National Dental Assisting Examining Board (NDAEB) Practice Exam

What is formed at the junction of three tooth surfaces?

1. Point angle

2. Line angle

3. Edge

4. Corner

The correct answer is: Point angle

The term that describes the area formed at the junction of three tooth surfaces is known as a point angle. In dental anatomy, a point angle specifically indicates the location where three different surfaces of a tooth meet. This is relevant in understanding the geometry of a tooth for various dental procedures, such as cavity preparation and restoration. For example, in a posterior tooth, the intersection of the occlusal surface, and two adjacent proximal surfaces can be identified as a point angle. Point angles are significant in dental charting, diagnosis, and treatment planning since they help in precisely locating areas of concern on a tooth. Line angles, on the other hand, refer to where two tooth surfaces meet, not three, and are essential for understanding shapes and contours but do not describe the junction involving three surfaces. The terms edge and corner are less commonly used in the context of dental anatomy and do not accurately capture the specificity that point angles do in tooth morphology.