24 Interceptive extractions
I saw this dog when I was working in general practice. He was presented to me for first vaccination, a healthy puppy with a severe skeletal malocclusion, of which the owner was totally unaware.
ORAL EXAMINATION – CONSCIOUS
He was a well-behaved puppy that allowed careful conscious evaluation, which revealed the following:
ORAL EXAMINATION – UNDER GENERAL ANAESTHETIC
A thorough oral and dental examination, including investigating periodontal parameters, was performed. All findings were noted on the dental record sheet.
In summary, examination under general anaesthesia identified the following:
Radiographs were taken of the maloccluding primary lower canine teeth (to determine the anatomy of the primary tooth, and the position and stage of development of the permanent counterpart).
The primary canines were fully developed with closed apices. The permanent canines were in the normal position with respect to the primary canines (upper permanent are rostral to the primary and lower permanent are lingual to the primary). Root development of the permanent canines was in early stages, with only around one-third of the total root length formed. As expected, the permanent canines were still within the alveolar bone, i.e. not yet erupting.
Primary teeth involved in malocclusion should be extracted as early as possible, i.e. at 6–8 weeks of age. This will allow the maxilla and mandible to develop to their full genetic potential independently before the permanent teeth erupt and dental interlock forms. Extracting maloccluding primary teeth before eruption of their permanent counterparts is called ‘interceptive orthodontics’. It aims to prevent dental interlock-induced malocclusion from developing. However, if the developing malocclusion is skeletal in origin (as in this case), then the permanent teeth are likely to form the same incorrect interlock when they erupt. Malocclusion causing discomfort and pathology always needs treating, and interceptive orthodontics will remove discomfort or pain associated with maloccluding teeth.
The roots of primary teeth are longer and narrower than the roots of the permanent teeth. They may also be resorbing, which makes them fragile structures to handle. Extraction requires care and patience to avoid tooth fracture. It is essential not to fracture the root, as a remnant may continue to cause deviation of the eruption pathway of the permanent tooth. Preoperative radiographs to determine the anatomy of the primary tooth, but also the position and stage of development of the permanent counterpart, should always be taken.
This type of malocclusion, i.e. where the maloccluding teeth are due to a discrepancy in size of the upper and lower jaw, is inheritable and this dog should not be used for breeding.