CASE REPORT
Concomitant dilaceration, transposition, and intraosseous migration: Report of a patient treated with maxillary canine-central incisor substitution Ciara M. Campbell,a Andrew DiBiase,b and Padhraig S. Flemingc Kent and London, United Kingdom
This case report describes the multidisciplinary treatment of a male with a dilacerated maxillary left central incisor and transposition of the ipsilateral maxillary canine and lateral incisor. The initial treatment plan involved removal of the dilacerated incisor with mechanical eruption and alignment of the ectopic left canine, aiming to substitute the lateral incisor for the missing central incisor. However, the plan was modified to include eruption of the canine in the central incisor region in response to progressive ectopic development and mesial transmigration of the maxillary left canine. Although substitution of a maxillary canine for a central incisor is comparatively rare, the canines offer a relatively favorable template to simulate a central incisor. For this growing patient with a combination of dental trauma and developmental anomalies, maxillary canine-central incisor replacement was a viable option, offering excellent esthetic results without recourse to prosthetic replacement. (Am J Orthod Dentofacial Orthop 2014;146:514-21)
T
he primary aims of orthodontic treatment are invariably to optimize dental and facial esthetics and occlusal function. Typically, realizing these goals involves alignment of the teeth in their intended natural sequence. Rarely, gross displacements and transpositions that result from ectopic development, occurring either in isolation or together, require compromises to these goals to achieve realistic yet acceptable esthetic and functional outcomes. Dilaceration is characterized by an abrupt deviation of the axial angulation of a tooth; this can occur anywhere along the crown, cementoenamel junction, root, or apex.1,2 It is thought to relate to either traumatic injury or ectopic development of the tooth germ.3 Dilaceration has been reported in the maxillary deciduous incisors,4 mandibular permanent incisors,5 and maxillary
a Senior registrar, East Kent Hospitals University NHS Trust, Kent, United Kingdom. b Consultant, East Kent Hospitals NHS Trust, Kent, United Kingdom. c Senior clinical lecturer and honorary consultant, Queen Mary University of London, London, United Kingdom. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Address correspondence to: Padhraig S. Fleming, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Turner St, London E1 2AD; e-mail, padhraig.fl[email protected]. Submitted, March 2013; revised and accepted, November 2013. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.11.024
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canines and premolars,6 but it most commonly affects a maxillary central incisor. Typically, dilaceration manifests as either failure of eruption or displacement of the affected tooth. Transposition, defined as the positional interchange of 2 adjacent or nonadjacent teeth, has a prevalence of 0.3%.7 The most common teeth to be transposed are the maxillary canine with the maxillary first premolar, followed by the maxillary lateral incisor and the canine. Maxillary canine ectopia is a more common dental anomaly, with a palatal predilection.8 Although these developmental conditions most commonly arise in isolation, co-occurrence of dental abnormalities is well established. This article describes a patient with multiple dental anomalies, including a dilacerated maxillary central incisor and transposed, ectopic maxillary lateral incisor and canine, requiring combined orthodontic, surgical, and prosthodontic management.
DIAGNOSIS AND ETIOLOGY
A 7-year-old boy was referred to the orthodontic department of the Kent and Canterbury Hospital by his general dental practitioner regarding an unerupted maxillary left central incisor. The patient was concerned about the apparent absence of the maxillary incisor. The patient and parents reported a history of trauma to both the maxillary right and left deciduous central incisors at
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3 years of age, resulting in loss of vitality of the affected teeth. Both teeth were monitored but untreated by the general dental practitioner. The patient had wellcontrolled asthma. On clinical examination, there was a skeletal Class I pattern with average vertical facial proportions (Fig 1). The lips were competent and protrusive to the E-line, with an acute nasolabial angle, 4 mm of incisor show at rest, and reduced incisor show on smiling. The temporomandibular joints were symptomless. Intraorally, the patient was in the mixed dentition with good oral hygiene. The mandibular arch was mildly crowded, with the anterior segment of average inclination, with an average curve of Spee. The maxillary arch was spaced, with average inclination of the anterior teeth. In occlusion, the molar relationships were Angle Class I bilaterally; the incisor relationship was also Class I. There was a crossbite without displacement associated with the maxillary right lateral incisor, and overjet was reduced, at 1 mm. Overbite was average and complete with noncoincident centerlines; the maxillary centerline was displaced 2 mm to the left side (Fig 2). A dentopantomograph confirmed the presence of all teeth and highlighted a root dilaceration affecting the maxillary left central incisor and an ectopic position of the maxillary left lateral incisor (Fig 3). The cephalometric analysis confirmed the clinical findings and also showed the extent of the dilaceration of the maxillary left central incisor (Fig 4).
515
2.
3.
4.
TREATMENT OBJECTIVES
The initial plan involved removal of the dilacerated maxillary left central incisor with a poor prognosis with mechanical eruption and alignment of the ectopic maxillary left lateral incisor, aiming to substitute the maxillary left lateral incisor for the maxillary left central incisor. This was to be followed by space reopening upon eruption of the canines, facilitating prosthetic replacement of the maxillary left central incisor with adhesive bridgework as an interim measure. Other objectives included relief of crowding, alignment of both dental arches, and correction of the anterior crossbite and centerline discrepancy with maintenance of the Class I incisor and molar relationships. However, this plan and some objectives were modified in response to progressive ectopic development and transmigration of the maxillary left canine. TREATMENT ALTERNATIVES
The following treatment alternatives were considered and discussed with the patient and his parents. 1.
Extraction of the dilacerated maxillary left central incisor and mechanical alignment of the maxillary left lateral incisor and maxillary left canine into their
respective positions with prosthetic replacement of the maxillary left central incisor with a Maryland bridge initially, followed by dental implant replacement at skeletal maturity. Extraction of the dilacerated central incisor and mechanical alignment of the maxillary left lateral incisor to substitute for the maxillary left central incisor. To facilitate substitution, the maxillary left lateral incisor would be intruded to harmonize the gingival marginal height with direct composite recontouring. Space closure in the maxillary left quadrant would be directed using a temporary anchorage device for protraction of the buccal segment, finishing to a full-unit Class II molar relationship on the left side. Alignment of all maxillary anterior teeth in their correct developmental positions with attempts to optimally align the dilacerated maxillary left central incisor. Alignment would be resisted by encroachment on the buccal cortical plate. With this approach, provision would be made for an apicoectomy to permit improved alignment of the maxillary left central incisor. Extraction of the dilacerated maxillary left central incisor, in addition to the maxillary right second premolar, mandibular left second premolar, and the mandibular left second premolar with autotransplantation of a mandibular premolar into the maxillary central incisor position. This approach would necessitate restorative treatment to simulate the appearance of the maxillary left central incisor initially with direct composite recontouring.
TREATMENT PROGRESS
The maxillary left central incisor was extracted under general anesthesia; surgical exposure and bonding of the maxillary left lateral incisor were performed simultaneously. A transpalatal arch (0.9 mm, stainless steel) was fitted to the maxillary first molars to maintain the transverse dimension and provide vertical anchorage during mechanical eruption of the maxillary left lateral incisor. Subsequently, preadjusted edgewise appliances with a 0.022 3 0.28-in slot were bonded to the maxillary dentition including the deciduous molars. After initial alignment, an 0.018-in stainless steel base wire was placed with an accessory piggyback 0.014-in nickel-titanium wire delivering an extrusive force to the maxillary left lateral incisor (Fig 5). This was reactivated over a number of visits until the maxillary left lateral incisor was mechanically erupted, at which stage a bracket was placed permitting detailing of the tooth position.
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Fig 1. Photographs of malocclusion before treatment.
Fig 2. Pretreatment dental casts.
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Fig 3. Panoramic radiograph showing unerupted and dilacerated maxillary left central incisor.
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Fig 5. Mechanical eruption of the maxillary left lateral incisor after extraction of the dilacerated central incisor.
Fig 6. Panoramic radiograph showing mesial migration of the unerupted maxillary left canine.
Fig 4. Pretreatment lateral cephalometric radiograph.
After alignment of the maxillary left lateral incisor, the transpalatal arch was removed, and the dentopantomograph was updated to assess the developing permanent dentition, highlighting the ectopic maxillary left canine, which had migrated intraosseously, assuming a medial position, high and mesial to the maxillary left lateral incisor (Fig 6). Because of the degree of mesial dislocation of the maxillary left canine, the treatment plan was modified to attempt mechanical alignment of this tooth into the maxillary left central incisor position. A referral was made for a second surgical procedure comprising closed exposure and bonding of the maxillary left canine and removal of the maxillary deciduous canines. Space was recreated between the maxillary left central incisor and the maxillary left lateral incisor with
sliding mechanics using an open-coil spring on a 0.018-in stainless steel base wire to generate space to accommodate the maxillary left canine in the arch. Attachments were placed on the erupting maxillary premolars; after alignment, vertical traction was placed on the maxillary left canine with a piggyback wire. After eruption of the maxillary left canine, a maxillary left central incisor attachment was placed on this tooth (Fig 7). At this stage, a joint orthodontic and restorative consultation was held; after this visit, it was decided to distalize the maxillary left lateral incisor into the maxillary left canine position to facilitate prosthetic replacement in the region of maxillary left lateral incisor. Thereafter, the mandibular appliance was placed to promote alignment and leveling of the mandibular arch and optimal intercuspation. Stainless steel archwires (0.019 3 0.025 in) were placed in both arches, with supplementary torque added to the maxillary left lateral incisor. After removal of the appliances, the maxillary left canine was reshaped to resemble a central incisor, and a bonded retainer was placed from the maxillary right central incisor to the maxillary left canine (Fig 8). A distal cantilever Maryland resin-bonded bridge was subsequently placed on the maxillary left canine
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Fig 7. Mechanical eruption of the maxillary left canine into the central incisor position.
Fig 8. Maxillary left canine restored with direct composite restoration to mimic a central incisor.
with a pontic in the maxillary left lateral incisor position (Fig 9). Maxillary and mandibular vacuum-formed retainers were provided with instructions for prolonged nocturnal wear.
architecture. Nevertheless, modifications of crown morphology and color are essential if reasonable esthetics are to be achieved with this approach. In our patient, direct composite addition was sufficient to produce acceptable esthetics. A more definitive solution can be planned after gingival maturation at skeletal maturity. Consideration was given to gingival recontouring to improve the gingival harmony; however, this was ultimately deemed unnecessary. This case was also remarkable in that the treatment aims evolved because of unexpected deterioration in the position of an unerupted tooth. It is possible that because the maxillary left canine had a mesial orientation, vertical movement of the maxillary left lateral incisor removed restraint by the lateral incisor, allowing the mesial development of the canine to assert itself. Consequently, the maxillary left canine underwent significant mesial intraosseous migration, encroaching on the maxillary dental midline and prompting the decision to revise the treatment plan and to substitute the canine for the missing central incisor, rather than the lateral incisor. After eruption of the maxillary left canine, a decision was made to distalize the maxillary left central incisor. This necessitated a further extension of the treatment but had the advantage of promoting alveolar ridge development, simplifying dental implant replacement at skeletal maturity. The generated bone width is likely to be stable, with minimal bone loss reported at 4 years posttreatment.11 In the intervening period, prosthetic replacement was achieved with a Maryland adhesive bridge. Adhesive bridgework is minimally invasive, providing excellent esthetics and offering acceptable levels of predictability in the medium term; survival rates of 74% at 4 years are typical.12 A further advantage of distal movement of the lateral incisor was to locate a natural tooth in the canine position. This ensured that the pontic could be located farther anteriorly, avoiding dynamic occlusal loading on the pontic in lateral excursive movements and making survival more predictable.13
TREATMENT RESULTS
All treatment objectives were achieved with functional and esthetic occlusal results (Figs 10 and 11). The final molar and incisor relationships were Class I with the buccal occlusion well intercupated and the centerlines almost coincident. Smile esthetics were enhanced with full incisor show in an unposed smile. The dental esthetics were also acceptable, with restorative adjustment to the maxillary left canine providing an excellent replacement for the maxillary left central incisor, with acceptable gingival harmony. Superimposition of the lateral cephalometric radio-graphs shows favorable growth and minimal change in incisor inclination (Fig 12). The outcome was tempered by an extended overall duration of treatment of 48 months; this could be attributed to the early commencement of treatment necessitated by the dilaceration of the maxillary left central incisor, compounded by unfavorable intraosseous migration of the maxillary left canine and the time taken for complete establishment of the permanent dentition. DISCUSSION
Canine substitution for maxillary lateral incisors is an accepted and established approach typically used for patients with hypodontia.9 Substitution of maxillary canines for central incisors is comparatively rare, although previous reports have been described.10 Morphologically, however, canines offer a relatively favorable template to simulate a central incisor because they are closer in mesiodistal width to a central incisor than the lateral incisor is, approximating a central incisor in vertical height and having more compatible gingival
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Fig 9. Photographs of the resin retained bridge.
Fig 10. Posttreatment photographs.
The coexistence of dental anomalies including ectopic maxillary canines, hypodontia, microdontia, transpositions, and impacted maxillary first molars is well established.14 Dilaceration is more common in
female patients, who are less susceptible to dental trauma, suggesting that this anomaly can also be developmental.15 However, because of the clear history of traumatic injury to the maxillary deciduous incisors,
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Fig 11. Posttreatment dental casts.
Fig 12. Superimposition of start and near end of treatment cephalometric tracings.
dilaceration in this instance was likely to have had a traumatic origin. Approximately 54% of traumatic intrusive injuries to the deciduous incisors are thought to result in abnormalities of the permanent dentition16; one such manifestation is root dilaceration.
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Management of dilaceration is complex, often multidisciplinary and lengthy, and might require indefinite maintenance.17 Complications of orthodontic treatment of a dilacerated tooth include ankylosis, periodontal attachment loss, and external root resorption resulting in tooth loss. Because of the extent of the dilaceration, extraction was unavoidable for this patient. This decision was based on 2-dimensional radiographs; arguably, cone-beam computed tomography might have been considered as an adjunct to treatment planning for this patient.18 Although the initial replacement in the maxillary left lateral incisor region was undertaken with an adhesive bridge, this might be regarded as an interim replacement before definitive implant restoration at skeletal maturity.19 The decision regarding the timing of implant replacement is complex, although radiographic superimposition is thought to be helpful.19 In view of the hiatus between completion of orthodontics and definitive implant replacement, there is a significant onus on retention. Convergence of roots after space recreation has been demonstrated20; diligent wear of removable retainers should prevent this, although unexpected changes are possible. The harmony and symmetry of the anterior gingival margins were also major considerations in this patient. Electrosurgery was undertaken on the alveolar ridge to improve the emergence profile of the prosthetic maxillary left lateral incisor. However, further gingival recontouring
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was avoided at this stage because of the likely alteration in marginal heights during adolescent growth and maturation. Further gingival reshaping might be considered at the time of definitive implant replacement. CONCLUSIONS
Maxillary canine-central incisor replacement can offer excellent esthetic results in complex interdisciplinary cases involving a combination of dental trauma and developmental anomalies. ACKNOWLEDGMENTS
The authors are grateful to Mr Andrew Elder for the Maryland bridge replacement. REFERENCES 1. British Standards Institution. Glossary of terms relating to dentistry. London, United Kingdom: British Standards Institution; 1983. 2. Smith DM, Winter GB. Root dilaceration of maxillary incisors. Br Dent J 1981;150:125-7. 3. Andreasen JO. Textbook and color atlas of traumatic injuries to the teeth. 3rd ed. Copenhagen, Denmark: Munksgaard; 1994. p. 457-94. 4. Kilpatrick NM, Hardmann PJ, Welbury RR. Dilaceration of a primary tooth. Int J Paediatr Dent 1991;1:151-3. 5. Chadwick SM, Millet D. Dilaceration of a permanent mandibular incisor: a case report. Br J Orthod 1995;22:279-81. 6. Ødegaard J. The treatment of a Class I malocclusion with two horizontally impacted maxillary canines. Am J Orthod Dentofacial Orthop 1997;111:357-65. 7. Peck S. Classification of maxillary tooth transpositions. Am J Orthod Dentofacial Orthop 1995;107:505-17. 8. Ericson S, Kurol J. Radiographic assessment of maxillary canine eruption in children with clinical signs of eruption disturbance. Eur J Orthod 1986;8:133-40.
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9. Kokich VO, Kinzer GA. Managing congenitally missing lateral incisors. Part I: canine substitution. J Esthet Restor Dent 2005;17:5-10. 10. Zimmer B, Seifi-Shirvandehm N. Routine treatment of bilateral aplasia of upper lateral incisors by orthodontic space closure without mandibular extractions. Eur J Orthod 2009; 31:320-5. 11. Zachrisson BU. Orthodontic tooth movement to relocate gingival margins and regenerate alveolar bone for single-tooth implants. Growth and treatment: a meeting of the minds. Monograph 41. Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development; University of Michigan; 2004. p. 73-88. 12. Creugers NHJ, De Kanter RJAM, van't Hof MA. Long-term survival data from clinical trial on resin-bonded bridges. J Dent 1997;25: 239-42. 13. Pjetursson BE, Tan WC, Tan K, Br€agger U, Zwahlen M, Lang NP. A systematic review of the survival and complication rates of resinbonded bridges after an observation period of at least 5 years. Clin Oral Implants Res 2008;19:131-41. 14. Peck S, Peck L, Kataja M. Mandibular lateral incisor-canine transposition, concomitant dental anomalies, and genetic control. Angle Orthod 1998;68:455-66. 15. Stewart DJ. Dilacerated unerupted maxillary central incisors. Br Dent J 1978;145:229-33. 16. Locks A, Ritter DE, Morona AR, Haertel GB, Ribeiro GLU, Menezes LM. Orthodontic-surgical treatment of a dilacerated maxillary central incisor—clinical report. Ortodon Ortop Facial 2000;5:75-9. 17. Maia RL, Vieira AP. Auto-transplantation of central incisor with root dilaceration. Int J Oral Maxillofac Surg 2005;34:89-91. 18. Botticelli S, Verna C, Cattaneo PM, Heidmann J, Melsen B. Twoversus three-dimensional imaging in subjects with unerupted maxillary canines. Eur J Orthod 2011;33:344-9. 19. Thilander B, Odman J, Lekholm U. Orthodontic aspects of the use of oral implants in adolescents: a 10 year follow up. Eur J Orthod 2001;23:715-31. 20. Olsen TM, Kokich VG Sr. Postorthodontic root approximation after opening space for maxillary lateral incisor implants. Am J Orthod Dentofacial Orthop 2010;137:158-9.
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Concomitant dilaceration, transposition, and intraosseous migration: Report of a patient treated with maxillary canine-central incisor substitution Ciara M. Campbell,a Andrew DiBiase,b and Padhraig S. Flemingc Kent and London, United Kingdom
This case report describes the multidisciplinary treatment of a male with a dilacerated maxillary left central incisor and transposition of the ipsilateral maxillary canine and lateral incisor. The initial treatment plan involved removal of the dilacerated incisor with mechanical eruption and alignment of the ectopic left canine, aiming to substitute the lateral incisor for the missing central incisor. However, the plan was modified to include eruption of the canine in the central incisor region in response to progressive ectopic development and mesial transmigration of the maxillary left canine. Although substitution of a maxillary canine for a central incisor is comparatively rare, the canines offer a relatively favorable template to simulate a central incisor. For this growing patient with a combination of dental trauma and developmental anomalies, maxillary canine-central incisor replacement was a viable option, offering excellent esthetic results without recourse to prosthetic replacement. (Am J Orthod Dentofacial Orthop 2014;146:514-21)
T
he primary aims of orthodontic treatment are invariably to optimize dental and facial esthetics and occlusal function. Typically, realizing these goals involves alignment of the teeth in their intended natural sequence. Rarely, gross displacements and transpositions that result from ectopic development, occurring either in isolation or together, require compromises to these goals to achieve realistic yet acceptable esthetic and functional outcomes. Dilaceration is characterized by an abrupt deviation of the axial angulation of a tooth; this can occur anywhere along the crown, cementoenamel junction, root, or apex.1,2 It is thought to relate to either traumatic injury or ectopic development of the tooth germ.3 Dilaceration has been reported in the maxillary deciduous incisors,4 mandibular permanent incisors,5 and maxillary
a Senior registrar, East Kent Hospitals University NHS Trust, Kent, United Kingdom. b Consultant, East Kent Hospitals NHS Trust, Kent, United Kingdom. c Senior clinical lecturer and honorary consultant, Queen Mary University of London, London, United Kingdom. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Address correspondence to: Padhraig S. Fleming, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Turner St, London E1 2AD; e-mail, padhraig.fl[email protected]. Submitted, March 2013; revised and accepted, November 2013. 0889-5406/$36.00 Copyright Ó 2014 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.11.024
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canines and premolars,6 but it most commonly affects a maxillary central incisor. Typically, dilaceration manifests as either failure of eruption or displacement of the affected tooth. Transposition, defined as the positional interchange of 2 adjacent or nonadjacent teeth, has a prevalence of 0.3%.7 The most common teeth to be transposed are the maxillary canine with the maxillary first premolar, followed by the maxillary lateral incisor and the canine. Maxillary canine ectopia is a more common dental anomaly, with a palatal predilection.8 Although these developmental conditions most commonly arise in isolation, co-occurrence of dental abnormalities is well established. This article describes a patient with multiple dental anomalies, including a dilacerated maxillary central incisor and transposed, ectopic maxillary lateral incisor and canine, requiring combined orthodontic, surgical, and prosthodontic management.
DIAGNOSIS AND ETIOLOGY
A 7-year-old boy was referred to the orthodontic department of the Kent and Canterbury Hospital by his general dental practitioner regarding an unerupted maxillary left central incisor. The patient was concerned about the apparent absence of the maxillary incisor. The patient and parents reported a history of trauma to both the maxillary right and left deciduous central incisors at
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3 years of age, resulting in loss of vitality of the affected teeth. Both teeth were monitored but untreated by the general dental practitioner. The patient had wellcontrolled asthma. On clinical examination, there was a skeletal Class I pattern with average vertical facial proportions (Fig 1). The lips were competent and protrusive to the E-line, with an acute nasolabial angle, 4 mm of incisor show at rest, and reduced incisor show on smiling. The temporomandibular joints were symptomless. Intraorally, the patient was in the mixed dentition with good oral hygiene. The mandibular arch was mildly crowded, with the anterior segment of average inclination, with an average curve of Spee. The maxillary arch was spaced, with average inclination of the anterior teeth. In occlusion, the molar relationships were Angle Class I bilaterally; the incisor relationship was also Class I. There was a crossbite without displacement associated with the maxillary right lateral incisor, and overjet was reduced, at 1 mm. Overbite was average and complete with noncoincident centerlines; the maxillary centerline was displaced 2 mm to the left side (Fig 2). A dentopantomograph confirmed the presence of all teeth and highlighted a root dilaceration affecting the maxillary left central incisor and an ectopic position of the maxillary left lateral incisor (Fig 3). The cephalometric analysis confirmed the clinical findings and also showed the extent of the dilaceration of the maxillary left central incisor (Fig 4).
515
2.
3.
4.
TREATMENT OBJECTIVES
The initial plan involved removal of the dilacerated maxillary left central incisor with a poor prognosis with mechanical eruption and alignment of the ectopic maxillary left lateral incisor, aiming to substitute the maxillary left lateral incisor for the maxillary left central incisor. This was to be followed by space reopening upon eruption of the canines, facilitating prosthetic replacement of the maxillary left central incisor with adhesive bridgework as an interim measure. Other objectives included relief of crowding, alignment of both dental arches, and correction of the anterior crossbite and centerline discrepancy with maintenance of the Class I incisor and molar relationships. However, this plan and some objectives were modified in response to progressive ectopic development and transmigration of the maxillary left canine. TREATMENT ALTERNATIVES
The following treatment alternatives were considered and discussed with the patient and his parents. 1.
Extraction of the dilacerated maxillary left central incisor and mechanical alignment of the maxillary left lateral incisor and maxillary left canine into their
respective positions with prosthetic replacement of the maxillary left central incisor with a Maryland bridge initially, followed by dental implant replacement at skeletal maturity. Extraction of the dilacerated central incisor and mechanical alignment of the maxillary left lateral incisor to substitute for the maxillary left central incisor. To facilitate substitution, the maxillary left lateral incisor would be intruded to harmonize the gingival marginal height with direct composite recontouring. Space closure in the maxillary left quadrant would be directed using a temporary anchorage device for protraction of the buccal segment, finishing to a full-unit Class II molar relationship on the left side. Alignment of all maxillary anterior teeth in their correct developmental positions with attempts to optimally align the dilacerated maxillary left central incisor. Alignment would be resisted by encroachment on the buccal cortical plate. With this approach, provision would be made for an apicoectomy to permit improved alignment of the maxillary left central incisor. Extraction of the dilacerated maxillary left central incisor, in addition to the maxillary right second premolar, mandibular left second premolar, and the mandibular left second premolar with autotransplantation of a mandibular premolar into the maxillary central incisor position. This approach would necessitate restorative treatment to simulate the appearance of the maxillary left central incisor initially with direct composite recontouring.
TREATMENT PROGRESS
The maxillary left central incisor was extracted under general anesthesia; surgical exposure and bonding of the maxillary left lateral incisor were performed simultaneously. A transpalatal arch (0.9 mm, stainless steel) was fitted to the maxillary first molars to maintain the transverse dimension and provide vertical anchorage during mechanical eruption of the maxillary left lateral incisor. Subsequently, preadjusted edgewise appliances with a 0.022 3 0.28-in slot were bonded to the maxillary dentition including the deciduous molars. After initial alignment, an 0.018-in stainless steel base wire was placed with an accessory piggyback 0.014-in nickel-titanium wire delivering an extrusive force to the maxillary left lateral incisor (Fig 5). This was reactivated over a number of visits until the maxillary left lateral incisor was mechanically erupted, at which stage a bracket was placed permitting detailing of the tooth position.
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Fig 1. Photographs of malocclusion before treatment.
Fig 2. Pretreatment dental casts.
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Fig 3. Panoramic radiograph showing unerupted and dilacerated maxillary left central incisor.
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Fig 5. Mechanical eruption of the maxillary left lateral incisor after extraction of the dilacerated central incisor.
Fig 6. Panoramic radiograph showing mesial migration of the unerupted maxillary left canine.
Fig 4. Pretreatment lateral cephalometric radiograph.
After alignment of the maxillary left lateral incisor, the transpalatal arch was removed, and the dentopantomograph was updated to assess the developing permanent dentition, highlighting the ectopic maxillary left canine, which had migrated intraosseously, assuming a medial position, high and mesial to the maxillary left lateral incisor (Fig 6). Because of the degree of mesial dislocation of the maxillary left canine, the treatment plan was modified to attempt mechanical alignment of this tooth into the maxillary left central incisor position. A referral was made for a second surgical procedure comprising closed exposure and bonding of the maxillary left canine and removal of the maxillary deciduous canines. Space was recreated between the maxillary left central incisor and the maxillary left lateral incisor with
sliding mechanics using an open-coil spring on a 0.018-in stainless steel base wire to generate space to accommodate the maxillary left canine in the arch. Attachments were placed on the erupting maxillary premolars; after alignment, vertical traction was placed on the maxillary left canine with a piggyback wire. After eruption of the maxillary left canine, a maxillary left central incisor attachment was placed on this tooth (Fig 7). At this stage, a joint orthodontic and restorative consultation was held; after this visit, it was decided to distalize the maxillary left lateral incisor into the maxillary left canine position to facilitate prosthetic replacement in the region of maxillary left lateral incisor. Thereafter, the mandibular appliance was placed to promote alignment and leveling of the mandibular arch and optimal intercuspation. Stainless steel archwires (0.019 3 0.025 in) were placed in both arches, with supplementary torque added to the maxillary left lateral incisor. After removal of the appliances, the maxillary left canine was reshaped to resemble a central incisor, and a bonded retainer was placed from the maxillary right central incisor to the maxillary left canine (Fig 8). A distal cantilever Maryland resin-bonded bridge was subsequently placed on the maxillary left canine
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Fig 7. Mechanical eruption of the maxillary left canine into the central incisor position.
Fig 8. Maxillary left canine restored with direct composite restoration to mimic a central incisor.
with a pontic in the maxillary left lateral incisor position (Fig 9). Maxillary and mandibular vacuum-formed retainers were provided with instructions for prolonged nocturnal wear.
architecture. Nevertheless, modifications of crown morphology and color are essential if reasonable esthetics are to be achieved with this approach. In our patient, direct composite addition was sufficient to produce acceptable esthetics. A more definitive solution can be planned after gingival maturation at skeletal maturity. Consideration was given to gingival recontouring to improve the gingival harmony; however, this was ultimately deemed unnecessary. This case was also remarkable in that the treatment aims evolved because of unexpected deterioration in the position of an unerupted tooth. It is possible that because the maxillary left canine had a mesial orientation, vertical movement of the maxillary left lateral incisor removed restraint by the lateral incisor, allowing the mesial development of the canine to assert itself. Consequently, the maxillary left canine underwent significant mesial intraosseous migration, encroaching on the maxillary dental midline and prompting the decision to revise the treatment plan and to substitute the canine for the missing central incisor, rather than the lateral incisor. After eruption of the maxillary left canine, a decision was made to distalize the maxillary left central incisor. This necessitated a further extension of the treatment but had the advantage of promoting alveolar ridge development, simplifying dental implant replacement at skeletal maturity. The generated bone width is likely to be stable, with minimal bone loss reported at 4 years posttreatment.11 In the intervening period, prosthetic replacement was achieved with a Maryland adhesive bridge. Adhesive bridgework is minimally invasive, providing excellent esthetics and offering acceptable levels of predictability in the medium term; survival rates of 74% at 4 years are typical.12 A further advantage of distal movement of the lateral incisor was to locate a natural tooth in the canine position. This ensured that the pontic could be located farther anteriorly, avoiding dynamic occlusal loading on the pontic in lateral excursive movements and making survival more predictable.13
TREATMENT RESULTS
All treatment objectives were achieved with functional and esthetic occlusal results (Figs 10 and 11). The final molar and incisor relationships were Class I with the buccal occlusion well intercupated and the centerlines almost coincident. Smile esthetics were enhanced with full incisor show in an unposed smile. The dental esthetics were also acceptable, with restorative adjustment to the maxillary left canine providing an excellent replacement for the maxillary left central incisor, with acceptable gingival harmony. Superimposition of the lateral cephalometric radio-graphs shows favorable growth and minimal change in incisor inclination (Fig 12). The outcome was tempered by an extended overall duration of treatment of 48 months; this could be attributed to the early commencement of treatment necessitated by the dilaceration of the maxillary left central incisor, compounded by unfavorable intraosseous migration of the maxillary left canine and the time taken for complete establishment of the permanent dentition. DISCUSSION
Canine substitution for maxillary lateral incisors is an accepted and established approach typically used for patients with hypodontia.9 Substitution of maxillary canines for central incisors is comparatively rare, although previous reports have been described.10 Morphologically, however, canines offer a relatively favorable template to simulate a central incisor because they are closer in mesiodistal width to a central incisor than the lateral incisor is, approximating a central incisor in vertical height and having more compatible gingival
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Fig 9. Photographs of the resin retained bridge.
Fig 10. Posttreatment photographs.
The coexistence of dental anomalies including ectopic maxillary canines, hypodontia, microdontia, transpositions, and impacted maxillary first molars is well established.14 Dilaceration is more common in
female patients, who are less susceptible to dental trauma, suggesting that this anomaly can also be developmental.15 However, because of the clear history of traumatic injury to the maxillary deciduous incisors,
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Fig 11. Posttreatment dental casts.
Fig 12. Superimposition of start and near end of treatment cephalometric tracings.
dilaceration in this instance was likely to have had a traumatic origin. Approximately 54% of traumatic intrusive injuries to the deciduous incisors are thought to result in abnormalities of the permanent dentition16; one such manifestation is root dilaceration.
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Management of dilaceration is complex, often multidisciplinary and lengthy, and might require indefinite maintenance.17 Complications of orthodontic treatment of a dilacerated tooth include ankylosis, periodontal attachment loss, and external root resorption resulting in tooth loss. Because of the extent of the dilaceration, extraction was unavoidable for this patient. This decision was based on 2-dimensional radiographs; arguably, cone-beam computed tomography might have been considered as an adjunct to treatment planning for this patient.18 Although the initial replacement in the maxillary left lateral incisor region was undertaken with an adhesive bridge, this might be regarded as an interim replacement before definitive implant restoration at skeletal maturity.19 The decision regarding the timing of implant replacement is complex, although radiographic superimposition is thought to be helpful.19 In view of the hiatus between completion of orthodontics and definitive implant replacement, there is a significant onus on retention. Convergence of roots after space recreation has been demonstrated20; diligent wear of removable retainers should prevent this, although unexpected changes are possible. The harmony and symmetry of the anterior gingival margins were also major considerations in this patient. Electrosurgery was undertaken on the alveolar ridge to improve the emergence profile of the prosthetic maxillary left lateral incisor. However, further gingival recontouring
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was avoided at this stage because of the likely alteration in marginal heights during adolescent growth and maturation. Further gingival reshaping might be considered at the time of definitive implant replacement. CONCLUSIONS
Maxillary canine-central incisor replacement can offer excellent esthetic results in complex interdisciplinary cases involving a combination of dental trauma and developmental anomalies. ACKNOWLEDGMENTS
The authors are grateful to Mr Andrew Elder for the Maryland bridge replacement. REFERENCES 1. British Standards Institution. Glossary of terms relating to dentistry. London, United Kingdom: British Standards Institution; 1983. 2. Smith DM, Winter GB. Root dilaceration of maxillary incisors. Br Dent J 1981;150:125-7. 3. Andreasen JO. Textbook and color atlas of traumatic injuries to the teeth. 3rd ed. Copenhagen, Denmark: Munksgaard; 1994. p. 457-94. 4. Kilpatrick NM, Hardmann PJ, Welbury RR. Dilaceration of a primary tooth. Int J Paediatr Dent 1991;1:151-3. 5. Chadwick SM, Millet D. Dilaceration of a permanent mandibular incisor: a case report. Br J Orthod 1995;22:279-81. 6. Ødegaard J. The treatment of a Class I malocclusion with two horizontally impacted maxillary canines. Am J Orthod Dentofacial Orthop 1997;111:357-65. 7. Peck S. Classification of maxillary tooth transpositions. Am J Orthod Dentofacial Orthop 1995;107:505-17. 8. Ericson S, Kurol J. Radiographic assessment of maxillary canine eruption in children with clinical signs of eruption disturbance. Eur J Orthod 1986;8:133-40.
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9. Kokich VO, Kinzer GA. Managing congenitally missing lateral incisors. Part I: canine substitution. J Esthet Restor Dent 2005;17:5-10. 10. Zimmer B, Seifi-Shirvandehm N. Routine treatment of bilateral aplasia of upper lateral incisors by orthodontic space closure without mandibular extractions. Eur J Orthod 2009; 31:320-5. 11. Zachrisson BU. Orthodontic tooth movement to relocate gingival margins and regenerate alveolar bone for single-tooth implants. Growth and treatment: a meeting of the minds. Monograph 41. Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development; University of Michigan; 2004. p. 73-88. 12. Creugers NHJ, De Kanter RJAM, van't Hof MA. Long-term survival data from clinical trial on resin-bonded bridges. J Dent 1997;25: 239-42. 13. Pjetursson BE, Tan WC, Tan K, Br€agger U, Zwahlen M, Lang NP. A systematic review of the survival and complication rates of resinbonded bridges after an observation period of at least 5 years. Clin Oral Implants Res 2008;19:131-41. 14. Peck S, Peck L, Kataja M. Mandibular lateral incisor-canine transposition, concomitant dental anomalies, and genetic control. Angle Orthod 1998;68:455-66. 15. Stewart DJ. Dilacerated unerupted maxillary central incisors. Br Dent J 1978;145:229-33. 16. Locks A, Ritter DE, Morona AR, Haertel GB, Ribeiro GLU, Menezes LM. Orthodontic-surgical treatment of a dilacerated maxillary central incisor—clinical report. Ortodon Ortop Facial 2000;5:75-9. 17. Maia RL, Vieira AP. Auto-transplantation of central incisor with root dilaceration. Int J Oral Maxillofac Surg 2005;34:89-91. 18. Botticelli S, Verna C, Cattaneo PM, Heidmann J, Melsen B. Twoversus three-dimensional imaging in subjects with unerupted maxillary canines. Eur J Orthod 2011;33:344-9. 19. Thilander B, Odman J, Lekholm U. Orthodontic aspects of the use of oral implants in adolescents: a 10 year follow up. Eur J Orthod 2001;23:715-31. 20. Olsen TM, Kokich VG Sr. Postorthodontic root approximation after opening space for maxillary lateral incisor implants. Am J Orthod Dentofacial Orthop 2010;137:158-9.
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