In the thesis ‘Barriers to effective periodontal care’, published in 1984, an investigation was described on professional periodontal care lagging behind the development of periodontology. The objectives of the investigation were to assess whether dentists were treating periodontal disease as a behavioural problem using effective communication techniques, and whether serious periodontal disease had such low frequency that dentists had not the opportunity to become experienced in recognizing the disease. It was concluded that serious periodontal disease had a low frequency and was not influenced by communication on periodontal care. After 25 years, these conclusions are still valid: the percentage of risk patients is still 5-10% and the correlation between seriousness of periodontal disease and periodontal care provided is still limited. Not all dentists do have affinity to periodontal care, but they do have affinity to practical aspects, such as removing dental calculus deposits. A classification of obvious recognizable diseases and treatments would make periodontal care more manageable for dentists.