Which of the following finish lines is indicated for facial surfaces of metal ceramic restorations
**Core Concept**
Metal ceramic restorations require a finish line that allows for optimal cementation and minimizes the risk of fracture or debonding. The finish line should be designed to provide a smooth surface for the ceramic veneer to bond with the metal substructure.
**Why the Correct Answer is Right**
The correct finish line for metal ceramic restorations is a chamfer finish line, which is a 45-degree angle cut around the margin of the restoration. This allows for a smooth surface for cementation and minimizes the risk of fracture or debonding. The chamfer finish line also provides a clean and well-defined margin for the ceramic veneer to bond with the metal substructure.
**Why Each Wrong Option is Incorrect**
* **Option A:** A shoulder finish line is not indicated for metal ceramic restorations because it can create a ledge that can trap cement and increase the risk of fracture or debonding.
* **Option B:** A bevel finish line is not typically used for metal ceramic restorations because it can be difficult to achieve a smooth surface for cementation.
* **Option C:** A shoulder finish line with a bevel is not typically used for metal ceramic restorations because it can create a complex margin that can be difficult to clean and cement.
**Clinical Pearl / High-Yield Fact**
A chamfer finish line is typically indicated for metal ceramic restorations because it provides a smooth surface for cementation and minimizes the risk of fracture or debonding.
**Correct Answer: C. A bevel finish line is not typically used for metal ceramic restorations.**