Correlation between cortical plate proximity and apical root resorption.

Root resorption is one of the most common iatrogenic sequelae of orthodontic treatment. Recently, root contact with the labial or palatal cortical plate at root apex level during orthodontic tooth movement was reported to be related to root resorption, and dentofacial morphology was suggested to predispose certain persons to root contact with the cortical plate. In this study, we constructed a best-fit straight line for the maxillary palatal cortical plate and set a line for the labial cortical plate from A point to Prosthion point in order to obtain measurements of proximity of root apices with the cortical plates of the maxillary alveolus. We investigated the correlation between apical root resorption and the measured variables. Our findings suggest that root approximation to the palatal cortical plate during orthodontic treatment could explain approximately 12% of the variance observed in the level of root resorption and the maxillary alveolar bone width about 2%. Tooth extrusion and crown lingualization also contributed to root resorption. We concluded that maxillary central incisor apical root resorption is influenced by root approximation to the palatal cortical plate during orthodontic treatment.