Date of Graduation


Document Type


Degree Type



School of Dentistry


Not Listed

Committee Chair

Peter Ngan.


Objectives. To evaluate the short and long-term results of using a Modified Hyrax Expander with Protraction Facemask at an early age. Methods. Twenty three patients were treated with Dr. Kiebach's Modified Hyrax Expander and Protraction Facemask at an early age. Lateral Cephalograms were taken at three time points: pre-treatment (T1), post-treatment (T2), and 2 years post-treatment (T3) and evaluated using cephalometric analysis. Results. Statistically significant results were found for all three time points: T2-T1, T3-T2, and T3-T1. The Palatal Plane, Mandibular Plane, and the Occlusal Plane were the only values to show non-significant results throughout the three time points. The overjet and correction for T2-T1 was 52% dental and 48% skeletal. The molar correction for T2-T1 was 115% skeletal and -15% dental. The T3-T2 findings for overjet correction showed a negative 2 mm skeletal correction, but a 1.9 mm dental correction. The same was true for the molar correction for T3-T2. There was a negative 2.16 mm skeletal relapse, but a positive 1.92 mm dental correction. Evaluating the overall change using T3-T1, the results showed a mostly dental correction for overjet at 105% and a molar correction that was 113% dental. Overall, the maxilla moved forward 4.2 mm while the mandible moved forward 4.4 mm. Conclusions. Treatment at a young age using a Modified Hyrax Expander with Protraction Facemask is successful in treating a Class III malocclusion. The correction is both skeletal and dental.