Dental amalgam has been a traditional restorative material for many years, known for its durability and strength. However, there is a growing trend towards the use of more aesthetic materials, such as composites and glass ionomers, which blend better with natural tooth structure.

For class V composite restoration, the best method to retract gingiva is by using a rubber dam. This provides isolation, visualization, and moisture control, which are crucial for successful adhesive techniques. While other methods like retraction cords or electrosurgery may be used in some cases, they are not the most suitable for routine class V restorations.

The discoloration of amalgam restorations is often due to the formation of silver sulfide on the surface, which can occur due to the reaction of silver with sulfur compounds in the oral environment. The gamma I phase is a strong component of amalgam, while the gamma II phase is weaker and less stable. Oxides can form as well, but sulfides are more directly associated with the discoloration observed in clinical settings.

Explanation: The external shape of a Class V amalgam restoration is closely related to the contour of the marginal gingiva. This is important for aesthetic and functional reasons, as the restoration must blend seamlessly with the surrounding gingival tissue. The outline form should respect the natural contours to minimize plaque accumulation and promote periodontal health. While axial line angles and the direction of enamel rods are relevant to the preparation, they do not primarily dictate the external shape of the restoration.

Proximal carious lesions often appear smaller on radiographs than they are clinically due to the limitations of radiographic imaging.