Early Orthopedic Class III Treatment with a Modified Tandem Appliance

The Modified Tandem Appliance^* (MTA) shown in this article is designed for Class III patients with skeletal midfacial deficiencies.

Appliance Design

The MTA has three components, one fixed and two removable. The upper fixed appliance can be a traditional maxillary expander, with or without palatal acrylic (Fig. 1A), a QuadHelix^**, or a Nance appliance. Soldered buccal arms are used for elastic traction. Upper brackets can be added, depending on the patient's age and clinical situation.

The lower appliance comprises a removable acrylic retainer with posterior occlusal coverage and buccal headgear tubes embedded in the area of the lower first molars (Fig. 1B). An .045" headgear facebow with the outer bows bent out for elastic attachment is inserted into the lower tubes.

Delta clasps on the first permanent molars or second deciduous molars and "C" clasps on the lower deciduous canines are used for mechanical retention, which is essential for stability and cooperation. I recommend bonding small acrylic buttons to the labial surfaces of the lower canines so that the "C" clasps will snap over the buttons. In the deciduous dentition, where retention may be more of an issue, I have also added a lower midline expansion screw. I advise the parent to activate the screw one-quarter turn as necessary to ensure adequate retention between visits.

Heavy orthopedic elastic traction (400g per side) from the facebow to the buccal arms of the upper fixed appliance delivers the protraction force to the maxilla (Fig. 1C). However, patients are instructed to begin wearing the appliance with lighter 230g training elastics. I have found that the duration of wear is more significant than the force of the elastic. I request a minimum of 10-12 hours per day, including while sleeping. To my surprise, it is not unusual for patients to wear the MTA 14-16 hours per day, as esthetics and comfort do not seem to present problems (Fig.1D).

I see the patient one week later to verify compliance and check the appliance. On occasion, the buccal arms may irritate the inside of the cheeks, requiring minor adjustment. The patient is then scheduled every six weeks to monitor progress.

Case Report

A female patient, age 3 years, 9 months, was initially referred by her pediatrician to an oral and maxillofacial surgeon. Clinical examination revealed a Class III malocclusion with a significant maxillary deficiency, an anterior crossbite, and a midfacial deficiency.

The patient's family had a history of thalassemia, but she had not been diagnosed with this condition. Her mother did relate that the patient had had multiple episodes of earache, with fluid behind the drums, and had difficulty breathing through her nose. The patient also demonstrated some lisping, and her mother confirmed that her articulation was affected.

It has been well documented that mouth-breathing as a result of nasopharyngeal blockage can have a significant effect on facial growth and development, causing maxillary retrusion and a downward and forward positioning of the mandible in an effort to open the airway.^17,18 The patient was referred to an otolaryngologist with are commendation for a speech evaluation. Based on her age and level of maturity, she was placed on one-year recall.

A year later, initial orthodontic records were taken (Fig. 2). My original plan was to place an upper fixed expander and initiate maxillary protraction with a conventional facemask, but my previous results with facemask therapy had been mixed due to cooperation problems. After reading an article on a Tandem Appliance for orthopedic Class III correction that seemed much more patient-friendly than a facemask,¹⁹ I discussed the appliance with the patient's mother and obtained informed consent.

Instead of using two removable appliances, I modified the design to include a fixed maxillary component. The upper appliance had both palatal and labial bows for stability and soldered buccal arms for elastic attachment. In subsequent cases, I have used fixed expanders and transpalatal arches with equal effectiveness. A recent study has shown no significant orthopedic benefit from palatal expansion prior to facemask therapy.²⁰

After the upper second deciduous molars were banded, we took upper and lower impressions and sent them with a wax bite registration to the laboratory for fabrication of an MTA appliance. Upon delivery, an 8oz, 230g training elastic (Panther^***) was used for six weeks, followed by a 14oz, 400g elastic (Walrus^***).

The patient was seen at six-week intervals for 12 months. The upper fixed appliance was then removed at the request of the otolaryngologist for removal of the tonsils and adenoids. After surgery, the appliance was recemented; the upper permanent incisors erupted favorably three months later. The MTA was removed after another four months (Fig. 3).

Cephalometric evaluation revealed a significant skeletal improvement, an increased vertical dimension, and a substantial improvement in facial balance (Table 1).

No retention appliances were used. A year or more after treatment, the patient has shown a stable Class I occlusion with good facial esthetics (Fig. 4). The relapse tendency toward a skeletal Class III pattern (Fig. 5) would be expected and has not been clinically significant.