Brief History of Functional Appliances

Functional appliances are used to develop arches and to move mandibles or maxillae forward. They employ a non-extraction technique and were developed in Europe in the early 1900s. For over 100 years, clinicians worldwide have been using these appliances to improve facial esthetics in patients. Extracting teeth is very common in many countries, but when one extracts the bicuspid teeth, which are 8 mm wide, the upper arch is left 16 mm smaller, making for narrow smiles. Often if the teeth are retracted, the result is an un-esthetic retrognathic profile. Functional appliances were originally used to bring the lower jaw forward and thereby improve the patient’s esthetics. More recently, bringing the lower jaw forward has been shown to improve TMJ health as well as prevent snoring and sleep apnea later in life. Not only do the patients look better, but they are healthier, which should be one of the most important treatment objectives. Practitioners of esthetic dentistry, orthodontics, prosthodontics, or restorative dentistry should strive to improve patients’ health and their appearance.

In orthodontics, one moves the teeth, originally mostly using metal brackets. In the 1980s clear brackets became available. In the author’s practice, 90% of the adults want clear brackets because of esthetic considerations. More recently, manufacturers have developed self-ligating clear brackets that do not stain and are highly esthetic. Clear brackets have encouraged many adults to choose orthodontic treatment.

About 20% of the orthodontists worldwide use functional appliances, with higher percentages in Europe and South America. In South America general dentists learn, in dental school, how to use functional appliances for treating children early while in dental school, then patients are referred to an orthodontist for tooth straightening and fixed braces. Dental schools in North America should start offering courses for general dentists regarding early orthodontic treatment for children. General dentists worldwide need to embrace the philosophy of developing arches at an early age.

When the patient has dental crowding, there are two options: (1) view the teeth as too large for the size of the jaws and extract some teeth, or (2) view the upper or lower arches as too narrow and use an orthopedic appliance that moves the bone. Orthodontic clinicians alter the shape of the bone and the shape of the arch by expanding the arch. This is easily accomplished in children. The mid-palatal suture widens and fills in with bone, it is a true orthopedic change that allows patients to keep all their teeth.

As far as facial esthetics is concerned, the primary goal is a broad, attractive smile. The actors and actresses on TV are often the standard used to evaluate everyone’s smile and smile width. When teeth are extracted, the result is a narrow smile, rather than the broad smile sought through esthetic dentistry. Some clinicians who do not do orthodontics can still create a broader smile by putting veneers on the bicuspids and cuspids, trying to widen the look of the arch. That is not quite the same as developing the arch early on.

Techniques and appliances now exist that allow practitioners to develop adults’ arches. These include self-activating, nickel titanium coil springs that use 150 grams of force to develop adult arches. Although it is amazing what can be accomplished, the key is improved health for the patient. First, practitioners should create a proper-sized maxillary arch without any extractions, and then relate the mandible properly to the maxilla. That ensures a healthy TMJ and an improved appearance. Patients who have unstable TMJs have unstable occlusions, with the mandible often moving to a retrognathic position, which is not considered esthetically pleasing. A straight profile is preferred to either a retrognathic or a prognathic look.

Functional appliances are the key to success in early orthodontic treatment. Children should be seen before age 7 years to detect problems with the arches. These include arches that are too narrow, the lower jaw being too far back, the presence of a deep overbite, or habits such as thumb sucking or tongue thrusting. Those must be corrected early when patients are more cooperative.

In Europe and South America, functional orthopedic appliances have been used to establish the correct relationship between the maxilla and mandible transversely, sagittally, and vertically. In North America an increasing number of orthodontists and general dentists have used fixed and removable functional appliances to treat younger patients. A reason for this is that mothers are constantly asking general dentists to treat the orthodontic problems of their children at an early age, before the permanent teeth erupt. Another reason is that patients are more likely to cooperate when wearing fixed functional appliances.

Relating Function and Esthetics

Patients want three things: straight teeth, white teeth, and broad arches. When functional jaw orthopedic appliances are used in young children and teenagers, clinicians can obtain broad arches and therefore broad smiles.

From an orthopedic (bone) standpoint, the seven keys to TMJ health are as follows:

Clinical Considerations

Proper Maxillary Width

In developing the maxilla to its correct width using functional appliances, the simplest apparatus is the Schwarz appliance, which consists of two pieces of acrylic with a midline screw and four retaining clasps, i.e. Adam’s clasps, on both sides. These appliances are extremely comfortable and can be used to treat patients as young as age 5 years. The midline screw of these appliances is activated twice a week, which equals 0.5 mm per week or 2 mm per month. They are well tolerated by children and teenagers alike, as there is no discomfort involved. The appliance should be worn at all times except when cleaning or for active sports. If a 6 mm expansion is required, then the appliance is activated for 3 months and held for 6 months to prevent a relapse. Statistics show that the results are extremely stable in patients who are nasal breathers and have no airway obstruction (Figure 29-1).

FIGURE 29-1 A, Constricted upper arch, no room for lateral incisors. B, Traumatic occlusion upper left central incisor. C, Constricted upper arch, no room for upper central and lateral incisors. D, Constricted lower arch, no room for lower central and lateral incisors. E, Upper removable Schwarz appliance, one midline expansion screw, two double Adam’s clasps for retention. F, Lower removable Schwarz appliance, one midline expansion screw, four ball clasps for retention. G, Upper removable Schwarz appliance, one midline expansion screw, two double Adam’s clasps for retention. H, Schwarz appliance midline screw opened 6 mm. Adequate space for upper centrals and lateral incisors. I, Constricted upper arch, no room for upper central and lateral incisors. J, Broad arch, upper centrals and lateral incisors have erupted. K, Traumatic occlusion, upper left central incisor. L, Broad arch, normal overjet, normal overbite. M, Constricted arch, no room for upper and lower central and laterals. N, Broad arch, adequate space for upper and lower centrals and lateral incisors.

There are basically two theories regarding how to correct the problem of crowded teeth in a dental arch:

1. Retractive technique. This involves treatment of the permanent dentition and recommends extraction of teeth, usually the bicuspids, to eliminate crowding. Proponents believe the teeth are too large for the arches so permanent teeth are extracted to solve the crowding problem. The consequence of this can be a narrow smile and a posteriorly displaced condyle with resultant internal derangement (temporomandibular dysfunction [TMD]).

2. Functional technique. This involves treatment of the mixed or permanent dentition using functional appliances to expand and lengthen the arches so all the permanent teeth fit. Proponents believe the problem results from the arch being too small for normal-sized teeth, so the arch is expanded to a normal width. Patients treated with a functional philosophy routinely have normal, symptom-free TMJs.

The advantages of using functional appliances to expand constricted maxillary arches include expanding the nasal cavity transversely and vertically (when the palate subsequently drops), which encourages nasal breathing; making more room for the eruption of the permanent teeth; and gaining more space for the tongue, which helps ensure proper speech. Some children with narrow arches have speech impediments. The treatment of choice might be to develop the upper arch to normal first, which in the vast majority of cases provides more room for the tongue, which solves the speech problem. The expanded upper arch is the first key to achieving long-term health and also ensures that the patient will have a broad smile.

One important fact that must be recognized is that if the maxilla is too narrow and the mandible is deficient and requires advancement, the case will not be stable because the maxillary teeth will be in buccal crossbite. The retrognathic mandible must be advanced to improve facial esthetics and to move the condyle downward and forward to its proper position in the glenoid fossa. Therefore the first step in the treatment of patients with Class II skeletal malocclusion with narrow maxillae and retrognathic mandibles is to expand the maxillary arch with a fixed or removable functional appliance.

Another important point is to never attempt any cosmetic procedures, such as crowns or veneers, if the patient has a bilateral or unilateral posterior crossbite. This problem must be corrected first with functional appliances to expand the maxillary arch to normal before restorative treatment.

Maxilla Positioned Correctly Antero-posteriorly

Despite the fact that only 5% of malocclusions are Class III skeletal, approximately 80% of these younger patients in the mixed dentition stage have retrognathic or underdeveloped maxillae. The ideal time to treat these patients using functional appliances is at ages 5 to 12 years to improve their facial esthetics.

One of the most popular fixed functional appliances for children is the Tandem Appliance, which effectively advances the entire maxilla. Patients with TMDs caused by anteriorly displaced disks and posteriorly displaced condyles must have the maxilla properly positioned anteriorly first. Once the maxilla is moved forward with a functional appliance, such as the Tandem Appliance, and an overjet has been created, the mandible can be advanced, moving the condyle down and forward. Hopefully, this will recapture the anteriorly displaced disk and eliminate the signs and symptoms of TMD (Figure 29-2).

FIGURE 29-2 A, Male age 5, anterior crossbite, deep overbite. B, Anterior crossbite, deep overbite, Class III skeletal malocclusion, class III molars. C, Anterior crossbite, class III cuspid, class III molar. D, Tandem Appliance, move maxilla forward, class III elastics. E, Anterior crossbite, class III cuspid, class III molar. F, Anterior crossbite corrected, Tandem Appliance at 7 months, maxilla moved forward. G, Pre-treatment, 5-year-old boy, Class III skeletal malocclusion, deficient maxilla, normal mandible. H, Tandem Appliance at 7 months, maxilla moved forward, normal maxilla, normal mandible.

Proper Relationship between Maxilla and Mandible

An estimated 70% of all malocclusions are Class II, and approximately 80% are Class II skeletal malocclusion with normally positioned maxillae and retrognathic mandibles. These patients traditionally have narrow maxillary arches, moderate to large overjets, and deep overbites. Routinely, these patients have internal derangements (problems within the jaw joints), evidenced by posteriorly displaced condyles and anteriorly displaced disks. Condyles that are posteriorly displaced frequently compress the nerves and blood vessels in the bilaminar zone distal to the condyle. Functional appliances effectively reposition the lower jaw forward, which results in the condyle moving downward and forward, away from the nerves and blood vessels.

Two methods of determining whether the condyles are in a pathologic position are described in the following sections.

Tomographic Radiographs of the Temporomandibular Joint

The tomogram shows the position of the condyle in the fossa when the patient is occluding in centric occlusion. In a recent article in the Journal of the American Dental Association, the correct position of the condyle in the fossa was identified as downward and forward, not rearmost and uppermost, as reported in many old textbooks. The ideal position of the condyle in the fossa in centric occlusion is to have a larger posterior joint space than an anterior joint space. The posterior joint space should be at least 4 mm to allow room for the nerves and blood vessels in the bilaminar zone plus a 2 mm superior joint space to allow room for the posterior ligament and a 2 mm anterior joint space to allow room for the disk (Figure 29-3).

FIGURE 29-3 A, Pre-treatment radiograph (tomograms) showing centric occlusion, condyles posteriorly displaced. B, Tomographic radiograph with mandibular repositioning splint. Condyles in proper position, posterior joint space larger than anterior joint space. C, Gelb 4/7 position, ideal position of the condyle in the glenoid fossa. Patient occluding in centric occlusion.

Joint Vibration Analysis

The joint vibration analysis (JVA) device measures vibrations within the joint. Each of the five stages of internal derangements has a distinct vibration that indicates to the clinician just how serious the problem is before treatment. A normal healthy TMJ makes no noise, causes no pain, and makes no vibrations. The JVA diagnostic device can also be helpful during treatment with anterior repositioning splints (adults) or with the Twin Block appliance or Mandibular Anterior Repositioning Appliance (MARA) in children or adults to confirm that the disk has been recaptured (Figure 29-4).

FIGURE 29-4 Joint vibration analysis diagnostic device to evaluate the health of the temporomandibular joint (TMJ). The device measures vibrations within the TMJ when the joint opens and closes.

The treatment of choice for a patient with a retrognathic profile, in order to improve the appearance, is to reposition the lower jaw forward using a functional appliance such as a Twin Block (removable appliance) or MARA (fixed functional appliance). The literature is clear that if the disk can be recaptured with the functional appliance that moves the mandible forward, then most patients have a significant reduction in the signs and symptoms of TMD. The treatment objective for these patients is to improve not only the facial esthetics but also the TMJ health (Figure 29-5).

FIGURE 29-5 A, Mandibular Anterior Repositioning Appliance (MARA) on model; lower arm is attached to lower first molar S.S crown. Upper elbow attached to upper first molar S.S crown. Lower arm in front of upper elbow holds the mandible forward. B, MARA. Lower arm in front of elbow holds mandible forward. C, Patient with Class III skeletal malocclusion with deficient mandible, deep overbite, class II cuspid, overjet 6 mm. D, MARA after 7 months. Mandible advanced 5 mm, normal overjet, normal overbite. E, Pre-treatment Class II skeletal malocclusion, normal maxilla, retrognathic mandible, retrognathic profile. F, MARA after 7 months. Normal maxilla, normal mandible, Class I skeletal malocclusion, straight profile.

Clinicians who are concerned with esthetic dentistry must be concerned first and foremost with the health of the TMJ. Patients go to dental offices for straight teeth and white teeth. The solution may be orthodontics followed by tooth whitening, or, alternatively, some patients may prefer porcelain veneers, porcelain crowns, or implants. It is important for the clinician to first properly evaluate the patient’s existing occlusion and malocclusion.

Patients who were treated orthodontically previously may or may not have stable TMJs after treatment. This is particularly true if the guidelines for a healthy TMJ, as outlined previously, were not followed.

Proper Inclination of Maxillary Incisors

If the maxillary central incisors are too vertical, or, in the case of patients with Class II, division 2 malocclusion, if they are lingually inclined, this frequently results in trapping of the mandible so that it cannot come forward to its correct position. These patients, who also routinely have a deep overbite, often exhibit signs and symptoms of TMD. This is particularly prevalent in women age 20 to 40 years. It is virtually impossible to correct the TMD using crowns and veneers. These patients must be referred to an orthodontist or general dentist trained in orthodontics to correct the malocclusion and TMD before restorative or prosthetic work is preformed.

Dentists who fabricate crowns and bridges for patients with Class II, division 2 malocclusion must be extremely careful to diagnose and treat the TMD that exists in most cases before treatment. When the maxillary central incisors are lingually inclined, this frequently traps the mandible and causes the condyles to be posteriorly displaced and the disks to be anteriorly displaced (internal derangement) (Figure 29-6).

FIGURE 29-6 Class II, division 2 malocclusion. The maxillary incisors are lingually displaced, restricting forward movement of the mandible, causing posterior displacement of the condyles and temporomandibular joint dysfunction.

The treatment of choice is to orthopedically (using functional appliances) or orthodontically (with fixed braces) torque the maxillary centrals forward, thereby creating an overjet. Functional appliances that can torque lingually inclined maxillary central incisors forward include a removable appliance, Maxillary Anterior Sagittal, or fixed appliance (Barrel Three-Way Fixed Sagittal). This sometimes allows the mandible to come forward to its proper position and permits decompression of the TMJ, relieving, it is hoped, the TMD. Sometimes, however, it is necessary to use a functional appliance such as a Rick-A-Nator to advance the mandible slightly using an incisal ramp and to allow for the eruption of the lower posterior teeth to increase the posterior vertical dimension. Clinicians who are contemplating treating patients with Class II, division 2 malocclusion by endodontically treating the lateral incisor and then placing crowns on all four incisors should reconsider their treatment options. The author has seen cases where dentists have placed crowns on lingually inclined central incisors that increased the thickness of the restored teeth on the lingual, causing the mandible to be distalized further and increasing the TMD. Therefore the author recommends that general dentists consider an orthodontic or orthopedic treatment option before placing crowns on patients with Class II, division 2 malocclusion with TMD. The treatment of choice for Class II, division 2 malocclusions is to torque the crowns and roots of the four incisors, ideally using either functional appliances or fixed braces. Then the mandible is advanced with a functional appliance such as a Rick-A-Nator to establish a normal maxillary-mandibular relationship. This stabilizes the TMJ before any cosmetic procedure.

Correction of Unilateral Crossbite

Patients, young and old, can have unilateral posterior crossbites caused by the shifting of the mandible to one side when the patient closes in centric occlusion. This is usually the only position in which the patient has maximum intercuspation. This causes a facial asymmetry that results in the condyle becoming posteriorly displaced on the side to which the mandible shifts during closing. This posterior displacement of the condyle can actually lead to osteoarthritis of the condyle as it continues to break down and to shorten in length. Posteriorly displaced condyles can often lead to anteriorly displaced disks and internal derangement within the TMJ. This problem should be corrected as soon as possible to avoid further damage to the condyle and to prevent TMD.

The treatment of choice is to treat these patients at an early age (4 to 12 years) with a Schwarz appliance (removable) or a Hyrax appliance (fixed) to expand the maxillary arch. Both of these appliances accomplish this with midline screws adjusted twice per week. This bilateral expansion allows the mandible to center itself within a properly developed maxilla. Treatment is usually completed successfully within 3 months, including correction of the unilateral crossbite, TMD, and facial asymmetry. The patient is then encouraged to wear the appliance for 6 more months to prevent relapse (Figure 29-7).

FIGURE 29-7 A, Seven-year-old girl with mandible shifted right in centric occlusion and facial asymmetry. B, Patient occluding in centric occlusion, with constricted upper arch causing the mandible to shift 3 mm to the right. C, Constricted upper arch with lack of space for the central and lateral incisors. D, An upper removable Schwarz appliance used to expand the upper arch, with one midline expansion screw and two double Adams clasps for retention. E, Upper expansion appliance widened the upper arch in 3 months and corrected the midline shift. F, Photograph showing the lower jaw shifted to the right, causing a facial asymmetry. G, After 3 months, the upper arch has expanded. The lower jaw has been centered and facial symmetry achieved. H, Profile view of 7-year-old girl with thin upper lip. I, Profile view of patient at age 9 with full upper lip. A removable orthodontic appliance, an upper Anterior Sagittal Appliance, was used to advance the pre-maxilla. Treatment time was 5 months.

Uprighting of Lower Posterior Teeth over the Basal Bone

When the lower posterior teeth are lingually inclined, it is very difficult to obtain a proper occlusion. Certainly, it is not the ideal situation in which to fabricate crowns or bridges; it is preferable to have the teeth upright over the basal bone so that the direction of forces can be along the long axis of the teeth and not in a lingual direction, which tends to alter the occlusion. Lower posterior teeth that are lingually inclined can be uprighted with functional appliances to help ensure a proper occlusion and TMJ health. This uprighting of the posterior teeth widens the lower arch and increases posterior vertical dimension, which is one of the keys to TMJ health. This increased width of the lower arch also makes more room for the tongue, which ensures proper speech (Figure 29-8).

FIGURE 29-8 A, Seven-year-old boy with constricted lower arch and no room for central or lateral incisors. B, Lower Schwarz appliance, a removable orthodontic expansion appliance, with one midline expansion screw and four ball clasps for retention. C, Lower Schwarz appliance with one midline expansion screw inserted. No room for lower central or lateral incisors. D, Lower Schwarz appliance with midline screw expanded 4 mm 6 months later, allowing adequate space for lower centrals and lateral incisors. E, Lower arch expanded through use of lower Schwarz appliance 6 months later; lower incisors erupted.

Establishment of Proper Vertical Dimension

Clinicians who routinely treat patients with TMD are well aware of the fact that patients with teeth that are overclosed vertically, evidenced by short lower face heights, large submental creases under the lower lips, and deep overbites, commonly have TMD. The cause of the deep overbite can be traced back to mouth-breathing problems, which cause the tongue to assume a lower position in the mouth and depress the lower posterior teeth. This causes a deep curve of Spee. Obviously, the solution to the problem is to solve the airway constriction that caused the mouth-breathing problem and then to erupt the lower posterior teeth back to their original heights, reestablish correct posterior vertical dimension, and eliminate the deep overbite. This improves not only the TMD symptoms but also the patient’s appearance from the front by increasing lower face height. It also improves the appearance of the profile by helping to eliminate the submental crease.

Patients with deep overbites routinely have their condyles posteriorly displaced, which compresses the nerves and blood vessels distal to the condyle in the bilaminar zone. This compression can cause many symptoms, such as headaches, earaches, dizziness, neck pain, ringing in the ears, pain behind the eyes, ear congestion, tingling of the hands and arms, difficulty swallowing, and even shoulder and back pain. Depression of the lower posterior teeth by the tongue often causes the muscles to become shortened as the lower face height decreases. This can lead to excessive contraction of the muscles of mastication and other surrounding muscles.

One of the causes of bruxism is TMD caused by unstable TMJs (internal derangement). Frequently, patients who brux all night end up with headaches in the morning. Shortened muscles and bruxing can also increase muscle soreness and, in many cases, cause the formation of trigger points. A trigger point is a knotted part in a muscle and is extremely painful. These trigger points often refer pain to different parts of the body, including the head, neck, ear, and shoulder areas.

The solution to the problem is to use a functional appliance such as a Rick-A-Nator with an incisal ramp to stabilize the lower jaw. The incisal ramp prevents the eruption of the anterior teeth and encourages the eruption of the lower posterior teeth. When treating in the mixed dentition, the ideal treatment is to reline the incisal ramp with Triad Provisional Material (DENTSPLY International, York, Pennsylvania) to an ideal overjet and overbite (1 mm overjet, 1 mm overbite).

Patients with deep overbites now have a posterior open bite, making it extremely difficult to chew and causing the TMJ to be unstable. The solution is to build up the first and second lower primary molars with composite to allow the patient to chew and to stabilize the TMJ. This is the treatment of choice for children who brux, have headaches, or experience ear symptoms such as ringing or congestion in the ears. Clinicians must take a complete TMJ history for each patient, regardless of age, to determine whether or not these younger patients have a problem. This technique leaves a space between the upper and lower first molars. Within 2 to 3 months the lower first molars will passively erupt to contact the upper first molars and close the posterior open bite. A new occlusal plane has now been created for the patient. The composite is left on the lower first and second primary molars to support the posterior vertical dimension. When the primary molars are exfoliated, hopefully the lower bicuspids will erupt to the level of the new occlusal plane. The author cannot overemphasize the importance of establishing proper vertical dimension in achieving TMJ health (Figure 29-9).

FIGURE 29-9 A, Ten-year-old boy with 6 mm deep overbite, headaches, Temporomandibular Dysfunction. B, Deep overbite, Class II malocclusion, condyles posteriorly displaced, overjet 4 mm. C, Normal overbite, normal overjet, Rick-A-Nator, composite buildups, eliminate TM dysfunction. D, Rick-A-Nator, fixed appliance to correct deep overbite and move lower jaw forward. Two molar bands, .045 S.S connector wires, incisal ramp (indexed). E, Normal overbite, normal overjet, Rick-A-Nator, composite buildups, eliminate TM Dysfunction.F, Normal overbite, normal overjet, Rick-A-Nator, composite buildups, eliminate TM dysfunction. G, Lower jaw comes forward because of Rick-A-Nator. The patient occludes in front of the incisal ramp. Composite buildups are created on lower primary molars to help patient chew. Lower first molars passively erupted to correct deep overbite, 3 mm in 3 months. H, Class II skeletal malocclusion, normal maxilla, retrognathic mandible, TMD headaches, retrognathic profile. I, Rick-A-Nator after 6 months. Class I skeletal malocclusion, normal maxilla, normal mandible, no headaches, straight profile.

Two-Phase Orthodontic Treatment

Functional jaw orthopedic appliances can significantly change a patient’s profile and hence facial esthetics (Table 29-1). The ideal time to implement treatment is between ages 6 and 11 years, while the child is actively growing. The treatment of choice is two-phase orthodontic treatment, the objective being to solve the orthopedic problems early in the mixed dentition before the eruption of the permanent teeth. The objective in Phase I is to treat all Class II and Class III skeletal malocclusions with functional appliances to a normal Class I skeletal occlusion in the mixed dentition. Therefore, when all the permanent teeth erupt, the orthopedic (bone or skeletal) problems have been corrected, and the only concern will be orthodontics (crooked teeth). The advantage of this type of treatment is that it produces excellent facial esthetics and drastically shortens the treatment time in fixed braces.

TABLE 29-1 Two-Phase Orthodontic Treatment

Treatment Considerations