FIG. 1. is a perspective view showing the device measuring one depth;
FIG. 2. is a left hand side view of the device measuring another depth;
FIG. 3. is a right hand side view of the device seen in FIG. 2;
FIG. 4. is a plan view from below;
FIG. 5. is a plan view from above;
FIG. 6. is a plan view from the front; and,
FIG. 7. is a plan view from the rear side.
I claim the ornamental design for a dental instrument for measuring depth, as shown and described.