Australian Dental Council (ADC) Practice Test

When considering the effect of more cutting blades on carbide burs operating at low speed, it is important to understand the mechanics involved in cutting efficiency and surface finish. Increasing the number of cutting blades on a carbide bur typically results in a greater number of cutting edges coming into contact with the material being worked on.

At low speeds, these additional cutting blades can help in distributing the cutting action more evenly across the surface, leading to less aggressive material removal. This phenomenon often results in less efficient cutting because the blades may not be able to engage with the material as effectively compared to fewer blades operating at higher speeds, where the cutting edges can more easily chip away at the material.

Furthermore, the presence of multiple blades can contribute to creating a smoother surface finish. This occurs because the numerous cutting edges reduce the amount of material being removed at any single point in time, allowing for a finer surface texture as the remaining material is polished or smoothed out rather than gouged. Thus, while the overall cutting action may be less efficient, it facilitates a more refined surface.

In this context, having more cutting blades at low speed leads to less efficient cutting yet results in a smoother surface finish, aligning with the correct answer.