Which part of the blade is not involved in cutting?

The back of the blade is not involved in the cutting process. In dental instruments, particularly scalers and curettes, each part of the blade serves a specific function. The cutting action primarily occurs along the lateral edges and the tip; these areas are sharpened to effectively slice through soft or hard tissue during periodontal procedures.

The lateral edge is designed for precision and is the main area for cutting, while the tip can be used for initiating cuts or accessing tight spaces. The face of the blade may also contribute to cutting, particularly in how it is angled relative to the surface being treated. However, the back is typically flat and smooth, often used for resting on the tooth surface or providing support, but it does not engage in the cutting action. Therefore, the back is distinctly not a functional part of the blade when it comes to the effectiveness of cutting.