In the past, even if a case only required minor corrections, the only Invisalign option available was the Invisalign Full Arch option. In 2010, Align Technology, Inc launched Invisalign Lite which is a 14 aligner treatment option. Whilst this treatment option made Invisalign more financially attractive to patients; in very minor crowding cases, 14 aligners were just too much. Patients were not prepared to pay the fees requested for the Invisalign Lite and full arch treatments and would therefore consider other appliance systems that were more affordable. The release of the Invisalign i7 treatment option in 2012 for minor crowding cases included a seven-aligner treatment option at a laboratory fee that was extremely attractive to Invisalign providers. This, in turn, made it an affordable treatment option for interested patients.
The clinical parameters of i7 are as follows:
- First premolar to first premolar (4-4) movement only.
- Mild crowding/Relapse – Up to 2mm.
- Mild spacing/Diastema closure/ Space re-distribution - Up to 2mm.
- Rotations – Up to 10 degrees.
- Midline correction with mild IPR – Up to 1mm.
- Intrusion/Extrusion – Up to 0.5mm.
In our practice, i7 is primarily used for minor crowding or spacing cases, orthodontic relapse cases and pre-restorative alignment cases. The following case studies illustrate how successful i7 has been in treating these cases requiring minor tooth movement.
Case study 1
Patient A presented with minor crowding on both upper and lower arches (fig 1). The patient’s main complaint was the UR2 minor rotation and the crowding on the lower arch.
The treatment plan included Invisalign i7 treatment with directbonded optimised attachments on the UL2, UL3 and LL3. The Clincheck treatment plan included seven aligners to correct the crowding. Screenshots of the Clincheck treatment plan (expected post-treatment images) for this patient are shown in figure 2.
A refinement was carried out for this patient with the use of optimised attachments on the UL2. Fixed bonded retainers and removable Essix retainers were provided at the end of the treatment (fig 3).
Case study 2:
Patient B presented with spacing on the upper arch and mild crowding on the lower arch. This patient was treated over two years ago in fixed appliances, however relapse of both arches had occurred. The patient’s main concern was the spacing in the upper arch (fig 4).
Treatment with Invisalign i7 was carried out and the treatment plan included seven aligners in both arches. The spaces were closed in the upper arch by retracting the upper central and lateral incisors and the lower arch crowding was resolved with IPR of 0.3mm between LL3 and LR3 (fig 5).
No refinement was necessary. Final photographs are shown in figure 6. The patient was provided with removable Vivera retainers.
Case study 3
Patient C had suffered trauma to the UR1 resulting in the fracture of the crown at the gingival level. The patient was interested in having an implant to replace the missing crown and ideally wanted the crown of the UR1 to be‘in line’ with the UL1. However, due to the occlusion, any implant and subsequent prosthesis would have been at risk of failure (fig 7).
A discussion about minor tooth movement in the form of Invisalign i7 to improve the lower arch alignment and relieve the possible traumatic occlusion that would occur on the UR1 ensured that the patient was able to make an informed decision about pursuing Invisalign i7 treatment. The patient also had previous orthodontic treatment and despite the lower fixed retainer, some relapse had occurred, thereby i7 would serve a dual purpose, improve the anterior occlusion for the future restoration on UR1 and correct the mild crowding on the lower arch. Photos at the beginning of treatment are shown in figure 8.
Both upper and lower arches were treated using Invisalign i7. The upper arch comprised of four aligners (plus three overcorrection aligners) whilst the lower arch included seven aligners. A Pontic was used to mask the missing UR1 as shown in figure 9.
No refinement was necessary in this case. Photos following the Invisalign i7 treatment, with a temporary restoration on the UR1 can be seen in figure 10. The patient has been provided with removable Essix retainers until the permanent restoration on the UR1 has been completed.
Discussion
Invisalign i7 can be used for minor tooth movements where the crowding or spacing is less than or equal to 2mm. It is ideal in cases where restorative work is planned as the improvement in tooth positions allows one to be more conservative when preparing teeth for restorations. Finally a few points to remember are:
- Expansion is limited as the treatment moves first premolar to first premolar only.
- All attachments will be placed at stage 0 (at the start of the treatment).
- An automated refinement is available for final finishing of the treatment.
- Round-tripping can be avoided to reduce the number of aligners and IPR can also be incorporated where necessary.
- Like with all orthodontic treatments, case selection is key to the success of Invisalign i7 treatments.
References available on request.