This is one of the most popular fixed arch expansion appliances for mixed and permanent dentition. Since it is fixed, cooperation is guaranteed.
The hyrax appliance consists of a midline hyrax screw, first molar bands, mesial rests on the first primary molars or first bicuspids usually. These mesial rests must be secured with flowable composite for added retention.
The hyrax is adjusted slowly, twice per week. After the desired amount of expansion has been achieved the appliance must be left in for an additional 6 months to avoid a relapse.
Maxillary Banded Hyrax with Crib
This is the most popular fixed appliance to be used mainly in mixed dentition to help develop the upper arch to normal width as well as to use a fixed crib to stop the tongue or thumb habit. To prevent habits, particularly at night, when the patient is asleep, you need a fixed appliance to successfully correct the habits.
This appliance consists of a hyrax screw, a habit crib, first molar bands, mesial rests on the first primary molars. These mesial rests must be secured with flowable composite for added retention.
The hyrax with a crib must be adjusted slowly twice per week. The crib should be left in for 5 months in order to correct the tongue or thumb habit. Usually the open bite will be corrected as the incisors will erupt when the habit has been corrected.
After 5 months, remove the crib but leave in the appliance for 6 months after the last adjustment of the hyrax screw to prevent a relapse.