California Registered Dental Assistant (RDA) Written Practice Exam

What classification would require the use of a matrix system?

1. Class II only

2. Class I and Class IV

3. Class III and Class V

4. Class I and Class III

The correct answer is: Class II only

The classification that requires the use of a matrix system is primarily Class II restorations. A matrix system is used in dentistry to create a temporary wall around a cavity preparation that is being filled with restorative material. This is particularly important in Class II cavities, which are located on the proximal surfaces of posterior teeth. When a cavity is prepared on these surfaces, the matrix provides support for the filling material, allowing it to form a proper contour and to properly restore the proximal contact with adjacent teeth. Without a matrix, it would be challenging to achieve the appropriate shape, form, and contact area required for proper function and aesthetics. While Class I restorations involve fillings on the chewing surfaces of teeth and do not usually require a matrix, Class IV restorations, which are for anterior teeth and involve the incisal edge, may also require a matrix to achieve proper contour. However, the question asks specifically about classifications that 'require' a matrix system, and the answer focuses on the definitive need in Class II restorations. Other classifications may not universally require a matrix and therefore would not fit the question as precisely as Class II restorations do.