What is the correct pocket depth measurement that indicates periodontitis when applying a pressure of 0.25N?

A pocket depth measurement of 4 mm indicates periodontitis when applying a pressure of 0.25N. In periodontal health, normal probing depth is generally considered to be 1-3 mm. Measurements greater than this range can suggest the presence of periodontal disease, with deeper pockets indicating more severe forms of the condition.

Specifically, when probing depths reach 4 mm or more, this typically signifies the onset of periodontitis rather than just gingivitis, which is usually characterized by shallower pockets. The pressure applied during probing also plays a role, and in this questionnaire, a pressure of 0.25N effectively reflects the clinician's standard method of assessing periodontal health.

Therefore, the selection of 4 mm as the threshold aligns with the clinical guidelines used to diagnose periodontitis, marking it as a point where tissue attachment loss can begin to occur, accompanied by potential inflammation and other related periodontal issues.