I started my Cerec Journey in 2008 and over the years I have placed thousands of Cerec restorations. I have seen my fair share of failures. Most failures have happened because of under reduction and sharp internals leading to fractures and inadequate bonding protocol leading to debonds.
However , I have noticed that if you follow the fundamentals of milled porcelain restorations all materials work and they all last.
Here are a few suggestions :
1. 1.5 mm reduction in the central fissure.
2. Exit angles on partial coverage restorations must draw.
3. No undercuts on the prep.
4. Complete visualization of margins aided by proper tissue management
5. Straight axial wall with no ledges
6. Isthmus width of atleast 1.5 mm
7. Internal of the preparation should be rounded and smooth
8. Proximal walls of adjacent teeth should be smooth without undercuts.
9. Maintaining proper bonding protocol as per manufacturer’s recommendation.
Here is a case of a patient that presented to my practice in 2008 wanting to change all her amalgam restorations.
Over the years I have placed 6 different partial coverage restoration with  4 different materials like Emax, Vita Mark 2, Empress Cad and Cerasmart.
The following X-rays were taken at her recall exam in May 2017 showing the dates and material used. All the restorations show absence of recurrent decay and good marginal fit.
Keep Cerecing.
