Dr. Carrière describes the use of the Carrière Distalizer during the initial phase of treatment

One philosophy for simplifying the nonextraction treatment of certain Class II cases is to achieve Class I occlusion in the posterior segment prior to correcting individual tooth positions. This protocol is focused on uncomplicating treatment by eliminating the collateral distorting vectors and internal binding forces that traditional corrective methods create when Class II traction is combined with successive wire activations via fixed appliances.

The Carrière philosophy espouses this approach. The Carrière Distalizer is utilized to correct cases to a Class I platform during the initial phase of treatment—when patient compliance is at its best—for the macro-correction of the occlusion. The clinician can then finish the case with the fixed or aligner appliance system of choice.1

While Angle considered the molar relationship the primary reference for defining a Class I occlusion, the Carrière methodology subscribes to a comprehensive definition of Class I referred to as the Class I platform: perfect buccal segment intercuspidation from cuspids to molars in which centric relation coincides with centric occlusion.

When maxillary and mandibular cuspids occlude properly in a Class I relationship, the buccal segment can establish itself naturally in Class I if the maxillary first molars are properly distally rotated. Research indicates, however, that 83% of maloccluded patients present with mesial rotation of the maxillary first molars.2 This phenomenon results from the maxillary first molars displacing naturally into the mesial leeway left after the exfoliation of the deciduous maxillary second molars. When a maxillary first molar is mesially rotated, the rhomboidal geometry of its anatomy causes it to occupy additional arch length that precludes the cuspid from occluding in Class I. It also creates an unbalanced occlusion with the opposing arch, suggesting a tooth size discrepancy, which it is not (Figure 1).

A primary means of achieving perfect intercuspidation between the maxillary and mandibular cuspids and molars is recovering this space by correcting the first molar rotation and mesial inclination, then distalizing the buccal segments. With this correction, the distal cusp of the maxillary first molar will match with the embrasure of the first and second mandibular molars, and the bicuspids and cuspids will occlude in a perfect Class I platform. Such intercuspidation offers a valuable point for stability in preventing relapse to the original Class II or in inducing the maxillary cuspids to push against the distal inclines of the mandibular cuspids, causing mandibular incisor crowding.3    

Biomechanics of the appliance

The challenge inherent in employing traditional Class II correctors for distalizing the buccal segment is controlling the unwanted effects of reciprocal movement. These challenges include maxillary molar tipping, maxillary bicuspid anchorage loss, and mandibular incisor proclination. The Carrière Distalizer is designed to cultivate cuspid and buccal segment distalization that precludes such undesired side effects (Figures 2A and 2B) as well as to offer technique simplicity and ease of delivery. It is based on the innovative biomechanical concept of “free but controlled” tooth positioning.

The primary biomechanical objectives for the Carrière Distalizer are to:

•    Provide controlled rotational movement of the maxillary first molar around its palatal root
•    Upright the maxillary first molar
•    Create a uniform biomimetic force to obtain univectorial dental displacement
•    Distalize the maxillary posterior segment (cuspid to molar) as a unit while controlling for unwanted torquing and tipping
•    Require only a light force to be activated yet be completely passive when traction is not being employed
•    Respect periodontal structures
•    Establish a Class I platform from which the clinician can finish the case simply and efficiently using the finishing appliance of choice

The cuspid and first molar have different positions in the dental arch, and therefore, require an individualized approach to their dental displacement inside the alveolar bone. Because of this situation, the biomechanical design of the Carrière Distalizer fosters the expression of two completely different types of movement.

Cuspid movement

The maxillary cuspid requires a bodily movement along the corner of the alveolar ridge with inclination control of its longitudinal axis. The portion of the distalizer attached to it has to be a fixed element that provides stability to the tooth itself while simultaneously directing movement longitudinally and distally. The anterior pad of the Carrière Distalizer that attaches to the maxillary cuspid (or first bicuspid if the cuspid is inaccessible) is a rigid half-round arm that affords this stability (Figure 3). The arm then curves posteriorally over the bicuspids, ending as an articulation ball within a socket on the posterior pad, which direct-bonds to the maxillary first molar.



To prevent the tendency for relapse, it is important to surpass the neutrocclusion of the cuspids to a Super Class I by continuing the distalization process until the distal incline plane of the maxillary cuspid establishes a contact against the mesial incline plane of the mandibular first bicuspid (Figure 4A). Once accomplished, and after the clinician has removed the distalizer and bonded the arches with the fixed appliance of choice to finish treatment, it is necessary to ligate the distalized teeth under the arch wire using a .012” stainless-steel ligature wire tied in a figure eight from the maxillary cuspids to the maxillary first molars, maintaining the consolidation throughout the remainder of treatment (Figure 4B). If using aligners to finish treatment, follow the protocol outlined in “Full esthetic treatment,” below.

First molar movement

The maxillary first molar requires a triple movement: distal rotation around its palatal root and controlled distal displacement while preventing the distal tipping of its crown and even uprighting, if necessary. Obviously, the Carrière Distalizer must first derotate and upright the molar so that the distalizing movement can proceed unfettered. Once the molar uprights, the articulation of the ball within the socket prevents unwanted distal tipping (Figure 3). In true biomimetic design, the ball and socket imitates the construction of the body’s hip joint. This joint provides maximum freedom of movement with minimal friction while causing the molar to travel directly to the desired position after derotating and uprighting it. There are several predefined points that stop movement for controlling undesired consequences. Polar cuts on the ball articulate with flat surfaces in the socket at a maximum orientation of -15 degrees to the longitudinal axis of the arm, which act as a stop, limiting undesirable movements and providing torque control over the cuspid and molar (Figures 5A and 5B). When the molar has derotated, the mesial shoulder of the posterior base contacts with an eminence in the distal end of the arm that runs between the anterior and posterior pads that prevents overrotation. While the movement of the molar is independent and qualitatively different from the movement of the cuspid, it must also be coordinated with it in order to express a simultaneous response as a unit.

Indications

Primary indications
The Carrière Distalizer is ideal for treating growing patients and effective for treating adults. Clinicians can usually expect the same amount of distalization and molar rotation in adults as children, although, as one would expect, treatment time for adults will be longer. On average, adult distalization takes 5 months; growing children, 3 months.

Brachyfacial patterns respond best to this treatment followed by mesofacial patterns; dolichofacial types are less responsive. The Carrière Distalizer is indicated in the following types of cases if deemed to warrant nonextraction therapy:

•    Class II malocclusions, both division 1 and division 2, symmetrical or asymmetrical
•    Class I and pseudo Class I cases with mesially positioned maxillary molars
•    Class II mixed dentition and adult  cases with maxillarydentoalveolar protrusion
•    Phase I treatment of mixed dentition Class II cases with fully erupted maxillary first molars. In this case, deciduous cuspids must be in good position to hold the anterior segment of the appliance.

Secondary indications
The Carrière Distalizer can be used creatively in the treatment of:

•    Class I and Class II cases in which four extractions would seem necessary. In such cases, the number of extractions can often be minimized and a more esthetic facial result achieved
•    Unilateral Class II cases
•    Space recovery for retained maxillary cuspids in Class II cases, unilateral and bilateral
•    Dentoalveolar Class III cases using the Distalizer in the lower arch
•    Cases already treated with four extractions that did not achieve a perfect Class I occlusion due to a loss of anchorage. In those cases, the Distalizer can be used to achieve a solid posterior class I platform.

Possible sources of anchorage

To avoid protrusion of the mandibular incisors during activation of the Carrière Distalizer, clinicians must determine an adequate source of anchorage based on each patient’s skeletal and neuromuscular pattern (Figures 6A and 6B). A sound diagnosis for the proper selection of anchorage is a fundamental requirement to prevent anchorage loss. There are four primary sources for establishing anchorage that will each be discussed:

•    A passive mandibular lingual arch with molar tubes welded buccally and lingually on mandibular molar bands
•    A mandibular Essix® (Dentsply Raintree Essix) appliance with direct-bonded buccal tubes on the mandibular molars
•    Full mandibular fixed appliances with direct-bonded buccal tubes on the mandibular molars
•    Temporary anchorage devices (TADs).

Forming the passive lingual arch

A mandibular lingual arch to sustain Class II elastics traction is one means of preparing anchorage for the Carrière Distalizer and is particularly suited to patients with strong musculature. A .036” lingual arch adapted to the mandibular dental anatomy must run passively from first molar to first molar (second molars, if they have erupted). When second molars are fully erupted, it is advisable to band them (with buccal tubes) in order to obtain the maximum amount of force from elastics and create better anchorage resistance.

The clinician must remain vigilant that the lingual arch does not create protrusion of mandibular anteriors. The arch wire must remain completely passive in order to disallow reciprocal movement of the mandibular dentition. It must also fit the length of the arch exactly and be perfectly anatomically adapted; otherwise, spaces will emerge between the mandibular incisors, an indication of anchorage loss. Clinicians must monitor and control against rotations and torque changes in the mandibular molars at every appointment. Patient acceptance of the lingual arch is excellent: it is invisible, comfortable, requires minimal patient care, and is hygienic.  

Mandibular Essix® appliance

The Essix® appliance provides a very good source of anchorage for Class II elastics traction. It unlocks the occlusion, is highly efficient, and has become the anchorage method of choice for most clinicians (Figures 9A and 9B). It must be worn full-time, except during meals, and is particularly applicable to patients with weak musculature. The recommended material is A+ with .040” (1 mm) thickness.

Essix® fabrication

1.    Bond buccal tubes with hooks onto the buccal surface of the mandibular first or second molar
2.    Cut a window in the thermoformed Essix® appliance to allow the buccal tubes to protrude
3.    To provide maximum traction and maintain the appliance in position: a. Ensure it fits properly to the dental arch, or b.   Fabricate the appliance with small composite wedges bonded to the buccal surfaces that fit over the mandibular bicuspids.

Full-bonded appliance in the mandibular arch

For patients who present with a severe curve of Spee or mild crowding in the mandibular arch, it is advisable to bond brackets to the mandibular dentition to prepare anchorage for supporting Class II traction. After leveling the case with round wires, advance to a .016 x .025 dimension arch wire and then to a .019 x .025 Bio-Kinetix™ arch wire before attaching the Class II elastics.

Temporary skeletal anchorage (TADs)

A variety of TADs, such as mini-implants, miniplates, and miniscrews, are designed with heads that offer mechanisms to receive the insertion of elastics for anchorage maintenance. The suggested TAD placement in the mandibular arch is between the first and second molar where there is adequate dense cortical bone to hold the Class II elastic traction. The recommended TAD length for this position is 8 mm.

Sizing the appliance

Measure for the appropriate size distalizer by using calipers or the disposable Carrière Distalizer Ruler provided with the appliance. There are 23 sizes available to accommodate the majority of case requirements for bonding from cuspid or first bicuspid to first molar. See below for a complete listing of sizes and accessories.

Taking the measurement

1.    In cases with accessible cuspids, take the measurement from the buccal surface midpoint of the maxillary first molar to the midpoint of the maxillary cuspid crown.
2.    In cases with an inaccessible high cuspid when the second maxillary molars are present, take the measurement from the buccal surface midpoint of the first molar to the buccal surface midpoint of the first bicuspid. The appliance can then be bonded to these teeth so that the posterior teeth can be distalized to provide space for the blocked-out cuspid.
3.    Use the measurement to choose the appropriate size appliance. When the measurement is between two sizes (e.g., between 24 mm and 25 mm), select the appliance size based on the amount of rotation desired: a. For more rotation, select the smaller size b. For less rotation, select the larger size.

Appliance selection

Select a right side distalizer (R) or a left size distalizer (L).

Prepping the teeth for bonding

1.    Isolate the area being bonded.
2.    Clean the teeth being bonded with prophy paste (Figure 10).
3.    Rinse the teeth thoroughly with water (Figure 11).
4.    Dry the teeth with air (Figure 12).
5.    Etch the surfaces of the teeth being bonded appropriate to the adhesive selected (Figure 13).
6.    Rinse the teeth thoroughly with water (Figure 14).
7.    Dry the etched teeth with a brief air burst. Ensure that the entire isolated area is dry.
8.    Prime the teeth being bonded with a uniform coating of primer/sealant (Figure 15).

Adhesive application

a.    Using a locking hemostat, forceps, or tweezers, grasp the distalizer by the arm and coat both pads of the appliance with a small amount of light-curing adhesive, covering them completely (Figure 16).

Placement

a.    Use the instrument to position the appliance onto the appropriate teeth, placing the posterior pad first and then the anterior pad.
b.    There is a vertical line engraved on the posterior pad to be used as a reference in aligning the pad coincident with the longitudinal axis of the molar. Position the posterior pad in the center of the buccal surface of the molar. In cases of exaggerated
mesial molar rotations, the arm of the distalizer can open laterally up to 45 degrees, easing placement.
c.    Position the anterior pad on the mesial third of the vestibular surface of the crown of the cuspid or first bicuspid (not on the midline).

Alignment
                                                                                                                                        
a.    Using the placement instrument, align the pads on the tooth surfaces (Figure 17).
b.    Generally, little if any adjustment to the curvature of the appliance arm is necessary.  
c.    Using the placement instrument, remove excess adhesive from the tooth surface while maintaining the appliance alignment.

Light curing

Fully light cure the appliance pads, beginning with the molar, then the cuspid or bicuspid (Figure 18). If the distalizer requires adjustment prior to placement, place it on a solid, flat surface and use gentle finger pressure on the middle of the arm (Figure 19). Do not use an instrument to adjust the bar or the pad. Avoid making repeated adjustments, bending and straightening the bar. Repeated bending will fatigue the appliance and may cause it to break. Avoid trying the appliance on the patient’s teeth prior to bonding it; this action may contaminate the bonding pads with saliva.

Elastics traction

Alternative I—for convergent patients
Force 1/first month: Class II elastics: 6 oz, ¼”, full-time wear
Force 2/after the first month: Class II elastics: 8 oz, 3/16”, full-time wear

Alternative II—for divergent patients
Force 1 daytime wear: Class II elastics: 6 oz, ¼”
Force 2 nighttime wear: Class II elastics: 8 oz, 3/16”

Instruct patients to wear elastics 24 hours a day, except when eating, because of the vertical force vector that opening the mouth while chewing produces. A predominantly vertical force vector may result in a mild extrusion of the cuspids during distalization. Night-time wear can compensate for this phenomenon because it produces a more horizontal vector of traction but will prolong the distalization period. Patients should change their elastics after each time they eat.

Appointment checks at 6-week intervals should take only a few minutes. Each is used to observe treatment progress, explain the progress to the patient, and praise and/or encourage compliance.

There are seldom emergencies associated with the Carrière Distalizer because if one end of it becomes debonded, the patient will generally play with the appliance until the other end debonds. To preclude debonding, ensure that the appliance goes immediately from its packaging to placement. Do not determine the size of the distalizer by placing it in the mouth. Doing so contaminates the retention pad and compromises bond strength, which can cause debonding.

Full esthetic treatment

Carrière Distalizer correction dovetails ideally with Invisalign® for finishing treatment. The Carrière Distalizer is the perfect solution for patients who want Invisalign® (Align Technologies) or other clear aligner treatment but display a Class II malocclusion. The small profile of the Carrière Distalizer will satisfy most patients who are concerned about esthetics, and after using it for the sagittal correction, the clinician is free to utilize any fixed appliance system—including Invisalign®—to complete treatment. Teenagers are predisposed to wearing Invisalign® and easily understand how the Carrière Distalizer can jump start Class II treatment to provide the indiscernible orthodontic correction they seek.

Transitioning from the Carrière Distalizer to Invisalign®

After removing the Carrière Distalizer and Class II elastics, transition to an Essix® appliance in the maxillary arch until the aligners arrive. If you used a lingual arch or TADs for anchorage, transition to an Essix® appliance for the mandibular arch as well. If you used an Essix® appliance for anchorage in the mandibular arch, maintain it until the aligners arrive.

Taking impressions for Invisalign® finishing treatment

Clinicians take impressions for Invisalign® and the Essix® appliances by using PVS material for both or PVS for the aligners and alginate for the Essix® appliance. If using PVS material for both (and/or for models), a high-quality product is recommended (e.g., for the heavy body: 3M™ESPE™ Position™ Penta™ Quick impression material [a VPS alginate replacement]; for the wash: 3M™ESPE™ Imprint™ Garant™ Quick-Step Impression material).




Transitioning to fixed appliances for finishing treatment

When transitioning from the Carrière Distalizer to fixed appliances, it is advisable to have two bonding appointments. Bond only the maxillary arch at the first appointment. Run the round wire from first molar to first molar and keep the lingual arch wire or Essix® appliance in the mandibular arch until the next appointment (for as much as 10 weeks). At the next appointment, you can then remove the lingual arch or Essix® appliance and bond the mandibular arch. Of course, if you used fixed appliances for mandibular anchorage, you simply transition to fixed appliances in the maxillary arch. After removing the distalizer, it is important to ligate the distalized teeth under the arch wire using a .012” stainless-steel ligature wire tied in a figure eight from the maxillary cuspids to the maxillary first molars, maintaining the consolidation until the end of treatment.

 

Bio

Dr. Carrière obtained his PhD (Cum Laude) from the University of Barcelona in 2006, his MSD from the same university, and his DDS from the University Complutense, Madrid, Spain. He was the recipient of the Joseph E. Johnson Award given by the American Association of Orthodontists, San Francisco, May 1995. He is the inventor of the Carrière distalizer and the Carrière self-ligating bracket and received the International Design award, Delta Gold, ADI-FAD 2009 for the Carrière Distalizer MB.
He is a member of the Editorial Review Board of the American Journal of Orthodontics and Dentofacial Orthopedics.
He has been the invited Professor at several orthodontic departments of universities in United States, South America, Europe, and Asia, and guest speaker in many lectures and courses around the world.

References

1.  Carrière J (1991) The Inverse Anchorage Technique in Fixed Orthodontic Treatment. Quintessence Publishing Co., Chicago.

2. Henry RG (1956) Relationship of the maxillary first permanent molar in normal occlusion and malocclusion. Am J Orthod Dentofacial Orthoped 42:288-306.

3. Stoller AE (1954) The normal position of the maxillary first permanent molar. Am J Ortho Dentofacial Orthoped 40:259-271.