Treatment of Dilacerated Incisors in Early and Late Stages ...

497VOLUME XLIX NUMBER 8 © 2015 JCO, Inc.

Treatment of Dilacerated Incisors in Early and Late Stages of Root Development

LANG LEI, DDS, PhDFUHUA YAN, DDS, PhDHOUXUAN LI, MDS, PhDHUANG LI, DDS, PhD

Methodology

All patients in this study were referred to the Hospital of Stomatology, Fujian Medical Univer-sity, Fujian, China, for orthodontic consultation between 2004 and 2014. Nolla’s method was uti-lized to determine each patient’s dental age.15,16 A tooth with only one-third (stage 7) or two-thirds (stage 8) of its root formation was assigned to the early dental-age group; a tooth with an almost complete root but an open apex (stage 9), or with a complete apical end (stage 10), was assigned to the late dental-age group.

Orthodontic traction was successful in ex-truding 12 of the 13 early-stage DIs in our sample, with no need for root-canal therapy or apicectomy. On the other hand, eight of the 15 DIs in the late group had to be extracted due to crowding or se-vere crown-root angulations.

Although a dilacerated incisor (DI) is rarely encountered, such an anomaly makes it par-

ticularly demanding to restore facial esthetics. Treatment requires a well-synchronized, multi-disciplinary approach.1 Among all the modalities targeting impacted and dilacerated upper inci-sors—including extraction followed by space clo-sure or a fixed bridge,2 surgical repositioning,3 autotransplantation,4,5 apicectomy with root-canal therapy,6,7 and surgical exposure followed by orthodontic traction8-13—the last is the most wide-ly used. Because labially impacted upper central incisors still have some potential for further root development,14 however, early orthodontic inter-vention is advisable.

This article compares the results of ortho-dontic traction in a series of patients presenting with DIs in the early and later stages of dental root formation.

Dr. Houxuan Li Dr. Huang LiDr. YanDr. Lei

Dr. Lei is an Attending Doctor, Department of Orthodontics; Dr. Yan is a Professor and Vice Dean; Dr. Houxuan Li is an Associate Professor and Vice Dean, Department of Periodontics; and Dr. Huang Li is an Associate Professor and Dean, Department of Orthodontics, Nanjing Stomatological Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210008, China. E-mail Dr. Houxuan Li at [email protected].

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Treatment of Dilacerated Incisors in Early and Late Stages

Fig. 1 Case 1. 8-year-old female patient with delayed eruption of upper left central incisor. A. After injury at age 4. B. One year after injury. C. Immediately before treatment, showing labially rotated, impacted, and dilacerated upper left central incisor. D. Cone-beam computed tomography (CBCT), showing root one-half its full length.

A

C

D

B

499VOLUME XLIX NUMBER 8

Lei, Yan, Li, and Li

surface of the crown was facing forward like the hand of a traffic policeman.11 Cone-beam com-puted tomography (CBCT) confirmed the presence of an impacted central incisor with a labially ro-tated crown at the base of the nose (Fig. 1D). A sagittal section showed that the impacted incisor was in early formation (stage 8), with the root only half its full length and the open apex contacting the cortical plate of the palatal vault.

Since the root of the impacted incisor showed no obvious dilaceration and was only half the length of its contralateral counterpart, orthodontic intervention was undertaken to prevent further crown-root angulation.

The following reports, describing two cases in the early group (before full root formation) and two cases in the late group (after full root forma-tion), demonstrate that early intervention not only improves the success rate of orthodontic traction, but also produces longer roots with better confor-mation.

Case 1

An 8-year-old female was referred to the oral and maxillofacial surgery department for surgical removal of a DI, and the patient was then referred to the orthodontic department for consultation. Her parents reported an accidental injury to the upper lip and front teeth at age 4; the medical record noted a chipped crown, sulcular bleeding, and no obvious mobility of the deciduous upper left cen-tral incisor. A radiograph taken at that time did not show any obvious abnormalities (Fig. 1A), nor did a follow-up x-ray taken one year later (Fig. 1B). At age 8, the patient went to a dental office complain-ing of delayed eruption of the upper left central incisor.

Clinical examination found a healthy perio-dontium and mild caries. The patient was in the mixed dentition. Lateral cephalometric and pan-oramic radiographs revealed that the upper left central incisor was impacted, with its crown ro-tated more than 100° labially and its incisal tip just below the floor of the nose (Fig. 1C). The palatal

Fig. 3 Case 1. Eruption of impacted incisor with .012" superelastic nickel titanium archwire.

Fig. 2 Case 1. Flap surgery to expose palatal sur-face of impacted incisor.

Fig. 4 Case 1. Progress of incisor eruption after nine months of treatment.

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After two months, sufficient eruption space for the impacted incisor had been gained with a nickel titanium open-coil spring. A flap was then was raised to expose just enough of its palatal sur-face to minimize the risk of surgical injury (Fig. 2). The palatal surface of the incisor was acid-etched for bonding of a lingual button, and a liga-

ture wire was tied to the button. The incision was sutured to promote gingival recovery.

An .012" superelastic nickel titanium arch-wire was used to exert light, continuous force for eruption of the impacted incisor (Fig. 3). An .018" stainless steel wire was then placed to stabilize the arch. After nine months of treatment, the impact-

Fig. 5 Case 1. Patient after one year of treatment.

Fig. 6 Case 2. A. 6-year-old male patient six months before treatment, showing labially rotated, impacted, and dilacerated upper left central in-cisor. B. Immediately before treatment, after eruption of normal upper right central incisor.

A

B



ed incisor was almost in proper position (Fig. 4).Orthodontic traction was completed in one

year, leaving the incisor with an appropriate crown shape, nearly normal attached gingiva, and satis-factory alignment (Fig. 5). The root was not pal-pable labially; the panoramic radiograph showed that it was almost normal in shape, but still 20% shorter than its contralateral counterpart.

Case 2

A 6-year-old male with no history of dental trauma was referred to the orthodontic department for a follow-up examination. Clinical examination indicated severe caries and premature loss of some deciduous teeth, but the four first permanent mo-lars and both lower central permanent incisors had erupted (Fig. 6A). Cephalometric and panoramic radiographs showed the crown of the upper left central incisor rotated nearly 120° toward the nose. Since the root of the normal upper right central incisor was less than half its full length and the impacted incisor was only at stage 6, we elected to avoid unnecessary radiation exposure from CBCT imaging.

Orthodontic intervention was delayed until the upper right central incisor had erupted, six months later (Fig. 6B). A flap was then raised to expose a minimum palatal surface of the impacted incisor; a lingual button was bonded and tied with a ligature wire, and the incision was sutured (Fig. 7).

Fig. 8 Case 2. Eruption of impacted incisor with .012" superelastic nickel titanium archwire; adja-cent central incisor left unbracketed.

Fig. 7 Case 2. Flap surgery to expose palatal sur-face of impacted incisor and bond lingual button.

Fig. 9 Case 2. Incisor eruption and derotation af-ter seven months of treatment, with palatal but-ton moved to labial surface of incisor.

Fig. 10 Case 2. Progress of incisor eruption after 10 months of treatment.

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Fig. 12 Case 3. A. 11-year-old male patient with delayed eruption of impacted upper left central incisor one year before treatment. B. Immediately before treatment, showing labially rotated, impacted, and dilacer-ated upper left central incisor.

Fig. 11 Case 2. Patient after one year of treatment.

B

A



An .012" superelastic nickel titanium arch-wire was placed to exert light, continuous force on the impacted incisor, with the deciduous teeth providing anchorage and the right central incisor left unbracketed (Fig. 8). Four months later, the bulge of the impacted incisor could be seen in the vestibule, demonstrating that the rotation was be-ing corrected. In another three months, once enough of the labial surface had been exposed, the bonded button was moved from the palatal to the labial side (Fig. 9). After 10 months of treatment, both central incisors were bonded for final align-ment (Fig. 10).

After one year of traction, the impacted inci-sor had been brought into normal occlusion with no adverse effect on the adjacent central incisor (Fig. 11). The panoramic radiograph showed that both central incisors still had open root apices, with the root of the impacted incisor nearly the same length and shape as its counterpart.

Case 3

An 11-year-old male presented with his par-ents’ chief complaint of delayed eruption of the upper left central incisor. Although the parents did not recall any severe dental trauma at an early age, this did not preclude the possibility of moderate injury to the upper deciduous teeth. A panoramic x-ray taken one year earlier showed impaction of the upper left central incisor and incomplete root development of the other three upper incisors (Fig. 12A). Our clinical examination found a severe midline shift and reduced overbite and overjet (Fig. 12B). Radiographs revealed that the crown of the impacted incisor was rotated 100° labially and that the root apices of the three normally erupted inci-sors were closed.

Because enough space could be opened for incisor eruption, the parents chose to try ortho-dontic traction. If that failed, the incisor would be extracted and the space maintained for later im-plant placement.

After three months of treatment, sufficient space had been created, and a lingual button was bonded to the exposed palatal surface of the im-pacted incisor. An .012" superelastic nickel tita-

nium archwire was then used to bring the tooth into the arch (Fig. 13).

After 24 months of treatment, the impacted incisor had been aligned into normal occlusion, but its gingiva displayed some swelling and red-ness (Fig. 14A). The root was 20% shorter than that of the adjacent central incisor, with a mesio-distal bend in the median portion.

One year later, the swelling and redness were somewhat lessened (Fig. 14B). After five years of fixed retention, the gingival swelling had almost disappeared (Fig. 14C). The corrected incisor showed no mobility or root resorption.

Case 4

A 10-year-old female presented with her par-ents’ chief complaint of failed eruption of the up-per right central incisor. The patient had experi-enced a moderate injury to her upper front teeth at age 4; the deciduous incisors were partly chipped, but no mobility was noted. Cephalometric and panoramic radiographs showed the upper right central incisor to be impacted, with its crown ro-tated 120° labially (Fig. 15A). CBCT indicated that the root was only one-third to one-half its full length, but that the apex was almost closed, in a late stage 9 (Fig. 15B). There was inadequate space for eruption of the impacted incisor, and the mid-line was shifted to the right.

Because adequate space could be gained for the DI, the parents elected orthodontic traction. Even a dilacerated tooth with a root one-third to

Fig. 13 Case 3. Eruption of impacted incisor with .012" superelastic nickel titanium archwire.

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one-half its normal length could restore facial es-thetics and maintain the alveolar bone. If traction failed, the space would be maintained for future implant placement.

Four months later, after enough space had been opened with a nickel titanium open-coil spring (Fig. 16), a lingual button was bonded to the lingual surface of the impacted incisor. The tooth was moved mesially with power chain, then an .012" superelastic nickel titanium archwire was ligated for alignment. Once enough of the facial surface was exposed, after nine months of treat-

ment, the button was moved to the labial side for further traction (Fig. 17). Three months later, the right central incisor was bracketed for final align-ment (Fig. 18).

The impacted incisor was brought into nor-mal occlusion in 20 months of treatment; the pa-tient demonstrated satisfactory facial esthetics, with no bulge of the root in the vestibule (Fig. 19). The panoramic radiograph indicated that the root of the corrected incisor was still only half the length of the adjacent central incisor’s.

(continued on p. 506)

Fig. 14 Case 3. A. Patient after 24 months of treatment. B. After one year of retention. C. After five years of retention.

A

C

B



Fig. 15 Case 4. A. 10-year-old female patient with labially rotated, im-pacted, and dilacerated upper right central incisor before treatment. B. Sagittal section of CBCT, showing almost complete formation of root one-third to one-half its full length.

Fig. 16 Case 4. Space opening with nickel titani-um open-coil spring; lingual button bonded to impacted incisor for traction.

Fig. 17 Case 4. Impacted incisor brought into arch with .012" superelastic nickel titanium wire; button moved from palatal to labial surface.

A

B

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Discussion

The etiology of dilaceration is not fully un-derstood. Although it is commonly accepted that mechanical trauma to the calcified portion of a developing tooth in the deciduous dentition is the

most likely cause, the effect of trauma depends on the age of the patient and the cause and type of injury.17 Dilaceration frequently follows the avul-sion or intrusion of an overlying deciduous prede-cessor, usually before age 4.18

Some researchers contend that the etiology of DIs is idiopathic. For example, Stewart report-ed that only nine of 41 patients (22%) with DIs had experienced dental injuries.19 Although our Cases 1 and 4 showed a history of dental trauma, others did not. It should be noted, however, that because the parents might not remember moderate dental injuries, any study is likely to reflect a lower percentage of trauma-related DIs than may have actually occurred. Howe argued that an in-jury transmitted to the crown of an unerupted upper central incisor would result in an unusual orientation, with the crown facing upward and labially, unless the tooth germ of the permanent successor had already been displaced before the trauma.20 Nevertheless, it is possible that the mechanism of dilaceration may not be the exer-tion of a direct force on the tooth germ, but rath-er the disruption of a normal environment for eruption.

Whether an impacted DI can be successfully erupted and aligned depends on the degree of di-laceration and root formation.12 In our study, the roots of the DIs were significantly shorter than their contralateral counterparts, as observed in a study by Sun and colleagues.14 Cases 1 and 2 show that longer roots with better conformation can be obtained at an early dental age with incomplete root growth (stage 7 or 8); Cases 3 and 4 demon-strate that patients at a late dental age with nearly complete root development (stage 9 or 10) may end up with compromised tooth length and shape, em-phasizing the importance of early intervention.

Two theories have been advanced to explain the compromised root development of DIs. One is that an injury to the permanent tooth germ during odontogenesis may disrupt the growth of the Hert-wig epithelial root sheath, thus inhibiting root development.21 The second is that a labial rotation of the crown brings the Hertwig epithelial root sheath too close to the palatal cortical bone, limit-ing the space for root development14 (Fig. 1D).

Fig. 18 Case 4. Progress of incisor eruption after 12 months of treatment.

Fig. 19 Case 4. Patient after 20 months of treat-ment.



5. Maia, R.L. and Vieira, A.P.: Auto-transplantation of central incisor with root dilaceration: Technical note, Int. J. Oral Maxillofac. Surg. 34:89-91, 2005.

6. Muthumani, T.; Rajasekaran, M.; Veerabahu, M.; and Indra, R.: Interdisciplinary management of impacted maxillary cen-tral incisor with dilacerated crown, J. Endod. 37:269-271, 2011.

7. Valladares N.J.; de Pinho Costa, S.; and Estrela, C.: Orthodontic-surgical-endodontic management of unerupted maxillary central incisor with distoangular root dilaceration, J. Endod. 36:755-759, 2010.

8. McNamara, T.; Woolfe, S.N.; and McNamara, C.M.: Orthodontic management of a dilacerated maxillary central incisor with an unusual sequela, J. Clin. Orthod. 32:293-297, 1998.

9. Uematsu, S.; Uematsu, T.; Furusawa, K.; Deguchi, T.; and Kurihara, S.: Orthodontic treatment of an impacted dilacerat-ed maxillary central incisor combined with surgical exposure and apicoectomy, Angle Orthod. 74:132-136, 2004.

10. Kolokithas, G. and Karakasis, D.: Orthodontic movement of dilacerated maxillary central incisor: Report of a case, Am. J. Orthod. 76:310-315, 1979.

11. Pavlidis, D.; Daratsianos, N.; and Jäger A.: Treatment of an impacted dilacerated maxillary central incisor, Am. J. Orthod. 139:378-387, 2011.

12. Lin, Y.J.: Treatment of an impacted dilacerated maxillary central incisor, Am. J. Orthod. 115:406-409, 1999.

13. Tanaka, E.; Watanabe, M.; Nagaoka, K.; Yamaguchi, K.; and Tanne, K.: Orthodontic traction of an impacted maxillary central incisor, J. Clin. Orthod. 35:375-378, 2001.

14. Sun, H.; Wang, Y.; Sun, C.; Ye, Q.; Dai, W.; Wang, X.; Xu, Q.; Pan, S.; and Hu, R.: Root morphology and development of labial inversely impacted maxillary central incisors in the mixed dentition: A retrospective cone-beam computed tomo-graphy study, Am. J. Orthod. 146:709-716, 2014.

15. Miloglu, O.; Celikoglu, M.; Dane, A.; Cantekin, K.; and Yilmaz, A.B.: Is the assessment of dental age by the Nolla method valid for eastern Turkish children? J. Forensic Sci. 56:1025-1028, 2011.

16. Nur, B.; Kusgoz, A.; Bayram, M.; Celikoglu, M.; Nur, M.; Kayipmaz, S.; and Yildirim, S.: Validity of Demirjian and Nolla methods for dental age estimation for Northeastern Turkish children aged 5-16 years old, Med. Oral Patol. Oral Cir. Bucal. 17:e871-e877, 2012.

17. Xuan, K.; Zhang, Y.F.; Liu, Y.L.; Jun, F.; Jin, F.; and Wei, K.W.: Comprehensive and sequential management of an im-pacted maxillary central incisor with severe crown-root dilac-erations, Dent. Traumatol. 26:516-520, 2010.

18. Colak, I.; Markovic, D.; Petrovic, B.; Peric, T.; and Milenkovic, A.: A retrospective study of intrusive injuries in primary dentition, Dent. Traumatol. 25:605-610, 2009.

19. Stewart, D.J.: Dilacerate unerupted maxillary central incisors, Br. Dent. J. 145:229-233, 1978.

20. Howe, G.L.: Minor Oral Surgery, John Wright and Sons Ltd., Bristol, U.K., 1971, pp. 135–137.

21. Von Gool, A.V.: Injury to the permanent tooth germ after trau-ma to the deciduous predecessor, Oral Surg. Oral Med. Oral Pathol. 35:2-12, 1973.

22. Topouzelis, N.; Tsaousoglou, P.; Pisoka, V.; and Zouloumis, L.: Dilaceration of maxillary central incisor: A literature re-view, Dent. Traumatol. 26:427-433, 2010.

In the latter case, it would be beneficial to correct the rotation as early as possible.

It was once thought that after dental trauma, the injured Hertwig epithelial root sheath contin-ued to produce dentin and cementum at a normal rate.22 In our Cases 1 and 2, however, the root for-mation of the injured incisors lagged behind that of its counterparts. Such delayed root development may be the result of a temporary inhibition by traumatic force,22 after which upward root growth may resume, resulting in a severe crown-root angulation.

If an impacted incisor is not treated at an early stage of development, adverse changes such as migration of the adjacent teeth and a consequent midline shift could make it impossible to open enough space for later eruption of the impacted tooth.3 In our study, eight of the 15 DIs in a late stage of development had to be extracted due to severe dilaceration or crowding. The extraction of an upper central incisor will definitely compro-mise facial esthetics. On the other hand, diagnosis of an impacted DI in the early mixed dentition will allow orthodontic treatment to create enough space and time for normal root development, ensuring a higher rate of success.

ACKNOWLEDGMENTS: We would like to thank Drs. Huang Wenxiu, Niu Gang, Zhang Duanqiang, and Xu Linyu for their help in performing the treatment. This work was supported by the National Natural Science Foundation of China (Grant No. 81400516) and the Key Project of Science and Technology Bureau of Jiangsu Province (No. BL2013002).

REFERENCES

1. Pomarico, L.; de Souza, I.P.; and Primo, L.G.: Multi-disciplinary therapy for treating sequelae of trauma in prima-ry teeth: 11 years of follow-up and maintenance, Quintess. Int. 36:71-75, 2005.

2. Sakai, V.T.; Moretti, A.B.; Oliveira, T.M.; Silva, T.C.; Abdo, R.C.; Santos, C.F.; and Macahado, M.A.: Replantation of an avulsed maxillary primary central incisor and management of dilaceration as a sequel on the permanent successor, Dent. Traumatol. 24:569-573, 2008.

3. Tsai, T.P.: Surgical repositioning of an impacted dilacerated incisor in mixed dentition, J. Am. Dent. Assoc. 133:61-66, 2002.

4. Filippi, A.; Pohl, Y.; and Tekin, U.: Transplantation of dis-placed and dilacerated anterior teeth, Endod. Dent. Traumatol. 14:93-98, 1998.

Treatment of Dilacerated Incisors in Early and Late Stages ...

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