Starting with a presentation of “the father of social medicine”, Alfred Grotjahn, the concept of essentialism is presented. From an overview of ideas about health and sickness, it is contended that the current concepts of health and disease still contain essentialist elements, primarily biological ones but also social and psychological. The consequence is a paradigmatic crisis of medicine and odontology - the essentialist theoretical foundation is not concordant with the practical application. A strictly rational evidence-based model is not feasible. Since it is not possible to construe health sciences with consensual theoretical definitions, they should be based on practice and practical experience. Three sets of practices can be discerned, sickness-oriented, patient-oriented and social-oriented, with the aims of curing sickness, caring for the patient, and promoting health, respectively. Sicknesses are not given entities, but changing, emerging and disappearing as conceptual objects. There are social and professional structures determining the emergence of a sickness entity. The biological essentialism which dominates limits the choices of therapies. Patient-orientation implies understanding latent needs and mechanisms for their becoming manifest. Health is a process and not a state, and the self-efficacy of patients should be the strategical target. A social, health-promoting practice should imply the realization that sickness and ill health are not due to evil Nature but socially conditioned and created. Society is neither the state nor the market, but should imply the reconstruction of the real life; the goal of salutogenic health promotion.