Dental Probe, PCP12. Stainless Steel Handle. The working ends are marked in millimeters (3-6-9-12) for precise measurements. The calibrated periodontal probe is an instrument of assessment. The calibrated probe is used to 1) determine the consistency of the gingival tissue 2) survey sulcus and pockets depths 3) measure clinical attachment levels 4) measure the width of attached gingival 5) verify whether bleeding and/or purulent exudate is in presence.