As is already well known, demographic changes will presumably lead to a rising number of old aged individuals and loneliness is a tremendous concern in aging populations. Poor health can be a potential consequence of loneliness, as well as a determining factor. Thus, the objective of the current study was to determine whether postponed dental appointments due to costs affect loneliness longitudinally. Focusing on Germany, data from two waves (waves 5 and 6) of the “Survey of Health Ageing, and Retirement in Europe” (SHARE) were analyzed (n = 7703). The three-item loneliness scale (modified version of the revised UCLA Loneliness scale) was used to quantify loneliness. The presence of postponed dental appointments due to costs in the past 12 months (no; yes) served as a key independent variable. Socioeconomic factors as well as health-related factors were adjusted in the longitudinal regression analysis. After adjusting for confounding variables, regression analyses revealed that loneliness increased with decreases in self-rated health among men. Among women, loneliness increased when self-rated health decreased, when fewer chronic diseases and postponed dental appointments due to costs were reported. Among older women, postponed dental appointments due to costs are associated with feelings of loneliness. The study results add evidence that proper dental care (i.e., regular and appropriate visits to the dentist) is vital not only to one’s oral health, but also plays a role in one’s physical and emotional health.