BACKGROUND: The objective of this study was to explore and compare patient's experience with the use of a removable functional appliance or fixed orthodontic appliance and its influence on oral health-related quality of life. MATERIAL AND METHODS: This clinical trial included 81 participants having Class II Division 1 and age ranging between 10 and 16 years. The participants were included in any of a three equal groups according to the set inclusion and exclusion criteria; Group 1: patients treated with a Twin-Block functional appliance; Group 2: patients treated with a fixed orthodontic appliance only; and Group 3 (control group): patients not in orthodontic treatment yet. The COHIP SF-19 was used. Patients were given the questionnaire as follows: Group 1: (1) after at least 8 months from starting treatment; (2) after completing phase 1 by 2-3 months without wearing the appliance; Group 2: (1) just before debonding; (2) after finishing the treatment by 2-3 months without any appliances; and Group 3: (1) at the patient's first visit to the orthodontic clinic; (2) after 2-3 months from the first visit to the orthodontic clinic and before starting any treatment. RESULTS: The 81 participants were 31 males and 50 females with median age of 13 years. The total COHIP SF-19 scores at baseline were 57 (49-64), 67 (63-72), and 47 (42-53) for the Twin-Block, the fixed appliance, and the malocclusion groups, respectively. Two-month mean scores adjusted to the baseline scores were 64.82 ± 1.15, 65.65 ± 1.47, and 54.45 ± 1.44 for the Twin-Block, the fixed appliance, and the malocclusion groups, respectively. CONCLUSIONS: Both at baseline and two-months (adjusted to the baseline scores), participants in the malocclusion group showed compromised socio-emotional quality of life and reported the poorest total OHRQoL. At the baseline, better socio-emotional and total OHRQoL was reported by the fixed appliance group compared to the Twin-Block group but, after two months both groups gave similar sores. Therefore; patients' perceptions about their experience with the orthodontic appliance might change.