How to prevent root resorption using the Golden Rule of Orthodontics

There are four things that cause an orthodontist to lose sleep. Here, Joseph Morneau, DDS, chief of orthodontics in two hospitals, focuses on one—root resorption. In this article you'll learn a protocol to prevent root resorption by using the Golden Rule of Orthodontics.

Mar 1st, 2016
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This article first appeared in the newsletter, DE's Breakthrough Clinical with Stacey Simmons, DDS. Subscribe here.

As chief of orthodontics at NYU Lutheran Pediatric Dental Residency and at Rady Children’s Hospital–San Diego, I regularly provide didactic and clinical instruction to nonorthodontic residents. I find that orthodontics is a topic that most of my residents are eager to learn about. I structure this education so that the learning experience will be rewarding rather than punishing, so with that in mind, I begin instruction for each new class of residents with the Golden Rule of Orthodontics: Primum non nocere.

While not specifically in the Hippocratic Oath, primum non nocere is believed to be derived from it and means first, do no harm or above all else, do no harm. In other words, before you do anything to a patient, make sure that you are not making matters worse. What good does it do to straighten teeth if in doing so you cause the patient to lose them? The point of this article is not to scare or deter you from engaging in orthodontics, but to give you a foundation that will protect both you and the patient.

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What is the worst thing that could happen? The answer, of course, is death. While treatment may have gone horribly awry, if your patient dies due to orthodontic treatment, that is the worst possible outcome. Always make sure to check the medical history.

Other than death, what will cause an orthodontist to lose sleep? Four things top the list:

  1. Root resorption
  2. White spot lesions (also known as decalcification)
  3. Periodontal disease
  4. Moving teeth out of bone

In this article, I will discuss the first—root resorption. Root resorption (figure 1), or shortening of the roots, occurs in almost every case of orthodontic tooth movement. In most cases, it is so insignificant that it is hardly—if at all—noticeable on successive x-rays. However, some patients react more severely. If the roots become too short, the teeth can obviously become mobile or even be lost. While there are theories about what causes the roots of some patients to resorb more than others, there is no reliable way to predict root resorption.

Figure 1:Root resorption

Figure 2:Severe root resorption evident on maxillary lateral incisors

Figure 3:2x4 appliance

Figure 4a:Fixed lingual retainers placed from lateral incisor to lateral incisor

Figure 4b:Two years later, root resorption is evident on the maxillary left lateral incisor

Before you begin treatment, take records. These include photos, x-rays, and diagnostic models. It is important to document the state of the patient prior to treatment. Regarding root resorption, it is essential to take radiographs. Any orthodontic treatment should include pretreatment and post-treatment radiographs that allow visualization of the roots. I recommend panoramic radiographs for this purpose. While it is common in general dentistry to take panoramic x-rays every five years, this is too long for patients in orthodontic treatment. Root resorption can be evident radiographically in as little as six months of orthodontic treatment. Because of this, I take panoramic x-rays every six to eight months in my practice.

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Notice the resorption on the roots of the maxillary lateral incisors in Figure 2. This was caused not by orthodontics but by the erupting canines. Now imagine an orthodontic setup commonly called a 2x4 (figure 3). A 2x4 typically means the placement of orthodontic brackets on both first molars and the four incisors in the same arch. This is often used to correct an anterior crossbite in the mixed dentition. If done improperly, the roots of the maxillary lateral incisors can be forced into the hard enamel crowns of the erupting permanent canines. This sort of error can lead to the same result seen in Figure 2. The patient could ultimately lose teeth because of this. This is something to always be mindful of when doing orthodontics in the mixed dentition. You don’t have to be a perfectionist when bonding brackets, but the general rule of thumb should be to avoid distalizing the roots of the maxillary lateral incisors. In other words, when bonding the lateral incisors in situations like this, err on the side of mesializing the roots. This will prevent the roots from being driven into the crowns of the canines. You may be thinking that this does not provide the ideal esthetic result. You are right! However, esthetics is not the primary goal of this early treatment. And remember, if the patient loses a tooth, that is certainly not an ideal esthetic result.

In my practice, I typically do not provide a retainer for this treatment. I normally use such a procedure to correct an anterior crossbite. Once corrected, it is very rare for an anterior crossbite to relapse. Furthermore, I explain to parents that a retainer could inhibit needed flexibility of tooth movement. While I’m willing to place an occasional fixed splint lingual to upper central incisors, I will not splint the upper lateral incisors to the central incisors. The roots of the lateral incisors need to be free to move out of the way if the erupting canines bump into them. Splinting the lateral incisors increases the chance of root resorption (figures 4a and 4b). Removable retainers can also be used, but they are not perfect either. They can inhibit or alter develop off the maxilla and the erupting dentition. Whatever retention protocol you choose, remember the golden rule to do no harm.

When root resorption is noticed, the best option is to stop treatment. It is important to explain that some degree of root resorption occurs in all orthodontic patients. In most cases, it is insignificant. Severe root resorption is rare, and there is no way to reliably predict who will experience it. All we can do is monitor for it and react appropriately when we recognize it.

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Some evidence exists that stopping orthodontic tooth movement for six months or more will minimize root resorption if treatment is reinitiated. However, this is not conclusive, and there is no guarantee that such a protocol will work. Any decision to reinitiate should probably be made by an orthodontist.

Providing orthodontic treatment can be a very rewarding experience, when performed properly. Proper treatment requires planning. The safety of the patient is of paramount importance and the foundation upon which a good treatment plan is built. Always remember the Golden Rule of Orthodontics: Do no harm.

This article first appeared in the newsletter, DE's Breakthrough Clinical with Stacey Simmons, DDS. Subscribe here.

Joseph Morneau, DDS, is a 2001 graduate from Louisiana State University School of Dentistry. He received his orthodontic specialty certificate from St. Barnabas Hospital in New York. He is a veteran of the US Navy and has served as a dental officer in Italy, Japan, the Middle East, and California. It was during this time that he realized his passion for orthodontics. He now practices full time as an orthodontist in private practice in San Marcos, California. Dr. Morneau is also chief of orthodontics at NYU Lutheran Pediatric Dental Residency and at Rady Children’s Hospital–San Diego. He likes spending time with his beautiful wife, Vera, and their happy and healthy son, Hugo. He also enjoys surfing and travel in his spare time.

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