Objective <p>To introduce and apply Functional Dentition Life Expectancy (FDLE) as an indicator integrating tooth retention with longevity, alongside Edentulism-Free Life Expectancy (EFLE), using Chile as a case study.</p> Materials and methods <p>This study applied FDLE and compared its performance with EFLE as population oral health indicators. Using data from the Chilean National Health Survey 2016–2017 (<i>n</i> = 5,516) and national life tables. Survey-weighted estimates of mean tooth count and the prevalence of edentulism and functional dentition (≥ 20 teeth) were calculated by age, sex, and educational level. EFLE and FDLE were then estimated by sex using the Sullivan method, integrating age-specific oral health prevalences with mortality data.</p> Results <p>Tooth retention declined markedly with age. Women and individuals with lower educational attainment experienced earlier and more severe tooth loss. Although women had higher life expectancy than men at all ages, they lived fewer years with functional dentition and more years edentulous. At ages 60–64, men were expected to live 19.7 years, including 15.6 years edentulism-free and 5.3 years with FD, whereas women had a life expectancy of 23.2 years but only 14.2 years edentulism-free and 3.9 years with FD. FDLE declined earlier than EFLE, indicating a prolonged period of non-functional dentition preceding edentulism.</p> Conclusion <p>FDLE reveals substantial years lived with compromised oral function, underscoring the need to ensure access to restorative care and establish explicit tooth retention goals.</p> Clinical relevance <p>FDLE offers a meaningful indicator to advocate for long-term preservation of natural teeth, monitor population oral health, inform policy, and set measurable goals.</p> Graphical abstract <p></p>