Purpose: This study investigated changes in oral health-related quality of life (OHRQoL) in partially edentulous patients treated with removable dental prostheses (RDPs), fixed dental prostheses (FDPs), fixed-removable (combined) restorations (COMBs), and implant-supported fixed prostheses (ISFPs). Materials and Methods: A total of 200 patients (30 to 50 years old) were enrolled: 45 received RDPs, 32 received FDPs, 66 received COMBs, and 57 received ISFPs. OHRQoL was measured using the shortened version of the Oral Health Impact Profile (OHIP-14) before treatment and 6 weeks and 6 months after treatment. Treatment groups were sex-neutral; however, significant differences were found relative to age and Kennedy classification. A general linear model was used to explore the interaction of age and Kennedy classification with treatment modality. Results: Pretreatment analysis revealed that the psychologic discomfort domain showed the greatest negative impact on OHRQoL, while functional limitation had the smallest effect. Within-group comparison revealed a significant decrease in OHIP scores throughout the study in all groups except the younger age group treated with RDPs after 6 weeks. Between-group comparison revealed significant differences among the treatment groups. The least amount of OHRQoL improvement was recorded for RDPs for both age groups at 6 weeks and for the younger age group at 6 months. There were no significant differences between FDPs and ISFPs. Conclusions: All treatments produced significant improvement in OHRQoL. The least amount of improvement was observed in patients with RDPs. OHRQoL changes in patients treated with FDPs and ISFPs were comparable. The same treatment can have different impacts on the OHRQoL of partially edentulous individuals depending on their age and Kennedy classification.