Master of Science (MS)
First Committee Member
Second Committee Member
Third Committee Member
Fourth Committee Member
Number of Pages
The aim of this study is to gather and analyze data representing detailed changes in model and cephalometric variables that will support clinicians in the premolar extraction decision- making process during camouflage treatment of class II dental patients. It is expected that the models, as measured by intra-arch dimensions, overjet, overbite, and mandibular crowding, and cephalometric radiographs, evaluated by their anteroposterior skeletal discrepancy, incisor inclinations, dental and skeletal vertical positions, and soft tissue characteristics, will significantly differ from within the same treatment group, pre-treatment to post-treatment, and between treatment groups. This retrospective study evaluated the model and cephalometric changes in a total of 74 subjects, with 33 subjects in group 1, who received extraction of maxillary first premolars as part of their comprehensive orthodontic treatment, 27 subjects in group 2, who received extraction of maxillary and mandibular first premolars, and 14 subjects in group 3, who received extraction of maxillary first premolars and mandibular second premolars. Intra-arch dimension at the canines, premolars, and molars for both upper and lower arches, overbite, overjet, and mandibular crowding were measured on digital models on OrthoCAD or OrthoAnalyzer software. Digital cephalometric radiographs were traced on Dolphin and analysis included SNA (°), SNB (°), ANB (°), Wits (mm), maxillary incisor inclination (U1-SN) (°), maxillary incisor protrusion (U1-NPog) (mm), mandibular incisor inclination (IMPA) (°), interincisal angle (U1-L1) (°), mandibular plane angle FMA (MP-FH) (°), anterior facial height (mm), posterior facial height (mm), upper lip to E-plane (mm), lower lip to E-plane (mm), nasolabial angle (°), soft tissue convexity (°), upper lip thickness (mm), and lower lip thickness (mm). The varying premolar extraction patterns do have a significant impact on the model and cephalometric characteristics, both within treatment groups and between treatment groups. All three treatments successfully and significantly reduced the amount of overjet and mandibular crowding. Extraction of maxillary and mandibular first premolars allowed a greater amount of mandibular crowding to be relieved. Nonextraction in the lower arch significantly increased the degree of lower incisor flaring. Inclusion of a larger patient population in future studies would allow the collection of more definitive and detailed documentation to identify exactly how removal of different premolars affect skeletal, dental, and soft tissue esthetics.
Model and cephalometric variables; Premolar extraction decision- making process; Class II dental patients
University of Nevada, Las Vegas
Ven Dange, Melissa Marie, "A Comparison of Lateral Cephalometric and Arch Dimension Changes in Patients with Class II Malocclusions Treated With 2-Premolar and 4-Premolar Extraction Patterns" (2020). UNLV Theses, Dissertations, Professional Papers, and Capstones. 3971.
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