Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact—the dimensions of oral health-related quality of life—capture dental patients’ oral health problems worldwide and regardless of whether the patient currently suffers from oral diseases or intends to prevent them in the future. Using scores for these dimensions, the project Mapping Oral Disease Impact with a Common Metric (MOM) aims to provide four-dimensional oral health impact information across oral diseases and settings. In this article, project authors summarize MOM’s findings and provide recommendations about how to improve standardized oral health impact assessment. Project MOM’s systematic reviews identified four-dimensional impact information for 189 adult and 22 pediatric patient populations that were contained in 170 publications. A typical functional, pain-related, aesthetical, and psychosocial impact (on a 0-8 impact metric based on two items with a response format 0 = never, 1 = hardly ever, 2 = occasionally, 3 = fairly often, 4 = very often) was about 2 to 3 units. Project MOM provides five recommendations to improve standardized oral health impact assessment for all oral diseases in all settings.