Sequence of treatment with Invisalign® aligners
Here are intraoral pictures of a woman in her forties who desires an orthodontic treatment using “invisible braces”. In fact, she asks for a treatment using Invisalign® trays.
She presents an ideal malocclusion for that kind of treatment. There is no significant shift between the upper and lower teeth, except for the upper right molar where we observe a Class II of 2 mm. The occlusal view below shows the dental irregularities, rotations and tilting problems. The white arrows indicate the attachments bonded to the teeth after wearing aligner #3.
With 3D modeling of the patient’s dentition, a virtual treatment is performed by technicians at Align Technology. Here is thus the ClinCheck® virtual treatment for this woman.
The algorithm of treatment determined that it will take 28 aligners in the maxilla and 31 aligners for the lower teeth. The number of aligners is indicated by the double horizontal line at the bottom of the figure. The lozenge containing the number 0.4 means that a proximal reduction of 0.4 mm is required. The ClinCheck® algorithm indicates that this reduction needs to be done at the stage of aligner #18.
When the scroll bars are blue, this means that there are active forces on the teeth. Toward the end, starting at tray #28, finalization of the position of teeth is performed and when the scroll bar is grey, there are no more movements.
Notice the little red arrows at stage 3. This is the stage where attachments need to be bonded and this is what you can see on the pictures, because they are shown by arrows.
The tray contains small incorporated dips that engage on these attachments. Dental movement is ensured by the gradual displacement of these dips in the aligners and a constant pressure is applied to the attachments thus allowing the teeth to move based on the ClinCheck® prediction.
The picture below shows aligner #1 without attachments and aligner #3 with the attachments.
Each Invisalign® aligner is worn 22 hours per day, 7 days a week. The patient does not eat with her trays. In that sense, the patient had me notice that it was more pleasant wearing the Invisalign® trays to hide the attachments. She says that the attachments, compared to the trays, are rather rough.
The above picture represents evolution after aligner #9 and 18 weeks of treatment. Notice that teeth #12 and #42 are no longer in crossbite compared to what we can see on the initial pictures.
During the follow-up visit, the evolution of dental movements obtained in the mouth is compared to the ClinCheck®. The ClinCheck® occlusal view on the right is exactly comparable to the occlusal view in the mouth (in situ). Adaptation to trays is excellent. Teeth thus follow the movement prescribed by the aligners.
The same analysis is done with the lower dentition and the ClinCheck® with aligner #9. Spaces are starting to appear on the lower right side to allow displacement of the canine. The lower ClinCheck® is compliant with the movement observed in the mouth.
Evolution after Invisalign® aligner #25 shows good alignment of the upper front teeth and a significant improvement of the lower teeth alignment. The algorithm of treatment predicted 28 aligners in the maxilla and 31 in the mandible. At this stage of treatment, it is important to look at the details and evaluate if the remaining aligners will be able to achieve ideal alignment. The devil being in the details, we determined that it was better to request “refinement” of the ClinCheck® virtual treatment rather than continue with the initial ClinCheck®.
First, we can observe that tooth #42 is too much tilted to the right and the arrow indicates absence of contact between the opposing teeth.
The upper occlusal view shows that the contact between the premolar and the canine (circle 1) and between the canine and the lateral incisor (circle 2) is not ideal and that rotations of these teeth remain. In theory, according to the ClinCheck®, these rotations should be corrected. The movement prescribed in the trays was thus not 100% obtained. For more details see link: clinical implication.
In the mandibular arch, the contacts between the canines and the lateral incisors are the ones that are not adequate and do not match the ClinCheck® occlusal view on the right.
The right intraoral view shows absence of opposing contact with the lower teeth and the position of teeth obviously does not match the ClinCheck® view on the right.
The left intraoral view shows a Class I canine and molar relationship and good contact between the upper and lower teeth.
For all the reasons explained previously, we asked for refinement of the ClinCheck® virtual treatment. In order to do this, all the attachments must be removed, new imprints or a digital imprint with an iTtero® scanner must be taken again.
Here is the occlusion obtained in 50 weeks of Invisalign® treatment.
Refinement of the ClinCheck® shows a new sequence of 15 aligners of which 11 will be active in the maxilla and 12 are active in the mandible. The last 3-4 aligners are used to consolidate the dental movements. In all, about 40 aligners will have been necessary, that is 90 weeks, without taking into account the waiting time for making and delivering the aligners.
The 3D virtual treatment of the refinement is available for viewing below. The intraoral sequences front view, upper occlusal view, lower occlusal view, right view, left view and composite (5 views at the same time) are illustrated.