Relines require a wash impression.
-Add impression adhesive to the tissue side of the appliance and 2 mm of the borders.
-Using thermoplastic impression material, fill the inside of the appliance.
-Take an impression of the patients mouth, using the appliance as the tray.
-Make sure to have the patient bite down to get an even impression. Don't just take the impression fully by hand.
These steps will ensure an accurate reline that will fit perfectly.