What type of dental dam frame is positioned underneath the dam material?

The plastic frame, commonly known as Otsby frame, is specifically designed to be positioned underneath the dam material. This design allows for the dental dam to be stretched tightly over the frame, which secures it in place and creates an effective barrier for the area being treated. The use of a plastic frame helps in providing a clear view and access to the operative field while also enhancing the stability of the dam during dental procedures.

The other frame types do have their specific uses in dental procedures, but they typically function differently. For instance, a metal frame, like Young's frame, is placed outside the dam material and provides a stable base but does not interface with the fabric of the dam in the way needed for support underneath it. Rubber frames and wooden frames also do not typically serve the same function as the plastic frame. The Otsby frame's unique positioning and structure make it the preferred choice for dental professionals looking to maintain the integrity and effectiveness of the dental dam during a procedure.