Root resorption has been a common incident during orthodontic treatments. This is mostly due to orthodontic forces causing bone resorption and remodeling which allows the tooth movement during treatment. Compression and tensile forces trigger osteoclastic and osteoblastic activities which results in bone resorption and remodeling and facilitate the tooth movement. Root resorptin may occur as a result of this osteoclastic activity.
New study conducted by Henrik Lund et al at the University of Gothenburg, Sweden, evaluated the amount of root shortening during orthodontic treatment by using cone beam CT (CBCT). . Most studies have been conducted with the aid of intraoral radiography, which means that only root shortening and resorption on the mesial and distal aspects of the roots could be evaluated. Cone beam CT (CBCT) offers the possibility of assessing root surfaces not displayed on conventional radiographs and creating scenes similar to previous ones despite changes in tooth/root position. Therefore, it may be safe to assume that measurements of root length changes can be made reliably with CBCT.
Almost all patients and between 55% and 91% of teeth showed some degree of root shortening.
- Nearly 7% of patients had one tooth or more with root shortening exceeding 4 mm, but none had more than three teeth affected to this degree. Few factors other than those already known had a statistically significant effect on the degree of root shortening.
- Slanted root resorption was found in up to 15% of palatal root surfaces and could be evaluated only on tomographic images.(1)
1. Henrik Lund, Kerstin Gröndahl, Ken Hansen, and Hans-Göran Gröndahl (2012) Apical root resorption during orthodontic treatment. The Angle Orthodontist: May 2012, Vol. 82, No. 3, pp. 480-487.