The purpose of this study was to determine which factors related to patient self-assessment of dentures are associated with changes in oral health-related quality of life (OHRQoL) among edentulous patients after replacement of complete dentures, and to determine whether masticatory performance as determined using an objective method affects the changes in OHRQoL among edentulous patients. As a preliminary study, the existing questionnaire regarding self-assessment of dentures consisting of 39 question items, measured with a 100-mm visual analogue scale, was analysed by factor analysis. Then a questionnaire, composed of 22 question items, was developed containing six subscales of 'function', 'lower denture', 'upper denture', 'expectation', 'aesthetic and speech' and 'importance'. Final participants in the present study comprised 93 edentulous patients requiring new conventional complete dentures (44 men, 49 women; mean age, 75·0 years). These patients were asked to complete the Japanese version of the Oral Health Impact Profile (OHIP)-EDENT, comprising 19 question items for assessment of OHRQoL in edentulous patients, along with the developed questionnaire regarding self-assessment of dentures. Moreover, masticatory performance was measured using a colour-changeable chewing gum. The questionnaire and measurement were completed twice; before and after replacement of complete dentures. Stepwise multiple regression analysis identified 'lower denture' and 'aesthetic and speech' as significant independent variables besides OHIP-EDENT scores before replacement. These results suggest that sufficient retention of lower dentures and appropriate appearance may lead to improved OHRQoL in edentulous patients.