During tooth preparation, which structure is least likely to be damaged?

The least likely structure to be damaged during tooth preparation is the lymph nodes. Lymph nodes are part of the immune system and are located throughout the body, often deep within the tissues. They do not reside directly in the area being treated during dental procedures, such as tooth preparation, which typically involves the hard and soft tissues immediately surrounding the tooth itself.

In contrast, adjacent teeth are directly in proximity to the tooth being prepared and can be at risk of damage from drills or instruments during the procedure. Similarly, soft tissues, including the gums and oral mucosa, are also vulnerable during tooth preparation, as they are in close contact with the work area. The pulp, which is the innermost part of the tooth containing nerves and blood vessels, can be at risk if the preparation extends too deeply into the tooth structure, leading to potential exposure or trauma.

Therefore, while adjacent teeth, soft tissues, and pulp can all be affected by the mechanical actions of tooth preparation, lymph nodes are situated far enough away that they are not impacted by these dental procedures.