By Dr. Pablo Echarri and Dr. Martín Pedernera
Removable or fixed orthodontic treatments are based on the insertion of the appliances and their periodical activation. It should be always started with a very mild activation and then the appliance should be progressively reactivated so the movement can be effective. In this way, removable appliances should be activated through their screws, arches, springs, etc., and fixed appliances require replacement of the arches, elastic chains, etc. so the treatment progresses adequately.
In all cases, failure in the use of removable appliances and debonding of fixed appliances (treatment interruption), or failure in periodical activation of them, means the increase of the treatment time.
Biological bases of CA® CLEAR-ALIGNER Protocol
CA® CLEAR-ALIGNER protocol is based on sequential aligners carried out over the impressions, and plaster casts carried out each 4 weeks. One “step” of treatment includes a plaster cast set-up, 3 aligners (CA®-soft, CA®-medium, CA®-hard) pressure moulded over this plaster cast set-up, and a report on movements carried out in the set-up. It corresponds to one month of treatment.
The treatment starts when the diagnosis is finished. The impressions are taken, and a 0.5 mm dental movement is carried out in the plaster cast set-up. Over this plaster cast, 3 CA® CLEAR-ALIGNERS of 3 different thicknesses are pressure moulded (Figs. 1 and 2).
- – CA®-soft, a 0.5 mm aligner.
- – CA®-medium, a 0.625 mm aligner.
- – CA®-hard, a 0.75 mm aligner.
The patient should use CA®-soft during the first week; CA®-medium, during the second week, and CA®-hard, during the third week. After the third week, the patient should go to the clinic so the new impressions can be taken. He will use a CA®-hard during the fourth week while the new step is prepared in the laboratory.
In the first step of treatment, a 0.5 mm movement of the tooth is carried out. An inclination of the tooth is searched for inside the periodontal space (Fig. 3). A vasodilation is carried out, as well as the increase of ostoblasts and osteoclasts, which enables the treatment with these aligners. Clinically, dental movement will not be observed.
In the following steps, a 1 mm movement is carried out in the set-up (Fig. 4). This activation produces pressure zones and traction zones in periodontal ligament. In pressure zones, bony resorption is produced, and the tooth moves in this direction. In traction zones of ligament, bony apposition is started, and it is much slower.
If the patient doesn’t use enough the CA® CLEAR-ALIGNER (17 hours per day) the tooth returns to the initial position and it also might present the mobility because the bony resorption has been produced, but not bony apposition in the opposite zone.
If a patient doesn’t come to the clinic so the new impressions can be taken and the new step carried out, and he continues using the same CA® CLEAR-ALIGNER, the tooth will remain in that position, but the density of osteoblasts and osteoclasts is reduced. In this way, when the treatment is re-activated, it won’t be possible to continue with 1 mm movements in the set-up, but it will be necessary to start again with the 0.5 mm movement, which means the delay of the treatment (Fig. 5).
Fig. 5: Scheme of the biological reaction when there’s no activation.
Therefore, it is very important to motivate the patient to use the CA® CLEAR-ALIGNER 17 hours per day, and to make sure they come regularly to the activation appointments, so the treatment time or number of CA® CLEAR-ALIGNERS is not increased.
When treatment objectives are achieved, the patient should use a 1 mm thick aligner, CA® RETENTION (Fig. 2). CA® RETENTION is formed over the final plaster cast, without any dental movement (Fig. 6). This appliance keeps the tooth in the final position and periodontal ligament traction in the zones in which the bony apposition is needed (Fig. 7).
The patient should use CA® RETENTION at least 6 months, but fixed permanent retention is recommended to avoid the relapse. The stability is achieved when the alveolar bone remodelling is finished (Fig. 8). If the use of CA® RETENTION is not sufficient, the relapse will take place (Fig. 9).
During the active phase of the treatment, other types of CA® CLEAR-ALIGNER which increase the treatment effectiveness can be used.
When a plaster cast set-up is carried out in the laboratory, the aligners CA®-soft, CA®-medium and CA®-hard are carried out, but CA® Bubbles can also be made (Fig. 10) so when the patient can use it during the fourth week and achieve greater movement.
When a plaster cast set-up is carried out in the laboratory, the aligners CA®-soft, CA®-medium and CA®-hard are carried out, but before the CA®-hard is pressure moulded, a space can be created in the direction of the movement of the tooth (Fig. 11), so the clinician can create an activation bubble in the clinic using the CA®-Tip 1 Pliers when impressions are taken for the next step.
To achieve an effective extrusion movement, CA® POWER GRIP will be used, bonded on the tooth, 2 buttons in CA® CLEAR-ALIGNER and extrusion elastics, as it is shown on the scheme of the figure 12. It is activated by changing the elastics 3 to 4 times per day. The CA® CLEAR-ALIGNER is carried out in such a way that when the necessary extrusion is finished, the tooth stops to extrude.
CA Forced intrusion (Fig. 13) has buttons for anchorage of the intrusion elastics and it is activated by changing the elastics 3 to 4 times a day. The CA® CLEAR-ALIGNER is carried out in a such a way that when the necessary intrusion is finished, the tooth stops to intrude.
To adjust midline or overjet, upper and lower CA® CLEAR-ALIGNER can be used with intermaxillary elastics (Fig. 14). It is activated by changing the elastics 3 to 4 times a day.
During the expansion phase, CA®-hard can be used with the expansion screw Vector 40 (Fig. 15). These appliances are activated by a screw turn each 3-4 days.
It is very important to maintain the rhythm of activations to complete the treatment within the planned time. It is important to make sure patients come to control appointments by organizing a “reminder system”, as well as a system to motivate the patient in using, cleaning and taking care of the CA® CLEAR-ALIGNER, so the treatment can be completely effective.
Echarri P. Clear Aligner. 1st Ed. Madrid (Spain):Ripano Médica; 2012