## 4 Discussion
Combined with previous studies, the results of this study suggest that paying attention to the patient's bite depth, removing the premature contact spots of brackets in time, and controlling the force of the archive within the shear bond strength of the adhesive may help to decrease the BF rate in IDBS, particularly for the mandibular anterior tooth. Interestingly, the anterior teeth showed a higher position error rate than the premolars and molars (Table 4). In this study, we used a one-body transfer jig system based on CAD/CAM technology. The 3D-printed transfer trays had higher bracket transfer accuracy than the other methods [28]. Moreover, the one-body transfer jig system accommodated only one bracket, which eliminated interference from adjacent teeth, and the transfer accuracy was verified to be within a clinically acceptable level for anterior teeth [9]. Excluding appliance errors based on previous studies, the position error of brackets might occur during the process of virtual set-up and clinical transfer. Anterior teeth have sharp incisal edges and cusps, which make it difficult to obtain a smooth scan of these areas. Additionally, overlapping areas caused by dental crowding obstruct the entry of the scan ray. This affected the accuracy of the virtual dentition model [29]. In contrast, clinical transfer errors also need to be considered. During bracket transfer by one-body transfer jigs, pressure from the occlusal and buccal directions must be applied to ensure the accuracy and stability of the bracket position [30]. The shape of the occlusal surface of molars and premolars is polygonal in a large contact area with a transfer jig, which makes it easy to apply a stable occlusal pressure without any sliding. However, the anterior incisal edge is in linear or point contact with the transfer jig, which is usually accompanied by sliding and shaking during bracket transfer. Additionally, the molars and premolars are more upright in the jaws, which makes it easier for occlusal pressure to pass through the rotation center of the jig and the long axis of the tooth to maintain the stability of the transfer jigs. However, anterior teeth are often accompanied by crowding and inclination, which makes it difficult to apply a vertical force along the direction of the long axis of the tooth from the jig at the occlusal surface [31]. Considering the occlusal anatomy and smaller buccolingual inclination of molars and premolars, it is easier to apply a steady and sustained force to transfer the brackets more precisely for molars and premolars (Figure 3). A similar difference in which the bracket position between the actual and virtual models was the largest in the anterior teeth has been reported [1]. The vertical skeletal pattern was significantly associated with BF and the total responding rate. Compared to patients with vertical skeletal patterns, patients with hyperdivergent skeletal patterns showed a higher total re-bonding rate, which was caused by the higher bonding failure rate. This result is assumed to be affected by muscle force. Patients with hyperdivergent skeletal patterns had a lower maximum voluntary bite force, which means that, when chewing the same food, hyperdivergent patients need to chew more times because of the lower bite force [32]. Additionally, research has found higher resting temporal muscle activity in patients with hyperdivergent skeletal patterns [33]. This causes the brackets to receive a certain shear force even in the resting state. In other words, brackets in patients with hyperdivergent skeletal patterns received more frequency and sustained cyclic occlusal forces than patients with other skeletal patterns. [PERSON] et al. found that cyclic loading, including occlusal forces, could reduce bond strength [34]. Another survival analysis of bracket bonds also supports this hypothesis. A high mechanical loading level significantly affects the bracket bond failure [35].