What type of separators are placed between contacts using a "sawing" or flossing motion?

The correct answer is elastomeric separators. These separators are specifically designed to create space between teeth, typically using a gentle "sawing" or flossing motion. The elastomeric material is flexible and can easily fit into tight contacts, making them effective for separating teeth in preparation for orthodontic appliances or other dental treatments.

Elastomeric separators are often softer and gentler on the teeth and gums compared to other options, which helps minimize discomfort for the patient during the process of separation. The elasticity of these separators allows for them to adjust as they exert a consistent, gentle force, leading to an effective separation process over time.

In contrast, the other types of separators mentioned have different applications and design characteristics. Metal separators may be used for more permanent separation tasks but do not typically utilize a sawing motion. Elastic separators, while they can create space, tend to be employed in different contexts or applications in dentistry. Plastic separators also hold specific uses but do not align with the technique described in the question.