Objectives: To develop prototype rotary selective dentin caries excavators and to demonstrate their ability to remove only carious dentin in extracted teeth. Method and materials: Milled polymer prototype and formed wire loop prototype burs were made. They were tested on normal dentin with standardized force application and compared to carbide burs for ability to cut by weighing three extracted teeth at pre- and postcutting for each prototype version. They were tested on carious dentin of three teeth for each prototype version. The resulting excavated surfaces were analyzed with dentin caries dye, the teeth were decalcified and examined histologically, and the used prototypes were examined in light and scanning electron microscopes. Results: For both prototypes, noncarious teeth did not lose weight from prototype instrumentation, but each lost 9 or 10 mg after instrumentation with the control carbide bur. Both prototypes quickly removed carious dentin in each of the carious teeth until a definitive cutting endpoint was reached. The excavated surfaces from the milled polymer prototypes did not stain with caries dye, but those from the wire loop prototypes stained lightly in some areas. In the light microscope, all sections of excavated carious teeth were bacteria-free. Light and scanning electron microscope images of the prototypes revealed scratch patterns on the wire loop prototypes and deformation of blades on the polymer prototypes. Conclusion: Both prototypes removed carious dentin but did not remove normal dentin in the extracted teeth used in this study. Further development is indicated.