What type of strip is used for contouring Class III and IV composite restorations?

The use of a Mylar strip for contouring Class III and IV composite restorations is essential due to its unique properties. Mylar strips are made from a thin, flexible plastic material that allows for a smooth finish and helps achieve the desired contouring and polishing of the restoration. These strips are clear, which provides visibility during placement and contouring, making it easier for the dental assistant or dentist to assess the restoration's shape and alignment with adjacent teeth.

When working with Class III and IV restorations, the goal is to recreate both the anatomy and esthetics of the tooth. The smooth surface of Mylar strips prevents the composite material from sticking too much, allowing for easier manipulation while also ensuring a superior finish once the restoration is complete.

In contrast, other types of strips, such as metal matrix strips, are more suited for other types of restorations or for providing a different type of contour and support during the placement of materials that are heavier or don't require a smooth surface finish. Celluloid and polymer strips also have their specific uses but may not provide the optimal finish and visibility required under the circumstances typical of Class III and Class IV procedures.