Zirconias, the strongest of the dental ceramics, are increasingly being fabricated in monolithic form for a range of clinical applications. Y-TZP (yttria-stabilized tetragonal zirconia polycrystal) is the most widely used variant. However, current Y-TZP ceramics on the market lack the aesthetics of competitive glass-ceramics and are therefore somewhat restricted in the anterior region. This article reviews the progressive development of currently available and next-generation zirconias, representing a concerted drive toward greater translucency while preserving adequate strength and toughness. Limitations of efforts directed toward this end are examined, such as reducing the content of light-scattering alumina sintering aid or incorporating a component of optically isotropic cubic phase into the tetragonal structure. The latest fabrication routes based on refined starting powders and dopants, with innovative sintering protocols and associated surface treatments, are described. The need to understand the several, often complex, mechanisms of long-term failure in relation to routine laboratory test data is presented as a vital step in bridging the gaps among material scientist, dental manufacturer, and clinical provider.

/pdf/novel-zirconia-materials-in-dentistry-1js6tfkdvl.pdf

Novel Zirconia Materials in Dentistry

Adhesion/cementation to zirconia and other non-silicate ceramics: where are we now?

Statement of problem Surface treatment methods used for resin bonding to conventional silica-based dental ceramics are not reliable for zirconium-oxide ceramics. Purpose The aim of this study was to compare the effects of airborne-particle abrasion, silanization, tribochemical silica coating, and a combination of bonding/silane coupling agent surface treatment methods on the bond strength of zirconium-oxide ceramic to a resin luting agent. Material and methods Sixty square-shaped (5 × 5 × 1.5 mm) zirconium-oxide ceramic (Cercon) specimens and composite resin (Z-250) cylinders (3 × 3 mm) were prepared. The ceramic surfaces were airborne-particle abraded with 125-μm aluminum-oxide (Al 2 O 3 ) particles and then divided into 6 groups (n=10) that were subsequently treated as follows: Group C, no treatment (control); Group SIL, silanized with a silane coupling agent (Clearfil Porcelain Bond Activator); Group BSIL, application of the adhesive 10-methacryloyloxydecyl dihydrogen phosphate monomer (MDP)–containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/ Porcelain Bond Activator); Group SC, silica coating using 30-μm Al 2 O 3 particles modified by silica (CoJet System); Group SCSIL, silica coating and silanization (CoJet System); and Group SCBSIL, silica coating and application of an MDP–containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/Porcelain Bond Activator). The composite resin cylinders were bonded to the treated ceramic surfaces using an adhesive phosphate monomer–containing resin luting agent (Panavia F). After the specimens were stored in distilled water at 37°C for 24 hours, their shear bonding strength was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Debonded specimen surfaces were examined with a stereomicroscope to assess the mode of failure, and the treated surfaces were observed by scanning electron microscopy. Bond strength data were analyzed using 1-way analysis of variance and the Duncan test ( α =.05). Results The bond strengths (mean ± SD; MPa) in the groups were as follows: Group C, 15.7 ± 2.9; Group SIL, 16.5 ± 3.4; Group BSIL, 18.8 ± 2.8; Group SC, 21.6 ± 3.6; Group SCSIL, 21.9 ± 3.9; and Group SCBSIL, 22.9 ± 3.1. The bond strength was significantly higher in Group SCBSIL than in Groups C, SIL, and BSIL ( P Conclusion Tribochemical silica coating (CoJet System) and the application of an MDP–containing bonding/silane coupling agent mixture increased the shear bond strength between zirconium-oxide ceramic and resin luting agent (Panavia F).

Effect of zirconium-oxide ceramic surface treatments on the bond strength to adhesive resin.

Ceramic dental biomaterials and CAD/CAM technology: state of the art.

Statement of problem The few available studies on the resin bond to zirconium-oxide ceramic recommend airborne-particle abrasion and modified resin luting agents containing adhesive monomers for superior and long-term durable bond strengths. It is unknown whether this regimen can also be successfully applied to the intaglio surface of a commercial zirconia-based all-ceramic system. Purpose The purpose of this study was to evaluate and compare bond strengths of different bonding/silane coupling agents and resin luting agents to zirconia ceramic before and after artificial aging. Material and methods Composite cylinders (2.9 mm × 3.0 mm) were bonded to airborne-particle–abraded intaglio surfaces of Procera AllZirkon specimens (n=80) with either Panavia F (PAN) or Rely X ARC (REL) resin luting agents after pretreatment with Clearfil SE Bond/ Porcelain Bond Activator (Group SE). In another group, Rely X ARC was used with its bonding/silane coupling agent (Single Bond/Ceramic Primer, Group SB). PAN without any bonding/silane agent (Group NO) was the control. Subgroups of 10 specimens were stored in distilled water for either 3 or 180 days before shear bond strength was tested. One hundred eighty–day–old specimens were repeatedly thermal cycled for 12,000 cycles between 5 and 60°C with a 15-second dwell time. Data were analyzed with 1- and 2-way analysis of variance and the Tukey multiple comparisons test (α=.05). Failure modes were examined under original magnification ×25. Results After 3 days, SE-REL (25.15 ± 3.48 MPa) and SE-PAN (20.14 ± 2.59 MPa) groups had significantly superior mean shear bond strengths ( P =.0007) compared with either NO-PAN (17.36 ± 3.05 MPa) or SB-REL (16.90 ± 7.22 MPa). SE-PAN, NO-PAN, and SB-REL groups were not significantly different. Artificial aging significantly reduced bond strengths. After 180-day storage, SE-PAN (16.85 ± 3.72 MPa), and SE-REL (15.45 ± 3.79 MPa) groups demonstrated significantly higher shear bond strengths than NO-PAN (9.45 ± 5.06 MPa) or SB-REL (1.08 ± 1.85 MPa) groups. The modes of failure varied among 3-day groups but were 100% adhesive at the ceramic surfaces after artificial aging. Conclusion Artificial aging significantly reduced bond strength. A bonding/silane coupling agent containing an adhesive phosphate monomer can achieve superior long-term shear bond strength to airborne-particle– abraded Procera AllZirkon restorations with either one of the 2 resin luting agents tested.

In vitro evaluation of shear bond strengths of resin to densely-sintered high-purity zirconium-oxide ceramic after long-term storage and thermal cycling

Current ceramic materials offer preferred optical properties for highly esthetic restorations. The inherent brittleness of some ceramic materials, specific treatment modalities, and certain clinical situations require resin bonding of the completed ceramic restoration to the supporting tooth structures for long-term clinical success. This article presents a literature review on the resin bond to dental ceramics. A PubMed database search was conducted for in vitro studies pertaining to the resin bond to ceramic materials. The search was limited to peer-reviewed articles published in English between 1966 and 2001. Although the resin bond to silica-based ceramics is well researched and documented, few in vitro studies on the resin bond to high-strength ceramic materials were identified. Available data suggest that resin bonding to these materials is less predictable and requires substantially different bonding methods than to silica-based ceramics. Further in vitro studies, as well as controlled clinical trials, are needed.

/pdf/resin-ceramic-bonding-a-review-of-the-literature-3mhy0pbzjv.pdf

Avishani Sadan

Papers

Resin-ceramic bonding: a review of the literature.