Figure 1:
Illustration describing the anchorage preparation required in rectangular stainless steel archwires for the use of Class II elastics.
Figure 2:
Illustration demonstrating the side effects commonly observed with the use of Class II elastics.
Figure 3:
Patient treated with Class II 5/16-in medium force elastics. The elastics were used bilaterally, in the final phase of the treatment, to correct a Class II relationship of 2 mm.
Figure 4:
Illustration describing the anchorage preparation required in rectangular stainless steel archwires for the use of Class III elastics.
Figure 5:
Illustration demonstrating the side effects commonly observed with the use of Class III elastics.
Figure 6:
Patient treated with Class III 5/16-in elastics of medium force. In this case, Class III elastics were used as a resource to increase the loss of anchorage in the upper arch after extraction of the first premolars, and as a resource to improve the inclination of the lower incisors that were proclined before treatment, facilitating the finishing procedures with correct overjet and overbite.
Figure 7:
Side effects normally observed with the unilateral use of Class II elastics.
Figure 8:
Illustration demonstrating the two possibilities of reducing side effects in situations in which a greater unilateral gain is needed in the Class II correction: Elastic association with the same direction but reduced force on the opposite side (A), and the association of vertical elastics in the canine region, with greater force on the left side, where there is no need for AP correction (B). In the first situation, there is still a greater tendency to extrusion on the right side of the upper arch, as shown by the arrows in red. In the second situation, the extrusive force is similar on both sides of the upper arch; however, there is a greater extrusive force on the left side of the lower arch. To minimize the effects on the lower arch, thicker rectangular archwires can be used.
Figure 9:
Patient treated with unilateral Class II elastic on the left side, without control of side effects, promoting cant of the upper occlusal plane ( roll axis ) and need for retreatment to level the plane by means of intrusion with a miniscrew, followed by extrusion of the lower arch with vertical elastics.
Figure 10:
Patient treated with unilateral Class II elastic in the final phase of treatment, promoting cant of the lower occlusal plane ( roll axis ) by extrusion of the posterior region and intrusion of the anterior region on the left side. Vertical elastic was then used on the left side, associated to an asymmetric curve in the archwire to level the lower plane. The upper arch required slight extrusion on the left side, so the extrusive effect was not considered adverse, as it promoted the leveling of the upper arch.
Figure 11:
Illustration showing the effects involved in biomechanics with unilateral Class II elastic associated with sliding jig. The extrusive effect in the anterior region is minimized and, mainly, the effect of asymmetric anterior contraction of the arch is eliminated, as the distalization force is moved from the anterior region to the posterior region of the arch.
Figure 12:
Patient treated with a unilateral Class II elastic associated with a sliding jig. In this case, the patient chose not to use skeletal anchorage or to extract a premolar; so, to minimize side effects, mechanics with a sliding jig was used for tooth-by-tooth distalization and correction of the Class II, subdivision right. To minimize the effects on the lower arch, a 0.021 x 0.025-in rectangular arch was initially used and later a 0.022 x 0.028-in arch was used. The space between teeth #12 and #13 would be closed by means of a composite restoration.
Figure 13:
Illustration demonstrating the side effects normally observed with the use of vertical elastics for intercuspation in the posterior region.
Figure 14:
Illustration demonstrating the intercuspation performed with vertical elastic and rectangular wires, with torque control, promoting correct buccal and lingual contacts at the end of the treatment; and the intercuspation performed with vertical elastic and round wires, promoting torque change and lack of contact in the lingual region after treatment.
Figure 15:
Illustration demonstrating two possibilities (triangular and trapezoidal) of vertical elastics with Class I orientation.
Figure 16:
Illustration demonstrating two possibilities (M and W) of vertical elastics with Class I orientation.
Figure 17:
Patient treated with light force 3/8-in vertical elastics in an M-shape, in a case with a Class I anteroposterior relationship.
Figure 18:
Illustration demonstrating two possibilities (triangular and trapezoidal) of vertical elastics with Class II orientation.
Figure 19:
Illustration demonstrating two possibilities (N and N more angled) of vertical elastics with Class II orientation.
Figure 20:
Patient treated with 5/16-in vertical elastics of light force in the shape of an N, for intercuspation and with orientation for Class II correction, being more angled on the left side, where there was a greater need for anteroposterior correction.
Figure 21:
Illustration demonstrating two possibilities (triangular and trapezoidal) of vertical elastics with Class III orientation.
Figure 22:
Illustration demonstrating two possibilities (inverse N and more angled inverse N) of vertical elastics with Class III orientation.
Figure 23:
Patient treated with light force 5/16-in vertical elastics in a more angled inverse N shape, for intercuspation and with orientation for Class III correction, with improvement on the lower incisors position, obtaining overjet and allowing the upper spaces closure.
Figure 24:
Patient treated with 3/8-in vertical elastics of light force in a W-shape, for unilateral extrusion, after correction of the cant of the upper occlusal plane with intrusion supported by a miniscrew. After leveling the lower arch, the patient started to use bilateral 5/16-in vertical elastics of light force with Class III direction (inverse angled N), for finishing procedures.
Figure 25:
Patient treated with 3/8-in vertical elastics of light force in the anterior region, to improve the overbite.
Figure 26:
Illustration demonstrating the desired and undesired effects involved in biomechanics of midline correction with elastics.
Figure 27:
Patient treated with 3/16-in of medium force midline correction elastics connected to a hook initially fixed for occlusal direction in the lower arch and, later, being transferred to cervical, due to overbite gain.
Figure 28:
Intermaxillary elastics with anteroposterior direction with clear aligners, with posterior connection made with bonded buttons and anterior connection made direct to precision cuts in the aligners (Images provided by Dr. Guilherme Bernd).
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