Referral & Clinical

Lingually Displaced Mandibular Canines

Often spotted at the six-month puppy check. The permanent lower canines occlude into the hard palate causing severe discomfort and, possibly, oral nasal fistulae. See our article from Vet Times 18 Dec 2006 or our new FAQ sheet for this. The fact sheet answers many questions you may have about the cause of this problem and the various treatments available.

Owners with young puppies identified with this problem at first presentation should be counselled to have the deciduous lower canines removed as soon as possible. It is necessary to remove these surgically via wide based flaps as the root is fragile and typically 75% of the total length of the teeth. See our Powerpoint file for illustration of removal of deciduous lower canines.

Our FAQ sheet (see link above) coves the reasons why . In the main, time is of the essence to influence the eruption of the permanent canines at 22 - 26 weeks. Surgery to remove the deciduous canines may not prevent to need for surgery on the permanent canines - but without it few cases will resolve if left to nature. Occasionally we advocate the use of a soft ball to assist tipping of the lower canines buccally. This must be done under veterinary supervision.

If the permanent teeth are lingually displaced the pup is usually older than 26 weeks. The trauma caused by this can be considerable with pain as a consequence.

These permanent teeth can be treated by various methods - surgical removal of the lower canines teeth (and often incisors too), crown amputation and partial pulpectomy or by orthodontics via an inclined bite plane bonded to the upper canines and incisors. The latter option may not be available to all dogs if the diastema between the upper incisor and canine is too small for the lower canines to move into or if the lower canines are located behind (palatal) to the upper canines.

Crown amputation involves reducing the height of the lower canines to that of the adjacent incisors. Clearly this surgery exposes the pulp and requires a partial coronal pulpectomy with a direct pulp dressing. This procedure carries a failure rate (the pulp dies) of around 15%. In order to monitor this we require to radiograph the teeth on a regular basis for the first two years Post-Op.

Surgical extraction is attractive to many clients as the problem is immediately dealt with without the uncertainties and post-op. checks that are part of any crown amputation procedure. Many clients are concerned about the loss of the tooth and the weakness it may cause to the lower jaw(s). As there are elective procedures (i.e.clean) we can use an ossepromotive agent such as Consil (BioGlass) or Easy-Graft (beta-tricalciumphosphate crystals) to fill the void created by the loss of the large canine tooth. Both these materials will provide a scaffolding for new bone growth within six weeks.

The images below show a lingually displaced left lower canine before treatment and after application of a bite plane. The bite plane remains in the mouth as long as it takes for the power of the bite to tip the lower canine into the normal position by pushing it up the incline - about 4-6 weeks on average.