Dental OSCE (Objective Structured Clinical Examination) Practice Exam

What is the recommended facial reduction for a PFM crown?

1. 1.0 mm

2. 1.5 mm

3. 2.0 mm

4. 2.5 mm

The correct answer is: 1.5 mm

The recommended facial reduction for a porcelain-fused-to-metal (PFM) crown is indeed 1.5 mm. This dimension is essential for achieving an appropriate thickness of porcelain that allows for aesthetic restoration while also ensuring adequate strength and durability. Facial reduction needs to strike a balance between providing enough material for the porcelain layer to reflect light properly and match the natural tooth color, while also maintaining sufficient metal thickness for structural integrity. Reducing the facial surface by approximately 1.5 mm allows the dentist to achieve this optimal aesthetic and functional outcome. If the reduction is too little, the porcelain may be at risk of fracture or chipping, compromising both the longevity and appearance of the crown. Conversely, excessive reduction could compromise the underlying tooth structure and may also affect the occlusion and overall fit of the crown. Thus, the 1.5 mm facial reduction is not only a standard guideline but is also based on the need to ensure that the crown performs well in both function and aesthetics over time.