Normal occlusion is important for the function and health of the oral cavity. Abnormal occlusion can predispose to oral diseases (such as periodontal disease) and can cause significant pain and dysfunction – especially when teeth traumatise oral soft tissues.
There are many instances where malocclusion does not cause functional problems, pain or oral disease and in these instances there is no indication for treatment.
Genetic counselling and advice regarding future breeding are central aspects of the treatment of hereditary malocclusions.
The two commonest malocclusions that require treatment are lingually displaced lower canines (this is often accompanied by mandibular micrognathia) and lance canines which is often seen in Shelties.
Lingually Displaced Lower Canine Teeth
This is a common malocclusion seen in a number of breeds. The Bearded Collie is over represented. It can be associated with persistence of the deciduous lower canines causing abnormal eruption of the permanent teeth and/or mandibular micrognathia where the lower jaw is smaller and narrower than it should be.
The lingually displaced lower canines contact and traumatise the hard palate causing ulceration and infection of soft tissues, localised bone resorption and pain. In extreme cases oro-nasal fistulae can be caused.
Early extraction of persistent deciduous canine teeth can prevent lingual displacement of the lower canine teeth. Once the condition has occurred treatment consists of either shortening the lower canines (this can be done in small incremental stages without entering the pulp chamber or by partial crown amputation which will also necessitate endodontic treatment) or use of a bite plane to move the lower canines into an acceptable position or tooth extraction.
Fig 1: The lingually displaced lower canine is occluding on the palatal side of the upper canine causing trauma to the hard palate
Fig 2: Trauma to the hard palate caused by lingually displaced lower canines
Lance Canines in Shelties
This is an hereditary condition in Shelties where the maxillary canine erupts in an abnormal position, often pointing horizontally at the adjacent maxillary third incisor.
Affected dogs often can not close their mouths comfortably and the abnormal position of the canine tooth predisposes to periodontal disease.
The lance canine tooth can be extracted or moved into an acceptable position using orthodontic band or power chain.
Fig 1: Lance canine in a one year old male Sheltie
Fig 2: Orthodontic band attached to the lance canine and anchored on the upper fourth pre-molar and first molar which will move the lance canine into a normal position.
Fig 3: Post treatment occlusion showing a normal canine interlock