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The last type of resorption that we’ll discuss is that which occurs during orthodontic tooth movement.
Root resorption or ‘shortening of the roots’ occurs in nearly all cases of orthodontics, but is so insignificant that it may not be possible to see it on an x ray. However, some individuals may experience noticeable resorption of their roots. This can range from mild to moderate to severe. The roots may become so short that they loosen up or fall out. Unfortunately, it’s hard to predict who will be susceptible to root resorption.
Before beginning an orthodontic case, it is important to take pre-op x rays, to have a baseline view of the roots. Ideally the patient should see their dentist every six months for a cleaning and checkup. At these times (every six months), it is best for the family dentist to take x rays to verify whether the roots of the teeth have shortened. If root resorption occurs we must stop treatment on the patient immediately.
Severe root resorption
Severe root resorption is rare. As mentioned previously, there is no way to predict who will experience it. This is why it is key to monitor it and treat appropriately if noticed.
Risk factors for orthodontic resorption
1) Prolonged treatment time.
2) Direction and amount of orthodontic forces being applied: Heavy forces have a harmful effect. It is recommended to use light forces and leave intervals before activation of new forces.
3) Teeth that are moved too quickly.
Amongst all the teeth in the mouth, the maxillary incisors (upper front teeth) show the most resorption. This is followed by the mandibular incisors (lower front teeth) and lower first molars (back teeth).
When orthodontic therapy is terminated, root resorption ceases. When orthodontic treatment has ended a reparative process occurs which smooths and remodels the ‘sharpened’ edges caused by the orthodontics. After the braces are removed, it is best not to load severely eroded teeth with large forces. Large ‘functional’ forces may lead to further resorption. In general however, variable and every day forces don’t usually lead to further resorption, but it is a possibility. One can imagine though, that if heavy forces are applied to severely resorbed teeth, then the result may be an increased mobility (movement).
Support of the root
It has been shown that most of the support of the root in the jaw comes from ‘crestal’ attachment as opposed to ‘apical’ attachment i.e. Three millimeters of apical root loss is equivalent to one millimeter of crestal bone loss. The crestal ‘attachment part’ of the bone is that part of the bone just below the gum. It is here that special connective tissue fibers attach the root to the bone. Apical bone is the part of the bone that encompasses the ‘tip’ of the root.
Cone beam technology
It is best to take a three dimensional image (cone beam technology) of resorbed roots as opposed to just two dimensional x rays, especially if severely resorbed. Cone beam technology (CAT scan) will be able to show the degree of severity of resorption and also the ‘geometry’ or shape of the resorption.
Consent before treatment
Before treatment, patients need to know (and be informed verbally) that there is a possibility or risk of resorption. And if root resorption does occur, the patient must be notified about it.
Strategy of Orthodontic treatment
1) Apply light forces.
2) Leave long intervals of time before reactivation of orthodontic forces.
3) Take x rays every 6-12 months.
4) If resorption is identified from an x ray, pause treatment for 2-3 months and place a passive wire to hold the teeth in place.
Worst case scenario
If resorption is occurring and we still need to close gaps between the teeth, consider placing a prosthetic restoration i.e. an implant. In this way, orthodontic forces are terminated and there’s no further chance of resorption.
If there is apical root resorption (ARR), remove the orthodontic brackets and place a fixed retention wire that is ‘passive’ in nature. Of utmost importance in these situations is optimal oral hygiene. One cannot afford to develop periodontal (gum) disease as the roots of these teeth are already compromised (shortened).
In the past few blogs, we have seen that resorption, whether internal or external, or whether it affects the root or tooth portion, can be quite a serious problem.
The key is early detection by having regular visits to your dentist.
Yours in dental health,
Dr. Robert Axelrad, Brampton Dentist
For any dental questions or concerns, please give us a call today @ 905.791.3867…you’ll be glad you did!
Based in Brampton, Ontario, Brampton Dentist Dr. Robert Axelrad has been practicing gentle and pain-free dentistry for over two decades. During this time, he has helped to improve the dental health of countless satisfied patients in Peel Region, Brampton and beyond!