Case Description. The author presents the case of a 9-year-old girl with an impacted dilacerated maxillary central incisor to demonstrate the timing, technique and results of the surgical repositioning treatment approach. The advantages of this approach include immediate esthetic improvement, use of a single and simplified surgical procedure, simple and short orthodontic therapy, a normal gingival margin and the possibility of the developing root’s adapting to the new position.

Clinical Implications. Surgical repositioning is a simplified treatment for dilacerated incisors. It is especially valuable in cases of difficult-to-treat impaction. Timing of surgical repositioning depends on the incisor’s root development and the space available for the transplant.

Extraction or surgical/orthodontic therapy is the most common treatment for a dilacerated maxillary incisor.^1,6–11 If the extraction option is chosen, the space can be closed orthodontically or replaced with a fixed prosthesis. Nonetheless, for a young patient, either solution takes an extended amount of treatment time. Because of the need for esthetic recontouring, a fixed partial denture or implant cannot be placed properly until early adulthood. Owing to the esthetic importance of the maxillary incisors, patients’ parents always request that such teeth be saved. Surgical exposure followed by orthodontic traction is the solution most widely adopted to save an impacted dilacerated incisor. Because of the root angulation of the impacted incisor, multiple surgeries, complicated orthodontic management, additional periodontal surgery and a compromised gingival margin usually are inevitable.^6–16

For example, tooth autotransplantation using premolars is advocated to replace missing anterior teeth in growing patients—an option with advantages over those of implants or fixed prostheses.^17–21 The availability of donor teeth is the greatest limitation of autotransplantation. Another limiting factor is the bone available in the recipient site.

This article reports the treatment of this unique problem by surgical repositioning of an impacted dilacerated incisor. This approach represents a simplified treatment of a dilacerated incisor in mixed dentition.

	CASE REPORT

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A 9-year-old girl had an impacted maxillary incisor. The maxillary right central incisor, with a dilacerated root and the crown directed upward, was visible on a radiograph (Figure 1). There was a space deficiency in the maxillary anterior area due to migration of the left central incisor and right lateral incisor into the space that would have been occupied by the impacted dilacerated incisor (Figure 2). The treatment goal was to reopen the incisor space and bring the impacted incisor into proper alignment.

View larger version (110K): [in this window] [in a new window]   Figure 1. Pretreatment radiograph of mixed dentition. The maxillary right central incisor is dilacerated and impacted, with the crown directed upward.

View larger version (101K): [in this window] [in a new window]   Figure 2. Pretreatment photograph shows that the maxillary right central incisor is unerupted. The incisor space decreased owing to drifting of the adjacent teeth.

View larger version (97K): [in this window] [in a new window]   Figure 3. Photograph taken during surgical exposure shows the impacted incisor with its crown inverted.

View larger version (114K): [in this window] [in a new window]   Figure 4. The dilacerated incisor was surgically repositioned in the normal direction and semierupted position. A suture was used to lightly splint the incisor with the adjacent teeth.

View larger version (97K): [in this window] [in a new window]   Figure 5. Posttreatment photograph shows incisors in good alignment. The cervical margin of the right central incisor shows no scar and a normal appearance.

View larger version (94K): [in this window] [in a new window]   Figure 6. Posttreatment radiograph shows continued root development of the repositioned incisor toward the distal aspect. Note that the levels of alveolar height have been restored with completion of orthodontic treatment.

	DISCUSSION

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Extraction. Extraction of a dilacerated incisor is a quick solution but results in the most complications after treatment. Early loss of a maxillary anterior tooth may result in midline shift, the space’s being occupied by an adjacent tooth and, most critically, loss of alveolar height in the anterior region of the maxilla. The extraction space can be closed orthodontically if the child has crowded dentition or accompanying Class II malocclusion.^22,23 The orthodontic treatment is lengthy, and crown recontouring is a must to achieve proper esthetics. In mature patients, the incisor space can be filled with a prosthesis. However, in young patients, the nature of their growing dentition makes a permanent prosthesis or implant unsuitable. A removable interim prosthesis or space maintainer is needed until early adulthood when definitive prosthetic treatment can be done. A single-tooth implant, composite resin–bonded partial denture or conventional partial denture are common options for the problem in adults. Rehabilitation in adulthood may require ridge augmentation or expansion before an implant or esthetic prosthesis can be placed.²⁴ Because of significant ridge resorption resulting from early extraction of the incisor, the esthetic outcome usually is compromised.

Surgical exposure and orthodontic traction. Surgical exposure and orthodontic traction is the treatment most often used for impacted dilacerated incisors, according to the dental literature.^{6–12,14–16} This intervention must be done early so that normal root development can continue in a correct spatial relationship to the aligned crown.

From the standpoint of force mechanisms, an attachment bonded on the labial side of the crown might allow the dilacerated incisor to assume a more vertical position before its eruption into the arch, thus ensuring a better gingival contour. If bonding on the labial surface is desired, then radical removal of the bone surrounding the inverted crown is required during surgical exposure of the tooth. Other modifications have been reported. Noar and Gaukroger¹¹ used a customized metal coping for traction of a dilacerated maxillary incisor. Invasive methods such as creating a penetration hole on the crown also have been reported.²⁵

To avoid the aforementioned shortcomings, multiple stages of surgical exposure are recommended.¹⁰ The closed eruption technique is superior to the apical repositioning flap in terms of crown length and gingival scarring.¹⁵ Different designs of mechanotherapy are used to prevent the incisor from erupting through the vestibule.^{6,8,9,12,14,16} In the latter situation, a gingival graft may be needed to obtain attached gingiva. The treatment time for surgery/orthodontic treatment usually is between two and three years.^6–11 In summary, the surgery/orthodontic traction approach is lengthy, requires complicated orthodontic mechanics and compromises the gingival contour.

Autotransplantation with premolars or supernumerary teeth. Autotransplantation of a different tooth into the incisal area has been reported with satisfactory results.^17–21 Premolar or supernumerary teeth are the most commonly used donor teeth, but are not always available.²⁰ Furthermore, for an impacted dilacerated incisor, this approach may not be feasible. Because the dilacerated incisor rides on the ridge of the alveolar crest, the height of the alveolar bone remaining after removal of the incisor may not be enough to accommodate the full length of a donor tooth, unless a short developing tooth is used.^19,20 This approach requires atraumatic removal of the donor tooth and preparation of the recipient site, thus creating at least two surgical sites. Recontouring and orthodontic treatment of the transplanted tooth are needed to achieve esthetic and occlusal harmony.²¹

Autoalloplastic tooth transplantation. Filippi and colleagues²⁶ described an interesting technique with a combination of implant and autotransplantation. After extracting the dilacerated incisor, the clinician left the coronal 3 millimeters of the periodontal ligament intact, while he dissected the rest of the malformed root and cemented a porcelain post into the root canal orifice. He then transplanted the alloplastic tooth into normal occlusion. They reported successful three-year results in 10 cases of dilacerated incisors.²⁶

	SURGICAL REPOSITIONING OF A DILACERATED INCISOR

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Surgical repositioning or transalveolar autotransplantation of impacted teeth has been reported.^20,27–29 A longitudinal study of surgical repositioning in the 1980s showed severe complications,³⁰ which resulted in limited application of this approach for impacted teeth. Studies of dental trauma provided researchers with knowledge of and experience needed to perform tooth autotransplantation. Much was learned from these studies about healing of the periodontal ligament, etiology of root resorption after replantation and the association of pulpal inflammation with root resorption.²⁰ Autotransplantation is, in a sense, controlled dental trauma, with every effort made to optimize the healing potential of the periodontal ligament and tooth pulp. Andreasen²⁰ showed that if the procedure was carefully done, the success rate of autotransplantation is higher than 95 percent.

There are many advantages to surgical repositioning of an impacted dilacerated incisor. Only one surgical site and one procedure are needed. The surgical technique is relatively simple compared with that of transplanting a premolar into the incisor area. A regular clinical setting, with local anesthesia, is adequate for the procedure. Children older than 7 or 8 years of age usually tolerate the surgical procedure under proper behavioral management; otherwise, general anesthesia may be indicated.

The success rate of surgical repositioning of an impacted dilacerated incisor depends on the degree of dilaceration and on the tooth’s position and root formation.¹⁰ Surgical repositioning provides freedom of tooth movement, which is of great importance in cases of difficult-to-treat impaction. An impacted tooth used as a donor tooth has the advantage of a thick, wide periodontal membrane, which is more suitable for reattachment than the narrow periodontal membrane found in an erupted, functioning tooth.³¹

Autotransplantation of an immature tooth provides for possible adaptation of the developing root apex to the new position. In the case described here, on the immediate posttreatment radiograph, the apex of the dilacerated root protruded outside the labial cortical plate. In the later stage of orthodontic treatment, the anterolateral radiograph showed that the apex of the repositioned incisor could not be identified clearly. This may be due to occlusal movement of the tooth or to the developing root’s adaptation to its new position by distal growth (Figure 6). The radiographs taken immediately postoperatively and after active orthodontic treatment demonstrated that the root of the repositioned incisor continued root development, with normal appearance of the periodontal ligament space and lamina dura. A root with an open apex has good chance of pulp revascularization after transplantation.¹⁵ For an immature tooth, endodontic treatment is indicated when signs of pulp necrosis are noted. Saad and Abdellatief ²⁹ demonstrated successful surgical repositioning of impacted anterior teeth with mature root formation. They performed endodontic therapy at the end of the second week after repositioning.

Because the impacted incisor in my patient’s case was transplanted in a semierupted position, immediate esthetic improvement was achieved. This can be a good compliance incentive for both children and parents. Bonding of the bracket or button on the labial side of the crown is easy, because the tooth now is in the normal direction and semierupted. The need for a second surgical exposure is eliminated, unlike in the conventional surgical/orthodontic method. Orthodontic treatment may start three to four months after surgery if the semierupted incisor does not erupt spontaneously.¹ Because the tooth is placed in the normal direction, orthodontic mechanics are simple.

The incisor is positioned in a semierupted position to safeguard marginal bone regeneration.¹ Orthodontic occlusal movement of the tooth will restore the height of the alveolar ridge and is compatible with normal dental and skeletal growth. Normal periodontal attachment and gingival margins can be achieved, thus eliminating the need for additional periodontal therapy. Because the incisor itself, not another tooth, is used in this therapeutic approach, there is no need for crown recontouring.²¹ The total cost and treatment time is reduced greatly from that required for extraction or the conventional surgical/orthodontic approach.

Theoretically, timing of the surgical phase depends on the incisor’s root development and the availability of space. Andreasen²⁰ suggested that the best timing for tooth transplantation is when the root is two-thirds to three-fourths formed. This helps ensure revascularization of the pulp. Early surgery may risk damaging the adjacent lateral incisor if it has not yet erupted. The younger the patient, the more difficult for the child to cope with the stress of the surgical procedure, thus resulting in problems of behavior management. If surgery is postponed, the apex opening of the impacted incisor will become small and endodontic treatment after autotransplantation may be needed.^28,29 With late surgery, the lateral incisor may erupt into the space of central incisor and will require extra orthodontic treatment to reopen the space. In addition to root development and space issues, the decision of timing also may be varied by the clinician’s experience and judgment, and by the behavior and age of the child seeking treatment.

It has been suggested that surgical repositioning of an impacted tooth should be considered only when more conservative methods have been attempted or are not indicated.¹ Because of the trauma induced during the surgical procedure, complications may arise.^1,30 If surgical exposure of a tooth is too radical, there is the possibility of damage to the adjacent tooth, loss of attachment and creation of variations in interdental bone height.³¹

Major complications of autotransplantation include injury to the periodontal ligament resulting in root resorption and/or ankylosis; damage to the pulp, possibly leading to pulp necrosis; and injury to Hertwig’s root sheath, potentially resulting in partial or total arrest of further root development.^1,20,30 It seems reasonable that unless there is extreme acute crown-root angulation, the surgical repositioning approach can be applied in most cases of impacted dilacerated incisors in mixed dentition. With careful surgical manipulation and close adherence to the principles of tooth autotransplantation, the advantages of surgical repositioning clearly outweigh its shortcomings.

	CONCLUSION

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Surgical repositioning offers a simplified treatment for dilacerated incisors. The advantages include immediate esthetic improvement; use of a single, simplified surgical procedure; simple and short orthodontic therapy; normal gingival margins; and the possibility of the developing root’s adapting to its new position. Surgical repositioning is especially valuable in cases of difficult impaction. The timing of surgical repositioning depends on root development of the incisor and space available for the transplant.

View larger version (135K): [in this window] [in a new window]   Dr. Tsai is attending staff, Dental Department, Chang Gung Memorial Hospital, 199 Tung-Hwa North Road, Taipei, Taiwan 105. Address reprint requests to Dr. Tsai.