22
Asymmetries

After its introduction in 1997, the Invisalign system has been continually developed and improved thanks to considerable investment in research and development, including new attachment designs – SmartTrack material – designed to enable additional treatment biomechanics such as those seen in this book.

Invisalign aligners can perform major tooth movements, such as desrotation up to 50 degrees and intrusions, but despite the efficiency of the treatment, its clinical development remains controversial among professionals, some arguing that there are significant limitations, especially in the treatment of complex malocclusions.

For this reason, complex cases are covered the end of this book, in order to show how any patient might benefit from this technique, the advantages of which have been already been described.

Schematic illustration of asymmetries can be managed with specific aligner biomechanics — **Fig. 22.1** Asymmetries can be managed with specific aligner biomechanics.

22.1 Growing Patients with Asymmetry

22.1.1 Skeletal Class II with Asymmetry

Photo depicts initial view — **Fig. 22.2** Initial view.

Diagnosis

A 14‐year‐old boy with hyperdivergent skeletal Class II presented with a dental Class II right subdivision, midfacial asymmetry with slight canted occlusal planes, canted maxillary occlusal plane, left‐side deviation of the upper midline (the deviation of both midlines was equal to the width of one lower incisor) and a unilateral scissor bite on left side that led to a facial asymmetry. The patient had unilateral right side mastication.

Treatment Plan

Maxilla:

Compress left premolars to coordinate both arches
This movement of compression allows increasing arch length simultaneously, so for that reason it was planned to make the compression and the right sequential distalization simultaneously

Mandible:

Uprighting of lower incisors to create positive overjet to correct the Class II
Mesialize the fourth quadrant in order to reduce the amount of upper right distalization needed

Functional treatment:

The patient was asked to use the left side for mastication during all the treatment.

Requirements for the Technician

Maxilla:

Compress the upper left quadrant simultaneously to the upper right sequential distalization

Mandible:

Reciprocal movement of lower incisors retraction and 4s‐7s mesialization to correct the Class II on the right side
Centre the lower midline at the same time that as the retraction of the lower incisors to make it more predictable

Treatment Summary

Total treatment time was 18 months.
Patient wore two series of aligners replaced at 10‐day intervals.
Patient used Class II 24‐hour elastic on right side and only night use on the left.
Buccal occlusion was corrected into a Class I relationship.
Careful management of the reciprocal staging of movements were critical for a successful treatment outcome.

Photos depict class II subdivision right, deviation of both midlines equal to the width of one incisor. There is a unilateral scissor bite on left side that leads to facial asymmetry — **Fig. 22.3** Class II subdivision right, deviation of both midlines equal to the width of one incisor. There is a unilateral scissor bite on left side that leads to facial asymmetry.

Photos depict pretreatment intraoral views — **Fig. 22.4** Pretreatment intraoral views.

Photos depict initial panoramic X-ray, teleradiograph and cephalometry — **Fig. 22.5** Initial panoramic X‐ray, teleradiograph and cephalometry.

Schematic illustration of initial frontal Clincheck view — **Fig. 22.6** Initial frontal Clincheck view.

Schematic illustration of Upper and lower ClinCheck archshape changes and instructions to CAD designer. — **Fig. 22.7** Upper and lower ClinCheck archshape changes and instructions to CAD designer.

Schematic illustration of Upper and lower CC superimposition and instructions to CAD designer. — **Fig. 22.8** Upper and lower CC superimposition and instructions to CAD designer.

Schematic illustration of lateral ClinCheck views — **Fig. 22.9** Lateral ClinCheck views.

Photos depict final intraoral views — **Fig. 22.10** Final intraoral views.

Photos depict initial and final smile and overjet — **Fig. 22.11** Initial and final smile and overjet.

Photos depict final panoramic and lateral X-rays — **Fig. 22.12** Final panoramic and lateral X‐rays.

22.1.2 Skeletal Class II with Asymmetry

Photo depicts initial intraoral view — **Fig. 22.13** Initial intraoral view.

Diagnosis

A 13‐year‐old girl with a hypodivergent skeletal Class III pattern presented with mandibular asymmetry, left‐side deviation of the lower jaw, dental unilateral class III on right side and a class I on left side. The upper midline was centred with facial midline and she had a deep bite with mild upper and lower crowding

Treatment Plan

Maxilla:

Symmetrical expansion and proclination of upper incisors
Tipping and rotation of 11 to be corrected during the anteroposterior movement of the incisor

Mandible:

Expand and use the retraction movement of the incisors to move lower midline to the right
Virtual jump (elastic simulation) to centre both midlines, simulating the asymmetric elastics to be used (Class III on right side and Class II on left side)

Requirements for the Technician

Correct the rotation and tipping of 11 in two steps:

First, procline and rotate mesial‐out
Second, make IPR between 11 and 12 to make room for the intrusion, rotation distal‐in and mesial crown tipping of 11

A vertical attachment was placed in the labial surface of 11 to increase predictability (double attachment was not placed by the software as it was a crown tipping, not a root one).

Treatment Summary

Total treatment time was 26 months.
Patient used 35 aligners replaced at 2‐week intervals.
After the first set of aligners the patient had a relapse in the asymmetry because of interruption in the use of the elastics and asymmetric growth. At that time a series of additional aligners replaced at 10‐day intervals was requested.
Patient used Class II elastic on left side and Class III elastics on right side (both full‐time wear) until 6 weeks before to the end of the treatment.
Buccal occlusion was corrected into a class I.
Careful management of the sequential movement of 11 made the correction of the incisor’s rotation and tipping possible.
Mandible was centred, and as retainer patient is using a Damon splint that maintains the the lower midline centred with the upper midline.