Figure 1
Clinical case with indication of mini-implants in the IZC for dentoalveolar en masse retraction of the entire maxillary arch.
Figure 2
Distalization made through canine and premolar sliding, in order to obtain anterior space, in a patient with severe maxillary crowding.
Figure 3
Posterior teeth intrusion, associated to retraction of the entire maxillary arch.
Figure 4
En masse retraction with mini-implants in the IZC and BS to reduce Class I biprotrusion.
Figure 5
Asymmetrical clinical case (roll, transverse plane rotational axis): oblique line of force action, from the mini-implant in the right IZC to the arch, allows roll axis asymmetry correction and simultaneous correction of the midline.
Figure 6
Clinical case of impacted maxillary right canine, treated with extra-alveolar anchorage supporting a cantilever for canine traction.
Figure 7
Orthodontic-surgical case preparation by means of mini-implant, in order to accelerate Class III decompensation and maxillary teeth retraction.
Figure 8
Class III compensatory treatment (camouflage) with mini-implants in BS and entire mandibular arch retraction.
Figure 9
Excessive anterior mandibular crowding case, treated with canine distalization by means of sliding mechanics, using mini-implants in the BS.
Figure 10
Mandibular teeth mesialization mechanics, using mesioangulated mini-implant in the BS, associated to entire maxillary arch retraction with mini-implants in the IZC.
Figure 11
Mandibular midline asymmetry correction, with the aid of one mini-implant in the right BS.
Figure 12
Class II orthodontic-surgical case, in which retraction mechanics of the entire mandibular arch was used, in order to create overjet for future mandibular advancement.
Figure 13
Scheme illustrating the transition from the first generation (2D) of classic Biomechanics to the second generation (3D), with finite elements, and an analysis of stress levels as well as periodontal ligament tension in determinate mechanics, using extra-alveolar mini-implants.
Figure 14
Determinate mechanics, according to Roberts et al.1818 Roberts WE, Viecilli RF, Chang C, Katona TR, Paydar NH. Biology of biomechanics: finite element analysis of a statically determinate system to rotate the occlusal plane for correction of a skeletal Class III open bite malocclusion. Am J Orthod Dentofacial Orthop. 2015 Dec;148(6):943-55., stems from retraction mechanics of the mandibular dentition, produced by two mini-implants in the BS and full-size rectangular arch with NiTi springs, applying 200g of constant force, in Class III patients. Source: Almeida et al.33 Almeida MR, Almeida PR, Chang C. Biomecânica do tratamento compensatório da má-oclusão de Classe III utilizando ancoragem esquelética extra-alveolar. Rev Clín Ortod Dental Press. 2016 Abr-Maio;15(2):74-6.
Figure 15
Scheme showing, by means of finite elements, mandibular posterior rotation over a rotational axis in the canine area. Source: Roberts et al.1818 Roberts WE, Viecilli RF, Chang C, Katona TR, Paydar NH. Biology of biomechanics: finite element analysis of a statically determinate system to rotate the occlusal plane for correction of a skeletal Class III open bite malocclusion. Am J Orthod Dentofacial Orthop. 2015 Dec;148(6):943-55.
Figure 16
Scheme illustrating the application of mini-implants mechanics in the BS, in order to retract the entire mandibular dentition in a single block. Counterclockwise rotation of the mandibular occlusal plane can be seen, due to the force action line being placed occlusal to the mandibular center of resistance. Thus, the generated moment causes incisor extrusion and molar intrusion.
Figure 17
Initial photographs: A) Without brackets, and B) with brackets from second molar to second molar, occlusal build-up and retraction biomechanics of mandibular teeth. Mechanics with mini-implants in the BS for en masse retraction of mandibular dentition, in patient with Class III malocclusion and retreatment. A mandibular CuNiTi 0,014 x 0,025-in archwire was used. This mechanics lasted four months. In C, the sagittal relationship correction and improvement in the vertical direction can be observed, caused by the rotation of the occlusal plane, due to the force action line being occlusal to the center of resistance of the arch. Thus, a moment is created, causing incisor extrusion and molar intrusion. In D and E, the comparison between the initial profile and after four months of treatment: there is a discernible improvement in the facial profile, especially in the lower lip, which was retracted after mandibular incisor lingual movement.
Figure 18
Scheme illustrating the application of mini-implants mechanics in the IZC to retract the entire maxillary dentition in a single block: a clockwise rotation in the occlusal plane can be observed, due to the force action line being occlusal to the center of resistance of the arch. Thus, a moment is generated, which leads to incisor extrusion and molar intrusion.
Figure 19
Clinical case of patient with Class II malocclusion and anterior open bite, treated with two mini-implants in the IZC. Clockwise rotation of the occlusal plane around the Cr favored open bite closure, as well as simultaneous Class II correction.
Figure 20
Scheme illustrating the application of a mechanics with mini-implants in the IZC and BS for retraction of the entire dentition, maxillary and mandibular, in a single step. It can be observed that counterclockwise rotation in the mandibular occlusal plane happens because the force action line is occlusal to the arch's center of resistance; generating a moment, which leads to incisor extrusion and molar intrusion. In a similar manner, a clockwise rotation occurs in the maxilla due to the force action line being occlusal to the arch's center of resistance, thus, a moment is generated, causing incisor extrusion and molar intrusion.
Figure 21
A, B) Patient with biprotrusion and anterior open bite, treated with mini-implants in the IZC and BS for distalizing mechanics. B) Curved yellow arrows represent moments generated around the maxilla and mandible's center of resistance, causing occlusal plane rotation (clockwise for the maxilla and counterclockwise for the mandible). Vertical red arrows demonstrate extrusion vectors over the incisors and intrusion vectors over the molars. In C, after four months of treatment, an improvement can be seen in the anterior vertical relationship. A clear uprighting of the incisors can be expected.
Figure 22
Scheme exemplifying how to modify the force action line when using extra-alveolar mini-implants: the mini-implants' installation height can be changed or the height of hooks in the anterior area can be altered.
Figure 23
A) Clinical case demonstrating a sagittal occlusal relationship between the arches' in unilateral Class II molars, in which there were a complete Class II on the right side and a Class I relationship on the left side. B) The maxillary dental midline was deviated 3mm to the left in relation to the middle sagittal plane, while the mandibular dental midline was centralized. The chosen treatment was by the use of mini-implant in the IZC and asymmetric mechanics for unilateral distalization. The system was composed of rectangular 0,017 x 0,025-in steel archwire, used to adapt a modified hook with greater cervical extension (15 mm) in order to have the force action line as close as possible to the center of resistance (Cr) of all teeth and a translation movement of the midline could be obtained. The mini-implant is located in the same line as the modified hook, mesial to the canine. Because the patient presented a symmetrical mandibular occlusal plane (red dotted line) in relation to the frontal occlusal plane, thus, in order to prevent any inclination, a force parallel to the occlusal plane was required. C) Case completion.
Figure 24
Use of short hook during retraction of the entire arch with 350g/side force stemming from a NiTi spring connected from the mini-implant to the short hook attached to the archwire. The force passes under the Cr; which means the anterior teeth are likely to rotate clockwise (curved arrow), losing torque and generating a vertical extrusion force upon the incisors.
Figure 25
A) Patient with Class II malocclusion treated with mechanics for distalizing the entire maxillary arch, using mini-implant in the IZC. B) Force action line passes bellow the anterior teeth's Cr. When applying distalizing force in the entire maxilla, due to the oblique force (bellow the Cr), the anterior teeth tend to rotate clockwise (curved yellow arrow), losing torque, while a vertical extrusion force occurs upon the incisors (red arrow). C-E) A good maxillomandibular relationship was achieved, as well as in the vertical direction. Complete treatment lasted 24 months.
Figure 26
Scheme illustrating a biomechanics for retraction of the entire maxillary arch with a middle length hook: height of the hook positioned mesial to the canine allows the force action line to pass at the height of incisors' center of resistance.
Figure 27
A) Patient with Class II malocclusion and overbite, treated with mechanics for distalizing the entire maxillary arch, using mini-implants in the IZC. B) Force action line passes over the anterior teeth's Cr. By applying distalization force in the entire maxilla, using force parallel to occlusal plane (Gurin on the same level as the mini-implant), the anterior teeth usually keep their initial inclination (C), occurring no vertical force. D) Image illustrating case conclusion. E, F) Initial and final lateral teleradiographies.
Figure 28
Scheme illustrating a case with maxillary premolar extraction and the biomechanics for anterior retraction: height of the hook mesial to the canine allows the force action line to pass above the incisors' center of resistance. This procedure generates a anterior counterclockwise moment during simultaneous incisor retraction and extrusion. However, it is important to point out that this procedure may be more difficult to be done at the clinic, due to the possibility of injuring patient's oral mucosa.
Figure 29
A) Patient with Class II malocclusion, division 2, and overbite, treated with mechanics to distalize the entire maxillary dentition, using mini-implant in the IZC. B) A power arm made of TMA 0,017 x 0,025-in wire, supported by a a longer criss-cross tube, was used to elevate the force above the incisors' Cr. A counterclockwise moment can be observed, which will affect the incisors' torque. In C, a great torque control of the anterior teeth can be seen. D) Resin build-up was performed in the lateral incisor, due to a Bolton discrepancy. E, F) Initial and final lateral teleradiographies.
Figure 30
Sophisticated force system stemming from two mini-implants in the IZC and another two in the anterior area of maxilla: a dentoalveolar distalizing force of the entire maxillary dentition can be observed, due to the anchorage in the IZC. A clockwise rotation (moment) of the entire arch occurs around the maxilla's Cr. Intrusive vertical force occurs in the posterior area. A intrusive vertical force can be seen upon the incisors as well as a counterclockwise moment around the anterior teeth's Cr.
Figure 31
A) Young patient with Class II, division 2, malocclusion, overbite and gingival smile. B) Mechanics for distalizing the entire maxillary dentition with two mini-implants in the IZC, located between the first and second maxillary molars, and associated anterior intrusion, with two anterior mini-implants. C) Mechanics lasted for 12 months, after which an improvement in the sagittal arches relationship (Class I molars) could be observed.
