National Dental Assisting Examining Board (NDAEB) Practice Exam

A matrix must be used to create a temporary wall for which classifications of tooth restoration?

1. Class I only

2. Class II, IV, and V

3. Class II, III, and V

4. Class III only

The correct answer is: Class II, III, and V

A matrix is a critical tool in restorative dentistry, as it helps create a temporary wall to contain dental materials during the restoration process. This is particularly important for certain classifications of restorations. Class II restorations involve cavities that extend into the interproximal surfaces of posterior teeth, necessitating the use of a matrix to ensure that the filling material is properly shaped and contained. Class III restorations affect the interproximal surfaces of anterior teeth, which also benefit from a matrix to achieve the correct contour and to prevent material from spilling over into surrounding areas. Class V restorations, found on the gingival third of both anterior and posterior teeth, also require a matrix to manage the buildup of filling material and ensure proper adaptation of the restoration to the tooth structure. In contrast, Class I restorations typically involve fillings on the occlusal surface and do not necessitate a matrix, as these can be placed without the need for an external wall. Class IV restorations, which involve the proximal surfaces of anterior teeth and possibly the incisal edge, might not always require a matrix depending on the specific case, but a matrix can still be useful for achieving desirable aesthetics and function. Thus, the requirement of a matrix for Class II, III, and V restor