INTRODUCTION

Although impaction of a permanent tooth is rarely diagnosed during the mixed dentition period, an impacted central incisor is usually diagnosed accurately when there is delay in the eruption of the tooth. Many patients with impacted maxillary central incisors are referred to orthodontists by general practitioners or pediatric dentists because parents are concerned about the impaction of an incisor in the early mixed dentition, even though its occurrence is less frequent.1–3 Tooth impaction may result from a number of local causes. In an extensive review, Bishara4 lists the etiologic factors of tooth impaction. Although trauma was not included as a factor, he refers to the abnormal position of tooth bud, which might be caused by trauma.

Careful planning is required when moving an impacted tooth by orthodontic treatment. Impacted teeth can be properly positioned with orthodontic traction.235–7 However, orthodontists often hesitate to align an impacted incisor with severe dilaceration because there are chances of failure due to ankylosis, loss of attachment, external root resorption, and root exposure after orthodontic retraction.2 Patients usually want to retain and align the impacted teeth into proper position even after orthodontists suggest several treatment plans.

This article presents a case with a horizontally impacted and severely dilacerated maxillary right incisor that was aligned into proper position after orthodontic treatment combined with surgical exposure and apicoectomy, after which it showed good long-term periodontal stability.

Case history

A 11-year-old Japanese girl presented with an impacted right maxillary central incisor. The chief complaint was noneruption of the incisor (Figure 1). The child was in good health and had no history of medical or dental trauma.

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Diagnosis and treatment planning

The patient had a skeletal Class I malocclusion and a balanced facial pattern. Intraoral examination revealed an Angle Class II molar relationship, with an overbite of one mm and an overjet of two mm. The arch length discrepancy was −3 mm in the maxillary arch and zero mm in the mandibular arch, as calculated from Moyers' prediction tables. Hellman's dental developmental stage was III B. Analysis of the lateral cephalometric radiograph revealed normal values according to Japanese standards.8 The panoramic and periapical radiographs demonstrated an impacted maxillary right central incisor (Figure 2a,b). The incisor was positioned horizontally and appeared dilacerated with an angle of approximately 90° between the root and crown on the lateral cephalometric radiograph (Figure 2c).

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Several possible treatment options were explained to the patient and her parents, including (1) extraction of the impacted central incisor, closure of the space, and alignment of the lateral incisor in place of the central incisor; (2) extraction of the impacted central incisor and restoration with a bridge or an implant; and (3) orthodontic space opening for the impacted central incisor and traction of the impacted tooth. Although it is generally considered that a severely dilacerated impacted incisor has a poor prognosis, we decided to expose the tooth and bring it into the arch orthodontically because the patient and her parents requested nonextraction treatment. The treatment plan consisted of orthodontic space opening, surgical exposure, and traction of the impacted dilacerated central incisor into proper position.

Treatment progress

Bands were placed on the maxillary first permanent molars, and headgear was used for correction of the molar relationship and space maintenance. After distal movement of the first molars was achieved, a palatal arch was placed on the maxillary first molars. When the patient was 12 years old, 0.018″ × 0.025″ slot straight wire appliances were placed on the three maxillary permanent incisors, canines, and premolars. The initial leveling was performed with a 0.016-inch Ni-Ti wire, followed by a 0.016-inch stainless steel wire with an open coil spring in the position of the right central incisor. By activating the open coil spring, adequate space for aligning the impacted incisor was obtained (Figure 3a,b). The patient was transferred to the oral surgeon for exposure of the impacted incisor. The surgeon did not raise a wide mucoperiosteal flap similar to that described in the closed-eruption technique by Vermette et al.9 Instead, the overlying mucoperiosteum and follicle of the lingual surface were elevated to a minimum extent necessary to permit hemostasis and to bond a small button. The alveolar bone layer and follicle of the labial surface were kept intact. An attachment was bonded to the lingual surface of the impacted tooth during surgical exposure. Two weeks later, orthodontic traction of the impacted incisor was initiated. A force of approximately 90 g was applied by an elastic chain. The lingual button was removed, and a bracket was bonded when the incisor reached the occlusal plane. The root apex of the impacted tooth could be palpated just beneath the mobile mucosa of the labial sulcus (Figure 4), and the patient complained of spontaneous pain at the area. The cephalometric radiograph revealed root apex exposure. The patient was transferred to the endodontist and the oral surgeon for root canal filling and apicoectomy (Figure 5a,b). Four months later, orthodontic treatment was restarted. The total duration of orthodontic treatment, including final alignment, was 26 months. The bands and brackets were removed, and a bonding wire was attached to the upper incisors with a wraparound retainer. After 16 months of retention, the bonded wire was removed.

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RESULTS

The impacted right maxillary central incisor was successfully aligned in proper position. The repositioned incisor had an acceptable gingival contour and width of attached gingiva (Figure 6a). The posttreatment radiograph showed no root resorption or periodontal bone loss (Figure 6b,c). At follow-up, two years after removal of the bonded wire, the repositioned incisor did not exhibit any relapse or gingival recession at its labial margin, and it maintained the same clinical crown height as the left central incisor. After six years of retention, the patient was examined (Figure 7a through c). The periodontal status of the previously impacted central incisor and the contralateral central incisor was assessed as reported by Becker et al.10 No differences in oral hygiene or inflammation levels were observed. Probing depth was examined with a standard periodontal probe at the mesiolabial, midlabial, distolabial, mesiopalatal, midpalatal, and distopalatal surfaces of each tooth. Both the width of the attached gingiva and the clinical crown length were measured according to the methods described by Becker et al.10 Although the attached gingiva of the impacted incisor was slightly shorter than the contralateral central incisor, there were no significant differences in the probing depth and clinical crown length.

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DISCUSSION

Several reports have indicated that an impacted tooth can be brought to proper alignment in the dental arch.235–7 The following factors are used to determine whether successful alignment of an impacted tooth can take place: (1) the position and direction of the impacted tooth, (2) the degree of root completion, (3) the degree of dilacerations, and (4) the presence of space for the impacted tooth. Holland11 has recommended that the movement axis of the impacted tooth must be within 90°. Few cases of successful treatment of impacted maxillary incisors with severe dilaceration have been reported to date.61213 Lin2 presented a successful case of a dilacerated maxillary incisor and pointed out that the success rate of an impacted dilacerated tooth depends on the degree of dilaceration, stage of root formation, and position of the tooth. In the present case, the impacted incisor had a dilacerated root at a right angle (90°), positioned at a higher level in the alveolar bone (Figure 2c). The angle between the crown long axis and palatal plane was 220°. Orthodontists may generally opt to extract such a tooth because of difficulties in its management. Most patients probably would choose extraction and replacement by prosthesis. However, if extraction of the impacted central incisor and restoration with a bridge or an implant is planned, orthodontic traction of that tooth into the proper position should be performed initially to improve esthetics and to achieve and maintain an acceptable bone height. Lin2 suggested that the treatment approach requires the cooperation of the orthodontist, oral surgeon, and prosthodontist. In the present case, the orthodontist, oral surgeon, and endodontist discussed the treatment plan before the orthodontic treatment was initiated. Therefore, good results were obtained after root canal filling and apicoectomy (Figure 5a,b).

The present case did not use the closed-eruption surgical technique,9 which elevates a flap and returns it to the original location after placing an attachment on the impacted tooth. The oral surgeon removed a minimum area of buccal mucosa to locate the tip of the impacted incisor but retained the connective tissue follicle of the labial surface to permit hemostasis. From our results, we suggest that the labial epithelial attachment on the impacted incisor should be retained so that the repositioned incisor would present an acceptable gingival contour and attached gingiva.

CONCLUSIONS

Surgical exposure and orthodontic retraction of a severely dilacerated impacted incisor is a clinical challenge. Although treatment included apicoectomy, the severely dilacerated incisor was successfully positioned, and the repositioned incisor showed good stability.