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Impacted canines: So I’ve identified an impacted canine- what do I do?

We often get asked this question by dentists: When should I refer (to an orthodontist) for an impacted canine? 

Impacted canines are very difficult to treat orthodontically. They are very taxing on orthodontic anchorage and often can take a long time treat. Treatment times upwards of 2 to 4 years is not uncommon. There are also instances where the impacted canine may be ankylosed or develop ankylosis during its path down, all of which can be disappointing for patients.

A more important reason is as the canines erupt, they erupt into a narrower width of alveolar bone. There is therefore a greater risk of resorption of the roots of adjacent teeth if left in situ and observed, not to mention a greater risk of root resorption of the canine root or adjacent teeth during its orthodontic correction. 

It is therefore incumbent to identify early stages of impacted canines. Unerupted canines which are overlapping the lateral incisor radiographically are a concern, or if the canine tip appears to be angulated towards an adjacent teeth.

In rare cases, the canine long axis may be lying horizontal or transposed between the 1st and 2nd premolar. These are all early abnormal signs of canine eruption. 

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Our key orthodontic considerations would be whether an eyelet can be bonded safely to the canine tooth without damaging the adjacent developing adult teeth. As the canine tooth is usually one of the last permanent teeth to fully develop, this is a less significant consideration compared with an impacted central incisor tooth associated with a mesiodens supernumerary.

A principle that has worked well for us is where there is crowding present to regain space early (example below). This can be achieved usually through arch or orthopedic expansion, depending on the diagnosis. 

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Molar distalization works well if there are early signs of a developing transposed premolar tooth.  (see below of an impacted 15 & 23 in a 12 year old girl)

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Occasionally, the canine may be too severely impacted and an early exposure with a short period of uprighting would help significantly. Below is an example of a 11 year old where the CBCT film showed the 33 canine to be labial and contacting the apices of the lower incisors. After 7 months of careful uprighting and lateral movement, assisted by a lower lingual arch, 33 was safely uprighted. The tooth was observed to have held its corrected position over a course of 6 weeks and no orthodontic retention was needed after. 

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So to summarise, early referral to an orthodontist upon detection of an abnormal erupting canine is recommended as it can help to minimize or avoid resorption of adjacent incisor roots and can help to simplify future orthodontic treatment, both in terms of case complexity, reducing risks and potentially reducing overall treatment times.

A screening OPG x-ray at the initial examination is needed to often detect this.

What is the right age to start an orthodontic expander?

In the past month, I saw the mother of a young girl who had an upper fixed rapid maxillary expander for her bilateral crossbite. Fortunately, the girl was 9 years old and the RME worked as predicted. Her mother had a bilateral posterior crossbite with a really narrow maxilla and I knew if she was to have correction for this, she would need a maxillary surgically assisted expansion.

Do 3rd molars affect the occlusion post orthodontic treatment?

There is a RCT that shows that 3rd molars have a small but not clinically significant effect on lower incisor crowding once the braces are removed. But what about patients who had an anterior open bite or an anterior open bite tendency before treatment? All of us learn through observations of our patients and when they are on retainers- how does growth and not wearing retainers affect anterior open bites.

Does Extraction Orthodontic Treatment Worsen Facial Profiles?

It seems this question is something that pops up many times over and asked by many patients. A recent systematic review of all the studies looked at the highest quality of evidence ie: RCT’s and prospective observational cohort studies and found that extractions of 4 premolar teeth in borderline cases do not worsen facial profiles, and to the contrary, where the lips are protrusive to start, provide an improvement in this appearance, as judged by laypersons. What makes this study relevant is that the authors were dentists and not orthodontists, eliminating possibility of author bias.

The dilemma of early underbite treatment in late mixed dentition

It is generally advisable to manage patients with underbites early. This is because the maxilla articulates with many facial bones and the circummaxillary sutures become more ossified with age. Compliance with wear of a removable facemask at night when they are sleeping is generally better (see below). We also generally tend to overcorrect at this young age, in view of possible further mandibular growth later. The 2 patients below show the marked improvement seen in the upper cheek fullness and upper lip profile immediately after early Class 3 treatment. 

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Lingual arches- how a simple appliance can simplify orthodontic treatment

Lingual arches are a type of passive space maintainer. It comprises of an orthodontic band and usually an 0.036ss wire soldered to the bands on the lingual aspects.

Below is an case study that is representative of what can happen spontaneously with a lingual arch. Note the spontaneous improvement in the lower arch crowding

Tags:Lingual archesspace maintainer0.036 ss wirelingual aspectscase study

Ectopically erupting teeth- When and what to do

Below is a series of 3 sequential x-rays of the same patient. Note the ectopic unerupted 35 that is erupting distally on the initial OPG Jan 2015. It eventually erupts and contacts the mesial aspect of the 36 root (Nov 2015), then stops moving(compared with July 2016).

We referred him to an oral surgeon recently for an orthodontic exposure of 35, whom only had the last two x-rays, without the first panorex x-ray, and concluded that 35 was ankylosed. In our experience it is rare to see a tooth whose root is still developing be ankylosed. 

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Tags:Lingual archesspace maintainer0.036 ss wirelingual aspectscase study

Invisalign and clear aligner treatment- what has changed over the past 15 years

Invisalign was first introduced into Australia about 15 years ago. Since then a lot has changed. Over the past few years, there have been new entrants into the market too. So what has changed?

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