Most patients that present with a small lower jaw and a narrow upper jaw (see picture to the right) can attribute this to adverse muscle activity during the growth process. The form of the jaw bones follow closely with the function of the surrounding muscles. If the jaw muscles are too strong (i.e., from thumb or lip sucking, etc.), then the muscles resist the growth as it is occurring. Patients can inhibit 50% or more of what would have been their normal growth. Treatment to correct this problem is started roughly around age eight to nine years. Growth cannot be created. It is only enhanced/modified by altering the force muscles applied to portions of the jaw and dental arches during growth. After age 11, there is usually insufficient growth to make a correction with growth modification.
This is a Frankel II Orthopedic Appliance. Notice the acrylic pads around the arch that extend down to the attachment level of the cheeks and lips. Here, the lower "lip pads" are 2mm away from the teeth and bone; the upper pads rest directly against the upper teeth and bone. The lower jaw has also been postured forward to create tension in the joint spaces which, when the muscle forces are removed, enhances lower jaw growth.
Notice the correction of the lower jaw and the facial profile. This patient wore the Frankel II Orthopedic Appliance for about 24 months. There has not been any surgical correction. All visible changes are simply from growth modification and re-training muscles with a single removable retainer-like appliance. This is a lifetime correction.
Once the growth has been modified and stabilized and the upper and lower jaws are in their correct relative relationship (usually by age 11 to 12), the Frankel II Orthopedic Appliance is reduced to night wear and a custom removable appliance (known as a positioner/pre-finisher) is used to guide the permanent teeth into full contact.
The appliance to the right is a pre-finisher guidance appliance. It is made of a hard rubber that, when bitten into, forces the erupting and erupted teeth into an ideal occlusion as set up in the appliance. This appliance is worn four to eight hours daily. It can also be worn at night as a retainer after treatment.