What are gauges?

Measuring gauges give a direct reading where an estimate is not good enough. The two standard patterns do different jobs: a Boley gauge is a sliding caliper that measures linear distance — tooth width, space available, model dimensions — while an Iwanson gauge has curved opposing jaws made specifically to reach in and read the thickness of a crown, band or sheet of metal at a point a straight caliper cannot reach.

How the gauges range is organised

Boley:

Sliding caliper for linear measurement of teeth, spaces and models.

Iwanson:

Curved-jaw gauge for reading crown, band and sheet thickness.

Choosing the right gauge

Use a Boley for anything you can measure across, and an Iwanson when you need the thickness of something you can only reach around — checking that a crown has adequate occlusal thickness before it is fitted is the usual case.