Dental Problems

Common Appliances for Functional Jaw Orthopaedics

How to Clean Mouth GuardVarious common appliances for the functional jaw orthopaedics include activators, Bionator, Clark twin block, Frankel functional regulator, Horse shoe appliance, Head gear, pendulum appliance, chin cap, and the pre-orthodontic trainer. Read on to know more.

Common appliances in use for functional jaw orthopaedics:

  • Activators:

    The “monobloc” designed by Robin (1902), was the first reported dunctional appliance. This was modified by Andresen in 1936 and later termed activator in 1957.


    Partial or total correction of Class II division I, Class II division II, Class III open bites in a mixed and early permanent dentition. A typical indication would be Class II division I with deep bite.


    It is not advisable to use the appliance in cases of crowding or where individual tooth movements are required.

    Bite registration:

    Based on the amount of horizontal and vertical opening:

    • A. Schwarz (1956) suggests the optimal is a half of the individuals maximum range.
    • B. Woodside (1977) stated that mandible registered in a position protruded 3.0 mm distal to the most protrusive position that the patient can achieve.

    As a general rule the horizontal advancement is kept edge to edge or 2 mm less than the maximum protrusion. Vertical opening is kept 5 mm posteriorly. It is also advocated that in cases where the overjet is more than 10 mm, a stage-wise advancement is to be carried out.

    Duration of use:

    In general, an overjet of 8mm may require 10-12 months of wear. Though originally designed as a night wear appliance only, the time taken for correction may be reduced if the patient compliance is good and the patient can wear for more than 14 hours a day.

    Several modification have been suggested for the activator, which can be used for a variety of situations.

  • Bionator:

    Originally designed by Balters in 1964, these have been termed ‘open activators’in view of their reduced bulk. Three basic types of bionators have been used as per their indications. They are as follows:

    • The standard appliance is used in cases of a deficient mandible and is made up of an acrylic flange extending posteriorly. The palatal bar with a loop (to control tongue position) and the modified labial bow (with buccal extensions, that reduce the muscle forces) are used. With selective trimming, desired eruption of the teeth can be achieved.
    • The open bite appliance, which is used to inhibit any abnormal posture or function of the tongue.
    • The reversed or class III appliance, which is used to stimulate the growth of the under developed maxilla. The loop of the palatal bar is in the opposite direction and the trimming differs in that some acrylic is left between the teeth. The maximum benefit is obtained when the appliance is worn day and night.
  • Clark twin block:

    This type of appliance was introduced by Clark in 1988, and consists of upper and lower removable plates with acrylic hooks timed at an angle of 70 degrees with a midline expansion screw in the upper plate to allow a simultaneous expansion. They were originally designed for high angle cases and are often constructed with an attachment inserted into the upper block for high-pull headgear.

  • Frankel functional regulator:

    The functional regulator is the only true tissue -borne appliance: however, wirework does extend onto the occlusal surfaces of the maxillary canines and the first permanent molars. Much of the appliance is located in the vestibule and the appliance is said to work by altering both mandibular posture and the contour with the dentition. This appliance can be used to enhance dental eruption as well as correct anteroposterior and lateral arch discrepancies. Frankel advocates advancing the mandible 2 to 3 mm every 4 to 5 months and notching the maxillary teeth to aid retention.

  • Horse shoe appliance:

    The horse shoe appliance is used for the correction of class III molar relationship. Originally developed by Schwarz (1997), the appliance has the advantages that it is easy to construct, and it does not allow for the eruption of teeth due to the presence of acrylic resin over the upper and lower teeth.

  • Head gear:

    In cases, where a skeletal overgrowth is present in the maxillary arch, extra-oral force may be required to restrict the growth of the maxilla. The most commonly used appliance for this purpose is the head gear appliance.

    A significant factor for the success of the head gear appliance is the determination of whether it is the maxillary overgrowth that is the problem (and is it, how much) or if the mandible is lacking in growth (and if it will catch up).

    The forces applied are through the teeth. These forces have a horizontal and vertical component. Should these forces be improperly applied, as in where there is an excess of the vertical component, it may lead to molar extrusion. This may not only harm the molar but has the undesirable effect of impeding mandibular growth as well.

    Anchorage for the appliance is derived from various regions (cervical, occipital, parietal regions). As with all the removable appliances, the patients’cooperation is of paramount importance.

    Specifications for use:

    A duration of 12- 16 hours a day is the minimum requirement for an effect to occur. Generally, a force of 400 grams on either side is applied.

  • Pendulum appliance:

    this appliance has also been termed as non-compliance therapy for molar distalization. The pendulum appliance is a hybrid that uses a larger Nance acrylic button in the palate for anchorage along with 0.032 TMA springs that deliver a light continuous force to upper first molar. This appliance produces a broad swinging arch or pendulum of force from midline of palate to the upper molars.

    This is mostly used in the patient with Class I skeletal relationship and Class II dental malocclusion.

  • Chin cap:

    It is used in cases of excessive growth of the mandibule. The use and efficacy of the chin cap is not accepted by all the clinicians, but can be considered a valuable aid.

    Two philosophies exist to its use. They are concerned with the direction of force applied:

    1. They are used such that the force is applied through the condyle. Though animal experiments may have substantiated this, clinical findings are disappointing. This could. In part, be attributed to the basic difference in the mechanism of growth of the maxilla and the mandible.
    2. They are used with the forces directed below the condyle. The effect is that the chin is rotated downward and backward which is caused by the rotation of the mandible. This type of an appliance is ideal in cases with short vertical height.
  • The pre-orthodontic trainer:

    The starting (blue) trainer imparts only a light force on the teeth, then after 6-8 months the firmer (pink) trainer, which imparts a much higher force on the malaligned anterior teeth, is implemented. This is the principle behind the straight wire technique, starting with a light wire then progressing to a firmer wire as the teeth come into a better alignment.

The above article discusses about the

common appliances in use for functional jaw orthopaedics


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