A periodontal pocket depth measuring device comprising a body 100, a planar probe 10 extending from the body, itself comprising at least one inlaid concave structure 111 on its side located at the distal end of the probe, away from the body. A rod 20 also protrudes from the body in the same direction as the probe, which can freely be extended and retracted in a direction parallel to the probe. In use, this rod is mounted on the top of the gums while the probe extends into the periodontal pocket； the inwards movement of the rod allows the depth of the pocket to be inferred. The end of the rod may have a plate 21 at its end, mounted perpendicularly to the rod and the probe, with a hole 211 through with the probe passes. The probe may have angular edges and concave cut-outs along its edge, as seen in Figure 4, 13 and 121.
