Purpose: To investigate the relationship between oral health-related quality of life (OHRQoL) and usage period of complete dentures. Materials and Methods: Data were obtained from 432 edentulous patients who required complete dentures as part of an investigation registered in the University Hospital Medical Information Network (UMIN) Center (UMINCTR clinical trial, unique trial number: 000028711). Mandibular ridge form, denture quality, and usage period of the dentures were recorded and incorporated into a multiple linear regression analysis. Results: Multiple linear regression analysis in the 267 participants who completed the study demonstrated significant effects on OHRQoL of mandibular ridge form, mandibular denture stability and retention, accuracy of jaw relation recording, and usage period of dentures. Conclusion: A significant relationship between the usage period of dentures and OHRQoL in complete denture wearers was noted when the effects of mandibular ridge form and denture quality were controlled for.