Journal of Oral and Maxillofacial Radiology

: 2019  |  Volume : 7  |  Issue : 3  |  Page : 66--70

Role of cone-beam computed tomography for the diagnosis of the labially inverted impaction of maxillary central incisor

Virender Gombra, Mandeep Kaur 
 Department of Oral Medicine and Radiology, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Correspondence Address:
Virender Gombra
Department of Oral Medicine and Radiology, Faculty of Dentistry, Jamia Millia Islamia, New Delhi


Impaction of permanent maxillary central incisor is very rare. Inverted impaction of the maxillary central incisor is even more uncommon. Impacted central incisor can cause esthetic concern to the patient or can be associated with the dentigerous cyst. Conventional radiographs including intraoral periapical radiograph, occlusal radiograph, and pantomograph are most commonly advised for the diagnosis and evaluating the location of the impacted tooth. Two-dimensional imaging modality may not exactly locate and evaluate the tooth, root dilacerations, and effect on the surrounding structures. Cone-beam computed tomography (CBCT) will assist in locating the tooth and evaluating the morphology. Inverted impaction of the central incisor has been reported as a rare entity in literature. This article discusses the case report along with the role of CBCT in diagnosis and evaluation of the labially inverted impaction of the central incisor.

How to cite this article:
Gombra V, Kaur M. Role of cone-beam computed tomography for the diagnosis of the labially inverted impaction of maxillary central incisor.J Oral Maxillofac Radiol 2019;7:66-70

How to cite this URL:
Gombra V, Kaur M. Role of cone-beam computed tomography for the diagnosis of the labially inverted impaction of maxillary central incisor. J Oral Maxillofac Radiol [serial online] 2019 [cited 2020 Jun 7 ];7:66-70
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Full Text


An impacted tooth is one which is completely or partially unerupted and is positioned against another tooth, bone or soft tissue so that its further eruption is unlikely.[1] Inverted impaction of the tooth has been rarely observed and only a few cases of impacted maxillary central incisor have been reported in literature.[2] The prevalence of labial inversely impacted maxillary central incisor is 0.06%–0.20% which is characterized by its crown rotating more than 90° in an upward direction with its incisal edge reaching the level of anterior nasal spine.[3] The etiology of impacted maxillary incisors could be hereditary, environmental or local factors such as supernumerary teeth, odontomas and trauma.[2],[4]

It's complication may vary from facial esthetics to dental pathologies such as the dentigerous cyst. However, the condition could be less complicated when diagnosed and treated at an early age.[2] The presence of erupted lateral incisors associated with the clinically missing one or both of the central incisors should be provisionally considered as a pathology or missing tooth when a child's age is 8–10 years. An impacted central incisor is usually diagnosed when there is delayed eruption of the tooth. Unerupted maxillary central incisor can be associated with mild, moderate, or severe root dilacerations. Trauma can cause dilacerations which can further affect the treatment and prognosis of the impacted tooth. Hence, it is worthy to ensure the anatomical morphology of the impacted tooth before the treatment planning.[4] The maxillary impacted incisors can be divided into three categories based on the position of the crown in three-dimensional directions with further subdivisions in each group including Type I – labially impacted (inclined, horizontal, and inverted), Type II – palatally impacted (inclined and horizontal) and Type III – vertically impacted incisors.[5]

Conventional (two-dimensional [2D]) radiographs including periapical, occlusal and panoramic radiographs are commonly used for the diagnosis, localization and treatment planning of the impacted teeth. Conventional radiographs have limitation in providing details, such as the exact location of the teeth, anatomy of roots, and impact on neighboring teeth along with other structures [1] while cone-beam computed radiography (CBCT) is highly accurate in demonstrating superimpositions, exact location of tooth, locating any resorption or fracture, dilacerated root and alveolar dehiscence assessment in postorthodontic treatment cases.[3] CBCT overcomes the limitations of 2D imaging such as image enlargement and distortions, structure superimposition, limited identifiable landmarks and positioning problems.[6]

 Case Report

An 18-year-old male patient reported in the Outpatient Department of Oral Medicine and Radiology, with the complaint of missing front teeth since childhood. Medical and surgical history of the patient was not significant. On examination 11 and 21 were clinically missing with mild diffuse, hard and nontender anterior palatal swelling with normal overlying mucosa [Figure 1]. Provisional diagnosis of partially edentulous arch was given and differential diagnosis of impacted central incisor, supernumerary tooth and odontoma was considered. Maxillary occlusal radiograph [Figure 2] was advised which showed two well-defined radiopaque structures with small central radiolucency of size approximately 10 mm × 5 mm at its greatest dimension in the anterior palatal region. This radiopacity was surrounded by thin radiolucent margin and resembled crown of the teeth, but the root was not visible. Radiographic diagnosis of the impacted tooth was considered. To evaluate the exact morphology and location, CBCT was advised. CBCT with maxillary field of view was acquired with Imaging Siences International system, Model iCAT 17-19 machine (120 kVp, 5 mA, exposure time of 7 s) with image matrix 640 × 640 and voxel size 0.25 mm × 0.25 mm × 0.25 mm. CBCT revealed [Figure 3] and [Figure 4] the presence of two labially placed impacted central incisors in inverted position and severe root dilaceration [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]. Incisal edge of 11 and 21 crowns were in close proximity to the floor of the nasal fossa [Figure 4] and [Figure 9], measuring 2.25 mm and 2.75 mm from the incisal edge of 11 and 21 to the nasal fossa floor, respectively. Root apex of 11 and 21 was present lingual to 12 and 22, respectively [Figure 3] and [Figure 6]. Axial section showed the absence of bone labially in 11 and 21 [Figure 8]. With incisal edge overlapping of 11 and 21 crowns, the final diagnosis of labially inverted impaction of the central incisors was considered, and patient was referred to the department of Oral Surgery and Orthodontics for the treatment. We lost the patient's follow-up as he did not report after the diagnosis.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}{Figure 7}{Figure 8}{Figure 9}{Figure 10}


Impacted teeth are most commonly evaluated with traditional radiographs. In contrast to conventional radiographs, CBCT is highly accurate in the evaluation of position, morphology, superimposition, root dilacerations, fracture, resorption and the surrounding bone analysis.

It is also helpful in analyzing the exact location of the tooth; relative position to the nasopalatine canal and nasal floor; evaluation of the periodontium, root morphology, root apex closure; and assessment of the surrounding bone which assists in surgical and orthodontic treatment planning.[3] In our case routine radiography was not helpful in giving exact location and morphology of the tooth, while CBCT evaluation provided the final diagnosis of labially inverted central incisor impaction along with the assessment of dilacerated root and localization of the impacted tooth.

Treatment of such a case is challenging because of its position, direction and location. One treatment option is tooth extraction followed by a fixed prosthesis. Postextraction, the healing alveolar bone will be thin and deficient. Alternative treatment to avoid this drawback is orthodontic traction cooperated with surgical exposure, which may act as one of the suitable approaches for such impacted teeth. Management of an early diagnosed case of impacted tooth is more favorable compared to late treatment as most failures were associated with completely developed dilacerated root or too long root and if the root apex is not covered by labial osseous gingival lamella.[2] CBCT is a reliable tool in assessing the bone quality and the proximity of the tooth to vital structures that may cause iatrogenic damage to essential structures during surgery and may interfere with orthodontic treatment.[7],[8]

CT and CBCT both can visualize impacted teeth. However, CBCT requires less space, has a lower cost and delivers less radiation exposure compared to the conventional CT devices.[7] The radiation dose with CBCT is 40% lower than conventional CT and is 3–7 times more than a panoramic radiograph. The sum of the effective doses for panoramic and lateral cephalometric and periapical images would be in the same range or even higher than that of CBCT. Radiographs or CBCT for any patient should be prescribed if it is beneficial for the diagnosis and treatment planning. CBCT assessment should follow the “as low as reasonably achievable” principle.[9]

CBCT provides high-quality images with submillimeter resolution (2 line pair/mm) and shorter scanning times. Radiation exposure from CBCT is ten times lower than conventional CT scans during maxillofacial exposure (68 μSv compared with 600 μSv of conventional CT). Also, it has better dimensional accuracy. CBCT scan may replace conventional radiographs, but it should not be recommended as a routine diagnostic procedure because of the increased radiation dose.[10]

The selection criteria should be patient's clinical needs, as in our case, CBCT assisted in providing a final diagnosis of inverted central incisor impaction and ruled out any other odontogenic pathology. In such impacted cases, CBCT is a useful modality for the diagnosis and treatment planning.[9]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/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.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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