Medication-related osteonecrosis of the jaw (MRONJ) is a side effect of antiresorptive drugs. In this online survey, the awareness and knowledge of dentists regarding MRONJ was evaluated, and potential implications for oncologists are discussed. Questionnaires were emailed to dentists from Germany, Austria, Switzerland, and South Tyrol to evaluate disease-related knowledge and management. In addition to the overall score, a separate score was calculated for knowledge (maximum score: 15 points) and management (maximum score: 6 points) questions, and 1197 valid replies with completed questionnaires were received. The mean overall score was 10.45 ± 3.97 points, the mean knowledge score was 7.68 ± 3.05 points, and the mean management score was 2.76 ± 1.77 points. Factors influencing the outcome of the overall score were age, specialization, continuous professional education, and the number of dental screening exams in patients before antiresorptive therapy. Due to the considerable lack of knowledge regarding MRONJ among dentists, MRONJ patients and subjects at risk should be guided towards specialists for dental screening, treatment, and follow-up. This is important from an oncologic point of view to avoid any delay for treatment start of antiresorptives, and to reveal a potentially emerging osteonecrosis at an early stage, thus, avoiding the need for interruption or even cancellation of antiresorptive therapy.