Dental OSCE (Objective Structured Clinical Examination) Practice Exam

What is a desirable feature of the margin of a porcelain jacket crown?

1. It is smooth and untextured

2. It has a sharp edge for better adhesion

3. It should be visible to the patient

4. It needs to accommodate a wide range of restoratives

The correct answer is: It is smooth and untextured

A smooth and untextured margin for a porcelain jacket crown is desirable because it facilitates better adaptation to the tooth preparation, promoting a tight seal that reduces the risk of plaque accumulation and potential debonding. A smooth finish minimizes stress concentrations at the margin, making the crown less susceptible to fracture during function. Additionally, a smooth margin enhances the aesthetic appearance of the crown, providing a more natural look as it blends more seamlessly with the surrounding tooth structure and gum tissue. Other options focus on attributes that do not serve the primary goals of crown design effectively. While a sharp edge might seem advantageous for adhesion, it can actually lead to stress and potential chipping at the margin. Visibility to the patient is not necessary or desired, as the crown's margins should ideally be placed at or below the gum line for aesthetic purposes and tissue health. Lastly, needing to accommodate a wide range of restoratives does not align with the specific characteristics of a porcelain jacket crown, which is meant for a more precise fit and interaction with specific tooth preparations.