Why CEREC Restorations Suddenly Start Milling High (And How to Fix It)

For the last 20 years of using and teaching CEREC, one of the most common questions I receive is about parameters—particularly occlusal parameters. Understanding how your system mills, which burs you are using, the speed at which you mill, and whether you are working with a Prime Mill or an MCXL can have a significant impact on the final precision of a restoration.

Parameters exist for a reason. They allow us to customize the milling process based on the specific milling unit, restoration type, and milling strategy being used. While some of my parameter settings are similar between the MCXL and PrimeMill, there are also important differences that can affect the final fit and occlusion of the restoration.

Another key consideration is the milling refinement mode. Whether you are milling in Extra Fine mode or using a faster milling option such as Super Fast or Speed milling, the restoration can behave differently. These choices influence surface detail, adaptation, and ultimately how the restoration seats and contacts in the mouth.

In this video, I will review occlusal parameters and discuss a question that recently came in from a clinician whose occlusion had been working beautifully for some time and then suddenly began running high. When situations like this occur, there is one critical factor that can drift out of calibration without being immediately obvious, and it can significantly affect the final result.

This tutorial will walk through the process of dialing in occlusion with both the PrimeMill and the MCXL, helping you better understand how parameters, calibration, and milling strategies work together to create predictable restorative outcomes.