Mesiodistal angulation

The basic Clarity™ SL bracket design is the same as the conventional brackets – rhomboidal brackets with built-in angulation. The rhomboidal shape makes bracket positioning easier, along with the use of the individualized bracket positioning system^4–6 (Figs 1.8, 1.9 & 1.10).

Fig. 1.8 The Clarity™ SL appliance features rhomboidal-shape brackets. This bracket system favors accurate bracket positioning on the facial surface of each tooth.

Fig. 1.9 The rhomboidal Clarity™ SL brackets. The bracket is positioned on the facial surface of the clinical crown using the individual bracket positioning line as a reference.

Fig. 1.10 The built-in angulations in the Clarity™ SL Self-Ligating upper and lower brackets.

The rhomboidal bracket system used with the MBT™ Versatile + Appliance System orthodontic prescription and the individualized bracket positioning system prevents undesirable proclination of the anterior teeth, increased overbite and anchorage loss during the aligning and leveling stages of the orthodontic treatment. The individual bracket positioning system allows positioning of the teeth with due regard to their natural morphology, thus bringing stability to the occlusion that is attained at the end of the treatment.

Inclination (torque)

A highly sophisticated manufacturing process allows the addition of a metal slot into the ceramic bracket body of the Clarity™ SL bracket. The reliability of an orthodontic appliance depends on the degree of expression of the torque that is built into the bracket base and the bracket slot. A metal slot imparts greater strength to the bracket and allows full torque expression. Furthermore, the metal slot facilitates good sliding of the archwire during the orthodontic treatment by reducing friction.^7,8 The Clarity™ SL appliance also features built-in torque in the metal slots (Fig. 1.11).

Fig. 1.11 Profile view of the upper and lower Clarity™ SL brackets showing the torque prescriptions.

In-out

From the horizontal aspect, the functional harmony of the orthodontically created occlusion is determined by the in-out built into the appliance, the shapes of the archwires used, and the coordination achieved between the upper and the lower dental arches. The interarch relationships, including the anterior and the canine guidance, and the posterior relationship between the centric cusps and the buccal-occlusal and lingual-occlusal marginal ridges depends on good coordination between the upper and lower arches,^5–8 as well as the in-out prescription of the orthodontic appliance (Figs 1.12 & 1.13). The Clarity™ SL Self-Ligating brackets have been manufactured with this relationship in mind, which allows the simultaneous use of conventional appliances and the SmartClip Self-Ligating appliance in the same patient during orthodontic treatment (see Figs 1.5, 1.6 & 1.7).

Fig. 1.12 Occlusal view of the upper arch, showing the in-out prescription of the Clarity™ SL Self-Ligating brackets.

Fig. 1.13 Occlusal view of the lower arch, showing the in-out prescription of the Clarity™ SL Self-Ligating brackets.

Slot depth

As mentioned above, the Clarity™ SL Self-Ligating appliance is a passive appliance, that is, the clip does not exert active pressure on the archwire, unless it is required, e.g. to correct rotations. This allows the use of lower forces during the alignment and the leveling stages of treatment (Figs 1.14, 1.15 & 1.16).^9,10 These stages are completed when the bracket slot is fully filled by the orthodontic archwire in the horizontal plane. The .019/.025 rectangular archwire (Fig. 1.17) or an .016 archwire overlapping the .014 round Nitinol archwire should be engaged on the same visit (see Figs 1.34, 1.35 & 1.36 below).

Fig. 1.14

Fig. 1.15

Fig. 1.16 Figs 1.14, 1.15 & 1.16 Initiating the aligning stage with a .014 round Nitinol superelastic wire in the upper arch.

Fig. 1.17 Occlusal view of the upper arch with a .019/.025 rectangular Nitinol archwire in place. Note the good fill of the slot from the horizontal aspect.

The depth of the Clarity™ SL Self-Ligating appliance slot measures .0270 inches between the clip and the bottom of the bracket slot in the lower incisors, and .0275 inches in the remaining teeth. This has been done in order to have improved rotational control at the beginning of treatment (Figs 1.18 & 1.19).

Fig. 1.18

Fig. 1.19 Figs 1.18 & 1.19 Profile views showing the slot-depth between the clip and the bottom of the bracket slot of both upper and lower Clarity™ SL Self-Ligating brackets. Lower incisor brackets have .0270 inch slot depth.

Aligning

Alignment is the first stage of orthodontic treatment and, depending on the severity of crowding, a .014 round Nitinol or other superelastic archwire can be used regardless of the case being extraction or non-extraction. A .022/.028 bracket provides greater flexibility to .014 archwires, enabling perfect archwire engagement and disengagement using the Nitinol clips (Figs 1.22, 1.23 & 1.24).

Fig. 1.22

Fig. 1.23

Fig. 1.24 Figs 1.22, 1.23 & 1.24 The .022/.028 Clarity™ SL Self-Ligating Appliance in the upper arch and SmartClip™ Self-Ligating Appliance in the lower arch. An .014 round Nitinol superelastic archwire has been engaged in both the upper and lower dental arches, initiating the alignment stage.

In non-extraction cases, space can be created by proclination or stripping of the incisors, expansion of the intercanine, interpremolar or intermolar width, and distalization or stripping of the posterior teeth. The choice of procedure will depend on the orthodontic treatment plan, incorporating the dental visual treatment objective (dental VTO) analysis.¹³

In premolar extraction cases, the canines should be retracted with lacebacks (which consist of .009 ligature wires), to open up space for the alignment of the incisors (Figs 1.25 & 1.26).

Fig. 1.25

Fig. 1.26 Figs 1.25 & 1.26 Clarity™ SL Self-Ligating appliance in the upper arch, with initiation of canine retraction after premolar extraction.

The combination of passive brackets, muscular action and the masticatory function results in biomechanics that favor optimal biological action and tooth movement. In this situation, the initial correction of crowded and malaligned teeth is accomplished faster and with less force application. This stage is frequently finished with a .016 round Nitinol archwire.

Leveling

In the leveling stage, the correction of angulations and rotations is completed along with leveling of the bracket slots in the horizontal plane. As mentioned above, space creation in non-extraction cases can be achieved by stripping, proclination of the incisor teeth, distalization of the posterior teeth, and expansion of the intercanine, interpremolar and intermolar widths.

In extraction cases, leveling should be initiated after the retraction of the canines opens up spaces for the alignment of the incisors (Figs 1.27, 1.28, 1.29 & 1.30).

Fig. 1.27 Occlusal view after completion of canine retraction in a premolar extraction case.

Fig. 1.28

Fig. 1.29

Fig. 1.30 Figs 1.28, 1.29 & 1.30 Frontal and lateral views after canine distalization.

Leveling can be performed using two archwire sequences:

Fig. 1.31

Fig. 1.32

Fig. 1.33 Figs 1.31, 1.32 & 1.33 Frontal and occlusal views at the end of the leveling stage. There is a .019/.025 rectangular Nitinol archwire in both the upper and lower arches.

Fig. 1.34

Fig. 1.35

Fig. 1.36 Figs 1.34, 1.35 & 1.36 The Clarity™ SL Self-Ligating appliance with .016 and .014 round Nitinol archwires. Both archwires were engaged in the same appointment to finish the leveling.

For rotational corrections, self-ligating appliances present some disadvantages compared with conventional appliances, mainly in the lower anterior segment. This problem occurs due to the passivity of the self-ligating appliances in relation to the orthodontic archwire. However, the simultaneous use of .014 and the .016 archwires eliminates this problem. This alternative sequence is recommended for both extraction and non-extraction cases.

As mentioned above, the Clarity™ SL Self-Ligating .022/.028 bracket has a .0270 inch slot depth between the Nitinol clips and the bottom of the bracket slot for the lower incisors, and .0275 inch slot depth for the remaining teeth. This may seem as if there is not enough space to engage both wires horizontally (Fig. 1.37). However, when engaging the second wire, one wire slides cervically and the other wire slides occlusally, thereby completely filling the bracket slot both vertical and horizontally (Fig. 1.38). The .014 archwire overlying the .016 archwire in the lower anterior brackets is equivalent to a single .021 archwire (Fig. 1.39). Thus, this simultaneous use of two round archwires provides a very efficient mechanism for correcting rotations, angulations and leveling of the bracket slots. Moreover, with this archwire technique, after the leveling and the alignment stages, a .019/.025 rectangular Nitinol or stainless steel archwire can be used as the next archwire. The space-closing biomechanics can therefore be applied earlier in the treatment (Figs 1.40, 1.41 & 1.42).

Fig. 1.37

Fig. 1.38 Figs 1.37 & 1.38 A .014 and a .016 archwire inserted together results in a total wire diameter greater than the depth of the bracket slot. However, in practice, as shown in Figure 1.38, the force of engagement of the second wire directs one wire to the occlusal and the other to the cervical, thereby completely filling but not exceeding the bracket slot depth.

Fig. 1.39 A combination of .014 and a .016 round archwires is equivalent to a .021 round archwire.

Fig. 1.40

Fig. 1.41

Fig. 1.42 Figs 1.40, 1.41 & 1.42 A .019/.025 rectangular Nitinol archwire in both the upper and lower arches, after completion of leveling with .014 and .016 round Nitinol archwires.

Space closure

To assist with optimal expression of the torque, .009 passive ligatures should be used from the hooks on the archwire on the mesial of the canines to the hooks on the first or second molar buccal tube along with the .019/.025 rectangular archwires. This should be done 30 days before initiating the sliding mechanics (Fig. 1.43). With the SmartClip™ Self-Ligating appliance, it is recommended that sliding mechanics should not be used in the stages prior to the space closure stage of treatment.

Fig. 1.43 A .019/.025 rectangular stainless steel archwire with hooks prewelded to the mesial of the canines; passive ligatures have been inserted.

After the torque has been expressed, sliding mechanics can be initiated in both extraction and non-extraction cases. Again, hooks placed on the mesial of the canine on the archwires should be used to engage the retraction system anteriorly. The hooks can be welded in the office or may be supplied prewelded to the orthodontic archwire^12,14 (Figs 1.44 & 1.45).

Fig. 1.44 Brass hooks soldered on the mesial of the canine on a .019/.025 rectangular stainless steel archwire. The retraction system being used consists of metal ligatures and elastic modules.

Fig. 1.45 Crimped hooks placed on the mesial of the canine on a .019/.025 rectangular stainless steel archwire. The retraction system being used consists of metal ligatures and elastic modules.

Space closing mechanics can be carried out with elastic modules and ligatures or Nitinol springs^15,16 (Figs 1.46 & 1.47). The elastic modules used with ligatures or the Nitinol coil springs should remain in place from the start to the finish of space closure and for one additional month after space closure. The aim is to ensure that the roots are positioned in accordance with the angulation and torque values built in the brackets.

Fig. 1.46 Brass hooks soldered on the mesial of the canine on a .019/.025 rectangular stainless steel archwire. The retraction system being used consists of a Nitinol spring.

Fig. 1.47 Crimped hooks placed on the mesial of the canine on a .019/.025 rectangular stainless steel archwire. The retraction system being used consists of Nitinol spring.

Finishing and detailing

Finishing of the orthodontic treatment^5,6,17,18 with a .019/.025 rectangular stainless steel archwire is recommended after tridimensional control of each tooth has been achieved – angulation, inclination and rotation (Figs 1.5, 1.6 & 1.7). The occlusion is checked in centric relation, as well as the functional movements to check anterior guidance in protrusive excursions, and canine guidance in lateroprotrusive excursions (Figs 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55 & 1.56). At this time, a .019/.025 rectangular braided archwire should b/>