Malalignment & malocclusion of incisors and canine teeth due to undershot mandible

RE: Malalignment & malocclusion of incisors and canine teeth due to undershot mandible

jason davidson — Mon, 19 Jul 2021 18:25:58 GMT

Thanks very much for all your comments. I will continue to monitor this situation as it does not seem to be bothering the dog at the moment and there is no sign of attrition or trauma as a result of the defects. I apologize for my late reply but for some reason my forum notifications were muted and I thought I was being ignored!!

RE: Malalignment & malocclusion of incisors and canine teeth due to undershot mandible

Evelyn Barbour-Hill — Fri, 02 Jul 2021 01:25:55 GMT

What Martin says is quite true. The interesting thing is that it doesn't often happen. The soft tissues impinged upon by the maxilary incisors (in an undershot dog) or mandibular incisors (in an overshot dog) will adapt, and one may often see little depressions, but nothing further happens.

In a perfect occlusion there are two limits to closure, which as far as I can make out happen simultaneously: the incisal edges of the mandibular incisors meet the cingulae on the palatal side of the maxillary incisors; and the distal portion of the mandibular 9s intercuspates with the maxillary 9s. In the under- or overshot mouth obviously the former does not happen, but the latter is still happening and that's a very solid limit to closure.

Bad things do happen if an incisor occludes on the soft tissue only just on the lingual or palatal side of its chum in the other jaw. That can really wreck the periodontium at that point and then go on to chronic attrition of the root. One sees this sometimes all unsuspected by the owner.

So, if you're going to be over- or undershot, makes sure your are really well over- or undershot.

RE: Malalignment & malocclusion of incisors and canine teeth due to undershot mandible

Martin Hamilton — Thu, 01 Jul 2021 20:59:16 GMT

I'd also add that following extraction of the 202,203 and any of the more caudal teeth (as both Rob and Evelyn mentioned above), there may be further closure of the mouth and thus soft tissue trauma may develop lingual to the mandibular incisors caused by the maxillary incisors (and may lead to periodontal disease of the mandibular incisors). Something to warn the owner about - doesn't often occur but there remains the possibility. Orthodontics is often quite the challenge - addressing one problem can bring another to light and the client needs to be aware of that.

RE: Malalignment & malocclusion of incisors and canine teeth due to undershot mandible

Evelyn Barbour-Hill — Thu, 01 Jul 2021 16:28:11 GMT

I agree with Rob regarding the diagnosis and possible treatment, but I feel there's no need to rush into extractions. As there is no immediate soft tissue trauma, or any symptoms, I would wait and see for a few months. Various things could happen. There may be excessive attrition – but there may not. The abnormal forces may push the 203 distally and the 202 labially.

Jason, as you have seen the dog in the flesh, as it were, and gained a better impression than that from photographs, you are best placed to judge if there is already attrition taking place.

If required, treatment would consist of tactically extracting both 203 and 202.

The same approach applies to the caudal crossbite (and check the right side as well): no need to rush into treatment, but if there are signs of attrition or discomfort then extract the smaller tooth or teeth involved in the clash.

The upper third incisor can be a devil to extract, because of its shape. Patience and visualisation are the two essentials.

RE: Malalignment & malocclusion of incisors and canine teeth due to undershot mandible

Rob Davis — Thu, 01 Jul 2021 15:17:20 GMT

These are always difficult to assess well from photographs, but from what I can see I would suggest extraction of the upper left third incisor and possibly the second one too (202 and 203) to allow space for the lower left canine (304) to occlude unimpeded outside the palate.

It looks as though the upper right second incisor may be occluding against the lingual aspect of the lower right canine (404), so this may require extraction too to avoid attrition (tooth on tooth wear).

There also appears to be a caudal crossbite, ie the lower premolars appear to be occluding on the buccal aspect of the upper premolars. This may not require any treatment if it is not problematic.

Be aware that these may not be straightforward extractions - these immature teeth will have open apices and thin dentinal walls making them fragile - very gentle technique required and radiography so you know what you are trying to extract. Make sure you recheck the occlusion after the extractions, as allowing the mouth to close more fully may make other areas problematic....