## 4 Discussion  
Different studies evaluated the effects of orthodontic treatment on root length based on radiographs [18; 19; 20; 21]. In previous studies that compared orthopanoramic radiographs with CBCTs, root resorption was underestimated in panoramic radiographs, while CBCTs exhibited higher sensitivity and specificity [20; 22; 23]. Extraoral radiographs might be less accurate than other imaging procedures, such as periapical radiographs or 3D images on CT scans to evaluate root resorption [24]. CBCT provides high image quality and allows the operator to precisely measure root and crown length. CBCTs performed before treatment were used to evaluate whether the measurements detected on pre-treatment digital panoramic radiographs were precise. Most patients did not have post-treatment CBCT, because it was not required, in order to avoid further radiation exposure. The decision aimed to prioritize patient safety while acknowledging that CBCT was not a mandatory component of their treatment follow-up protocol. Patients who presented CBCT conducted before the treatment were selected for this study. The calculation method used in this study to quantify the apical root resorption was applied by various authors [21; 22; 23]. External apical root resorption is a complex phenomenon encountered during orthodontic treatment and is marked by an inflammatory cascade that culminates in ischemic necrosis localized within the periodontal ligament, upon the application of orthodontic force. This process involves the gradual loss of root structure, a concern that has been extensively explored in the literature. Surprisingly, severe root resorption during orthodontics is reported to be relatively uncommon, affecting only 1-5% of patients, according to existing studies. A study conducted by DeShields in 1969 reported an exceptionally high incidence of root resorption, affecting 99.08% of the patients examined [25]. Such wide-ranging disparities in radiographical findings prompt a closer examination of the variables and assessment methods employed across different studies. The divergent outcomes may be attributed to variations in research protocols, patient populations, and diagnostic techniques utilized for evaluating root resorption. Understanding the mechanisms and predisposing factors associated with external apical root resorption is crucial for orthodontic practitioners. As research continues to refine our comprehension of this phenomenon, clinicians must navigate the delicate balance between achieving optimal tooth movement and minimizing the risk of severe root resorption in orthodontic patients. Orthodontic tooth movement is accomplished by the simultaneous activation of bone resorption by osteoclasts and bone formation by osteoblasts. When orthodontic forces are applied, bone resorption obtained through the activation of osteoclasts occurs in the alveolar bone on the compression side, thus creating space for tooth displacement. Therefore, controlling the activity of the osteoclast is a key concept in orthodontic treatment; heavy forces do not allow this kind of control. On the tension side where the periodontal ligament is stretched, the work of the osteoblasts is enhanced, which results in osteoid deposition, subsequent mineralization, and eventually, new bone formation. Prolonged orthodontic treatment necessary for the disinclusion of impacted teeth could be due to the longer distance to reach the occlusion. The duration of orthodontic treatment in the literature has been suggested to contribute significantly to apical root resorption [13]. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Mean ARR** & **SD** \\ \hline  & (mm) & \\  Root shape & Normal (N = 15) & 0.81 & 0.27 \\ \hline   Blunt (N = 7) & 0.69 & 0.27 \\ \hline   Apically bent (N = 9) & 0.94 & 0.37 \\ \hline   Pipette-shaped root (N = 5) & 1.13 & 0.17 \\ \hline  \(p\) & 0.07 & \multicolumn{2}{c}{NS} \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Mean apical root resorption of impacted teeth and physiologically erupted teeth according to root shape.