## 4 Results and Discussion
### Macro-Staging and Micro-Staging
#### 4.3.1 Macro-Staging
Flattening the Spee curve deserves special attention during the staging due to negative reports regarding its management with clear aligners [48; 49]. To achieve a more effective anterior intrusion, we suggest organizing the Spee curve flattening staging into three phases: (1) alignment of anterior teeth (by buccal crown inclination and derotation) along with the preparation of anchorage in the posterior sectors (derotation and leveling of premolars), (2) intrusion of canines with or without simultaneous premolar extrusion, and (3) intrusion of incisors [50] (Figure 4). This strategy, in our opinion, presents several advantages:  
1. The first phase of alignment and anchorage preparation creates space in the anterior segment, alleviates crowding, and isolates absolute vertical movement for the final stage. It also allows the apex of the incisors to be relocated away from the cortical bone to avoid possible dehiscence or blockages during intrusion [51; 52]. Additionally, the anchorage provided by rotated or compressed posterior segments is less than that provided if they are correctly aligned and leveled. 2. Separating the intrusion movement of canines and incisors enhances the intrusive force on the target teeth and reduces the extrusive counterforce on anchor teeth. This is reflected in the study by [PERSON] and [PERSON] [53], which demonstrated greater intrusive efficacy in models where only lower canines were intruded or only lower incisors were intruded. Figure 3: The pattern of sequential \({}^{1}/_{2}\) staging is the most popular among orthodontists [22; 40]. (**A**) Real sequential \({}^{1}/_{2}\) staging, in which the movement begins with the second molar, and when it reaches halfway, the first molar begins to move. When the second molar finishes its movement, the second premolar starts to move. The staging continues, moving at most two teeth per hemiarch until the distalization of the first premolar is completed, at which point the incisors move along with the canine (three teeth in simultaneous movement). (**B**) False sequential \({}^{1}/_{2}\) staging, which begins by following the previously described sequence until the distalization of the second premolar is completed, at which point the first premolar, canine, and incisors are in motion (four teeth in simultaneous movement), with the potential risk of anchorage loss. Simultaneously requesting premolar extrusion with canine intrusion enhances both movements. 4. This scheme allows the use of rotation attachments, expansion control, or root control attachments on canines and/or premolars for the first phase of movement, to be replaced by retentive attachments when vertical movements begin. Figure 2 is an example of the results obtained using this staging of movements. This same approach of macro-staging that starts by aligning the anterior segments to then perform isolated pure vertical movement can also be used for anterior extrusion. The staging in cases of extractions and large space closures is complex, as it must reduce the risk of a bowing effect by trying to control the retraction of anterior teeth with torque control while also attempting to shift the root apices in mesiodistal movements [54; 55]. An interesting proposal was detailed by [PERSON] and [PERSON] [56], and it is now referred to as segmental tooth movements or \"_caterpillar motion_\" [57]. Extraction spaces would be closed in several stages of posterior alignment and canine retraction followed by incisor retraction (Figure 5). The proposal of segmented movements maximizes intra-arch anchorage and promotes root movement by allowing \"_pause_\" stages while other teeth are in motion [58]. To organize segmental tooth movements, it is important not to simultaneously shorten both ends of the arch to avoid bending the plastic and favor a bowing effect. Additionally, having immobile teeth throughout the treatment in intermediate segments of the arch seems to favor the correct movement of adjacent teeth and increase anchorage [59].