USING THE INVISALIGN SYSTEM™

Author and treatment by:

Ross J. Miller DDS MS

en francais
Deutsch

visit the Invisalign Clinical Education Center

ABSTRACT:

Invisalign is a new treatment method utilizing computer virtual treatments to create a series of clear, removable, esthetic appliances that can treat a wide range of malocclusions. Presented here are two cases with lower incisor crowding, the first was treated with interproximal reduction and the second was treated by extracting a lower right lateral incisor. While these cases illustrate limited treatment, more complex cases can be treated using the Invisalign System. We hope to present examples in a future article.

INTRODUCTION:

Invisalign is the product of Align Technology Inc. The company was founded in 1997 by Zia Chishti and Kelsey Wirth. The author of this article started working with Align Technology in 1998 after completing a three year orthodontic residency at UCSF. Presented here are two cases that were treated with Invisalign. One of which is a lower interproximal reduction case and the other a lower incisor extraction case. The reader should keep in mind that both of these patients were treated in a small clinical trial conducted by the author and funded by Align Technology. The author does have proprietary interest in Align Technology.

CASE 1: Upper and Lower Crowding Treated with Proclination of the Upper Teeth and Lower Incisor Interproximal Reduction.

Chief Complaint: This 39.4 year old female presented with the chief complaint of lower anterior crowding.

Initial Diagnosis: Class I malocclusion with narrow arches and posterior crossbite (Figures 1-6). The patient has a history of multiple large restorations and multiple root canals in the lower arch. Mild upper and lower crowding with rotated bicuspids and canines. Notice that the attending general dentist had build the restorations to the patient’s malocclusion including the bilateral cross bite. Although the posterior occlusion was in cross bite it was determined that the patient had a stable occlusion and this was not a part of the chief complaint.

Fig 1	Fig 2	Fig 3
Fig 4	Fig 5	Fig 6

History: No medical conditions and no history of orthodontic treatment

Panoramic Initial: Notice large number of posterior restorations (Fig. 7)

Cephalometric: Bimaxillary protrusion (Fig 8).

 

Treatment Plan: This case yields itself well to a large number of potential treatment plans ranging from limited treatment to full mouth reconstruction and surgery with surgically assisted maxillary expansion. It was decided to keep things simple and treat upper and lower 2-2. Please take a look at the virtual treatment plan (Fig.9)

Fig 9. Virtual treatment plan (Editor's note: this was converted to an animated GIF file to avoid the need for downloading an additonal program to view the treatment plan, some detail may have been lost in the conversion. It is a large file and will be slow to load.)

Case Summary: This case was done as simply as possible due to the fact that the patient was not interested in surgery and full mouth reconstruction. The plan was to treat 2-2 upper and lower (Fig 10-15). This patient had stripping performed before the PVS (polyvinylsiloxane) impression was taken and a retainer placed two days after the stripping was performed in order to hold the space while the patient was waiting for the aligners to be delivered. Stripping was done with disks and lightening strips on the mesial of the lower right 2, the lower left 1mesial and distal, 2 mesial and distal, and 3 mesial.

Fig 10	Fig 11	Fig 12
Fig 13	Fig 14	Fig 15

Start Date: 2/30/99

Case Refinement Start date: 3/7/00

Total aligners: 10 upper, 19 Lower

Retention Start Date: 4/24/00. Wear at night.

Time to completion: 12 months active treatment.

Fig 16 Panoramic Final

Fig 17 Ceph final

Fig 18 Close-up before treatment	Fig 19 Close-up after treatment

CASE 2. Upper Anterior Proclination and Lower Right Lateral Incisor Extraction.

Chief Complaint: This 33yr, 5m female presented with the chief complaint that she had lower incisor crowding and needed something done quickly since she was getting married in 3 months. An adult with a chief complaint in addition to a request for speed is not an uncommon occurrence.

Initial Diagnosis: Upper and lower crowding. Class I malocclusion with small upper laterals. Most of the lower crowding is associated with the lower right lateral incisor (Fig. 20-25). The lower midline is off to the right 1mm. The patient’s upper incisal edges are uneven. The patient has complete adult dentition except for missing 3^rd molars. The photos reveal fair oral hygiene with normal attached gingiva. In the posterior segments restorations are visible on the buccal of the teeth. The frontal photo shows a cross bite tendency of the lower right canine. The lower midline is to the right 1mm. The right and left buccal photo shows class I canine and molar. The upper occlusal photo shows a well-aligned arch with some minor discrepancies in the anterior region.

Fig 20	Fig 21	Fig 22
Fig 23	Fig 24	Fig 25

History: Patient had a history of orthognathic surgery12 years previously. It appears she might have had a maxillary impaction. Previous records were unavailable.

Pano: The panorex shows normal adult dentition with many restorations present. The bone levels appear to be healthy and root lengths appear normal (Fig 26). Notice the orthognathic surgery hardware is present superior to the maxillary canines and molars. The condyles appear to be normal.

Cephalometric: Patient is fairly orthognathic with previous fixed plates plainly visible on the x-rays. (Fig 27)

 

Fig 26 Panoramic Intial

Fig 27 Cephalometric Initial

                       

 

Treatment Plan: This patient had small upper laterals but did not want to take the time to do the dental expansion necessary for veneers or crowns on the upper laterals. Due to the Bolton discrepancy and the lower incisor crowding it was decided to extract a lower incisor. In this case the lower right lateral incisor was extracted due to the fact that it was the cause of the crowding. A standard wax set-up was made to evaluate the possibility of an extraction. Extracting the tooth to the lingual also may help with the post treatment quality of the gingiva. The Virtual Treatment Predications are shown in below (Fig 28 and 29). The red bars on the lower anteriors indicate placement of Silux composite attachments.

Fig 28 Frontal virtual treatment plan (Editor's note: modified from original to animated GIF file. Image will be slow to load.)	Fig 29 Mandibular virtual treatment plan (Editor's note: modified from original to animated GIF file. Image will be slow to load.)

Case Summary: The patient was happy with the treatment (Fig 30-35), but there was a little tipping of the lower right canine mesially as evidenced by the panoramic x-ray (Fig 34). If the movements had incorporated more root tip toward the extraction site and distal crown tip of the teeth adjacent to the extraction site the outcome would have been better. The fact that there was no attachment placed on the lower right canine may have lead to some of the crown tipping. Periodontal health was maintained and no obvious gingival problems are noted in the extraction site. Finally, close-ups of the lower anteriors showing before and after treatment (Fig 38 and 39)

Fig 30	Fig 31	Fig 32
Fig 33	Fig 34	Fig 35

 

Fig 38 Panoramic Final

Fig 39 Cephalometric Final

 

Fig 40 Close-up before treatment	Fig 41 Close-up after treatment

 

Discussion: This case was the second lower extraction case attempted. It again showed that these types of cases could be treated successfully. Although there was a little tipping, in the future if the treatments are set up with crown tipping away from the extraction site it may prove beneficial. The use of attachments should be placed on teeth adjacent to the extraction sites.

Conclusion: The Invisalign System opens the door to many more treatment possibilities for the orthodontist and the patient. These two patients are good examples of lower incisor crowding treatment strategies. For stripping cases, it appears that results are better when stripping is done before the PVS. There are number of reasons for this.

1) The impression that is poured from the impression and scanned has all the information in it regarding where and how much stripping has been decided to be done by the orthodontist. The treatment plan is then contained in the impression and the scanned model.

2) Retainers should be made to retain the space. Generally alginate impressions are taken right after the PVS and retainers made.

3) If much stripping is going to be done one should consider placing separators

Regarding extraction cases, those cases can have their teeth taken out virtually or you may want to take them out before the impression and again make them a retainer. The rule of thumb is the closer the scanned image to the actual clinical situation, the better and the higher quality end result.

The Invisalign System requires the doctor to go through a learning curve like all types of orthodontic appliances. The main areas to become proficient with are:

1) Diagnosis and treatment planning

2) PVS impression taking

3) ClinCheck evaluation

4) Attachment placement

5) Case evaluation

6) Finishing and detailing

Clinical expertise is gained through trial and error. If the orthodontist is willing to put the time and effort into learning how to use Invisalign, excellent results can be obtained on a wide range of clinical cases.