Orthodontically induced cervical root resorption in humans is associated with the amount of tooth movement.
BACKGROUND
The aim of this study was to investigate the variation in the amount of the orthodontically induced cervical root resorption and the association with several factors, such as the amount of tooth displacement, location of tooth in the maxilla or mandible, and presence of an interference that may influence the amount of root resorption.


METHODS
This study included 30 subjects (20 females, 10 males) with an age range of 11.3 to 43.0 years. Using a standardized experimental orthodontic tooth movement, 59 premolars were moved buccaly during 8 weeks with application of 1 N force. Fifty-eight contralateral premolars not subjected to orthodontic tooth movement served as controls. At the end of the experimental period the teeth were carefully extracted, scanned in a micro-computed tomography scanner with a resolution of 9 µm, and the reconstructed images were processed for volumetric evaluation of resorption craters at the cervical part of the root surface. Data were analyzed using unpaired t-test and the Pearson's correlation.


RESULTS
Higher amount of cervical root resorption was detected in the orthodontically moved teeth (0.00055 mm3) compared to controls (0.00003 mm3; P < 0.001). Moderate correlation was found between root resorption in the two experimental teeth within the same individual (R = 0.421, P = 0.023). Teeth located in the mandible presented more resorption than those in the maxilla (P = 0.046). The amount of root resorption was correlated to the amount of tooth movement (R = 0.318, P = 0.016).


CONCLUSIONS
Application of a 1 N force over a 2-month period provokes severe root resorption at the compression cervical sites. Resorption is correlated with the amount of tooth movement and the location of the teeth.
Department of Orthodontics.
Alexander
A
Dudic
Department of Periodontology.
Catherine
C
Giannopoulou
Departement of Cell Physiology and Metabolism, Medical School, University of Geneva, Switzerland.
Paolo
P
Meda
Division of Radiology, Geneva University Hospital, Switzerland.
Xavier
X
Montet
Department of Orthodontics.
Stavros
S
Kiliaridis
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001641:Bicuspid / Q000503:physiopathology; D002648:Child; D003739:Dental Cementum; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008334:Mandible / Q000503:physiopathology; D008437:Maxilla / Q000503:physiopathology; D012391:Root Resorption / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000009:adverse effects* / Q000379:methods; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000473:pathology; D055114:X-Ray Microtomography / Q000379:methods; D055815:Young Adult