Digital workflows explained: STL, PLY, OBJ and what your lab needs

Every intraoral scanner produces the same essential thing: a 3D mesh of the teeth. The differences between file formats are smaller than the marketing suggests — but they matter in a few specific situations.

STL — geometry only

STL is the oldest and most universal format: a pure surface mesh with no colour. Every design program accepts it. For most crown and bridge work, STL is entirely sufficient.

PLY and OBJ — geometry plus colour

PLY and OBJ can store per-vertex colour and texture. That colour information helps the designer identify margin lines, tissue boundaries and shade transitions. If your scanner offers it, send PLY or OBJ alongside STL for aesthetic cases.

What the lab actually needs

Regardless of format, the lab needs a complete record: prepared arch, opposing arch and a bite registration scan. Missing the bite is the most common reason a case stalls on day one.

• Prepared arch scan (STL/PLY/OBJ)
• Opposing arch scan
• Bite registration
• Photos for shade and characterisation (JPG/PNG)
• A written prescription (material, shade, margins, contacts)