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Can early treatment change root shape of a dilacerate incisor? Part 1

Published: November 2017

Bulletin #71 November 2017

Can early treatment change root shape of a dilacerate incisor?

A 7-year old patient arrives in your office together accompanied by his mother and a panoramic radiograph. The parent tells you that one of his maxillary central incisors erupted about a half year ago and the other has not.

He has been referred by a pediatric dentist who has treated the child over the past couple of years and has recognized an abnormal orientation of the unerupted incisor. In an effort to encourage the spontaneous eruption of this incisor, he recently extracted the other deciduous incisors in the maxilla with the intention of providing additional space. Months later, nothing has changed and mother is now quite concerned and sitting in your office looking to you for answers. She rapidly draws your attention to the panoramic film, pointing to the incisor which you recognize as dilacerate. With careful questioning, you may find that at around the age of 2 years, the child fell on his face, lacerated his lip and jarred his deciduous incisor. Alternatively, however, there may be no history of traumatic injury of which the parent is aware or, quite frequently, can remember.

71 1a_1

Fig. 1a. Intra-oral photographs of the initial condition at presentation with the teeth in occlusion - age 7.5 years.

71_fig_1bFig. 1b. Occlusal views of the dentition - age 7.5 years.

Your intra-oral examination reveals four erupted permanent first molars and all the primary molars and canines in both jaws. In addition to the lone maxillary central incisor, the mandibular four permanent incisors are erupted with a minor degree of malalignment for this early stage of the child’s dental development (Fig. 1a, b). 

71 Fig 2_1

Fig. 2a. Lateral view of the dentition, extracted from the lateral cephalometric film. The dilacerate incisor is indicated (arrow).

Fig. 2b. Panoramic film of the dentition showing the dilacerate incisor (arrow). The dental age is coincident with the chronologic age.

From the radiographic records (Fig. 2a, b), you are able to deduce that the child’s dental age corresponds with his chronologic age and, as expected, each of the erupted permanent teeth has an open root apex. The premolars and permanent canines have barely began root calcification, while early root formation can be seen on the maxillary lateral incisors. The single erupted maxillary incisor exhibits about half of its expected final root length. The presentation of the dilacerate incisor on the panoramic film is through the long axis of its crown, which would be equivalent to an occlusal view of most other teeth. This view offers no information of the shape and length of the root of the tooth, nor whether or not there is a root, because planar 2D film radiography can offer very little information in the bucco-lingual plane. In order to confirm the presence, length and form of its root, a CBCT scan needs to be conducted.

Notwithstanding, the clear indication is that the tooth is dilacerated in its most common and characteristic form, which I have termed the “classic” dilaceration and which I have described in earlier postings on this website. In the printed literature and contrary to the accepted views at the time, I first posited a hypothesis which describes how I believe this very special, always identical, yet unique type of anomaly occurs as a dynamic response to a specific traumatic episode.1, 2

Question: Is it necessary to provide a phase I treatment aimed only at the dilacerate tooth or is it preferable to wait till the eruption of the permanent dentition at age 12 years, when the tooth will be treated within a one-phase, comprehensive, orthodontic treatment program?

There are three aspects to consider in relation to this question:

1.   Will the situation worsen due to further root growth, if left untreated?71_Fig_3a

F   Fig. 3a. This series of cross-sectional cuts taken from the CBCT shows the curved root of the incisor. Note the curvature of the developing root with a wide-open apex, which appears to be exiting the palatal border of the alveolar ridge.


Fig. 3b. A 3D screen shot of the anterior dentition, taken from the CBCT.

The root of a healthy maxillary central incisor continues to elongate for about 3 years after it first appears in the mouth, until its completion at apexification (Fig. 3a, b). Normally, the direction of the growth of the root of a single rooted tooth is continuous with the orientation of the crown and with the eruption path and is a contributing factor to the eruption mechanism itself. While the root of a dilacerate tooth may be shorter because of the sustained trauma, the bucco-lingual imbalance of further root growth leads to a labial and superior displacement of the crown (our references).

At the same time, the root apex is developing against the periosteum on the palatal side of the anterior alveolar ridge, which influences the apex to curve further,3 in much the same way as the root apex of any other tooth which is developing in close proximity to an anatomical limiting factor, such as the floor of the nose, the maxillary sinus, the lower border of the mandible and the inferior dental canal.4, 5 In these circumstances, the further growth of the root apex becomes reoriented in a direction which is usually parallel to the plane of that structure. Thus, undisturbed continuation of root growth towards full apexification drives the incisal edge of the incisor to a progressively inaccessible location, propelling it ever upwards towards the anterior nasal spine.

If this is permitted to continue, the resulting final and tightly curved shape of the root may not permit full corrective realignment of the tooth while maintaining its root within the confines of the alveolar bony ridge. Overcoming the problem at that late stage, would dictate the need for surgical reshaping/amputation of the apex, which would secondarily necessitate elective root canal treatment. The tooth would be left with a short root, a reduced prognosis and the strong possibility of a deleterious change in color of the crown, in the long term.

2    Will the situation improve if a phase I orthodontic procedure is undertaken while the root is still growing?

If we base ourselves on the above evidence, it is reasonable to assume that early resolution of the impacted tooth and its alignment will distance the developing root apex from the palatal periosteum and lead to a more favorable shape of root end. The vitality of the affected incisor would be maintained and much would be gained in terms of its root length, its long term prognosis and its appearance.

3. Is it reasonable, fair or ethical to leave a child without a central incisor for 6 years?

I believe that this statement is both the question and its answer. For most children, the formative years of their childhood between the ages of 6-12 years are those in which their outlook on life develops. In no small part, a missing incisor is often the focus of derision among their own classmates at school and elsewhere, often having a profound effect on their personality.


Fig. 4. Occlusal and anterior views of the initial orthodontic set-up, showing a soldered transpalatal bar and brackets bonded to the deciduous teeth and the erupted central incisor. There is no bracket on the right deciduous canine, which was mobile and shed naturally within a short period thereafter. A plastic sleeve was threaded on to the archwire to prevent irritation of the lip.


Fig. 5a. In March 2014, a full flap of attached gingiva was raised from the crest of the ridge, to reveal the palatal side of the inverted central incisor.

Fig. 5b. An eyelet attachment is bonded to the palatal aspect of the incisor, as close as possible to the incisal edge. A twisted stainless steel ligature is drawn from the eyelet and hooked over the raised archwire, to apply extrusive force on the incisor.

Fig. 5c. The full surgical flap is sutured back to its former place, leaving only the steel ligature visible for further activation at succeeding visits.

The case presented here (Fig. 1-7) is of just such a child. His phase 1 treatment was completed in 16 months, in April 2015 and at the age of 9 years. He was provided with a maxillary removable Hawley-type of retainer, to be worn 12 hours per day (evening and night) and advised to return for re-evaluation 12 months later.

71 Fig 6_1

Fig. 6a. In September 2014, the incisor had erupted through the attached gingiva, without the need for additional reparative surgical periodontal procedures.

Fig. 6b. In October 2014, the palatal eyelet was removed and a bracket bonded to the labial side of the central incisor and on the newly erupted lateral incisors.

Fig. 6c. By December 2014, the 4 incisors had been aligned and spaces eliminated.


Fig. 7a. To achieve the considerable labial root torque required in this and most other dilacerate incisor cases, a Begg-type auxiliary labial torqueing spring was used “piggy-back” over the main archwire. The auxiliary is seen here in its passive state.

Fig. 7b. The torqueing force is exerted when the curved extremities of the torqueing spring are raised to the archwire and ligated in the brackets.

Until 10 days ago (October 2017), I had not heard from them and I therefore initiated a direct contact. The father informed me that all was well and that the boy had worn his retainer for about 6 months and then, 2 years ago, discarded it! They were happy with the result and were not keen to move on to a phase 2 treatment. I pointed out to him that follow-up of the developing permanent dentition was advised but that it was very important that an evaluation of the status of the dilacerate incisor should be made.

In next month’s bulletin, I shall describe the new findings, particularly in relation to the condition of the dilacerate incisor, to the interesting pattern of continuation of its root growth and to its long term prognosis.


1. Becker, A.: The orthodontic treatment of impacted teeth. London: Martin Dunitz Publishers. 1998. ISBN 1 85317 328 2.

2. Becker A. Bulletin #10 - April 2012. The “Classic Dilacerate Maxillary Incisor.

3. Hao Sun, Yi Wang, Chaofan Sun, Qingsong Ye, Weiwei Dai, Xiuying Wang, Qingchao Xu, Sis Pan, Rongdang Hu. Root morphology and development of labial inversely impacted maxillary central incisors in the mixed dentition: A retrospective cone-beam computed tomography study. American Journal of Orthodontics and Dental Orthopedics 2014;146:709-716

4. Becker A. Bulletin #42 – March 2015. Root development in Impacted Teeth.

5. Becker A. Bulletin #46 July 2015.The Dilemma of the Root Apex of a Dilacerate Incisor: questions and answers.