TABLE OF CONTENTS Jun 2004 - 1 comment

The Multipurpose Use of Essix® Thermoformed Appliances

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By: Ana-Maria Morris, DDS and Francis Abadie, DDS
ABSTRACT: Thermoformed Essix appliances have multiple uses in general dentistry and orthodontics, which greatly expand the many treatment options currently available. In office fabrication presents an additional asset, and because Essix appliances are clear plastic, the result is esthetically pleasing to the eye.

This article describes the most common and important applications, indications, fabrication techniques and the distinct advantages of using Essix thermoformed appliances.

Essix® plastics have been accepted worldwide for their strength, clarity, size and cost. They are proven, consistent and guaranteed; providing absolute stability and esthetics which, make teeth appear brilliant. They are used for retainers, Minor Tooth Movement (MTM), temporary bridges, stabilization and protection of the osteointegrating implant, whitening trays, temporary bridges and mouthguards. All applications put the clinician in control, not outside labs.

Essix Retainers are versatile; their flexibility and positioning capabilities make them an alternative to spring retainers in correcting minor tooth movements.1 They do not interfere with hygiene care, as opposed to fixed retainers which can interfere with proper care.

Essix thermoformed appliances for Minor Tooth Movement can be easily activated with the Hilliard Thermopliers. With the pliers one can create space, increase retention, close diastemas and increase force adjustments. In addition, bodily movement, rotation, tipping and torquing are easily achieved. Bite planes can be fabricated with the Hilliard Thermopliers without bonding or otherwise adding to the appliance. Essix whitening trays adapt well and cling to tooth surfaces - superior to EVA material -- without distortion.

Because the whitening trays are plastic they are practically invisible. The Essix temporary bridge is superior in all respects when compared with other temporary devices. They are inexpensive and esthetic appliances that not only replace missing anterior teeth, but also serve as an efficient retainer. Essix mouthguards provide excellent protection against dental injuries, fractures and concussions during sports; particularly when bodily contact is involved.

The purpose of this article is to alert generalists and orthodontists to some of the multiple applications and techniques of the Essix appliances and the multiple benefits and uses of the Hilliard Thermopliers.


Orthodontists' concept of retention is moving toward the idea that teeth will move unless retained indefinitely.7,8 However, permanent retention implies permanent supervision, and that is where reality clashes with practicality. An orthodontic practice basically consists of the treatment of active cases, which consume the most time and generate the most income, and supervision of retention cases, which takes less time and produces minimal, if any, income. This balance has been workable because, in due course, retention patients are either dismissed with wishes of good luck or simply fade away. When permanent retention is emphasized, the equilibrium is upset.

As an example, if 200 patients per year are given permanent retainers and seen twice a year, after 10 years this will add up to 4,000 retention appointments per year. At 10 minutes per visit, that would take up about three months' worth of appointments.

The cornerstone of Essix permanent retention is the complete delegation of responsibility to the patient. Essix retainers have nothing to adjust; the only thing that could be done on a recall visit would be to check the patient's compliance and listen to any comments. Telephone supervision is a time-and-money-saving service to our patients and is sincerely appreciated.4,5


The advantages include: The ability to supervise without office visits, absolute stability of the anterior teeth, durability, ease of cleaning, low cost, ease of fabrication and the brilliant appearance of the teeth caused by light reflecting through the appliance.4 The retainers are worn only at night, changing the rules of permanent retention.


1. Because accuracy of the impression is paramount, it is recommended that a polyvinyl siloxane (PVS) system be used (Fig. 1). This is especially true for accurately recording cuspid to cuspid retaining points. Since full arches have many retaining points alginate (Cavex) may also be used.

2. Use Debubblizer in both the impression and stone mix (Fig. 2).

3. Use die stone (Essix stone) for dimensional accuracy.

4. By placing a "cola" can tab into the distal extent of the impression a neat stone model can be poured (Fig. 3).

5. The resulting cast should be trimmed so that its height is no more than 3/4" (2cm) which aids vacuum adaptation of the Essix plastic (Figs. 4 & 5).


Essentially there are two types of Essix plastic used to fabricate appliances. Essix A+® is crystal clear and stiff. In use it lasts approximately six months. It is used for:

• Cuspid to cuspid retainers.

• Temporary bridges.

• Interim replacement over "fresh" implants.

• Wherever bonding is indicated.

• Secondary choice for use with Hilliard Thermopliers.

Essix C+® has a slightly cloudy appearance but in place has contact clarity. It is the most widely used Essix plastic. Its life is about two years when in use. It is used for:

• Cuspid to cuspid and full arch retainers;

• Plastic of choice to use with all of the Hilliard Thermopliers (Essix C+ does not bond). Essix C+ is stabilized by spraying a coolant (Essix Freeze Spray) immediately upon thermoforming to achieve optimal retentive points and prevent "lift" of the plastic from the model (Fig. 6).

Essix appliances can be cut out and finalized with mayo scissors (Fig. 7).

The Essix Vacuum Machine compliments the use of Essix plastics when used with its Essix vacuum maximizers. The thermoforming machine renders ideal adaptation and accuracy (Fig. 8).

Note: Have the patient seat the appliance and bite down on articulating paper. Grind through any spots on the retainer in order that the complete occlusion occurs.


Some prospective patients consider full orthodontia too costly or too lengthy (or both). Therefore, they simply decline the treatment.

Yet many, perhaps most of these patients could get the smile they want with only minor tooth movement of up to 3mm. This can be accomplished with relative ease and minimal expense with an Essix appliance modified with the Hilliard Thermopliers.

Smile enhancement techniques essentially require rotation, bodily movement, tipping, torquing, intrusion, extrusion, lateral movement, and/or opening a bite. All of these...any tooth movement... requires three things: space, force, and time.

SPACE -- There must be room in the arch for the tooth to move. For MTM, effective ways to create space include:

• Interproximal Reduction (IPR), reducing enamel with stainless steel strips in a movement not unlike flossing or stripping away enamel with slow-speed discs or burs.

• Air-Rotor Stripping (ARS); high-speed burs in the reduction of the proximal surface of a tooth.1

There must also be an opening within the thermoplastic appliance through which the target tooth can move. For without this opening, the tooth will not achieve any movement. The opening can be obtained three ways.

1. Cutting an opening into the thermoplastic appliance with the Essix Window Bur (Fig. 10).

2. Creating space, a bubble with Triad Gel or Blockout Compound, inside the appliance into which the targeted tooth can move (Fig. 11).

3. Creating a bubble inside the appliance into which the targeted tooth can move with the Hilliard Bubble-forming Thermopliers (Fig. 12). Heat the bubble tip of the Thermoplier and slowly squeeze the pliers on the targeted area of the appliance starting near the interproximal. Work the pliers around the area that the tooth will be moving into, bellying out the plastic as much as needed. It will be necessary to re-heat the pliers with the ATP Dental burner with each application, as it will cool (Fig. 13).

FORCE -- Pressure must be applied in the direction of desired movement.

Hilliard Thermopliers position each bump (divot) with complete precision. When plier tips are heated to correct temperature, the plastic retains its shape and the bump maintains its force. The same pliers can then increase the bump (force).

TIME -- Movement must be incremental over a number of weeks.

The Essix approach simply increases the force by increasing the bump as the tooth moves incrementally over time. Every few weeks, the patient returns and the bump is extended further, chairside and in a matter of seconds, again using Hilliard Thermopliers. When the appliance is worn full-time except while eating, a tooth can be moved approximately 1mm per month.

Chair time is reduced. Laboratory "back and forth" is totally eliminated all resulting in an increase in productivity, a reduction in overhead and improved patient satisfaction.2


The basic Essix appliance can be modified to serve as a temporary anterior bridge. The Essix technology provides a simpler, more efficient way to retain and replace missing anterior teeth. Exceptionally esthetic bridges can be fabricated quickly and inexpensive in the office. The appliances are made from .030" Essix A+.6


1. Fit a pontic of appropriate size and color into the edentulous area. Trim the base of the pontic to approximate the ridge (Fig. 14).

2. Cut a mesial-distal trench into the lingual surface of the pontic with the Essix trimming bur (Fig. 15).

3. Secure the pontic to the cast with Triad Gel (Fig. 16). Do not use wax, it will melt during thermoforming.4 Thermoform the Essix plastic over the cast.

5. The pontic will dislodge from the cast and mechanically lock into the appliance (Fig.17).

6. Trim the appliance as is done with the 3-3, or cuspid to cuspid, retainer.


Bleaching effectively brightens and whitens the teeth without causing any significant detrimental side effects when done according to established guidelines (ADA). Essix Tray-Rite® plastic and the Prestige Tooth Whitening system are highly recommended. Creating a gel reservoir in whitening trays is no longer considered useful (Fig. 18).

There are three types of plastic being used by practitioners for at home whitening:

1. .020" (1/2mm) Coping material - a hard, thin, opaque material that features a low melt temperature and excellent thermoforming properties.

2. .040" (1mm) EVA -- a soft, clear material easily vacuum formed and trimmed, however EVA stretches and the cervical third of a tooth can be challenging.

3. .020" (1/2mm) Tray-Rite® -- a semi-soft, clear material easily vacuum formed and trimmed without the stretching challenges of EVA.

Raintree recommends the Tray-Rite material for general use because it is smooth, pliable and comfortable to wear. It clings to the teeth providing better adaptation. Thus, the bleaching gel covers the entire tooth surface and doesn't spill over onto the gingiva.


1. Pre-heat the vacuum machine for at least 3 minutes or until the heating element is a solid orange color.

2. Spray the model with Trim-Rite Release Spray to prevent tray material from sticking to the model (Fig.19).

3. Place the plastic into the frame on the vacuum machine and the model on the base plate.

4. Swing the heating element over the plastic. Observe the plastic as it heats.

5. Essix Tray-Rite will become wavy then flatten to its original position--indicating the optimal thermoforming time.

6. Move the heating element away from the plastic.

7. Turn on the vacuum, then lower the plastic over the model.

8. Immediately spray the plastic encased model with Essix Freeze Spray. This is an essential step. Not only does it cool the plastic, prohibiting further thinning, but it "shrinks" the material around the cast, realizing a tighter fit (Fig. 20).

9. Let the vacuum continue to run for approximately 30 seconds or until the plastic is cool.

10. Trim the tray on the model using the Trim-Rite Electric Knife. Place the tip of the blade exactly where the tooth meets the gingiva and allow that ridge to guide your movements (Fig. 21).

11. Seat the whitening tray to check for tissue contact. Optimal results are obtained when the tray is cut 1mm short of the soft tissue.

12. Give the model with the tray on it to the patient for safekeeping (Fig. 22).

Tip: Instruct patients to dispense the gel on each tooth lingual to labial for less waste (Fig. 23).


Essix Mouthguards offer maximum protection and comfort without inhibiting the player's speech or oxygen intake. They are soft, comfortable and work well with braces.

Fabrication of mouthguards

1. Preheat the vacuum machine.

2. Spray the model with a separating medium such as Trim-Rite Release Spray (Fig. 24).

3. Place the mouthguard material into the frame and the model on the base of the vacuum machine (Fig. 25).

4. Position the Essix logo 3mm from the incisal edge on the palatal side (Fig. 26).

5. Thermoform the plastic (Fig. 27).

6. Spray with Freeze Spray.

7. Trim it with scissors or with the Trim-rite electric knife (Fig. 28).

8. Gently swipe a butane torch around the mouthguard's edges to smooth out rough spots (Fig. 29).

9. Heat the anteriors of the mouthguard using the microtorch (Fig. 30).

10. Heat the end of the strap. Fuse the strap to the anterior section of the mouthguard (Figs. 31 & 32).


The technology for fabricating an Essix bridge can be modified to isolate an implant while it is integrating with alveolar bone.3


1. The oral projection of the implant post will be blocked out to create an isolation chamber (Fig. 33).

2. The implant post needs to be protected from direct and transmucosal forces (Fig. 34).

3. Cover the orally exposed part of the implant on the working cast with a 2mm layer of acrylic or blockout compound.

4. Trim the base of the pontic to conform to the acrylic base on the alveolar ridge.

5. Cut a large and deep trench on the lingual of the pontic to mechanically lock the pontic into the thermoformed plastic.

6. Thermoform Essix C+ material over the cast.

7. Remove the plastic from the cast and trim as usual.

When the appliance is placed, there will be an isolation space between the base of the pontic and the implant due to the acrylic layer placed prior to pontic adaptation and thermoforming (Fig. 35). The implant, while it is integrating with alveolar bone, will be isolated from direct and transmucosal forces. During this interval the patient can enjoy an esthetic appliance.


1. Advise patients about demineralization.

Any plastic appliance that covers some or all of the teeth is, in effect, a tray. When fluoride is placed in the appliance, the enamel becomes more resistant to decay. When bleach is placed in it, the teeth become whiter. However, when acidic foods or beverages are retained in the appliance, it becomes an acid-containing trench causing the enamel to become susceptible to demineralization. This is one of the reasons that clear plastic retainers are to be worn only at night, after brushing and flossing--to minimize the possible effects of acid-containing foods and beverages that could be retained in the appliance.

When any clear plastic appliance is used, the patient should be informed of the dental side effects of acid-containing foods and beverages when they wear these devices for long periods of time, and to flush the mouth with water immediately after drinking acid-containing beverages (soft drinks, fruit juice, cola beverages, etc.). Commercially available daily fluoride remineralization rinses are also recommended. These precautions may prevent teeth from being marred by unsightly decalcification.

2. Essix full-coverage appliances should be equilibrated.

How to equilibrate the appliance:

With the appliance seated, check the occlusion with equilibrating paper (Fig. 36), where early contacts appear, reduce them by grinding the spots with the Essix Trimming bur (Fig. 37). This does not affect the efficiency or strength of the appliance. All posterior contacts should be adjusted until the anterior teeth contact.

If only one appliance is needed, equilibrate it. If upper and lower appliances are worn concurrently, place one and equilibrate it using articulating paper then place the other and equilibrate it until reasonable occlusal and incisal bites are established (Fig. 38).

If full arch appliances are not equilibrated, the result could cause significant premature occlusal contacts in the posterior teeth and, in turn induce an anterior open bite. This is due to the "1 to 3" prosthetic concept--1mm of bite-opening on the terminal molars will induce 3mm of movement from centric relation is purely rotational with a hinge-axis (center of rotation) around the condyles.

When a full coverage plastic appliance is seated, the thickness of the appliance between the terminal molars will inevitably cause hinge-axis interference. This will induce a disproportionately larger anterior open bite (Fig. 39).


- Essix plastics are FDA allowed and certified by ISO. They are considered to be the best in the dental and orthodontic industry and have caused a great impact among orthodontists and generalists closing the cycle of frustration by saving money, time and enhancing the quality of their practices.

- Essix laboratory results show that there is no need to continue using Hawley retainers because Essix retainers have nothing to adjust. Therefore the possibility of relapse is less, the supervision of the retention can be done by telephone, fabrication can be done in office, patients do not need to wear Essix retainers full time unlike Hawley retainers.

- Minor Tooth Movement with Essix plastics is a good alternative when patients consider full orthodontics too expensive and when movements needed are 3mm or less.

- Minor Tooth Movement also meets the needs of patients who care about esthetics and do not want braces.

- The esthetic result of the Essix temporary bridges suggests that there is no other method that can achieve this results in so short time.

- The stabilization and protection of the osteointegrating implant with the Essix bridge modified is excellent.

- Essix bleaching technique does not require blocking out the casts thereby reducing the amount of whitening gel used and protecting the patients' tissues.

- Essix laminated mouthguards have the highest tensile strength and uniform density because of its two laminated layers.


Thermoformed Essix appliances and techniques have multipurpose uses in general dentistry and orthodontics, offering the doctors tools to achieve better treatments.

The preferred way to align teeth is with fixed appliances. When for any reason this is not desirable or possible, modified Essix appliances offer more advantages than other removable appliances.

Because these appliances are practically invisible, patient acceptance is usually enthusiastic.

• A variety of forces can be achieved.

• Tooth movement is rapid and precise.

• Fabrication costs a fraction of conventional appliances

• Chairside modifications can be made quickly.

Essix temporary bridge is superior to conventional devices. It is very esthetic and not only replaces missing anterior teeth, but also serves as an efficient retainer.

The Essix whitening trays ensures superior tooth-whitening. They are nearly invisible when in place. The accuracy of the fit in the cervical one third is snug. This is important since this is the most difficult area of the tooth to whiten.

The Essix mouthguard has the ability to offer maximum protection and comfort without inhibiting the player's speech or oxygen intake.

One should be aware of the potential for occlusal and incisal disruptions that full time appliances can generate. In the case of a full arch plastic appliance, it should be equilibrated (with articulating paper and trimming burs) at the time that it is inserted.

Dr. Ana-María Morris is an Orthodontist graduated of the Military University of Bogot·, Colombia. Director of Clinical Operations of Raintree Essix.

Dr. Frank Abadie is Professor Emeritus of Louisiana State University School of Dentistry. He is a consultant to Raintree Essix.

Oral Health welcomes this original article.


1. Ballard, R.; Sheridan J.J.; Air Rotor Stripping with the Essix Anterior Anchor. J. Clin. Orthod. 30:371-373, 1996.

2. Hilliard, Keith; The Hilliard Smile Aligner Manual, Raintree Essix, 2002.

3. Sheridan, J.J.; Hilliard, K.; Armbuster P. Essix appliance Technology: Applications, Fabrication and Rationale. GAC international, Inc., 2003

4. Sheridan, J. J.; Ledoux, W.; McMinn, R. Essix Retainers: Fabrication and supervision for permanent retention. J. Clin. Orthod. 27: 37-45, 1993

5. Sheridan, J. J.; Ledoux W.; McMinn R. Essix Technology for the Fabrication of Temporary Anterior Bridges. J. Clin. Orthod. 28: 482-486, 1994

6. Sheridan, J.J.: The three keys of retention, Editor's Corner, J. Clin. Orthod. 25:717-718, 1991

7. Vanarsdall, R.L. and White, R.P.: Relapse and retention--professional and public attitudes, Am. J. Orthod. 98:184, 1990

8. Moscowitz E.; Sheridan J. Protecting the osteointegrating implant. New York State Dent J. 63 (4), 1977


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Reader Comments

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Can the same Essix retainer serve as a temporary bridge (for front tooth #21) in prep to getting an implant AND also open (MTM) the space approximately 1mm where the implant will be placed?

Posted December 13, 2012 11:55 PM

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