An introduction to OHA!, a tool currently being developed which aims to assist dentists in accessing the most reliable evidence regarding the effectiveness of common dental treatments. The OHA! repository has been purposefully crafted to be exceptionally selective and compact, ensuring that users can easily find straightforward and valuable answers to their dental clinical questions. During the presentation, Professor Paulo Nadanovsky will show two sample dental fact boxes (in draft form) that have been developed. One pertains to the success rate of root canal treatment, while the other focuses on the impact of shorter versus longer intervals between dental check-ups on oral health. Patients expect doctors to take action to help them, and the more treatment or diagnostic tests, the better they feel. Doctors genuinely want to help and can often come up with various treatment or testing options to try. Consequently, this leads to a situation where everyone becomes perpetual patients, regardless of their actual health needs and potential benefits – essentially, an overuse of healthcare. Furthermore, there is a pervasive illusion of certainty among healthcare professionals, including physicians and dentists. This illusion entails the belief that treatments are always effective, diagnostic tests are infallible, and there exists only a single, optimal treatment or management approach. Consequently, there is often a lack of systematic comparisons between the pros and cons of different options. To dispel this illusion of certainty, reduce excessive healthcare practices, and promote clear thinking when considering interventions, the provision of clear information is essential. The practice of evidence-based healthcare involves two distinct roles: that of evidence consumers and evidence producers. Consumers, including clinicians and the general public, often lack the expertise needed to evaluate and choose the most reliable evidence. Hence, it falls upon those producing healthcare evidence to assume the role of experts and develop tools that simplify the integration of the best available evidence into the decision-making process for clinicians and patients alike. Bio: Professor Nadanovsky graduated as a dentist in Rio de Janeiro, Brazil. He worked for a few years in the clinic (mainly periodontics), then migrated to public health and epidemiology and obtained a PhD from the University of London in 1993. He witnessed the birth of the evidence-based medicine movement and of the Cochrane Collaboration while working as a lecturer at the London Hospital Medical College and at University College London (afterwards it was renamed Queen Mary and Westfield College). Professor Nadanovsky taught evidence-based dentistry between 1993 and 1997 and since 1997 has been teaching epidemiology and evidence-based health care to physicians, dentists, nutritionists, and other health care professionals. He supervises PhD and MSc students, and his main interest is in overdiagnosis and overtreatment in health care in general, and more specifically, in dentistry.