Periodontal disease is detected by your dentist or dental hygienist during a periodontal examination. This type of exam should always be part of your regular dental check-up.
A periodontal probe (small measurement instrument) is gently used to measure the sulcus (space) between the tooth and the gums. The depth of a healthy sulcus generally measures three millimeters or less and does not bleed. As periodontal disease progresses, the pockets frequently get deeper.
Sulcus/pocket depths, amount of bleeding, radiographic bone level, tooth mobility, etc., are used in assessing periodontal condition.