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Figure 7: Captek Nano full-coverage restorations with metal to
the edge and subgingival margins will be placed on tooth #8
and #9, next to IPS e.max veneers on tooth #7 and #10.
benefit from the esthetics provided by all-porcelain materials,
but there are situations where strength is an issue. Bruxers
or occlusally involved patients need additional restorative
strength. Patients with flexure, as well as excessive shear and
tensile stress risk, are included in this group as well. 2 According
to McLaren and Whitman: “If a high-stress field is anticipated,
stronger and tougher ceramics are needed. The restoration
design should be engineered with such support that it will
redirect shear and tensile stress patterns to compression. The
substructure should reinforce the veneering porcelain by using
the reinforced porcelain system, which is generally accepted
in literature as a metal-ceramic concept.” 5
The Wynne Hybrid
Figure 8: The final result reveals an esthetic blend of restorations:
Esthetic transparent restorations matched to restorations
that fully block out discoloration yet artificially refract and reflect
light to match natural tooth structure.
Figure 9: A visible dark line surrounds the existing lateral PFM
that had been treated with a root canal.
Figure 10: Removal of the PFM restoration reveals dark
underlying tooth structure. Radiographic examination exposes
a screw-type post. It is decided to replace the crowns and
leave the post, for fear of fracturing the tooth.
The Wynne Hybrid, as the name suggests, involves two margin
designs: the facial and lingual pressed porcelain butt margins
on definitive shoulder or chamfer margins. Interproximally, a
knife-edge design developed to the edge with Captek Nano
material is conservative but also bacteriostatic. 2 In the author’s
opinion, this interproximal design is also the easiest for the
clinician to finish, especially in the often hard-to-reach molar
interproximal area.
When underlying tooth colors are heavily stained, as is often
the case when retreating old restorations, preparation blockout
techniques that require more tooth reduction are often
difficult to control (Fig. 9). Old metal posts in anterior endodontically
treated teeth pose another challenge 6 (Fig. 10).
When we attempt to remove and replace these post systems,
we run the risk of fracturing the tooth. The Wynne Hybrid
can be utilized in such situations to resolve this issue in a
conservative yet esthetic manner (Figs. 11, 12).
Another advantage of this design is the increase of the ferrule
effect. 10,11 This is due to the interproximal margin placement
that engages more of the diameter of the tooth. The reasoning
behind this is that crowns with metal copings are less likely to
snap off with the tooth still inside should they receive a blow.
Biological Width Considerations
When restoring teeth, biologic width issues can often be a
concern. The gold knife-edge margin is the most controllable
of all margins in the posterior interproximal areas. Some clinicians
advocate a 360-degree porcelain butt margin around all
teeth. The key to predictable margins is the ability to control
the finishing of all 360 degrees of tooth margin. Anterior teeth
have interproximal margins that can be reached and highly
polished. However, as we move from premolars to molars,
the facial-lingual dimension of the contact space increases.
This diminishes the ability of the clinician to control the interproximal
margins. Concave root surfaces eliminate or greatly
diminish the chance of properly finishing the margin. This
knife-edge margin is more easily cleaned with an explorer
The Wynne Hybrid59