The effects of disposable and custom-made impression trays on the accuracy of impressions.

This study indicates that some non-rigid impression trays, including disposable plastic trays and custom-made acrylic resin trays, may produce unreliable results when used with some medium-bodied elastomers. The study does not question the well-documented clinical accuracy of these elastomers when they are used with rigid trays. Disposable plastic trays are found to be acceptable when used with a combination of reversible and non-reversible hydrocolloid impression materials.