Expansion

Rapid Maxillary Expansion (RME) is the widening of the maxilla(upper jaw) by controlled stretching of the midpalatal suture (the soft connection between the two halves of the upper jaw), which is then returned to normal through the formation of new bone.

RME is needed when the maxilla is narrow compared to the mandible (lower jaw). Usually this presents as a posterior crossbite. Teeth are in crossbite when the lower teeth overlap the upper teeth. There are two important exceptions caused by tipping of the teeth: 1)  there is no crossbite present even though a RME is needed.  2) a crossbite is present even though RME is not indicated.

Tipping of the teeth can be evaluated clinically, but it is more precisely evaluated with digital study models that allow viewing and measuring in infinite ways. Once tipping has been taken into account, the amount of expansion needed can also be calculated by measuring the virtual study models.

Rapid Maxillary Expansion (RME) is the widening of the maxilla(upper jaw) by controlled stretching of the midpalatal suture (the soft connection between the two halves of the upper jaw), which is then returned to normal through the formation of new bone.

RME is needed when the maxilla is narrow compared to the mandible (lower jaw). Usually this presents as a posterior crossbite. Teeth are in crossbite when the lower teeth overlap the upper teeth. There are two important exceptions. 1) When the maxillary posteriors are tipped buccally and/or the mandibular posteriors are tipped lingually, a crossbite may not be present even though a TMMI exists and RME is indicated.  2) When the maxillary posteriors are tipped palatally and/or the mandibular posteriors are tipped buccally a crossbite may be present even though a TMMI does not exist and RME is not indicated.

Tipping of the teeth can be evaluated clinically, but it is more precisely evaluated with digital study models that allow viewing and measuring in infinite ways. Once tipping has been taken into account, the amount of expansion needed can also be calculated by measuring the virtual study models.

Several appliances are available for expansion.  The Rapid Palatal Expander (RPE) or “Hyrax” appliance is the most precise with the fewest potential complications. The RPE, when used correctly, is one of the most effective and predictable orthodontic appliances available. When fabricated properly it is also the appliance most easily tolerated by patients.

Once the first molars have grown in, distance between them doesn’t change.  Failure to expand where indicated will prevent correct occlusion and cause uneven jaw growth that can only be corrected with surgery as an adult. 

While expansion has the “bonus” effect of improving “crowding”, it should not be used as a treatment for crowding in the absence of a narrow upper jaw. This would result in the creation of a malocclusion.

Recently two other “bonus” benefits of RME have been identified.  In patients with conductive hearing loss, RME was 100% effective in improving hearing.  More puzzling was the effect on patients with nocturnal enuresis or “bedwetting”.  Patients who had RME were 50% more likely to exhibit improvement as compared to a control group.

While all patients with crossbite should have an orthodontic consultation, it is more prudent to for all children to have an orthodontic evaluation by 7 or 8 years of age.Several appliances are available for expansion.  The Rapid Palatal Expander (RPE) or “Hyrax” appliance is the appliance taht I prefer. It is the most precise with the fewest potential complications. The RPE, when used correctly, is one of the most effective and predictable orthodontic appliances available. When fabricated properly it is also the appliance most easily tolerated by patients.

Once the first molars have grown in, the distance between them doesn’t change.  Failure to expand where indicated will prevent correct occlusion and cause uneven jaw growth that can only be corrected with surgery as an adult. 

While expansion has the “bonus” effect of improving “crowding”, it should not be used as a treatment for crowding in the absence of a narrow upper jaw. This would result in the creation of a malocclusion.

Recently two other “bonus” benefits of RME have been identified.  In patients with conductive hearing loss, RME was 100% effective in improving hearing.  More puzzling was the effect on patients with nocturnal enuresis or “bedwetting”.  Patients who had RME were 50% more likely to exhibit improvement as compared to a control group.

While all patients with crossbite should have an orthodontic consultation, it is more prudent to for all children to have an orthodontic evaluation by 7 or 8 years of age.

Dr Frank R. Egan

www.TeethOnTheMove.com

First Orthodontic Checkup

I agree with the American Association of Orthodontists recommendation that all children have an orthodontic checkup no later than age 7. At this age, the permanent incisors(front teeth) have begun to erupt along with the first molars. Also, important facial features are beginning to take form. For a select few patients, treatment at this age will prevent the need for more invasive or unpredictable treatment in the future.

This is the best time to correct certain jaw growth problems including narrow maxilla or “upper jaw” (usually presenting as a posterior crossbite) and short maxilla (usually presenting as an anterior crossbite). It is also an excellent time to address open bites caused by habits such as thumbsucking and functional problems such as tongue-thrusting. Impaction (inability to erupt) of the permanent incisors and first molars should also be addressed at this time.

Other problems such as mandibular (lower jaw) deficiency and excess are usually not best addressed early. The same is true with spacing and crowding, except when social reasons are in play. Frequently incisor irregularity and incisor protrusion are disfiguring to the point that it would be cruel not to correct it early even though a good result could be achieved by starting later. This is determined in consultation with the child and parent.

It is important to remember that the first orthodontic examination usually does not result in immediate treatment. However, it does give parents greater peace of mind.  It also gives me information to use in the future when the patient is ready for treatment. I much prefer to have a record of three or four annual observations prior to evaluating a 12 year old for treatment rather than observations at one single point in time.

After the initial evaluation, I will monitor facial growth and development with periodic checkups while the permanent teeth erupt and the face and jaws continue to grow. During this period of “watchful waiting”, small problems in growth or development can be noticed and corrected before they become bigger problems.

For some patients, it is best to delay orthodontic treatment until all of the primary teeth are lost. With severe mandibular prognathism, it may even be best to wait until the jaws are finished growing.

By beginning treatment at the ideal time, the best results can be achieved in the least amount of time. 

Dr. Frank R. Egan

www.TeethOnTheMove.com