Palate Expansion

Many modern people have narrow palates, because a strained facial growth pattern has prevented good natural palate expansion. Palates can be expanded, but extensive misinformation about palate expansion has created controversy that has made it difficult for people to understand the process.

For decades, most dentists believed that palate expansion occurs simply by separation of the two maxillary bones at the midline suture, like sliding apart two tables; and therefore it must stop when the suture closes (ossifies) in the late teenage years. Now we know that palates can be expanded in adults by using light steady forces that reshape the upper jawbone by unfolding its two maxillary bones while remodeling occurs in and around them to fit the changed bite forces. At the end of treatment, the expansion can be maintained by stabilizing the natural bite and nightly use of a retainer that employs the forces of nocturnal bruxism to broadly load the expanded structure.

NATURAL PALATE EXPANSION -  The upper jawbone is a framework of two paired (right and left) maxillary bones. In children, they grow by spreading apart and also rotating away from each other until the upper dental arch becomes wide enough to fit around the tongue. In one direction, they rotate outward and upward around the midpalatal suture while lowering that suture and flattening the palate, as seen from left to right in the illustration below. In our ancestors, very strong chewers always had very shallow wide palates.    

In another direction, the two maxillary bones swing out around their front-most connection, as can be seen from left to right in the illustration below, which flattens the midface. In our ancestors, very strong chewers also had very flat faces.

However, this natural upper jawbone expansion depends on bite forces, and our average jaw muscle strength has diminished by about half during the last couple of centuries. As a result, many modern upper jawbones do not fully expand. Instead of growing wide enough to fit around the tongue, they only grow wide enough to fit around a thumb or a pacifier. The same types of narrow upper jawbones can be produced in monkeys and other animals by just softening their diets.

Also contributing to the narrowness of our upper jawbones is the excessive vertical facial growth that results from weak jaw muscles. When bite forces are too weak to limit the eruption of the teeth from elongating the front of the face, the teeth can super-erupt and lengthen the front of face, which tightens the cheeks, which pushes inward on the molars and premolars. The role of the tight cheeks in maintaining narrow palates can be seen in the ability of Frankel appliances to expand palates simply by holding the lips and cheeks out and away from the teeth.

Also contributing to the narrowness of our upper jawbones in many people is the deep overbite and steeply interdigitated teeth that lock the upper jawbone to a lower jawbone that cannot expand, because it is one thick piece of cortical bone. Because of the way the upper and lower dental arches fit together, widening the palate generally also brings the lower jawbone forward by eliminating the restrictions to natural mandibular advancement.

THE NASAL AIRWAY - When the upper jawbone remains narrow, the nasal airway just above it also remains narrow. Typically, the upper dental arch becomes V-shaped instead of U-shaped. The upper premolar area, where the narrowing is most common, is the floor of the anterior portion of the nasal cavity, where airway flow is usually restricted. 

The narrow nasal airway causes mouth breathing. People with very narrow palates are usually obligate mouth breathers, and they have to keep their lips parted to allow adequate oral airway flow. People with palates that are barely wide enough to accommodate a nasal airway become obligate mouth breathers whenever their nasal passages swell slightly due to colds or allergies. Habitual mouth breathers have enough space for a nasal airway, but they don't use it. 

Mouth breathing causes serious health problems. It prevents the nose from moistening, filtering, and warming the air before it hits the throat - making mouth breathers prone to upper respiratory problems. It also prevents the release from the paranasal sinuses of nitric oxide into the lungs; which has antibacterial properties, a vasodilating effect, and a role in endothelial health. It also impairs the effectiveness of respiration, because the nose acts like a little lung. Volunteers putting on nose clips immediately experience lower arterial oxygen levels. Mouth breathing increases airway resistance and decreases sleep quality.

Mouth breathing also sustains itself by the way it alters facial growth, which can turn habitual mouth breathing into obligate mouth breathing. Lowering mandibular posture to create space for an oral airway passage causes the face to grow vertically instead of horizontally, which prevents the nose from growing wide enough to allow normal nasal breathing. Monkeys forced to mouth breathe lower their mandibles to create an oral airway passage, which causes the face to follow it downward, resulting in long narrow faces. In humans, the mandible is much shorter, so lowering the mandible also rotates it backward; - resulting in long, narrow, and retrusive faces (recessed chin). 

TONGUE POSTURE - When the palate is too narrow to house the tongue, the tongue needs somewhere else to rest. If it shifts down and back, it can plug the airway and cause sleep apnea. It may reposition down and back into the pharynx, where it causes apnea; it may reposition between the molars and premolars, causing a visible scalloping in the sides the tongue; or it may reposition forward between the front teeth, leading to an anterior open bite.

NON-SURGICAL PALATE EXPANSION - can widen the base of the nose and thereby create enough space to restore nasal breathing by using an oral appliance that delivers light steady forces for 3 to 6 months transversely across the palate. In adults, the appliance does not separate the two maxillary bones at the midline or widen the gap between them, like it does in children. Instead, the two maxillary bones respond to light steady forces by rotating outward, like spreading a pair of wings, which lowers the suture; while the rest of the midface adapts by remodeling its structural elements to accommodate the altered bite forces. 

Pushing on the teeth to expand the palate also tips those teeth to an extent that depends on the mechanics used to provide the expansion forces. Bent wire appliances, such as quad helix appliances, bionators, Crozats, and ALF (advanced lightwire functional) appliances tend to do more tipping of teeth and less expansion of the bones. Expansion screw appliances; such as Schwartz, Haas, Biobloc, Homeoblock, DNA, RNA, and Hyrax appliances; employ powerful turnbuckles which can significantly move the maxillary bones, but they still cause tipping. Recently some orthodontists have been using fixed (glued in) palate expanders with TADs (temporary anchorage devices), which are tiny lag screws temporarily implanted in the palate (MARPE), to maximize movement of the bones and minimize the tipping of the teeth. They make palate expansion more effective, but they must be kept very clean.

Palate expansion can probably be enhanced by a chiropractic treatment called nasal release or nasal specific technique; which expands a little balloon  inside the nasal cavity.

OUR PALATE EXPANSION APPLIANCES are expansion screw appliances that have a thin metal expansion framework. There is no bulk in the front of the palate, where it would interfere with tongue posture and speech. Whether finger springs or orthopedic inclines are added depends on patient needs.  

 

Although palate expansion devices usually come with instructions to perform two turns weekly, we recommend making frequent turns that are as small as possible, because light steady forces shape bones. If the expansion produces pain, you are going too fast and triggering localized inflammation, which prevents smooth remodeling of bone. 

You can take your appliance out for meals and important social functions, but it cannot be worn only at night, unless the bite is very flat, or the interdigitation of upper and lower teeth will return the palatal bones to their pre-treatment positions every day.   

RETENTION - After the expansion, it needs to be retained by widely loading the upper dental arch in the newly expanded alignment, both in the natural bite and in the retainer worn every night. The retainer can also include orthopedic features such as a front flat bite plate for those who had a deep overbite before treatment, springs to continue moving individual teeth, or inclines that promote mandibular advancement.

RESTABILIZING THE BITE - The expansion process always destabilizes the bite, at least temporarily. The bite may then restabilize naturally, especially if combined with mandibular advancement, which brings a wider part of the lower dental arch underneath the widened portion of the upper dental arch. However, if the upper and lower teeth are steeply interdigitated, any change in their relative positions can cause uncomfortable collisions between teeth, and adjusting the bite may be necessary to facilitate post-treatment stabilization.   

If necessary, the lower teeth can be uprighted during palate expansion by including flanges that reach down along side the inner edges of the lower teeth; or they can be uprighted after palate expansion by wearing a small unobtrusive removeable "spring" type of appliance, a series of clear aligners, or orthodontic elastics attached to tiny buttons glued to the sides of the involved teeth to pull individual pairs of teeth into proper alignment.  

GAPS BETWEEN TEETH - result from palate widening. If the teeth were crowded before treatment, simply straightening the teeth can close the gaps and realign the teeth into a complete arch, which is incompressible and thereby functions as a good retainer. If some front teeth are unusually narrow, the gaps can be closed by widening those teeth using veneers or crowns. 

COMBINING PALATE EXPANSION WITH A SLEEP APNEA APPLIANCE - When a patient has both a narrow palate and obstructive sleep apnea, we can combine treatment mandibular advancement and palate expansion by using a palate expansion appliance to which the telescopic components and the lower member of the mandibular advancement appliance can be added every night. The process requires dexterity, but most people have no trouble with it.

COSTS - Our fee is $2,000 for the basic expansion screw appliance. If more widening is needed, a second stage of expansion can be made for about half that fee. If more tooth straightening is desired, springs can be added.