Background In recent years, health conditions have become the most commonly searched content for smartphone users. Moreover, digital health information about prevention and self-care will be in great demand in the near future. Although researchers from the domains of education, information technology, and dentistry have examined digital oral health education, their studies have lacked emphasis on user experience. In this study, we aimed to review and examine usability issues of commercially available oral health education apps. Afterward, we presented design guidelines for these applications. Methods First, we reviewed existing smartphone applications for oral health education and selected two accredited apps; Dentify and Toothflix. Second, for usability testing of these two apps, we adopted a heuristic evaluation system: creating usability checklists based on Peter Morville`s User Experience Honeycomb. Then, we conducted usability testing and performed in-depth interviews with dentists and UX design experts. Result We analyzed the results from the usability checklists using radar charts. Then, usability issues were categorized and summarized into oral health contents and four planes based on Jesse Garrett`s elements of user experience: the scope plane, the structure plane, skeleton plane, and surface plane. Conclusion In addition, we`ve suggested revisionary design guidelines in usability for these two apps; first, Dentify and Toothflix need to have a “Search” option. Second, the apps should incorporate multi-information channels, such as, text, images, videos, and audio. Third, these apps should require as little as possible cognitive burdens for users.