This specification applies to reusable and disposable impression trays used in dentistry for delivering impression materials into the oral cavity for the purpose of making impressions (negative copies) of teeth and oral tissues. It applies to trays made of plastic, aluminum, stainless steel and nickel or chrome plated brass for the purposes of full arch dentulous or edentulous, partially edentulous, partial arch and water cooled impressions. ADA87-1995D