Quantitative analysis of incisor root resorption before and after camouflaged orthodontic treatment of adult skeletal class Ⅲ malocclusion using cone beam CT

To explore the changes in root volume and root resorption in incisor arteries from adult patients with skeletal class Ⅲ malocclusion before and after camouflaged orthodontic treatment and to provide a reference for the clinic.

Thirty permanent dentition adult patients with skeletal class Ⅲ malocclusion were included from the Orthodontic Department. CBCT data of each patient at pretreatment and posttreatment were acquired, and 3D digital root models were reconstructed. The whole and segmented root volumes (cervical part, bodily part and apical part) of the right incisors were calculated.

The root volumes (whole, cervical part, bodily part and apical part) posttreatment were smaller than those pretreatment (P< 0.001). Maxillary central incisors and lateral incisors showed similar resorption in the cervical root and bodily root and more changes in the apical root, but there was no significant difference (P> 0.05). Mandibular central incisors and lateral incisors showed more root resorption in the apical root than in the cervical root and bodily root (P< 0.01). The absorption ratio of all segmented roots in each incisor showed a significant difference (P< 0.001), and apical absorption was the most obvious. There were no significant differences in root volume change amounts or the absorption ratio of the whole, cervical part and bodily part in all incisors (P> 0.05). The absorption ratio showed a significant difference in the mandibular lateral incisors (P = 0.028).

After camouflaged orthodontic treatment of adult skeletal class Ⅲ malocclusion, incisor root resorption occurred mainly in the apical part, but the cervical and bodily parts should also be considered. There was a high risk of root resorption in the mandibular incisors.