## 4 TSAD: The Use of C Minimplants and NiTi Arches  
In the BOS strategy, miniscrews with a diameter of 1.2-2.0 mm and a length of 6-12 mm are most often used for TSAD fixation for distalization, intrusion, protraction, or indirect anchoring, as well as partially bone-integrable mini-implants (C-implant) and miniplates with C tube [17; 19]. The latter allows for the multidirectional application of high-intensity force, consistent with the assumptions of biomechanics, opposing torque [20; 21; 54]. At the same time, wire arches can be used, such as conventional C-arches, which, in combination with a C-implant, make it possible to minimize friction and load on the posterior teeth during the retraction of the incisors and canines [22]. Implant C, thanks to its partial integration into the alveolar bone, provides strong support for the entire structure. The wire arch is attached to the C implant holes, and the apical arches are attached to it. In this way, an intrusion force is exerted on the anterior teeth, preventing their lingual tilt during en masse retraction [55]. In the study by [PERSON] et al. [56], nickel-titanium arches with reverse Spee curvature were used, attached to the C implant, which allowed the device to remain stable during therapy and avoid changes in the position of the posterior teeth. The on-lay nickel-titanium arch with reverse curve Spee exerts torque on the C-implant without loosening the screws and creates forces responsible for rotation and control of the vertical position of the incisors. Moreover, the size of the wire archwire can be easily adjusted and changed [54]. In a study by [PERSON] et al. [54], a three-dimensional model of maxillary teeth, periodontal ligaments, and alveolar processes was constructed after extraction of first premolars. A mini-implant was then placed with a 0.8 mm hole between the second premolar and first molar and an inversely curved NiTi archwire from the head of the C implant to the point between the central incisors and to the segmental arch of the six anterior teeth, using the mini-implant as a posterior orthodontic tube. The influence of different sizes of retraction hooks placed between the lateral incisor and the canine on the torque control and the effect of forces of varying intensity on the NiTi overlay arch were examined. No braces or brackets were placed on the back teeth. The results of the study confirmed that the forces caused by variable-sized retraction hooks on the NiTi arch caused measurable, desired intrusion of the incisors and extrusion of the canines, both tooth crowns and roots. It has been proven that the desired effect of en masse retraction of anterior teeth can be achieved by using a partially osseointegrable C mini-implant as the only source of anchorage, a NiTi overlay arch, and retraction hooks of a specific size without interfering with the position of the posterior teeth of the jaws (biocreative therapy type II). [54]. Before modern nickel-titanium archwires were used, conventional stainless steel archwires (SS archwires) were used to retain anterior teeth. However, they had certain limitations: their skillful preparation and installation required additional training and training from orthodontists, and during treatment, due to the high coefficient of deflection under load of the SS wires, they required frequent inspections and time-consuming adjustments [57; 58; 59; 22]. Therefore, [PERSON] et al., in their work [22], decided to create a new hybrid Biocreative retractor (CH-retractor), which consists of a nickel--titanium (NiTi) section covering the front teeth, from canine to canine, and rear sections of the SS arch, whose task is to transfer the force about the appropriate vector for the front teeth. The only source of anchoring the device is partially bone-integrable C implants and C-tube miniplates, which do not require the involvement of the posterior teeth.