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Surgical and orthodontic management of an impacted dilacerated maxillary central incisor and a partially transposed impacted canine: A case report
*Corresponding author: Chen-Jung Chang, Department of Stomatology, School of Dentistry, College of Medicine, National Cheng Kung University Hospital, National Cheng Kung University, Tainan, Taiwan. zoechang0405@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Su A, Chen M, Wu P, Chang C. Surgical and orthodontic management of an impacted dilacerated maxillary central incisor and a partially transposed impacted canine: A case report. APOS Trends Orthod. doi: 10.25259/APOS_29_2025
Abstract
Dilaceration of a maxillary central incisor and transposition of a maxillary canine are challenging conditions that are often accompanied by impaction, leading to both esthetic and functional concerns. Studies suggested that the closed-eruption approach of impacted incisors with root dilaceration should be initiated as early as possible. Therefore, early detection and diagnosis are crucial for the success of orthodontic traction. However, the characteristics of the dilacerated teeth, such as the angulation of the apical bend and the depth of impaction, can significantly influence treatment outcomes. In cases of central incisor impaction, eruption disturbances of the ipsilateral canine are likely to occur. For a transposed and impacted canine, careful selection of surgical exposure technique and precise control of traction mechanics are essential for achieving successful alignment and an esthetically pleasing gingival contour. This report presents a patient with three impacted teeth: A dilacerated maxillary right central incisor, a horizontally impacted left central incisor, and a partially transposed, impacted maxillary right canine. The treatment approach included surgical exposure using the closed eruption technique and the apically positioned flap, which preserved periodontal health while facilitating orthodontic traction. A segmental titanium molybdenum alloy with an L-loop was utilized to guide the canine into its proper position. This case highlights the importance of early diagnosis and the integration of effective surgical and orthodontic techniques in managing the complex challenges associated with impacted teeth. In addition, periodic follow-up was critical for monitoring post-treatment stability and ensuring long-term success.
Keywords
Esthetic
Impaction
Malocclusion
Orthodontic traction
Tooth abnormalities
INTRODUCTION
Tooth dilaceration is defined as a deviation from the normal root axis, with an apical bend >20° or at least 90° in the case of a mesiodistal bend.[1,2] The prevalence of root dilaceration in maxillary central incisors has been reported to range from 0.4% to 1.2%.[1] Several etiological factors have been proposed, including traumatic injuries to the primary predecessors, idiopathic ectopic eruption, and developmental disturbances. Previous studies suggested that the angulation of the bend and the depth of impaction can serve as prognostic indicators.[2]
Regarding impaction, the maxillary canine is the second most frequently impacted tooth after the third molar, with a prevalence of approximately 2%.[3] Studies have indicated that the initial vertical and horizontal position of the impacted canine might affect the choice of surgical and orthodontic technique.[3] However, potential complications associated with surgical exposure and orthodontic traction, such as gingival recession, external root resorption, or ankylosis, should be considered.[2,3]
Tooth transposition can be classified as complete or incomplete, depending on whether the two teeth are entirely transposed or only their crowns or roots have exchanged positions. Maxillary canine–lateral incisor transposition is the second most common type.[4] A key consideration in treatment planning is the positional relationship between the canine crown and the root of the lateral incisor.
Herein, we present the case involving a severely dilacerated and impacted maxillary right central incisor along with a partially transposed impacted canine. Through a combination of surgical exposure and orthodontic traction, both the dilacerated incisor and the transposed canine were successfully guided into their proper position. This report also discusses the relevant radiographic features, treatment considerations, and complications with such complex cases.
CASE REPORT
Diagnosis
An 8-year-old girl presented to our orthodontic department with a chief complaint of the non-eruption of her upper anterior teeth. Neither she nor her parents recalled any history of dental trauma. Extraoral examination revealed a convex profile with protrusive lips. Intraorally, teeth 12 and 22 had erupted. Teeth 51 and 61 were retained, while tooth 21 was palpated in the vestibular sulcus [Figure 1]. The panoramic film confirmed the impaction of teeth 11 and 21, both positioned abnormally high [Figure 1]. Cone-beam computed tomography images revealed that tooth 21 was horizontally impacted in a buccolingual direction [Figure 2a], while tooth 11 had a dilacerated root. The root of tooth 11 bent labially, with an angle of approximately 106.5° between the root and the crown axis [Figure 2b].
- Pre-treatment extraoral and intraoral photographs, and panoramic radiographs.
- Cone-beam computed tomography (CBCT) and periapical radiographs. (a) Pre-treatment CBCT showing tooth 21 positioned horizontally in a buccolingual direction. (b) The angle between the root and crown axis of tooth 11 measured approximately 106.5°. (yellow dotted arrow: the crown axis and the direction of expected normal root axis, yellow arrow: the deviated root axis, blue asterisks indicate the position of normal and deviated root.). (c) CBCT reconstruction showing the position of the three impacted teeth and the dilaceration of tooth 11. (green: tooth 21, blue: tooth 11, dark blue: tooth 13). (d and e) The “bull’s eye” appearance of the dilacerated tooth 11 in the periapical film, where the inner radiolucent circle represents the apical foramen and root canal when the X-ray beam is parallel to the deflected root segment.
The patient was diagnosed with a skeletal Class I relationship, bilateral angle Class I molar relationships, two impacted maxillary central incisors, and a transposed maxillary canine [Table 1 & Figures 2c and d].
| Measurement | Norm ±SD | Pre-Tx (8 Y 11M) | Norm ±SD | Post-Tx (15 Y 3 M) |
|---|---|---|---|---|
| Skeletal | ||||
| SNA (°) | 81.8±3.1 | 84.5 | 84.0±3.7 | 85.5 |
| SNB (°) | 77.5±2.5 | 81.5 | 81.5±3.7 | 82.0 |
| ANB (°) | 4.4±2.0 | 3.0 | 2.5±2.2 | 3.5 |
| SN-MP (°) | 34.5±3.6 | 31.5 | 29.1±5.0 | 32.5 |
| Dental | ||||
| U1-NA (mm) | 2.93~6.63 | x | 3.18~7.34 | 4 |
| U1-SN (°) | 104.2±5.2 | x | 109.9±8.0 | 114.0 |
| L1-NB (mm) | 3.84~7.46 | 5.5 | 4~8.44 | 4.5 |
| L1-MP (°) | 94.1±5.7 | 89.5 | 99.2±6.8 | 80.5 |
| Soft tissue | ||||
| U-lip to E-line (mm) | -2.93~0.41 | 4.5 | -2.93~0.41 | 2.0 |
| L-lip to E-line (mm) | -1.86~2.1 | 7.0 | -1.86~2.1 | 3.0 |
ANB: A-nasion-B, SNA: Sella-nasion-A, SNB: Sella-nasion-B, , SN-MP: SN plane to mandibular plane angle, UI-NA: the distance from upper incisor tip to NA line, UI-SN: upper incisor axis to SN plane angle, LI-MP: lower incisor to mandibular plane angle, U-lip to E-line: the distance from upper lip to E-line, L-lip t to E-line: the distance from lower lip to E-line. SD: Standard deviatio.
Treatment objectives
Given that the patient is still in the early mixed dentition stage and that central incisors play a key role in both esthetics and function, the primary treatment objective is to preserve the natural teeth while restoring both esthetic and functional integrity.
Treatment alternatives
However, if orthodontic traction proves unsuccessful, an alternative treatment plan would involve extracting the central incisors and substituting them with lateral incisors or implants at an appropriate adult age.
Treatment progress
The first stage involved extracting teeth 51 and 61, followed by surgical exposure and traction of the impacted incisors using the closed-eruption technique [Figure 3a-c]. However, tooth 13 showed no eruption after several months. Surgical exposure with an apically positioned flap (APF) was performed, and a 0.017 × 0.025-inch titanium molybdenum alloy (TMA) wire with an L-loop facilitated its distal, occlusal, and buccal movement [Figure 3d and e]. After successful traction of teeth 11, 21, and 13, full-mouth orthodontic treatment began. During the finish stage, a 0.5 mm space remained between teeth 11 and 21, and tooth 11 was immovable due to the severely dilacerated root. After the dilemma was explained to the patient’s parents, two treatment options were offered: One option involved apical surgery on tooth 11 with sectioning of the dilacerated root segment to close the residual space; the second option involved closing the diastema with restorative treatment. The patient opted for the second option. Following debanding and debonding, tooth 11 was restored.
- Treatment progress photographs. (a) Pre-treatment. (b and c) Orthodontic traction of teeth 11 and 21. (d) The titanium molybdenum alloy (TMA) L-loop for tooth 13 traction. (e) TMA L-loop mechanics. Activation and cinch-back of the loop facilitated the distal and occlusal movement of tooth 13. The wire segment within the bracket slot could add buccal crown torque (BCT) to guide the crown of tooth 13 away from the root of tooth 12. (White arrow: TMA wire activation direction; yellow arrow: movement direction of tooth 13. MGJ: Mucogingival junction.) TMA: Titanium molybdenum alloy, BCT: Buccal crown torque.
Treatment results
This case involved three impacted teeth: a dilacerated tooth 11, a horizontally buccolingually positioned tooth 21, and a partially transposed tooth 13 [Figure 2c]. Surgical exposure and orthodontic traction successfully aligned all impacted teeth [Figures 2d and 4]. The post-treatment panoramic film showed favorable root paralleling [Figure 4]. Cephalometric superimposition confirmed a normal ANB angle and significant maxillomandible growth over 6 years [Figure 5a-d]. Incisor angulation was greatly improved [Figure 5d]. The dilacerated root of tooth 11 was palpable labially but covered by the alveolar mucosa [Figure 4]. Despite its root apex being exposed to the alveolar bone, tooth 11 remained vital and asymptomatic throughout treatment and the 2-year follow-up [Figure 6].
- Post-treatment (finish) extraoral and intraoral photographs, and panoramic radiograph. The root apex of tooth 11 (yellow circle) was exposed to the alveolar bone but remained vital and asymptomatic throughout treatment.
- Lateral cephalometric radiographs. (a) Pre-treatment. (b) Post-treatment. (c) The initial crown axis angulation of tooth 11 measured 103°. The crown axis angulation represent the angle between the crown axis of the impacted dilacerated tooth and that of a normal tooth. (d) Superimposition of pre-and post-treatment cephalometric tracings showing maxillary and mandibular growth. (black: pre-treatment, red: post-treatment).
- Intraoral photographs at the 2-year follow-up. The diastema was restored, and tooth 11 remained vital and asymptomatic throughout follow-up.
DISCUSSION
Radiographic and treatment considerations
Radiographic images are crucial for detecting dilaceration. A previous study reported that a buccally or lingually dilacerated tooth exhibits a characteristic “bull’s eye” pattern on periapical films [Figure 2d and e], where the inner radiolucent circle represents the apical foramen and root canal when the X-ray beam is parallel to the deflected root segment.[5] Studies have also proposed guidelines for selecting orthodontic traction based on crown axis angulation and the degree of dilaceration.[6] Ideally, the crown axis angulation should not be exceed 90°, and the root dilaceration should be <60°. Favorable factors for orthodontic traction include an obtuse angle, incomplete root formation, and a lower position.[2] In our case, the patient had a severely dilacerated root with 103° crown axis angulation and 106.5° root dilaceration, nearly 3/4 root formation, and a high position [Figures 2b and c, and 5c]. All of which are unfavorable for traction. Despite this, due to the patient’s strong desire to preserve the incisor, treatment was attempted and successfully completed.
Complications and surgical considerations
Severely dilacerated impacted teeth are prone to complications, such as gingival recession, ankylosis, or root exposure. For cases of ankylosis or root exposure, one study suggested apical root amputation with subsequent obliteration.[7] In our patient, the root of tooth 11 was palpable in the vestibular sulcus, but it remained asymptomatic and vital. Thus, no endodontic intervention was performed.
Kokich proposed four criteria for determining the appropriate surgical exposure technique.[8] APF is indicated when the crown of the impacted canine is apical to the mucogingival junction, lacks adequate gingiva coverage, and is positioned over the lateral incisor root. For a dilacerated incisor, the closed-eruption technique has been reported to provide superior gingival and pulp outcomes compared to an APF.[2]
Management of canine transposition
According to Chaushu et al., unilateral central incisor impaction often disrupts the eruption of the ipsilateral canine.[9] This may occur because the unerupted central incisor encroaches on the space of the lateral incisor root, causing its apex tilts distally and obstruct the eruption path of the canine.[10] Ideally, early extraction of the primary maxillary canines is recommended for interceptive management of impacted canines.
When correcting transposed teeth to their original position, segmental wires, springs, and transpalatal arches are commonly used.[3] However, root resorption of the lateral incisor is a frequent complication. Treatment planning should prioritize root protection by maintaining sufficient distance between the canine crown and the lateral incisor root. In our case, the impacted maxillary right canine was labially positioned with incomplete transposition. A segmental TMA L-loop with buccal crown torque was used to move the canine distally, occlusally, and buccally along the correction path [Figure 3d and e]. Post-treatment evaluation showed no root resorption, and the gingival margin of teeth 11, 12, and 13 was esthetically harmonious.
CONCLUSION
Managing impacted dilacerated or transposed teeth is challenging. Surgical exposure combined with orthodontic traction offers a conservative and effective solution. With precise control of mechanics and force direction, even severe cases can be successfully aligned within the arch.
Ethical approval:
The Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript, and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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