Most of what we learned about periodontal disease in dental colleges is largely outdated. The old calculus-based theory of periodontal disease has been replaced by a newer paradigm, one derived from microbiological & immunological studies that compel us to rethink the traditional "notched metal stick" approach developed in the 1900's. Presently, the diagnosis & classification of periodontal diseases are almost entirely based on traditional clinical assessments. It has become clear that periodontal diseases are caused by specific, communicable bacteria that trigger a systemic immune response. The immune response does most of the clinical damage, not the microbes. Despite this, most dental professionals still use diagnostic tests developed in the early 1900's such as Disclosing Solutions, Bleeding on Probing, Pocket Depths and Radiographs, all of which are fraught with problems and none of which are predictive of future attachment loss. This article strives to compare the advantages and limitations of traditional clinical assays with the latest microbiological tests currently available.