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ORTHODONTIC CROSS-BITES AND PALATAL CONSTRICTION
Photos and discussion of how to do a palatal expander
Crossbites are a reverse position of one or more teeth. A crossbite can be due to either the teeth themselves being reversed in position, or more commonly, the upper jaw and palate are constricted to the extent that the upper teeth do not match the lower teeth on one or both sides. Think of normal as the upper teeth being like a jelly jar top fitting out and over the jar. The upper teeth should be to the outside of the lower teeth on both sides of the mouth.
What causes the palatal constriction and crossbite? Usually genetics, but sometimes unusual eruption of the teeth themselves or a myofunctional problem. A constricted palate, which causes the teeth to be in crossbite is usually genetic in nature, and can be traced to one side of the family. Another cause can be thumb sucking which functionally constricts the palate and deforms the upper jaw. Severe tongue thrusting, openbite and other habits can contribute to the narrow palate. In any case, the result is the same and it is not self-correcting.
Signs of a genetic type problem: the bone of the lower jaw is wider than the upper. The upper jaw has a "pinched", narrow look. Note the upper teeth in the back cross over to the inside on one side, but not the other. With this "unilateral" type of crossbite, the midline of the upper and lower teeth do not match. Sometimes the back teeth are reversed on both sides and this is due to an extremely narrow upper jaw.
Generally, correction of an upper jaw problem can be started as soon as the upper first molar is fully erupted. This usually occurs at age eight. If the molar is not fully erupted, then the correction appliance is too difficult to fit and maintain. The other reason to delay treatment is due to very immature or fearful children. In severely constricted cases, treatment as early as age five may be necessary and can be successfully completed in the same time frame as later treatment, however a second phase of treatment may be necessary.
In either type of crossbite, it is essential to start treatment before growth is completed. Consequences of not treating the problem are severe: one side of the jaw will grow longer than the other, the nasal airway will be too narrow, and the jaw joints will not function properly. If the early growth period (up to age 16) is missed, then a very, very slow special expansion or surgery will be required to correct the problem. The reason expansions don't do well and need to be completed prior to the end of the growth period, is because the bones which knit the pieces of the face and skull together are fused after about age sixteen in females and nineteen in males. It is possible to expand adults, but much easier in growing individuals. The earlier you do an expansion, the better the results.
At an early age, the facial bones are not fused to allow for brain and facial development. During this time, you can move the parts of the face without any problems. The later you expand the more likely various areas have fused and those areas do not expand as well, causing warping of the bones and less unpredictable results. For the same reason, it is best to hold the expansion with a fixed appliance on younger children. .
Positive results which occur from correcting the constricted palate are: widening of the cheek bones, opening up of the airway and nasal passages to improve breathing, better muscle control during chewing, more space to align the teeth and avoid crowding, allows normal growth of the lower jaw as the tongue moves higher in the oral cavity, and normal development of the jaw joints.
A few more comments about the jaw joints. With a constricted palate, the fossae of the skull, which the lower jaw articulates against, is not in a normal position. The lower jaw then has to swing out of position to function. When the lower jaw is not swinging normally against the skull, the fossa, where one bone fits against the other, can become worn and abnormally shaped. The result can be TMJ syndrome at a later age with clicks, pops, and pain in the joint in front of the ear. The earlier the correction is made, the better the chances of the fossae being normal in shape in position.
In our office, the palatal crossbite is corrected with a fixed (cemented) appliance, and usually requires about four to six months to get the correction. There are variations in the devices which are used to make the correction.
A longer acting fixed quad-helix appliance may be used when longer term expansion is needed. The doctor will decide which appliance is best suited for your particular problem.
This section contains information on orthodontic problems and treatment, however orthodontic treatment is highly personalized and varies from patient to patient depending on the situation and doctor.
