Short roots are a rare developmental anomaly characterized by full root formation, but with genetically determined foreshortening. The affected root is smaller or presents the same size of the dental crown, has a tendency towards bilateral involvement and presents no other etiological factors.
We are using this term in a general sense as a broad summary.
The cause for short roots in patients is normally a biological variation. This finding is not a contraindication for orthodontic tooth movement.
Unusually shaped roots are more prone to shortening during orthodontic tooth movement.
Roots that are fine, pipette shaped, dilacerated or bulbouse may be more susceptible to apical root resorption during orthodontic treatment.
Root shortening is also associated with a history of orthodontic treatment. Further, there are medical conditions such as imbalances of Calcium and Phosphate metabolism and metastatic disease that shorten tooth roots. An example is osteocarcoma that has metastasized to the oral cavity.
It is important to distinguish "short roots" from "roots that have been shortened", although the radiographic appearance may be similar.
In the former, this can be attributed to natural variation, medical conditions and syndromes, wherein a normal length tooth root simply did not form.
In the latter, there are numerous causes that shorten a root. A common cause is resorption from an adjacent erupting teeth. For example maxillary canines may resorb the root of the adjacent lateral incisor. Trauma and the resultant inflammation may also resorb and shorten the tooth root.
The first step in treating patients with "short roots" is to confirm that they indeed are short. Radiographic imaging often distorts the true length of the tooth. This can be the result of sensor/film position or the projection effect of proclined incisors. Teeth that are very proclined will often appear "short" on periapical views.
It is important to identify the above situations prior to treatment and to take progress radiographs to monitor changes during tooth movement. If root shortening is found, stop active tooth movement and stay in the last passive aligner for a period of approximately 3 months.
It is also important to evaluate short roots comprehensively. In situations such as external root resorption, the root may be shortened or shortened in the process thereof. Active resorption, either internal or external, must be managed prior to orthodontic treatment. An endodontic consult is encouraged in these situations.
Following re-evaluation using radiographs, if the situation is stable, orthodontic treatment may be resumed carefully. If there is evidence of ongoing activity, it is best to remain passive and continue to evaluate for stability at 3 month intervals.
It is also important to consider the medical history of patients. There are a number of disorders of Calcium and Phosphate metabolism that may produce short tooth roots. It is best to consult a physician in these situations.
Anytime a patient's roots seem to be shortening in the absence of a clear dental etiology, it is best to consult a physician.