Introduction: Measuring well-being in dental patients allows early detection of emotional disorders. Objective: To evaluate the psychometric properties of the Wellbeing index by the World Health Organization (WHO-5 WBI) in partially edentulous patients. Materials and methods: Scale validation study and diagnostic tests without reference standard performed in 105 patients treated at an oral implantology service. The WHO-5 WBI was applied before treatment and an exploratory factor analysis was performed to determine the amount of factors in the construct that confirmed its validity and internal consistency through Cronbach’s alpha and McDonald’s omega. Results: The exploratory factor analysis showed a single factor solution that accounted for 56.17% of the variance. The confirmatory analysis showed adjustment indexes X2=1120.516; df=10, p=0.04; RMSEA=0.134 (90% CI: 0.056-0.217); CFI=0.992; TLI=0.983 and WRMR= 0.61. Conclusions: The WHO-5 WBI showed acceptable reproducibility, one-dimensional factor structure and questionable construct validity.