What are the tests for periodontal disease?

A clinical exam. A clinical examination is the best starting step to test for periodontal disease. If there are areas of concern - then x-rays can be taken, although they are always advised to help us see and diagnose things that we can not see without them.
Tests for perio. A thorough periodontal exam, including x-rays to see bone levels, periodontal measurements (probing the pocket in 6 areas around each tooth), evaluating bleeding points, mobility of the teeth, and sometimes oral dna testing to see what pathogens are present. In addition, risk factors are eval'd, including smoking, oral hygiene effectiveness, history and overall health assessment.
Periodontal disease. There are some specific tests using saliva (spit samples) that are sent to a lab to determine different bacteria and enzymes present that could put you are risk for periodontal disease. A good clinical and radiographic (X-ray) examination by your dentist can determine if you have existing periodontal disease. See a dentist for an exam and put your worries to rest.
Various Tests. Up until recently, the gold standard for determining a proper diagnosis for gum disease was a complete series of x-rays to determine bone loss, 6 point full mouth periodontal charting to evaluate attachment lose and a comprehensive clinical exam. Today we can add oral dna testing for specific periodontal pathogens and presence of certain genes that lend an individual to be prone to gum disease.
Varies. A good history and clinical examination with adequate x-rays would be the starting point. The clinical examination would likely include a thorough head and neck examination, probing of each tooth, as well as evaluation of your occlusion (bite). Additional tests, such as a food intake diary or salivary analysis may also be suggested.