Onlays are used in condition where one or more cusps are damaged. The treatment involves taking an impression of the tooth to create a temporary onlay. After that, tooth is prepared for the placement of onlay. Next, another impression of the tooth is taken after it’s prepared. The doctor then puts the temporary onlay while the lab is working on the final restoration. The following appointments involve doctor removing the temporary onlay and replacing it with the final restoration. These restorations are more durable and last longer than typical filling.