Objectives: The present study was conducted to evaluate the dentoskeletal changes after distalization of maxillary molars using skeletally-anchored modified Hyrax appliance in the treatment of dental Class II orthodontic patients. Subjects and methods: Ten participants having Class II molar relation with deep overbite with age ranged from 11 to 14 years old were enrolled in the current study. All patients involved in the present study were selected from those seeking orthodontic treatment at different clinical orthodontic centers. Maxillary molar distalization was performed using modified skeletally anchored Hyrax palatal expander. The appliance was activated twice weekly. For each participant, skeletal and dental measurements were recorded from standardized cephalometric analyses before and after molar distalization. Statistical analyses including t-test were performed at a significance level of p<0.05. Results: The maxillary first molars were distalized successfully (6.16 mm) without tipping and Class Ι molar relation was obtained within a period of 6.2 months. Slight extrusion of the maxillary molars was observed which was reflected on the non-significant increase in lower anterior facial height, as the mandibular plane angle was increased by 0.58 0 . A marked improvement of the deep bite was observed. Conclusion: The modified Hyrax can be used as palatally skeletally anchored distalizer to effectively move the maxillary first molars distally. They are effective, minimally invasive and compliance free alternative for molar distalization and hence, molar Class II correction without anchorage loss.

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. Subjects and 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.