Third Molar Position and Angulation In Orthodontically Treated Patients With Class II Malocclusion
thesisposted on 27.10.2017 by Rory A Chong
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Purpose: To determine whether Class II correction with non-extraction appliance therapy with mandibular advancement results in favorable rotational and positional changes in the mandibular third molar. Objective: To evaluate in 3D the treatment effects on the mandibular third molar angulation and position of Class II Division 1 patients pre-treatment to post-treatment with non-extraction orthodontic therapy with mandibular advancement. Methods: The sample will consist of CBCT images, pre-treatment and post-treatment, of an experimental group of 34 subjects with Class II Division 1 malocclusion treated orthodontically into Class I with non-extraction appliance therapy. Pre-treatment and post-treatment changes in position and angulation will be compared for left and right mandibular third molars. Additionally, pre-treatment and post-treatment changes in a group of 35 subjects with Class I malocclusion treated orthodontically with non-extraction appliance therapy will be used as a control group to compare changes resulting from treatment. Invivo5 Dental Version 5.4(Anatomage, San Jose, CA) software will be used to measure the changes in position and angulation in 3-D from the pre-treatment and post-treatment CBCT images. An analysis will be conducted to determine the changes of third molar angulation and position resulting from growth and treatment. Results: Mesial angulation and buccal uprighting improved for the Class II group. Change in anterior displacement evident in both groups, but a greater change anteriorly noted for the Class II group. Change in transverse position medially for both groups as a result of treatment. Positional changes for total distance and transverse displacement within subjects of Class I subjects between left and right third molars evident due to treatment. Conclusions: Class II correction mandibular advancement appliance therapy results in favorable rotational and positional changes in mandibular third molars.