Background: In this study, we tried to comprehensively explore clinical dental hygienist's experience of a prevention-based incremental oral health care program, which was pilot-operated by dental clinics, define prevention-based incremental oral health care as experienced in the field, and identify factors to be considered. Methods: This study conducted a focus group interview with five dental hygienists who participated in an ongoing oral management pilot project in 2016. The interview was conducted by a researcher, and the co-research team attended as progress assistants and recorded characteristics of the participants, main dictations, and non-verbal characteristics. All interviews were recorded and underwent thematic analysis to examine the questions of the study as the main axis. Results: As a result of the study, 65 meaningful statements were extracted by code, integrated into 24 sub-categories, and structured into 11 categories. Finally, four keywords were drawn: characteristics, facilitating factors, conflicting factors, and improvement measures for prevention-based incremental oral health care. Regarding prevention-based incremental oral health care in dental clinics, dental hygienists were highly aware of the physical and mental burdens of personalized treatment and education for each individual. They were responsible for the patient and for facilitating changes in the behavior of the client, leading to professional satisfaction. The dental team's cooperation and supportive attitude were found essential to continue oral health care in the dental clinic. Conclusion: Through dental team-based treatment philosophy sharing and collaboration, it is possible to provide prevention-based incremental oral health care in dental clinics. In future, it is necessary to develop a system for establishing a sustainable preventative management system for public health promotion.