Interceptive Orthodontics 101 - Part One
For this series, I’m going to discuss Interceptive Orthodontics. What that means is early interventional orthodontic treatment or Phase 1 treatment. Interceptive orthodontics is offered to better guide dental and facial growth and development. The aim of this treatment is to simplify a comprehensive (aka Phase 2) orthodontic treatment when older or to avoid it entirely!
First, I would like to mention that the American Association of Orthodontists recommends that orthodontic consultations may start as early as six years old. Why? At this age, most conditions are easier and quicker to treat, while during an active phase of growth. The aim is to minimize more complicated dental/skeletal problems down the road.
Here are a few broad categories of problems to watch in children ages 6-8.
Excessive dental spacing: however, keep in mind, some spacing is actually normal and healthy.
Dental Crowding in children is a red flag for crowding with permanent adult teeth. As mentioned, we would like to see some spacing at this stage.
Open bite (i.e. the front teeth don’t overlap).
Overbite (also known as a deep bite).
Anterior Crossbite: meaning that bottom teeth are more anterior to the upper teeth.
Posterior Crossbite: meaning that the bottom teeth are positioned wider in the back. The upper jaw should be wider and more anterior than the lower.
Overjet: this is the opposite, wherein the upper teeth flare excessively. The top teeth should be anterior to the bottom teeth, but by no more than 2 mm.
Abnormal eruption patterns: teeth that appear malpositioned or very rotated. This may also include blocked out teeth (dental impactions).
First for this series, I will discuss abnormalities in dental development. In particular, I will go over three subtopics: traumatic occlusion, which is often associated with a functional shift. Next, abnormal dental eruption patterns, including dental impactions. Finally, severe crowding falls into this category, as well.
Traumatic occlusion often involves a dental interference that causes trauma to the adult anterior (front) teeth. This interference may sometimes cause a functional shift, meaning you will slide the lower jaw forward to alleviate the traumatic bite. Posturing the lower jaw forward is more comfortable, and may appear as an anterior crossbite or also associated class III malocclusion (where the lower jaw is abnormally advanced forward). It is important to properly diagnosis this, as it is not a true skeletal malocclusion. The lower jaw is well positioned, just sliding forward to avoid the traumatic interference.
The CO image represents the patient sliding the jaw more comfortably forward, meanwhile CR is the patient’s true bite and showing the interference. You may also notice that the front bottom teeth (which we call incisors) appear longer. That is not a coincidence. We call this “recession” – the gums have receded indirectly due to the trauma. Furthermore, those front teeth are at a higher risk of being chipped. For these reasons, orthodontists will intervene to alleviate this traumatic bite relationship.
Treatment is quite simple. We will often use a palatal expander the “jump the bite” – basically expand enough to remove that interference that is shown in the CR image. Localized braces on the front four teeth are also helpful to align, on top as well as on the bottom, if necessary.
Next, I will discuss abnormal eruption patterns and impacted teeth. It’s really important to always count teeth! You may be concerned if you notice that adult teeth are “not” erupting symmetrically. Or that a certain baby tooth does not become loose. This can be a sign that the adult tooth is misguided, and not erupting in the right direction.
Central incisors in particular become impacted due to the presence of an odontoma, which is a benign bony growth that needs to be removed. Sometimes it is important to get an x-ray to get the full story, and in the case shown here a 3-D image was also obtained to truly understand the eruption pattern of this incisor. This tooth is erupting off by 90 degrees – it will likely never come down in its own without orthodontic intervention!
One reason dental impactions occur is due to crowding. This may be a result of insufficient arch length (aka the mouth is too small) or early loss of baby teeth and the space was not maintained. As a consequence, the already-erupted adult teeth drift into that space and block out the unerupted adult tooth. Here is an example:
Meanwhile, canines are the most common impacted tooth in the mouth, second to wisdom teeth. Why? Canines have the longest path of eruption, they are one of the last teeth to erupt into the mouth, crowding affects them the most, and there is also a genetic component to having blocked on canines.
Here are a few early indicators of canine impactions: severe crowding, the adult lateral incisors flare outwards. This is because the unerupted canines are pushing on the roots of these teeth.
The goal is ultimately to prevent any dental impactions by maintaining spaces if baby/primary teeth are lost and by increasing arch length if crowding is severe. In particular, when discussing impacted canines, extracting the primary canine often resolves the impaction on its own, as long as the impaction is mild. Rapid palatal expansion is a great way to gain room and increase arch length.
Here is that same case with the flared lateral incisors where I expanded and the canines erupted without any surgical interventions:
Another interesting anomaly is developing extra teeth, which we call supernumerary teeth. When in the middle of the mouth, this is called a mesiodens and when behind the wisdom teeth, it is called a distodens. These usually occur in multiples and recur, which is unfortunate for the patient.
It is important to extract these once visible and large enough for the oral surgeon so that they do not damage other teeth. Also, taking follow-up x-rays is important since they do recur.
On the contrary, it is important to also mention missing teeth. The most common missing teeth (not including wisdom teeth) are the lower second premolars and upper lateral incisors. The cause is usually genetic, and often times will occur bilaterally.
Here is an x-ray showing missing premolars:
Often times, we will try to keep the baby teeth (primary molars) as long as they don’t become loose and fall out on their own or become fused with the bone. This leads to what we call the teeth submerging and a relative loss of bone will develop, which is not ideal. In these cases, we will likely have the primary teeth removed and plan for implants.
When it comes to missing lateral incisors, there are two predominating options. One is called canine substitution – which means the canine teeth are moved forward into the space of the laterals and recontoured to cosmetically appear like a lateral incisor. The first premolars can also be recontoured to appear as canines. This treatment is done in conjunction with a cosmetic dentist, as these teeth will likely need veneers or crowns to improve the cosmetics. The second option is leaving the space for implant placement when the patient is done growing (i.e. 16-18 for females, 18-20 for males). As the patient will continue to grow throughout life, sometimes the implants will appear to “submerge” as well, similar to the situation when the baby tooth becomes fused to the bone. In some cases, the patient will need a new/longer implant-crown to be made or even ceramic “gum” added to the design. This is a cosmetic choice made by the dentist, often depending on the patient’s smile esthetics. Needless to say, it is important to have a conversation with your orthodontist and cosmetic dentist when choosing how to address missing lateral incisors since there are a lot of esthetic considerations.
Lastly, I would like to discuss severe crowding for this part of the mini-series. Severe crowding is considered when a patient has greater than 10 mm crowding. There are several causes. First is simply having large teeth; for example, when central incisors’ width are measured greater than 10 mm. Another common cause is having an arch length and tooth size proportional discrepancy. This means that the teeth are relatively too large to be accommodated for by the patient’s jaw size. Often in these scenarios it is more that the patient’s jaw is too small. Finally, the other cause is early loss of baby teeth, and the space is not maintained, as previously mentioned.
There are a few treatment options to consider. First is serial extraction. This means pulling out the baby teeth, followed often by pulling out the adult first premolars. This is often done for patients that have very large teeth. Another option is increasing the dental arch perimeter (i.e. jaw size) through expansion. This expansion can be done orthopedically, with a rapid palatal expander, as well as by expanding and pushing the teeth out wider with orthodontic treatment. In addition, we can make the existing teeth more narrow or slender. This especially makes sense if there is a size discrepancy in only one jaw (i.e. the upper teeth are too large relative to the sizes of the lower teeth). Your orthodontist is able to ascertain this proportional relationship.
Here is a case where four premolars were pulled out to accommodate severe crowding and teeth that were blocked out from erupting. This patient had very large teeth and a wide smile at the end, despite having teeth removed.
As a quick review, this piece discussed abnormalities in dental development. If you see a child posturing his/her lower jaw forward. It is crucial to diagnose the cause and see if there is a traumatic interference as the root cause. It is also very important to monitor that primary/baby teeth are falling out and that the adult teeth are erupting symmetrically. Maintain spaces if baby teeth are lost early to prevent crowding or blocked out adult teeth! Remember to count teeth – see if there are any missing or extra teeth! If concerned, speak to your dentist and x-ray imaging can help offer a better explanation. Next topic I will discuss facial growth modification, which when there is a skeletal growth discrepancy.