GET FASTER AND MORE STABLE CLASS II CORRECTION WITH A TWIN BLOCK FROM JOHNS DENTAL. DOCTORS PREFER THE TWIN BLOCK TECHNIQUE BECAUSE THEY GET QUICKER RESULTS, IT'S EASY TO USE AND PATIENTS GET A COMFORTABLE FIT.

The Twin Block technique was developed by Dr. William Clark of Scotland during the early 1980's. He lectured and displayed the technique at the European Orthodontic meetings throughout this decade. Also, the technique was shown at the AAO in the late 80's. In 1986, Dr. Clark lectured for many of Johns Dental's customers and we have been making the appliance ever since.

Achieving Class II Correction

The basic Twin Block technique achieves Class II correction by taking advantage of the inclined occlusal planes to hold the mandible in the forward position.

The Basic Appliances

The basic appliances are separate upper and lower plates. The upper plate includes an expansion screw for lateral development and occlusal pads to cover the molars. The lower plate includes occlusal pads to cover the lower bicuspids. These plates interface at 70 degree angles to achieve (lock in) the desired forward position of the mandible.

Modifications from the Basic Design

Several options are available for the Twin Block appliance including the use of a Sagittal or Expansion design in the upper and/or lower arches. The appliances can be modified as the case requires and designs may be used in any combination. For example, upper and lower expansion screws may be used for lateral development, an upper Sagittal type appliance may be used with a basic lower appliance, or face bow may be incorporated in the case design. In addition to these options, a fixed/removable Twin Block can be made using a Wilson 3D type of appliance.

Adjustment Techniques for Gaining Vertical Development

At each appointment the occlusal contacts on the maxillary molar pads should be relieved approximately 1/2 mm. Once the AP is corrected, the appliances may be removed to allow the bicuspids to erupt.

Adjustment for the Expansion Screw

Lateral development may be achieved by instructing the patient to adjust the screw 1/4 turn each week.

Laboratory Requirements

The laboratory requires upper and lower stone models. A wax construction bite in a forward and open position is also required (usually 5 to 7 mm forward 4 to 5 mm open in the bicuspid area.)

References

• European Orthodontic Journal; 1982 (P. 129-138)
• American Journal of Orthodontics; January 1988
• The Functional Orthodontist

  May/June, 1990 (P. 4 - 8 )

  July/August, 1990 (P. 24 - 31)

  ©1989 Johns Dental Laboratories

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