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editorial
. 2014 May;84(3):568–569. doi: 10.2319/0003-3219-84.3.568

Defining and framing orthodontitis: A new term in orthodontics

Naphtali Brezniak, Atalia Wasserstein
PMCID: PMC8667484  PMID: 24749703

It is well known that orthodontic force application induces aseptic local inflammation due to necrosis in the periodontal ligament (PDL) and that there is no tooth movement without this inflammation process. It is also well known that the inflammation process is important for both the bone as well as the cementum remodeling processes.15 If we consider these well-known phenomena together, we can name the process related to orthodontic tooth movement, as well as the Inflammatory Root Resorption Concurrent with Orthodontics (IRRCWO),6 as “Orthodontitis”. Orthodontitis, then, is the inflammation behind tooth movement, where the prefix is our profession and the suffix “itis”7 is used in medical terminology to describe inflammation of an organ or a tissue. The combination, Orthodontitis, is therefore a term we would like to introduce along with a classification system to describe the inflammation resulting from orthodontic force application.

Orthodontitis is an aseptic local inflammation in the PDL induced by orthodontic forces. Orthodontitis can be divided into 2 groups: Instrumental Orthodontitis (IO) and Instrumental-Detrimental Orthodontitis (IDO):

Instrumental Orthodontitis (IO): IO initiates controlled bone modeling,8 as well as bone and cemental remodeling (reversible changes).8,9 IO enables tooth movement to occur due to frontal and undermining alveolar bone resorption and apposition on the pressure and tension sides, respectively.10 The roots next to IO areas also undergo surface resorption,11 mainly by cemental remodeling. This biological process ceases when orthodontic forces are removed. The periodontal ligament that surrounds the roots is fully regenerated. IO symptoms include mild to moderate tooth mobility and/or sensitivity, and pain during the first days following force application. IO signs include mild to moderate tooth mobility and radiographic PDL widening. Signs and symptoms disappear following orthodontic force cessation.

The mechanism behind the process is that orthodontic force enables normal blood flow, but induces local electrical current and pH changes as well as release of different biological materials from the damaged cells (e.g. cytokines and prostaglandins). These events trigger local inflammatory activity in the area surrounding the roots and is limited to the PDL, alveolar bone and cementum. The inflammation in the pressure area induces mainly a bone modeling process by resorbing the alveolar bone while the inflammation in the tension area induces bone modeling by apposition; new bone is being laid down on the affected surfaces. Surface cemental remodeling is induced in both areas as well.

The inflammation mechanism is genetically controlled. It is activated regularly during our lifetime and it remains behind the normal remodeling/modeling process.

Regarding treatment, analgesics are sometimes prescribed during orthodontic treatment. No further action is needed.

Instrumental and Detrimental Orthodontitis Grade 1 (IDO1): IDO1 is similar to IO. However, the inflammation in IDO1, for unknown reasons, changes its character on the cemental side (the effect on the bone on the pressure and tension sides is similar to that of IO) and the remodeling process becomes a modeling process; the resorption process goes beyond the cementum into the dentin. IDO1 causes minor to moderate root shortening12 as well as scattered lacunae on other root surfaces. Both of these are irreversible changes. The results are usually diagnosed using X-rays during, close to the end, or following orthodontic treatment. The symptoms and treatment are similar to IO. After orthodontic treatment is completed, there are only radiographic signs (root shortening or peripheral surface resorption) but no symptoms.

Instrumental and Detrimental Orthodontitis Grade 2 (IDO2): IDO2 is very similar to IDO1. However, in this case, the inflammation results in severe root shortening. The symptoms are tooth mobility and sensitivity during or following orthodontic treatment. The signs include tooth mobility/sensitivity and severe root shortening12 as viewed on X-rays. The consequences of IDO2 require treatment. The treatment for IDO2 depends on the time that it is discovered. If IDO2 is diagnosed after debonding, we suggest that fixed retention be used to splint the affected teeth together with unaffected teeth. In rare situations, fused crowns can be a good treatment solution. Extractions and implant replacements should be considered only in extremely rare cases, if ever.

The mechanism for both IDO1 and IDO2 is similar to that described for IO. However, the level of the resorptive activity on the root surface is different, and it is probably individually genetically determined.1316 The remodeling process is being disturbed in the transition between the resorption and the reversal stages.8,9 The coupling between resorption and apposition disappears or is delayed and, therefore, resorption continues into the dentin.

Furthermore, we suggest that IDO should be regarded as a self-defense mechanism of the body to an extreme local condition (similar to the body's reaction or behavior in hypovolemic shock)17 which occurs in the PDL following force application. By shortening the roots, the body decreases the current or future moments developed in the apical areas of the teeth due to the orthodontic force being applied at the crown. In addition, we suggest that the irreversible lacunar resorption along the roots' surfaces is a mechanism that may defend against the loss of teeth with resorbed short roots by increasing their surface areas, thereby keeping the damaged teeth in a stable condition. It has been demonstrated that those teeth can remain in the mouth for many years.18,19

We believe that the profession should adopt this new terminology and use it to explain the actual process underlying tooth movement and IRRCWO during consultation with the parents/patients/guardians. If patients and parents can understand this process better, the number of lawsuits against orthodontists in this matter would decrease tremendously. IRRCWO can be considered one of the body's self-defense mechanisms. Even today, it has not been determined conclusively the level of force and/or the duration of force application at which this reaction will be expressed.

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