A palatally impacted maxillary canine in a 12-year-old with a Class II division 1 malocclusion
A 12-year-old girl is referred because the upper right permanent canine (13) has not erupted. She is in the late mixed dentition with a Class II division 1 malocclusion, a 7 mm overjet and 5 mm of upper arch crowding. The retained upper right primary canine (53) is firm and the crown of 13 is palpable high in the palate. Small-field cone beam imaging shows 13 lying palatally, its crown 12 mm above the occlusal plane and angled at about 30 degrees to the midline, with the crown close to the roots of 12 and 14; there is no resorption of adjacent roots and no ankylosis. 14 and 24 are erupted. She is motivated for treatment. Her parents ask whether "the baby tooth can just be taken out and the tooth will come down by itself", and they are reluctant to consider a general anaesthetic. Her older brother had a similar problem and needed surgery.
1. Would you extract 53 as an interceptive step, and how do the CBCT findings and her age change the likely outcome?
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What the CBCT has already told you: the canine is palatal, high (12 mm above the occlusal plane), angled 30 degrees, and not resorbing 12 or 14. Those are the variables that predict whether the tooth will erupt, and they are not favourable: the further the crown from the occlusal plane and the more horizontal the angulation, the lower the chance of spontaneous eruption.
Interceptive extraction of 53. Removing the deciduous canine is low-morbidity, needs only local anaesthetic, and removes a physical obstruction while the permanent tooth still has eruptive potential. Its success varies widely in the literature and falls sharply with increasing depth and angulation. At 12 mm and 30 degrees this is a reasonable first step only if it is built into a plan that assumes orthodontic traction will be needed. If you extract 53, review radiographically at 6 to 9 months and start fixed appliances concurrently; do not extract and then wait indefinitely.
Space. 5 mm of crowding plus a 7 mm overjet means space will be needed for alignment and overjet reduction. Do not extract 14 or 24 reflexively to "make room" - measure the arch length discrepancy after 53 is removed and consider distalisation or interproximal reduction first.
Honesty with the parents. The tooth is unlikely to come down fully on its own at this depth and angulation; explain that extraction of 53 is a step, not a solution, and that the realistic plan is surgical exposure with orthodontic traction.
2. Compare open and closed surgical exposure for this canine and give the technical points that determine success.
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Open versus closed
- Open exposure leaves the crown uncovered to erupt spontaneously. It is simpler and avoids bonding, but the healed mucosa can migrate over the crown, and the tooth may erupt buccally with a poor gingival margin and a long clinical crown.
- Closed exposure with a bonded attachment and gold chain gives the orthodontist control of direction and of the final gingival contour, and is the usual choice for a palatally impacted canine in a patient who already has or will have fixed appliances.
Technical points that decide success
- Adequate local anaesthesia; a palatal flap design that gives access without compromising blood supply.
- Remove bone only around the crown tip, not the whole crown, to preserve attachment and reduce the risk of ankylosis and of exposing the cemento-enamel junction.
- Bond a button and chain to the palatal surface with a genuinely dry field; moisture is the main reason bonding fails and a second procedure is needed.
- Tunnel the chain to the arch and apply light traction (of the order of 50 to 60 g); heavy forces risk ankylosis, root resorption and tipping.
- Protect 12 and 14: the crown is close to their roots, so move it away from them before bringing it into the arch, and monitor with radiographs if it passes close.
General anaesthesia. A cooperative 12-year-old can usually have a closed exposure and bonding under local anaesthesia, with sedation if anxious. Offer that before a general anaesthetic is considered, and address the parents' concern directly rather than dismissing it. Refer jointly with an oral surgeon if the position is uncertain or previous exposure has failed.
3. Set out the overall treatment sequence, including overjet correction, and what must be covered in consent and retention planning.
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Sequence
- Records: intraoral scans or models, cephalometric radiograph, photographs, the existing CBCT, and consent.
- Remove the obstruction (53) and start upper fixed appliances or a 2x4 to create space and begin overjet reduction; have the arch reasonably aligned before traction starts, but do not delay traction for a perfect arch.
- Closed exposure and bonding, then traction over roughly 9 to 18 months depending on the distance and angulation, monitoring 12 and 14 radiographically.
- Correct the 7 mm overjet. At 12 years with a full permanent dentition a functional appliance is unlikely to be effective; consider Class II mechanics (elastics, headgear, or camouflage extractions) and reassess any skeletal component at the end of growth.
- Finishing, detailing and retention.
Consent
- Expected duration of 18 to 30 months and the number of visits.
- The canine may ankylose, resorb or fail to align, and may need extraction and prosthetic replacement.
- Risk of damage to the roots of 12 and 14, and of gingival recession or a poor gingival margin on the canine.
- The general anaesthetic question, and the offer of local anaesthesia with or without sedation.
- Cost, and the alternative of accepting the malocclusion.
- Her brother's experience is useful to the family but not predictive for her.
Retention. A fixed lingual retainer plus a removable retainer, with particular attention to the canine, which is prone to relapse; review retention for at least two years and explain why.