 2: Series of cone-beam computed tomography reconstruction views after surgical-orthodontic treatment of palatally impacted canine. Moderate resorption of left lateral incisor has decreased to slight resorption in sagittal (a and b) and axial (c and d) views. Note residual but healing bone defects\

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After treatment of impacted canines, buccal bone thickness at the apical end of the previously impacted canines' roots was greater than the contralateral canines [Table 2].
Table 2: Thickness of buccal bone of impacted and contralateral canine

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The evaluation of periodontal status revealed that the mean PD was deeper in the previously impacted canines (2.13 mm) compared with the contralateral canines (1.64 mm), as shown in [Table 3]. A significant difference in ABL was observed on the mesial, distal, and palatal surfaces of previously impacted canines versus contralateral canines [Table 3].
Table 3: Pocket depth (mm) and alveolar bone loss (mm) measurements

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   Discussion Top

The objective of this study was to assess incisor root resorption and to compare buccal bone thickness and periodontal status of impacted canine teeth versus contralateral canines. Recent CBCT-based studies of impacted canine teeth have only included the pretreatment records.[9],[12],[20],[21],[22] Our prospective study used pre- and post-treatment three-dimensional records and is therefore more comprehensive than past studies. A limitation of this study is its small sample size. However, we did ensure the homogeneity of the study group. Patients with severe crowding or sagittal discrepancy that affected the treatment time and periodontal health[23],[24] were excluded from the study. We were therefore able to assess the effect of impacted canines alone on root resorption and periodontal tissues.

The reported incidence of incisor root resorption related to ectopic eruption of the maxillary canines varies from 4.9% to 38%.[1],[19],[25],[26],[27] This large range could result from differences in sampling and diagnostic and imaging methods. The identification of root resorption is easier with CT than with other diagnostic methods.[19] We found that 40% of lateral incisors were affected by resorption. This percentage matches that reported by Ericson and Kurol[19] but is lower than the percentage (66.7%) reported by Walker et al.[22] A correlation was evident between incisor contact with the impacted canines and root resorption. This result is consistent with previous studies that found that physical proximity of the impacted canines to incisors increased root resorption.[9],[22],[26],[28] CBCT images after orthodontic treatment showed that regions with slight resorption had resolved and those with mild resorption had improved to slight resorption. This indicates that roots were reconstituted when the physiologic pressure produced by impacted canines was removed. Studies indicate that the resorptive process is interrupted when the impacted canine moves and that the long-term prognosis is quite good, even in cases with severe resorption.[29],[30] Our short-term results showed initial repair of incisor root resorption within 3 weeks of treatment. This finding is in agreement with the study of Owman-Moll and Kurol,[31] which found that resorption cavities associated with orthodontically induced root resorption were covered with reparative cementum after 2 weeks of retention.

In this clinical study, we compared the thickness of the buccal bone adjacent to impacted canines with that of the contralateral canines. Bone thickness was significantly different between the impacted and contralateral canines only in the apical region. This finding may result from differences in torque between the treated and contralateral canines. As reported in a previous study,[32] it is difficult to move the root of the treated canine buccally. Although additional torque was applied and delivered with rectangular stainless steel archwires, a loss of torque might have occurred.

During orthodontic treatment, increased plaque levels are often observed because of retention by the fixed appliances.[33],[34] In addition, it may be difficult to maintain adequate plaque control around palatally impacted canines. Surgical procedures and orthodontic tooth movement can affect the periodontal tissues around an impacted canine during treatment.[15],[18] Becker et al.,[14] Woloshyn et al.,[18] and Hansson and Rindler[15] observed greater PD and lower crestal bone height in repositioned impacted canines compared to the contralateral canines, findings that agree with those of the present study. However, the earlier studies evaluated crestal bone height with 2D radiographs, on which only the mesial and distal tooth surfaces can be viewed. According to recent studies, CT is preferable to other radiographic methods for evaluating bone destruction, especially on the buccal and palatal surfaces.[1],[19],[21] In addition to the mesial and distal surfaces, CBCT images revealed significant ABL on the palatal surface of the treated canine. According to Wisth et al.,[17] excessive bone removal during the surgical approach affects the alveolar bone level of palatally impacted canines. In the present study, one surgeon performed all surgeries and minimized bone removal. Another explanation for the palatal bone loss might be that the orthodontic forces applied in buccal and occlusal directions can tip the tooth root palatally, which can damage the periodontal tissues.[28] In addition, Kohavi et al.[16] mentioned that long-term periodontal health can be influenced by orthodontic mechanics; root torque movements applied to the impacted canine decrease the bone support more than tipping or extrusive movements. Our results confirm that orthodontic treatment of palatally impacted canines is associated with a loss of periodontal support. The mean PD did not exceed 3 mm and may be considered of minor clinical importance. However, ABL, especially at the palatal surface of previously impacted canines, may be a risk factor for increased PD and gingival recession over time.[35]

   Conclusions Top

Within the limitations of the present study, the following conclusions can be drawn:

  • Incisor root resorption resulting from impacted maxillary canines heals when the impacted tooth is moved with surgical-orthodontic treatment
  • CBCT scans provide more detailed visualization of resorption than other radiographic methods
  • Periodontal tissues are affected by the surgical-orthodontic treatment of palatally impacted canines and follow-up examination is recommended.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3]


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