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CD0412

I CE article _ mastering occlusal function 10 I cosmeticdentistry 4_2012 and they were tried in to evaluate fit and interproxi- mal contact. The crowns were then fired in a ceramic ovenCS(IvoclarVivadent)toconvertthelithiumme- tasilicate material (“blue block”) into the final lithium disilicate structure known as e.max (colour conver- sion and glazing also occurs during this process). Thecrownswereremovedfromtheoven,triedin and inserted. Because of the accuracy of CEREC’s designcalculations,easymodificationmethodsand milling accuracy, no adjustment was required for this case (Fig. 17). The patient was shocked that there were no adjustments, as she remembered multiple adjustments being made for her prior restorations. She was quite pleased with the result. _Using something old Many times, large direct restorations will fail and eventually require an indirect restoration. The oc- clusal pattern of the old restoration may not have detailed anatomy, but it most likely has the occlusal guidance paths already worked out over many years ofservice.Forinstance,atoothmayhaveaverylarge amalgam restoration with recurrent caries that re- quires replacement. Although failing, it has tremen- dous value to the design steps in the CAD software. The surfaces of the restoration have the occlusal motion paths developed over it (Fig. 18). Using the pre-operative surface as a guideline for a digital restorationcouldverywellaidinpreventingocclusal interferences from being designed into the restora- tion. This is a feature within the CEREC program, and is referred to as “Biogeneric Copy.” This is an al- ternative method from the Biogeneric Tooth Model “Biogeneric Individual” with buccal bite articulation. The pre-operative occlusal pattern is easily scanned into prior to treatment. This is usually done while waiting for anesthesia, and is done similarly Fig. 16_A comparison of the final Biogeneric anatomy and milled IPS e.max CAD prior to firing. Fig. 17_A comparison of the finalized CEREC occlusal contacts with occlusal contacts made intraorally. Fig. 18_An old restoration may still have valuable occlusion information. Fig. 19_The preoperative model is spliced with the preparation model during imaging. Fig. 18 Fig. 19 Fig. 16 Fig. 17