You have three Maryland bridge choices, none of them great as a permanent restoration.
Your prep design ideas are excellent: Go with the MOF onlay prep on tooth #3 and the distal rest/lingual wing on tooth #5.
Choice 1: PFM with metal wings and ceramic pontic tooth #4. The upside is you can bond to the metal with resin (alloy primer with Kuraray Panavia™ F [New York, N.Y.]); the downside is the MOF on tooth #3 is ugly if you can see it when the patient smiles.
Choice 2: Composite reinforced with fiber (Kerr Premise™ Indirect [Orange, Calif.] with Vectors® [Ivoclar Vivadent; Amherst, N.Y.]). The upside is that any resin cement will bond with it because it is resin; this will give you the best bond strength. The downside is that the bridge is weaker than the PFM Maryland.
Choice 3: Zirconia bridge (3M™ ESPE™ Lava™ [St. Paul, Minn.]). The upside is that the bridge is as strong as the PFM and better looking. The downside is you can’t bond to zirconia, even with Panavia F or Parkell C&B-Metabond® (Edgewood, N.Y.). It might be tough to get the distal rest and the lingual wing to bond to the tooth.
As you can see, there is really no right answer, per se. When my patient declines a single-tooth implant and we decide to use a Maryland bridge, I usually tell them that it is not a permanent restoration like a fixed bridge or an implant. When they agree to that concept, I will usually go with either Choice 1 or Choice 2, based on their esthetic needs and the size of their smile, thickness of their anterior teeth, so on and so forth.
I have tried a zirconia Maryland bridge or two and have not had good luck. Bisco claims its new bonding agent for zirconia, Z-PRIME™ Plus (Schaumburg, Ill.), will bond resin to zirconia, but I haven’t seen any independent confirmation of this yet. We are currently testing it in our R&D Department at the lab to see if we can observe an increase in bond strengths.
I hope that helps!
– Dr. DiTolla