Interaction Between Subspinale and Two Expansion Protocols in Class III

Objectives: to assess and compare skeletal,dental and soft tissue changes of three RME protocols using conventional Hyrax, Hybrid Hyrax, and four miniscrew supported Hyrax using alternated expansion and constriction. Methods: 21 patients enrolled in this study with Class III maxillary deficiency, with an average age of 10.5±6 months, and allocated into three groups of seven patients each. Maxillary expansion was done with conventional Hyrax in Group I. Group II: RME with Hybrid Hyrax. Group III: skeletal four-point supported custom-made Hyrax with four palatal micro-implants and alternating rapid maxillary expansion and contraction. A cephalometric tracing of standardized cephalometric x-ray was performed for each patient before and after expansion for various linear and angular measurements and statistically analyzed Results: SNA angle increased significantly (p ≤ 0.05) from pretreatment to post-expansion stage in all groups. There was a statistically significant difference between Groups II and III. When the three Groups were compared, a considerable forward movement of point A was detected in both Group I and Group II. The forward movement of point A, the angle of facial convexity and upper lip prominence improved considerably in GII. Conclusion: Hybrid Hyrax (Group II) showed a significant improvement in forward position of point A concomitant with a significant sagittal skeletal, dental and soft tissue profile improvement.