SUS2 is an acronym for Sabbagh Universal Spring.
The distributor of SUS2 correctors is the Dentaurum company.
A SUS2 corrector is made of a telescope rod that inserts into a guide tube. An inner spring ensures a compression force of 2.4 Newton (1 N = 110 g). An archwire adapter makes it possible to attach the corrector to the lower orthodontic archwire and an eye allows the appliance to be attached to a headgear tube on the bracket of the upper molar using an L ball pin.
The central telescope rod has an activation amplitude of 6 mm from the inner spring and provides a force of 2.4 N at full compression. Deactivation of the inner spring is possible by unscrewing the hexagon socket screw. The inner spring will then have an activation amplitude of 2.1 mm and will then provide a force of 1 N (110 g) at full compression.
An outer spring called “turbo-spring” placed on the telescope element provides an additional force of 3 N to the mechanism of the corrector. 1 mm or 2 mm spacer rings can be added to the telescope rod for reactivation. This is however rarely necessary.
Preparation of orthodontic archwires
Anchorage tubes are necessary to attach the correctors to the upper molars.
I use SPEED™ convertible tubes composed of a very wide bonding pad, a convertible main tube and a convertible tube welded to the occlusal of the main tube.
During the bonding of these tubes, it is important to pre-adapt the bonding pad on a stone model to maximize the contact between the pad and the labial surface of the tooth.
.The picture on the opposite side shows a perfect adaptation of the bonding pad against the tooth surface. The better the adaptation of the pad is, the better the bonding strength is.
To maximize the bonding strength, enamel is microetched with a blast of 90 micron aluminum oxide powder. After rinsing and drying, enamel is etched.
I use Assure® photopolymerizable bonding resin on the bonding pad and enamel. After photopolymerization of the resin, the pad is covered with Assure® paste and placed on the tooth. A firm pressure is applied to remove the excess of paste before proceeding with photopolymerization.
How to adjust the bracket bonding pad?
The bonding pad must be adjusted with bird peak pliers to obtain a tight adaptation with the buccal surface of the molar. It is easy to achieve on the study model, but nothing prevents from doing the same adaptation directly in the mouth prior to bonding if the model is unavailable.
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SPEED™ lower convertible tube
In the mandibular arch, it is beneficial to use convertible tubes such as those manufactured by SPEED.
The mechanism of the buccal clip allows a quick and easy insertion of an orthodontic archwire that is cinched back. A conventional tube is often likely to be debonded when the .020 X .025 steel archwire is bent.
Buccal offset bend
A buccal offset bend is done to the distal of each lower canine. The archwire adapter is put against this bend to maintain the correctors in place.
L ball pin and upper molar attachment
.An L ball pin is bent at its end in order to be inserted into the loop of the female part of the corrector. This bend allows the corrector to be cleared from the headgear tube bonded to the molar.
The L ball pin is inserted distally into the headgear tube. The bend near the loop is oriented buccally in order to keep the loop away from the headgear tube. The L ball pin must be 2-3 mm in length to the distal of the headgear tube, just enough to give freedom of movement, but not long enough to allow it to touch the bracket on the second molar.
To the mesial of the tube, the rod is bent toward the occlusal or gingival side. Note that it is easier to bend toward the occlusal side than the gingival side. Wiengart universal pliers are used for the bending. The whole force must come from the wrist and care must be taken not to press on the bonded attachment when the rod is bent to avoid debonding the bracket.
The above picture shows bending of the L ball pin to the occlusal. Notice the E-Link elastics of the canines to the first molars to distalize the canines at the same time as the molars. The maxillary archwire is cinched distally from the second molars.
Presentation of clinical cases
Here is a typical case of a Class II division 1 malocclusion with little or no crowding (lack of space). The discrepancy between the upper and lower teeth is obvious.
The cephalometric X-ray confirms a 4-mm skeletal backward shift of the lower jaw (ANB = 7°) and a prominent upper dentition.
The patient is 12 years old.
SUS2 correctors were used from the 45th to the 69th week of treatment, for a total of 24 weeks. Notice the presence of E-Link elastics linking the canines to the pin on the molars. This makes it possible to move the canines backward at the same time as the molars by the mechanism of the correctors. Notice that steel orthodontic archwires are used and they are cinched to the distal of the upper and lower second molars.
The treatment will have lasted 105 weeks. A canine and molar Class I relationship was obtained. The overjet and overbite are normal. We notice the presence of a few surface white lesions on the enamel of some teeth. We have re-explained oral hygiene measures and warnings on the risk of surface decalcifications very often. It is too bad. These lesions will subside a little bit with time, with the use of a fluoride toothpaste and with maintaining an impeccable oral hygiene.
Cephalometric tracing and superposition
.The cephalometric tracing shows a correction of the discrepancy between the upper and lower dentitions.
To better understand the movements that occurred, the initial and final superposition tracings must be looked at.
The difference between the final red tracing and the initial black tracing represents the movement of the dentition in the correction of the malocclusion. Condylar growth is expressed by an anterior and lower displacement of the mandible at the tip of the chin (green circles).
The tracing on the left shows that the upper teeth moved backward compared to their initial position, but this is explained by a decrease in the anterior maxillary growth. Indeed, the figure in the upper right corner called ANS-PNS@ASN shows a stable anteroposterior position of the upper incisors.
Superposition of the mandibular tracing (left corpus – Chin) on the symphysis shows that condylar growth occurred (green circle), that the lower molars shifted anteriorly and that the lower incisors intruded (ingression) and slightly tipped forward, because the red tracing of the incisor is not totally parallel to the black tracing of the incisor.
All these movements are normal and comply with the therapeutic effects reported in literature about fixed functional appliances. See page: How does a fixed functional appliance correct a Class II malocclusion?
Initial and final profile views. The lips remain prominent and are in contact at rest.
.Case #2, in addition to the Class II division 1 relationship, presents a deep supraocclusion with a deep overbite impinging palate. In other words, the lower teeth are in contact with the palate behind the upper incisors.
The lower lip is hemmed forward because the upper teeth are in contact with the lower lip. The skeletal shift is 7.5 mm compared to 4 mm for the previous case (case #1).
The patient is 13 years and 6 months of age, which means that she is advanced in her teenage years and less mandibular growth is available.
In addition to correcting the discrepancy between the upper and lower teeth, one of the objectives of treatment is to increase the vertical dimension and allow the posterior teeth to erupt.
The choices of treatment are:
1- Correction of the A-P relationship with fixed appliances and SUS2 correctors
2- Orthosurgery comprehensive treatment.
We opted for a treatment with SUS2 correctors while informing the patient about the risk of having to undergo an orthognathic surgery.
SUS2 correctors were inserted at the 26th week of treatment and stayed in place for 17 weeks. Note the E-Link elastics on the upper canines to help retract the canines to a Class I relationship. Notice the presence of bands on the molars instead of bonded brackets. Indeed, a palatal expansion phase preceded in order to coordinate the dental arches in a Class I relationship. I prefer a banded expander (Hilgers or Hyrax type), because it allows me to introduce the correctors faster than if I used a bonded expander with an occlusal covering made of acrylic.
The change in width of the maxillary arch is obvious on the picture on the right. The L ball pins used to hold the correctors are bent toward the occlusal.
Progression at 43 weeks
When the SUS2 correctors were removed, a 0.17 x 0.25 β-titanium archwire was engaged and activated to retract and intrude the anterior upper teeth. This mushroom loop archwire allows the fast retraction of the anterior teeth in a frictionless system.
Progression at 81 weeks
When the anterior teeth were retracted, a .021 x.025 β-titanium archwire and an elastomeric chain were engaged. This archwire allows the correction of the torque of the anterior teeth and the elastomeric chain allows the spaces to close.
A small condylar growth occurred despite the age of 13 years and a half.
In the mandibular arch, molars have erupted and the lower incisors tipped labially. In the maxilla, the upper incisors moved back.
These movements comply with those expected from Class II correctors. The eruption of the lower molars allowed the correction of the deep supraocclusion (deep overbite).
The fixed appliances will be removed in a few days. Pictures to come.