## 3 Results  
The study analyzed 672 teeth of the upper and lower arches before and after therapy from 28 patients treated with clear aligners. The ICC tests showed high intra-rater (0.9886 and 0.9883 for torque, 0.9839 and 0.9845 for root length) and inter-rater reliabilities (0.9884 for torque and 0.9880 for root length). To evaluate the changes in sagittal root positions relative to the orofacial cortical plates, the positions of the roots at the T0 and T1 stages were compared on the cross sections using the classification proposed by [PERSON] et al. [20] and modified by [PERSON] et al. [21]. In the upper and lower arches, no roots were found positioned against the palatal cortical plate or both cortical plates at either T0 or T1 stages. As regards the upper arch (Figure 4), an improvement in root position has been noticed, especially in the anterior sectors. The central incisors achieved more significant progress. Indeed, all roots were correctly positioned at the end of treatment; the amines showed lower effectiveness since 22% of their roots remained against the labial cortical plate at T1. For the lateral incisors and first premolars, all roots were in Class II al T1, except for only 6% positioned against the buccal cortical plate. Figure 4: Percentage of sagittal root positions before and after therapy in the upper arch. In the second bicuspid, 19% of their roots in class I at T0 were centered in the alveolus at T1. In the first molars, 6% of roots in contact with the labial cortical plate at T0 were found in class II at T1, so 100% of their roots were in the center of the alveolus at the end of therapy. The aligners satisfactorily managed the roots of the incisors, canines, and first preemlars positioned outside the labial cortical plate at T0. In the mandibular arch (Figure 5), the management of root position was better in the central incisors (from 22% in class II at T0 to 84% in class II at T1). However, 16% of the roots remained against the buccal cortical plate at the end of the therapy. Regarding the lateral incisors and canines, 81% of the roots were centered in the alveolus at T1, although 19% remained in contact with the labial cortical plate. The mandibular bicuspids and molars achieved a correct root position at the end of treatment: 91% of the first pre molars and 100% of the roots of the second premolars and first molars were positioned between the two cortical plates. We can notice that the initial root position was better in the posterior than in the anterior teeth. In the lower arch, no roots were found positioned outside the buccal cortical plate at T1. By comparing Figures 4 and 5, the control of root position after clear aligner therapy was more effective in the upper arch, especially in the anterior sectors. Subsequently, the torque values before and after therapy were evaluated and compared. Table 2 illustrates the torque variation of the upper teeth due to the orthodontic treatment. At the end of therapy, the highest mean torque changes were achieved in the incisors, while the lowest mean torque changes were in the posterior teeth. Figure 5: Percentage of sagittal root positions before and after therapy in the lower arch. The torque increase was less noticeable in the lateral incisors and canines than in the central incisors. The mean percentage of torque increment varied from 0.15 \(\pm\) 0.73% in the first molars to 22.82 \(\pm\) 12.62% in the central incisors. This appears to agree with the variations of the root positions at T1 (Figure 4). In the mandibular arch, the torque variations were the greatest in the central incisors, decreased in the lateral incisors and canines, and were minimal in the premolars and molars, as shown in Table 3.  
The mean increase among mandibular teeth varied between 2.97 \(\pm\) 2.53\({}^{\circ}\) (central incisors) and 0.02 \(\pm\) 0.07\({}^{\circ}\)/0.02 \(\pm\) 0.06\({}^{\circ}\) (second premolars/first molars). Overall, the torque increase in the lower arch was less than in the upper arch, decreasing from the anterior to posterior sectors.