Zirconia Crowns and Bridges Survival
For Zirconia crowns and bridges to survive a long time, these should be done.
1. All dentin and enamel do not have any decay left in the tooth preparation.
2. Avoid all contamination from saliva or water moisture.
3. Make Parallel tooth or metal preparation
4. Sandblast internal crowns/bridge abutments with Alumnia oxide powder
5. Use cement that contains 10-MDP primer (10-Methacryloyloxydecyl Dihydrogen Phosphate)
6. I use ClearFil Ceramic Primer Plus primer from Panavia V5 resin cement from Kuraray America Inc.
7. Follow the instruction from Manufacturer as in the attachment.
8. Follow these will do you and your patients great service and peace of mind.
The reasons for doing these are from the hard work of many graduate students and my teachers and researchers: Dr. Ronald Sakaguchi and John Powers. The writing below is taken from their text book, Craig’s Restorative Dental Materials, 14th Edition, published in 2018.
The clinical success of indirect ceramic restorations is highly dependent on the cementation procedure employed. In recent years there has been an increase in the popularity of zirconia-based prosthetics such as crowns and bridges due to the material’s superior mechanical strength, esthetic properties, versatility of clinical indications, and ability to be used in digital procedures involving computer-aided design/computer-aided manufacturing milling. However, conventional adhesive cementation procedures involving hydrofluoric acid treatment and application of silane primers do not work for zirconia restorations. This is because zirconia is a polycrystalline material with no amorphous silica glass component, thus making it resistant to acid etching by hydrofluoric acid and also unreactive toward silane primers.
Several strategies have been employed for formulating commercial zirconia primers. The primary approach has been to roughen the bonding surface of the zirconia by sandblasting and then use a specially formulated zirconia primer containing phosphate or phosphonate monomers as the key reactive ingredient. These acidic groups are believed to form a stable Zr–O–P bond with the surface of the zirconia. In addition to the phosphate or phosphonate functionality, these monomers contain a hydrophobic backbone and a methacrylate group that can copolymerize with the adhesive resin cement upon initiation to build up cohesive strength. The most widely used monomer in zirconia primers is 10-MDP. It has also been reported that combining phosphate/dithione and phosphate/carboxyl monomers produces a synergistic effect in bonding. Some manufacturers also incorporate a silane component in addition to the organophosphate monomer in the primer in order to expand their use to both zirconia and porcelain surfaces. However, the shelf stability of the silanes in the acidic environment of these primers has been questioned and refrigerated storage of the primers is indicated. In another approach, laboratory or chair-side air abrasion with 110- and 30-μm silica-coated aluminum particles have been used on the interior surface of the zirconia device to create a siliceous surface followed by the treatment with conventional silane-based primer (tribochemical bonding). This technique has given mixed results.
Bonding glass-infiltrated or densely sintered alumina, as well as yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics, remains a subject of debate among clinicians and researchers. Hydrofluoric acid etching is not efficient in highly crystalline ceramics. Therefore other methods such as airborne particle abrasion with 35 to 110 μm alumina are indicated to increase surface roughness. Tribochemical coating of Y-TZP surfaces using silica-modified alumina particles followed by silanization is also efficient. Organophosphate monomers such as 10-MDP, present in primers developed specifically for zirconia bonding, universal adhesive systems, and self-adhesive resin cements, were shown to form stable Zr–O–P bonds on the zirconia surface and improve its bond strength to other substrates, particularly when the surfaces were previously modified by air abrasion with alumina.