At age 13, the patient chooses surgery or maxillary protraction
Pre-treatment records. Check for parallel path of insertion of RPE along anchor teeth. Prior alignment is needed if teeth are tilted in opposite direction.
Banding of the lower first and second molars, bonded orthodontic brackets for the lower arch premolars and anterior teeth. Initiate leveling of mandibular dentition. Stabilize lower dentition in a stainless steel rectangular archwire,
Banding maxillary molars and premolar (or canines) for a Hyrax rapid palatal expander placed high in vault of palate.
Delivery of Hyrax expander. Demonstration of screw turns needed to expand and constrict the Hyrax expander. Sutural loosening is initiated by activating the appliance two turns in the morning and two turns in the evening. The expansion rate is 1 mm/day. The screw turns follow the same direction for one week.
At the end of the week, the patient returns to the clinic to demonstrate ability to insert the swivel key into the screw of the Hyrax expander. The swivel key is suspended in the RPE prior to activation to make sure that the key is fully inserted. The reverse direction is taught so that patient so that he/she is proficient in both directions with the swivel key.
Expansion and constriction is alternated each week. Recall after four weeks.
After eight weeks of alternating expansion with constriction, the facemask and Class III elastics are given to the patient to start protraction. The patients are instructed to wear the facemask at night to “pull” the maxilla forward and wear the Class III elastics during the day to “hold” the results obtained by the facemask. Expansion and constriction are continued during protraction. The facemask bar for protraction elastics is placed at the level of the lower lip to provide a slight downward direction of pull from the premolar bands in the Hyrax expander. The facemask is used with elastics to the premolar bands during the evening. Heavy force Class III elastics are placed from hooks anterior to the mandibular canine to the maxillary first molar bands of the Hyrax expander 24 hours/day with intermittent changes before and after meals. The elastics are stretched to their elastic limit to maximize force.
After two weeks, the patient returns to demonstrate ability to use facemask and intraoral elastics. Some correction such as edge-to-edge occlusion should have occurred by this time. The elastics are changed to heavier and shorter elastics as the distance between RPE and headgear is shorter.
Continue the facemask and Class III elastics until the underbite is over corrected into a Class II malocclusion by at least 3 mm. Maintain the correction with 24 hour Class III elastics.
After four months, remove RPE and replace with maxillary brackets and bands for orthodontic alignment.
Class III elastics are used for 18 months during the arch alignment, finishing and retention stages of treatment.
