The bachelor's thesis deals with the issue of focal infections of odontogenic origin. Its aim is to present current knowledge and connections regarding the impact of oral health on the development of potential systemic diseases, and to highlight the importance of oral hygiene – both individual and professional. The theoretical part includes information on the concept of focal infections and their sources. It describes the issue of oral microflora in relation to pathological conditions of the oral cavity, as well as the basic immune mechanisms. It also includes an assessment of patients in terms of systemic and dental risk, along with associated treatment management. One chapter is dedicated to oral hygiene, as it represents one of the most significant factors influencing the onset and progression of pathological processes in the oral cavity. The practical part presents a case study of a high-risk patient and their treatment by a dental hygienist in cooperation with a dentist.