An onlay is used when one or more cusps are damaged. The treatment targets saving as much of natural tooth as possible while restoring the damaged tooth to its optimal health and functioning. Onalys also last longer than filling. The process of getting one involves taking a 3-D image of your tooth. The scan is used to design the restoration. A single appointment is all that’s needed to create it. First of all, tooth is prepared for the treatment. After that, tooth is scanned and the doctor creates the onlay. Lastly, final adjustments are made where the onlay is secured in place.