Objective: The aim of this study was to assess the impact of occlusal problems on quality of life in 288 patients who had undergone fixed orthodontic therapy, as well as to investigate the factors associated with this impact. Material and Methods: The orthodontic treatment needed by the IOTN index and the adequacy of treatment through the PAR index were evaluated in models. The impact on quality of life was assessed using the CS-OIDP index. For data analysis, we used the MannWhitney and Kruskal-Wallis test for a confidence level of 95%. Results: The impact of malocclusion on quality of life was low, being present in 29.2% of cases. Performances of smiling, emotional state, and cleanliness of the mouth were the most affected. Factors related to the impact were the kind of service of the treatment performed, the need for orthodontic treatment, type of problem that motivated the treatment, and current age at the end of treatment. Conclusions: Despite the low impact, it was strengthened the hypothesis that patients undergoing orthodontic therapy had an improved quality of life.