Clinical Tips

Palatal Expansion: How much is enough?

with Raymond P. Howe, DDS, MS

OP: How long have you been working with palatal expanders?

Howe:I have been working with some form of palate expansion since I began my career in 1978. These have included rapid palatal expanders, Frankel appliances, and a 038-inch, stainless-steel W-shaped wire with four helical springs. For the past 20 years, I have used primarily helical-spring appliances for maxillary expansion.

OP:Have you found a difference in the effectiveness of adults and children with regard to expanders?

Howe:I have found that the earlier the expansion is undertaken and the longer the expansion is maintained, the more stable and successful the expansion will be. In my experience, rapid palatal expansion has limited success with adults, as does expansion with helical-spring appliances. A passive ligation bracket system shows promise in expansion in adults.

OP:Do you have compliance issues?

Howe:The helical-spring appliance is a nearly compliance-free device. However, it does require compliance with good oral hygiene and restrictions in diet, including avoidance of hard foods as well as the usual avoidance of soft drinks and sugary foods.

OP:Do you have more, less, or the same amount of relapse using the expander rather than other treatment modalities?

Howe:I have very little relapse in expansion. This is because I leave the appliance in place 24 months or longer after the expansion is complete.

OP:Is there such a thing as too much expansion?

Howe: The tooth size, arch width expansion study that Jim McNamara, Kathleen O’Connor, and I published in the mid 1980s1indicated that, on average, dental arch width at the first permanent molar-free gingival margin needs to be about 37 mm in girls and about 38 mm in boys to align average-sized teeth. I think it is important during expansion to assess facial balance and harmony so that the dentition and smile is compatible with the patient’s facial size and dental display.

OP:Do you have any tips for other orthodontists about the most effective way to build or place expanders?

Howe:I do have strong opinions about the construction of helical-spring appliances. In my view, these appliances are most effective if the wire is soldered directly to the molar bands. When attachments are used to make the appliance removable, these attachments allow tipping of the teeth so that the mesial cuspids of the maxillary molars are extruded.

Second, I think this appliance is best constructed on a holding jig or using spot welding to pre-position the bands so that the axial inclination of the bands is parallel both mesiodistally and buccolingually.

The third tip in constructing the appliance is to orient the bands so that maxillary molar rotation is ideal with the appliance in its passive state. If this appliance is constructed on a plaster model of the patient’s malocclusion, the resulting appliance will have undesirable mesiolingual rotation of the maxillary molars built in as well as lingual root torque of the first maxillary molar. Correction of torque and rotation should be built into the appliance prior to placement.

The principal advantages of the helical-spring appliance are that it is simple to construct in our office in a single appointment so that the patient does not have to return for spacers a second time. It requires no turning by parents or patients at home. It is easy to clean, and it does not interfere with speech. It is relatively comfortable, and once expansion is complete, the appliance may be left in place as a retainer of the expansion.

I am currently using a passive ligation bracket system for expansion, and I am comparing it to the results I have obtained with the helical-spring appliance.

Raymond P. Howe, DDS, MS, maintains a private practice in Chelsea, Mich. He has taught at the University of Detroit Orthodontic Department, published numerous journal articles, and taught continuing-education classes in the United States, Canada, Mexico, Central and South America, and Europe. He has been granted US patents on improvements in orthodontic appliances. He is a member of the Michigan Dental Association, the American Dental Association, and the AAO. He can be reached at

1. Howe RP, McNamara JA Jr, O’Connor KA. An examination of dental crowding and its relationship to tooth size and arch dimension. Am J Orthod. 1983;83(5):363-73.