Which part of the blade is referred to as the lateral edge?

The term "lateral edge" in the context of a dental blade typically refers to the outer sections that are used for cutting or scaling. In various types of blades, particularly periodontal instruments, the lateral edges are significant because they play a crucial role in effectively removing calculus and debris from tooth surfaces.

In this case, when identifying parts of the blade, parts that are described as "Part 3 and 6" likely encompass the sections that extend alongside the blade itself, enabling the clinician to utilize those edges during periodontal procedures. These lateral portions contribute to the blade's overall function by providing a sharp interface that assists in cleaning and smoothing tooth surfaces, which is fundamental in periodontal treatments.

The parts labeled as "Part 1," "Part 4," and "Part 7" may not encompass the full lateral functionality or characteristics that are characteristic of the lateral edges. Hence, the identification of parts 3 and 6 aligns with the correct understanding of where the lateral edges are located and how they are applied in practice.