Student Theses, Dissertations and Capstones

Document Type


Degree Name

Master of Science (M.S.) in Dentistry


College of Dental Medicine

First Advisor

Lin, Chin-Yu

Publication Date / Copyright Date



Nova Southeastern University


Objective: This study was conducted to determine how oral health-related quality of life (OHQoL) changes during the late stage of comprehensive fixed orthodontic treatment in adolescents and what factors may be involved. Background: Completion of orthodontic treatment has been shown to improve patients’ OHQoL due to the changes in esthetics, function and emotional well-being. The levels of OHQoL fluctuate throughout treatment where an initial decrease within the first 6 months occurs followed by an improvement towards patients’ pre-treatment levels. At 18 months of fixed orthodontic treatment, the level is unclear. The aims of this study were to clarify the changes of OHQoL during this late stage of fixed orthodontic treatment beyond 18 months in adolescents and to identify factors, including dental extractions, patient compliance, use of adjunctive appliances, and patient demographics, which may contribute to the OHQoL. Methods: This case-control study consisted of 154 adolescent patients undergoing comprehensive fixed orthodontic treatment from the Nova Southeastern University orthodontic department. Subjects were selected based upon the number of months in comprehensive fixed orthodontic treatment. Completion of the Oral Health Impact Profile short form (OHIP-14) as well as occurrence of dental extraction during orthodontic treatment, use of adjunctive appliances, frequency of emergency and failed appointments, level of oral hygiene, and subjects’ age and gender were all recorded. Statistical analysis using structural equation modeling was used to determine the direct and indirect effects to subjects’ OHQoL. Results: The model accounted for 35% of the variance in OHQoL. There were no significant differences in average OHIP-14 scores between the initial stage of 5-7 months and final stage of 18 months and over in orthodontic treatment. The analysis of direct factors showed that females and subjects with adjunctive appliances possessed higher OHIP-14 scores. Conclusions: Treatment time beyond 18 months of treatment was not a significant factor affecting adolescents’ OHQoL. Female patients and those with adjunctive appliances expressed poorer levels of OHQoL. These factors may be attributed to the scores within the physical and psychological domains as these patients experienced pain and discomfort from appliance wear as well as negative impact on their self-esteem during comprehensive fixed orthodontics.




Social sciences, Health and environmental sciences, Adolescents, Appliances, Late stage, Oral health, Orthodontics, Quality of life



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