The 20 Principles of the Alexander Discipline, Volume 3. R.G. "Wick" Alexander
joints (TMJs) for any clicks and gently pulling the lower lip down and asking the patient to swallow. By observing the movement of the tongue, we can easily see if a tongue thrust is present.
Historically, tongue thrusts have been attacked with tongue cribs. These appliances are barbaric in my estimation, and I have always preferred “tongue therapy” to retrain the tongue, as taught to me by a speech therapist. Volume 2 of this series outlines this five-step procedure (push, click, slurp, squeeze, and swallow; see page 172).
Weak occlusal forces
Although excessive occlusal forces can cause attrition and/ or TMJ problems, inadequate occlusal forces can allow the teeth to drift into undesirable positions, usually into an anterior open bite and a vertical skeletal pattern. In order to overcome this problem, patients should be taught how to train their muscles of mastication. Squeezing exercises can increase maximum bite force and increase resistance to fatigue (Thompson D, unpublished study, 1995).
Dr Laurie Parks studied the records of 50 patients with medium- to high-angle open bite malocclusions.1 She discovered that the performance of masticatory muscle exercises during treatment of skeletal open bite produced greater increases in overbite than treatment alone. She concluded that squeezing exercises in conjunction with tongue swallowing exercises significantly improve overbite and provide a much better chance for long-term stability.
Therefore, although open bites will not close by tongue control and squeezing exercises alone, these changes to the environment will ensure long-term stability once the open bite is closed orthodontically.
Traditional Orthopedic Approaches to Open Bite Treatment
High-pull facebow
If worn with extreme compliance, the high-pull facebow can intrude the maxillary molars (Fig 1-1). However, it is unrealistic to expect the patient to wear it full-time, so a better goal is to keep SN-MP at its initial position by wearing it 12 hours per day.
Fig 1-1 High-pull facebow.
Transpalatal arch
Clinical experience has taught me that this appliance can help to maintain the vertical skeletal angle but cannot reduce it.
Chin cup
Again, this appliance can help to maintain the vertical skeletal angle but certainly cannot reduce it. Clinically, wearing the chin cup will keep the teeth in occlusion, which prevents overeruption of the posterior teeth.
Temporary anchorage devices
The most exciting possibility for controlling and reducing the vertical skeletal angle involves intrusion of the maxillary and mandibular molars with temporary anchorage devices (TADs). If these devices are stable in the long term, this technique will change the approach to high-angle treatment in the future.
Alexander Discipline on Open Bite Mechanics
I can remember early in my career observing an open bite mandibular arch study model and how the arch was nicely leveled (Fig 1-2). It looked like a finished arch in a pretreatment deep bite occlusion. It made sense that I should treat this arch with mechanics opposite to those for a deep bite malocclusion.
Fig 1-2 (a and b) Open bite study models.
Diagnosis
• Observe the resting position of the upper lip. It should be 4 to 5 mm from the incisal edge of the central incisors.
• Observe the smiling position of the upper lip. It should be within 1 to 2 mm of the gingival line. See volume 2 of this series (page 112) for the “Gucci Gucci” technique on getting the patient to smile naturally.
In open bite cases, it is common for the upper lip to cover much of the maxillary anterior teeth during a smile. Part of the treatment includes extrusion of the incisors to create more incisor exposure. This is accomplished by placing a reverse curve in the 0.016 SS and 17 × 25 SS maxillary archwires (Fig 1-3) and later, if needed, up-and-down anterior box elastics (Fig 1-4).
Fig 1-3 (a and b) Reverse curve of Spee.
Fig 1-4 Anterior box elastics.
Dental open bite versus skeletal open bite
When the skeletal pattern is normal (low vertical skeletal angle) but the bite is open, this can be treated as a dental open bite. With proper biomechanics and exercises, this patient should have excellent results. When the open bite is skeletal, the problems are magnified. Surgery may be the only solution.
Open bite mechanics
• Bracket placement: The goal is to intrude the posterior teeth and extrude the anterior teeth. This is accomplished by changing the bracket height placement. For all of the teeth out of occlusion, the brackets are placed 0.5 mm more gingivally. For those teeth in occlusion, the brackets are placed 0.5 mm more occlusally.
• Angulation: An important deviation from the regular Alexander Discipline prescription is the angulation of 0 degrees on the mandibular first molars (Fig 1-5) instead of the usual –6 degrees. This will give the mandibular first molars a forward tip that will enhance the curve of Spee and help close the bite.
Fig 1-5 The mandibular first molar brackets are angulated to 0 degrees.
• Archwires: A reverse curve of Spee is placed in both archwires.
• Elastics: Anterior and buccal box elastics should be used.
• Squeezing exercises: The patient should be taught squeezing exercises to improve occlusal forces. The patient should also be advised to chew gum to encourage such occlusal forces.
• Extractions: Extractions may be necessary, depending on the specific conditions of the case.
Reference
1. Parks L. Masticatory exercise as an adjunctive treatment for hyperdivergent patients. Angle Orthod 2007;77:457–462.
Case 1-1
Overview
Although a conscientious practitioner can learn from every case treated, certain cases stand out as especially educational when the patients display unique conditions and then respond to treatment in unexpected ways. Such a patient was a 16-year-old girl who presented with an extremely high-angle, Class III skeletal pattern (Figs 1-6a to 1-6c). Dentally, she had a Class III molar relationship, a right posterior crossbite, and an anterior open bite of 4 mm (Figs 1-6d to 1-6h). She had a mandibular arch length discrepancy of 5 mm. Figures 1-6i and 1-6j