For class V direct filling gold, retention points are
**Question:** For class V direct filling gold, retention points are:
A. Marginal ridge
B. Enamel shoulder
C. Dentin shoulder
D. Cementum shoulder
**Core Concept:**
Class V carious lesions involve the enamel and dentin, and the restoration aims to ensure adequate retention to prevent detachment. In class V direct fillings using gold restorations, retention is primarily achieved through four retention points:
**Why the Correct Answer is Right:**
Gold restorations in class V lesions utilize four retention points:
1. Marginal ridge: The external bevel is created on the tooth structure to engage with the restoration, ensuring retention.
2. Enamel shoulder: The shoulder of the preparation is maintained at the enamel margin, allowing for retention through the bond between the gold restoration and the enamel.
3. Dentin shoulder: A shoulder is created at the dentin margin, enhancing retention through bond between the gold restoration and the dentin.
4. Cementum shoulder: The restoration's shoulder is maintained at the cementum margin, facilitating retention through the bond between the gold restoration and the cementum.
**Why Each Wrong Option is Incorrect:**
A. Marginal ridge (Option A): While the marginal ridge contributes to retention, it is not the primary retention point in class V gold restorations.
B. Enamel shoulder (Option B): While an enamel shoulder improves retention, the primary points are the other three mentioned.
C. Dentin shoulder (Option C): Similar to enamel shoulder, a dentin shoulder enhances retention; however, the primary points are the other three mentioned.
D. Cementum shoulder (Option D): Similar to dentin shoulder, a cementum shoulder improves retention; however, the primary points are the other three mentioned.
**Clinical Pearl:**
In class V direct gold restorations, the primary retention points are the marginal ridge, enamel shoulder, dentin shoulder, and cementum shoulder. These points ensure strong retention and durability of the gold restoration, which is essential for long-term success in class V lesions involving both enamel and dentin.