Do you ever specify to the technician how you want an anterior e.max restoration designed? From an esthetic standpoint, I generally want my anterior ceramic restoration to at least have the incisal 1/3 cut back and layered by hand. Doing this will create the most esthetic restoration, as the technician can layer in translucency and characterization into the incisal edge. In turn though, layering the incisal edge by hand will create the “weak link” of the restoration. It makes sense if you think about it….no matter how strong the restoration, it is the veneering ceramic that fails. The strength of the veneering ceramic (appox. 89 MPa) is well below that of the e.max (approx. 400 MPa).
With this in mind, there are times that I am willing to accept a restoration that will have a slight compromise in esthetics for the added strength that having e.max on the incisal edge provides. The type of patient in which I will request this design is generally a patient who has both “pathway” and “edge-to-edge” wear or as added assurance on a patient with an “edge-to-edge” wear pattern only. I will generally discover who these patients are either by evaluating what they did to their old restorations or during trial therapy.
For example, the patient in Fig. 1 presented with ceramic fractures in her existing restorations. The patient’s movement pattern matched that of the ceramic fractures. Although there was no problem in the trial therapy/provisional phase (Fig. 2), I felt that bringing the e.max to the incisal edge on this specific patient would lessen the potential chance of ceramic fracture. To help improve the esthetics, I did have the technician cut a facial window in the incisal 1/3 to allow some hand layering of ceramic, while leaving the incisal edge in e.max. The final result has added strength in the incisal edge while still maintaining adequate esthetics (Fig. 3).
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Gregg Kinzer, D.D.S., M.S., Spear Faculty and Contributing Author