Pressure-potential alopecia areata.

In order to create awareness of a potential adverse effect of extraoral orthodontic appliances, we report the development of alopecia areata in two patients. Both patients experienced the onset of alopecia areata directly under sites of pressure from thier "headgear." In one patient the hair loss began 2 weeks after she began using her appliance. The other girl noticed patchy alopecia 2 to 3 weeks following an increase in the pressure and duration of use of an extraoral appliance. One of the patients also developed other areas of alopecia areata in sites unrelated to pressure. In both cases relief of the pressure was accompanied by regrowth of hair in about 5 months. One of the patients received corticosteroid injections into the patches of alopecia areata; the other had no medical therapy. We conclude that alopecia areata can be made manifest by local pressure, such as that from orthodontic appliances.