Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Orthodontics

The aim of the study is to three dimensionally evaluate the treatment effect of the rapid molar intruder (RMI) for correction of skeletal anterior open bite in growing patients using cone beam CT. A prospective randomized controlled trial in which assessment of two parallel groups. The first group is the intervention group to which the molar intruder was applied along with the modified TPA and lingual arch. While the second group is a control group where only the modified TPA and lingual arch was applied along the study time. CBCT on the full face (maxilla and mandible) was carried on for each case before and after the period of 6 months of follow up, a questionnaire was filled by each patient to measure their satisfaction. Results showed the ability of rapid molar Intruder RMI to intrude the upper and lower molars about 1 mm and. 82 respectively, and this leads to mandibular auto rotation in a forward direction, bite closure anteriorly by average 1.61 mm and decrease in mandibular plane angle with no clinically significant root resorption or molar angulation problems. Although there were some limitations and side effects which include: high percentage fracture (60%), mild to moderate pain and disability. Conclusions RMI was able to achieve molar intrusion of the upper and lower molars about 1 mm and 82 respectively, mandibular forward rotation, decrease in mandibular plane angle and increase in the incisors over bite by average 1.61 mm and with no clinically significant root resorption or molar angulation problems. (Null hypothesis rejected) 2- Some limitations and side effects which include: high percentage fracture (60%), mild to moderate pain and disability are disadvantages of RMI

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