## 4 Discussion  
Bracket adhesion failure is directly related to the efficiency and effects of orthodontic treatment. [PERSON] et al. found that the treatment time would be extended by 0.3 months for each bracket adhesion failure, and three or more bracket adhesion failures would extend the treatment time by up to 1.5 months [10]. Analysis and control of the bracket re-bonding rate were consistent with the benefits of orthodontic treatment for both patients and clinicians. The precision and accuracy of an IDBS are influenced by digital technology and human factors. Digital technology factors come from the processes of intra-oral scanning, 3D modeling, and bracket visual setup, which assist in the fabrication of transfer jigs. These factors are easy to evaluate and analyze in laboratory environments. However, the \"Human factors\", which come from clinicians' and patients' variability, were not easy to simulate and analyze in the laboratory. Hence, it was more accurate and realistic to evaluate the failure rate of bracket bonding through in vivo studies, which are influenced by multiple factors in clinical practice. This study found that the total bracket re-bonding rate was 22.64% in clinical practice, which was higher than in some previous studies [9; 11]. However, it should be pointed out that failure rate of IDB has been demonstrated to be similar as the DB technique in the other study [12]. Operators should take this important factor into careful consideration before clinical choices. This discrepancy might be partly due to the gap between bases on the brackets and tooth surface. In the IDBS of brackets, the thickness of the resin between the bracket and tooth surface is inevitably greater than that of DBS [13]. According to the finite element analysis, the farther the applied force is from the bonding interface, the higher the momentum [14]. Moreover, the thicker the adhesive, the greater the shear stress on the brackets. [PERSON] et al. found that adhesive thickness affected the distribution of major principal stresses within the adhesive [15]. Another study showed that the failure rate at the tooth-adhesive interface increased with increased adhesive thickness in shear testing [16]. The total bracket re-bonding rate was further divided into subjective and objective reasons for group discussions, which are position \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & \multicolumn{4}{c}{**Bonding Failure**} & \multicolumn{4}{c}{**Position Failure**} & \multicolumn{4}{c}{**Total Re-Bonding**} \\ \cline{2-13}  & **Estimate** & **95\% CI** & \(p\)**-Value** & **Estimate** & **95\% CI** & \(p\)**-Value** & **Estimate** & **95\% CI** & \(p\)**-Value** \\ \hline Initial stage & 0.000 &. &. &. & 0.000 &. &. &. & 0.000 &. &. &. \\ Middle stage & 0.012 & 0.007 & 0.018 & \(<\)0.0001 ** & 0.024 & 0.020 & 0.028 & \(<\)0.0001 ** & 0.036 & 0.030 & 0.043 & \(<\)0.0001 ** \\ Late stage & \(-\)0.015 & \(-\)0.021 & \(-\)0.009 & \(<\)0.0001 ** & 0.006 & 0.002 & 0.010 & 0.0039 ** & \(-\)0.009 & \(-\)0.016 & \(-\)0.002 & 0.0070 ** \\ Incisors and & 0.000 &. &. &. &. & 0.000 &. &. &. &. &. \\ Canine & 0.000 &. &. &. &. &. &. &. &. &. &. \\ Premolars & 0.000 & \(-\)0.009 & 0.008 & 0.9057 & \(-\)0.010 & \(-\)0.015 & \(-\)0.005 & 0.0001 ** & \(-\)0.011 & \(-\)0.020 & \(-\)0.002 & 0.0222 ** \\ Molars & 0.004 & \(-\)0.004 & 0.012 & 0.3651 & \(-\)0.011 & \(-\)0.016 & \(-\)0.006 & \(<\)0.0001 ** & \(-\)0.008 & \(-\)0.017 & 0.002 & 0.1058 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Multiple linear regression analysis with dependent variables of treatment stage and tooth position.