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Bilateral Impacted Canines:diagnosis and treatment planning

Published: January 2018

Bulletin #73 January 2018

Bilateral impacted canines: diagnosis and treatment planning

An interesting case of bilateral maxillary canine impaction was sent to me by a colleague who runs a busy orthodontic practice in the North of Israel. It was sent in 2014 to the Clinical Consultation feature on this website.


Fig.1. Pre-treatment views of the teeth in occlusion.


Fig.2. Pre-treatment occlusal views of the teeth.

The background questionnaire that related to the patient’s general health, oral and dental health and other details was unremarkable and the material sent to me included clinical photographs of the 14 year old female patient’s extra-oral facial features and intra-oral views of the teeth in occlusion (Fig.1) and from the occlusal aspect (Fig.2).


Fig.3. A poorly executed pre-treatment panoramic view of the dentition in December 2012. Given the degree of root development of the permanent teeth, the dental age was assessed at 12 years.

A rather poor quality initial panoramic radiograph at age 12 years indicated a dental age matching the child’s chronologic age. The over-retained and almost completely resorbed remains of the maxillary deciduous right first and both deciduous second molars were still in evidence (Fig.3).

By contrast, the roots of the deciduous canines were largely unresorbed and the unerupted permanent canines were displaced mesially. Maxillary second permanent molars were unerupted. The unerupted premolars and canines in the maxilla exhibited more than two thirds of their expected final root length, with open apices. In the mandible, a full complement of permanent teeth was present up to and including the second molars.

The orthodontist tentatively diagnosed impaction of the maxillary canines and referred the patient for a CBCT scan that was performed shortly before the case was sent to me. The primary and secondary reconstructions of the DICOM’s had been expertly prepared by the imaging technician and the most relevant “slices” and video clips for the present diagnostic needs are presented here (Figs.4-8). Having studied these carefully, the practitioner quickly realized that orthodontic resolution of these maxillary permanent canines would be difficult to achieve. This was the reason for his having referred the records of the patient to this website for help with treatment planning.

From the CBCT records:


Fig.4a. A narrow CBCT “slice” of the panoramic view.

Fig.4b. A 3D screen shot of the maxilla from the left side. Note the mesio-distal orientation of the canine in relation to the desired eruption path, between lateral incisor and rotated first premolar.

On the left side of the maxilla, the canine was tipped lingually, but its apex was normally located, directly above the apices of the first premolar (Fig.4a, b). At the level of the root apices of the adjacent teeth, there was adequate space to accommodate the canine, but at the level of the crowns of these teeth, space was reduced in the dental arch and the premolar was slightly rotated bucco-distally (the facial aspect was rotated to the distal). Simple space opening needed to be done, a condition easily met using a compressed open coil spring. Careful bracket positioning would be required to maintain the two adjacent teeth in an upright orientation, so as not to reduce the distance between the apices of these teeth. Additionally, it was pointed out that, with the use of a coil spring, there would be a tendency for the premolar to rotate further bucco-distally as the space opened.

A point which is often overlooked with the rotation that occurs when opening space, concerns the equal and opposite effect that the rotation has on the palatal root of the premolar. There is a concomitant roll of the palatal root to the mesial, so to obstruct the intended eruption path of the canine. For this reason, the referring orthodontist in this case was advised to deliberately aim to de-rotate the premolar mesio-lingually prior to surgical exposure of the canine. It was judged that the space opening itself might also encourage the canine to erupt autonomously and that resolution of this left canine was relatively straightforward.


Fig.5. A 3D screen shot of the maxilla from the front. Note angulation of the right canine in relation to the lateral incisor. Note also the lingual orientation of the root of the lateral incisor and how the canine is attempting to insert itself palatal to the central incisor root.


Fig.6. A series of cross-sectional “slices” illustrating the labial relationship between canine crown and incisor root.

Fig.7 Click here to see a 3D video clip of the relationship between the two canines and their immediate neighbours.

Fig.8. Click here to see a 3D MPR video clip showing “slices” of the anterior maxilla in 3 planes of space, showing how a change in one plane reflects the representation of the teeth in the “slices” of the other two planes.

On the right side, the canine impaction was considered to be far more difficult. From the CBCT, it was determined that the lateral incisor root apex was displaced excessively to the palatal and would have been almost certainly palpable immediately under the palatal mucosa (Figs.5-8). Theoretically, there was enough space between first premolar and lateral incisor for the canine to find its place in the arch. The premolar crown was tipped distally, there were 2 labial and one palatal roots and the tooth was rotated slightly bucco-distally. This meant that the apex of its palatal root lay directly in the potential eruption path and was thus likely to interfere with the desired downward progress of the canine. The root apex of the canine was above the second premolar and close to its ideal bucco-lingual location. From there, the long axis of the canine was horizontal, with its crown directed strongly to the mesial. The eruptive potential of the canine was expressed in a mesial direction, towards the midline on the labial side of the palatally-displaced root of the lateral incisor. However, it was clear that there was a danger of its progressing to the palatal side of the central incisor, as may be seen in the illustration (Fig.5). This would place the canine labial to the lateral incisor and palatal to the central incisor – a location from which it would later be extremely difficult to extricate. Thus, early treatment of this canine was of prime importance.

Recommendations for treatment:

Certainly, there may be a variety of ways an orthodontist may adopt to successfully treat this case, but there are many more ways where the prospect of failure looms ominously bright, when important and available diagnostic tools are not fully exploited. There can be no excuse for ignorance of the accurate 3D relationships of the impacted teeth to the other structures in the immediate area, given the present level of sophistication that has been achieved with cone beam imaging (Fig.8). Moreover, the benefits afforded to us with the availability of internet and e-mail connection make the transference of visual information efficient and rapid.

The treatment recommendations given to the practitioner were as follows:-

1. In the maxilla, the recommendation was to place a fixed multi-bracketed appliance on all the teeth from first molar to first molar, but specifically excluding the right lateral incisor. It is advantageous that the bracket type should be an open bracket that requires the archwire to be secured with a ligature or elastomeric module and has the ability to accommodate a second horizontal wire in the same or parallel slot. In many of the more difficult cases, where one archwire needs to be used to stabilize the remainder of the dentition as a rigid anchor unit, a second full or sectional archwire or spring mechanism is needed to provide the elastic flexibility needed to move a single impacted tooth in a pre-determined direction. Self-ligating brackets cannot be used to maximum advantage in this setting. Double or triple buccal tubes are needed on the anchor molars.

2. On each side, the bracket on the first premolar should be placed slightly distal to the mid-buccal position and oriented with its mesial end slightly more occlusally angulated. In this way, a straight wire will upright its root to the distal and rotate it mesio-palatally, to distance the palatal root from the desired path of the canine, as noted above.

3. The lateral incisor should be ignored completely. The initial stage of alignment and leveling with a round wire will upright the root of a tooth until the bracket slot is horizontal. If a bracket were placed on the lateral incisors in this case, alignment and leveling would alter the intimate relationship between the impacted canine and the root apex of a bracket-bonded lateral incisor. Moreover if, as in some orthodontic treatment protocols, a rectangular archwire were to be used as the final stage of alignment and leveling, then there would also be a force labially root torqueing the lateral incisor directly into the crown of the canine. This would likely result in marked resorption that would lead to loss of the apical portion of the incisor root. Alternatively, the root may move distally, to become transposed with the canine.

4. Create space for the canines on each side while carefully controlling “tip” and rotations of the premolars on a heavy round base arch, as described above. Specifically, the palatal roots of the premolars need to be distanced from the canine, even if this demands a temporarily excessive distal over-uprighting – to be corrected later when the canine is in place.

5. Prepare a 0.016” steel labial auxiliary archwire with a horizontal loop for the right side only, to be placed “piggy-back style” over the heavy base arch.1, 2

6. Expose the canines on the labial side – most important.

7. Bond eyelet attachments in vertical orientation, parallel to the long axis of the tooth– do not use regular brackets.

8. On the left side, tie the canine direct to the labial archwire using elastic thread.

9. On the right side, make sure the loop of the auxiliary wire is not too high in the sulcus, because this will cause ulceration of the oral mucosa lining the inner surface of the lip. Its passive position is horizontal. It is activated by being brought up to the replaced flap tissue and ligated by the wire ligature that will have been threaded though the eyelet, to hold it against the flap.

10. The surgical flaps should be sutured back to their former position and the teeth completely re-covered.

11. Within weeks, the right canine should start to bulge the soft tissue on the labial aspect of the alveolus and, when it is in danger of breaking through the oral mucosa, it is advisable to perform an apically repositioned flap to place attached gingival tissue high on the crown of the tooth, for the remainder of the alignment.

12. The lateral incisor root will then be distanced from the canine and should (only then!) be bonded with a regular bracket.

13. The final aligning archwire should be threaded directly through the vertically-oriented eyelet attachments on the formerly impacted canines, before being tied into the brackets on the other teeth. Do not remove the eyelets until all the teeth are aligned on the archwire, including the lateral incisor. At this point it is essential to evaluate how much torque is needed, particularly on the right lateral incisor, but also on the canines.

14. Regular brackets should be substituted for the eyelets and the orthodontist will need to go through the archwire series again, from round NiTi to rectangular stainless steel, as indicated, to achieve ideal tooth position and orientation.

73-11. Post-tx pan_2

Fig.9. A panoramic view of the dentition seen immediately post treatment.


Fig.10. Post-treatment views of the teeth in occlusion


Fig.11. Post-treatment occlusal views of the teeth.

In the treatment of the present case, the orthodontist concerned followed these recommendations closely, successfully completing the case in August 2016, after 24 months (Figs. 9-11). I thank Dr. Albert Dackwar of Maalot Tarshiha, Northern Israel, who kindly shared the records with me for use in this bulletin and who agreed to the overt mention of his name as the orthodontist in this case.


1. Becker A. The orthodontic treatment of impacted teeth. 3rd edition, 2012. Oxford: Wiley-Blackwell Publishers. 2012. ISBN-13:978-1-4443-3675-7, ISBN-10:1-4443-3675-4. Fig. 7.8

2. Bulletin #5 November 2011 on this website. “Opening space for the canine – it’s not as simple as it seems!”, which can be viewed by clicking