Canines impinging on hard palate

RE: Canines impinging on hard palate

Evelyn Barbour-Hill — Thu, 05 Jan 2023 22:47:34 GMT

Of course without seeing the patient advice has to be a bit general, but it's fairly plain to me that you have two options:

1. Orthodontic movement

2. Tooth shortening with the necessary vital pulpectomy and pulp capping.

(I'm sure there are owners who would opt for "she seems all right, we'll wait and see" but let's assume your client is not one of those!)

Extraction is not an option in my opinion and should not even be considered.

Option 1. Orthodontic movement consists of fixing upon the teeth various possible appliances – e.g. crown extensions , inclined planes, modified omega-springs, etc – which either actively and continuously, or passively and intermittently, exert forces upon the teeth which, if the appliance is well-judged, move them in the right direction. These forces are small and "physiological": at no time will there be any tooth necrosis and the tooth remains firm in the jaw at all times; on the pressure side osteoclasis is induced and on the low-pressure side osteosynthesis is induced. Hence movement is slow (and if it is seen to be fast, there is a good suspicion that something is wrong)

When the tooth has reached its desired position, if all forces are removed immediately the tooth will relapse, unless there are measures to provide retention – as a rule of thumb, for as long as the active movement took. Very fortunately, in the case of lingually displaced mandibular canines, the oral conformation provides most of the retention needed and I'd usually be happy taking the hardware off say two weeks after the position is "satisfactory"

The time needed varies but you must allow say 3 months.

So that's say 3 months (OK, might be a little less) of foreign objects glued in the mouth, dismissed between appointments to take their chances in the rigours of doggy mouthy behaviour, frequent re-exams (weekly best), maybe adjustments, maybe GA for repair or replacement, certainly GA at the end for removal, periodontal disease or ulceration where the appliance has made cleaning impossibe, ulcers from protruding bits (even if they were made smooth and rounded...) ...

Now that's relatively straightforward if it's a simple movement, but as such dogs are often overshot or undershot, the lower canine may be hiding a bit behind the upper, or in a quite weird position, and there may not be the proper gap between upper canine and corner incisor. Now in theory any tooth rearrangement can be done by orthodontic means, but the necessary months, even years, of uncomfortable appliances would clearly be totally out of the question ethically.

SO after examination I might suggest, according to the conformation I see before me,

"I can do either tooth movement or tooth shortening for you: the choice is yours but I would recommend tooth shortening"

or "Tooth shortening is the only sensible option."

Option 2 Tooth shortening is all done in one comparatively brief GA session. After initial cleaning of the mouth and antiseptic swabbing the tooth is solated with rubber dam and draped in aseptic fashion. From here on until the tooth is closed again all is done in classic aseptic fashion, including the surgeon's garb, all instruments autoclaved, etc. I'm not going to describe the procedure in detail because I'm not writing a recipe book here; suffice it to say that (all with brand new hence sharp as possible burs) the tooth is cut to a length carefully calculated beforehand by the surgeon, a bit more pulp whizzed out, the haemorrhage (which should be slight) checked, and the tubular "cavity" filled with the biocompatible substance of the surgeon's choice (used to be calcium hydroxide, then MTA got fashionable but now I'm very fond of BioDentine) laid straight on to the pulp. Everything should be well-rehearsed and speedy so that the pulp is only actually exposed for maybe two minutes..

After that we can relax a bit while the BioDentine does its initial set. Then we can restore the tooth to an aesthetically satisfying rounded profile at its new height. Surgeons have their own preferences, but this usually involves resin composite of suitable grade.

The end result, just a nice tooth that if you bother to look is a bit shorter than normal. All done and dusted. Home for tea. The pulp is alive and healthy and will continue to lay down dentine as it's supposed to . Yes, we need some radiographs to check pulpal health in (rather arbitrary periods) say 2 months and 6 months time, but these can usually be done with moderate sedation only.

Success rate? I'm not boasting just saying: my success rate as far as I know is 100%. Yes, there's luck, and of course many have been lost to follow-up, but there it is. I think my point is that the success rate is really high if the procedure is done correctly.

(You must not confuse this with the success rate for vital pulpotomy plus pulp capping performed on a broken tooth as is sometimes done in young dogs. This is a completely different kettle of fish and the success rate will be much poorer)

Anyway Charlotte, after all that, seeing as the dog's jaw conformation is abnormal already, you've probably worked out that I firmly advise tooth shortening. It would be the cheaper option too!

RE: Canines impinging on hard palate

Martin Hamilton — Thu, 05 Jan 2023 13:13:28 GMT

Hi Charlotte,

Without photographs, or better a consultation in person, I cannot say for sure what the exact options are for this patient. For example, should there be a slight class 2 malocclusion whereby the mandibles are shorter than the maxilla then orthodontic movement may not be possible. Generally, for cases where the mandibles are of appropriate length but the mandibular canine teeth are linguoverted (known as a class 1 malocclusion), there are 3 "categories" of treatment I would offer:

1 - Orthodontic movement - passive - this may be attainable using crown extensions placed on the mandibular canine teeth, which when the patient closes the mouth, will passively move the teeth into a more appropriate position. Other options in this category would include an inclined plane, which is an appliance placed on the maxillary canines that has a "ramp" created upon it which will also help guide the movement of the mandibular canine teeth into a more appropriate position. The patients and clients have to be selected carefully for these cases, as rechecks are recommended every week or two, movement may take some time, is not always predictable, appliances can break of the puppy is a little hyper (which in my experience SBT usually are) etc. The appliances then have to be removed once movement is achieved, involving a second GA. If it's a mild case, then even ball therapy may be appropriate (http://www.toothvet.ca/PDFfiles/ball_therapy.pdf)

2 - Endodontic treatment - crown reduction with vital pulpotomy - the crown of the tooth is reduced in height, alleviating the contact but exposing the pulp. A vital pulpotomy is then performed, where some of the pulp tissue is removed, a material placed on the pulp in an attempt to keep the tooth alive, and then a filling placed on top of that. Success rate is favourable (the most recent paper I'm aware of had a 92% success rate in those cases where MTA, a newer material, was used), and if the tooth remains vital then the tooth will continue to mature and provide strength to the mandible(s). Root canal cannot be performed in these young patients as the apex of the root is still open, so if we tried to fill the tooth the material would just shoot out the other end. The dentin is also very thin, making the teeth very weak if rendered non-vital via root canal therapy. Radiographic rechecks for endodontic procedures are recommended 6 months following the procedure, and again annually to ensure success. Different practitioners tend to have differing recheck intervals (some will say 3 months, 6 months, or 1 year following the initial procedure depending on experience/preference/mentorship). In my practice, this would be the cheapest option for the client.

3 - Extraction - the permanent canine teeth can be extracted in order to alleviate traumatic. My least preferred option as the dog will lose two teeth that could have had some kind of functional use, requires healing from a surgery (dehiscence is a rare complication but if it's going to happen anywhere it tends to be in the region of the mandibular canines owing in part to the muscular frenulum). Additionally, the mandibular canines contribute to a significant proportion of the strength of the mandibles, and extracting them renders the mandible weaker that it normally would be. Pros are that this can certainly be performed in your own practice should you be comfortable doing so.

Hope this helps shed some light on the many options available to this puppy! There are some resources available online, but off the top of my head:

- Dental Vets (based in Scotland) - https://www.dentalvets.co.uk/common-cases/lingually-displaced-canines

- Hale Veterinary Clinic (from here in Canada) - http://www.toothvet.ca/PDFfiles/malocclusions.pdf

Edit: Norman beat me to it while I was typing out this tome. His site is a great resource!

RE: Canines impinging on hard palate

Norman Johnston — Thu, 05 Jan 2023 12:59:32 GMT