Ceramics

They lack a glassy phase.

Enamelling a metal surface distributes stresses, provides rigid support, and inhibits crack propagation from cracks at the interface.

900-1200 MPa

Machinable materials, such as pure Zirconia, are indicated for all restorations.

~470 MPa

Sandblast the area, use a metal primer, apply a layer of resin cement followed by a layer of composite, and then go through the normal workflow when the patient returns.

It may introduce surface flaws that compromise strength and reliability.

It increases surface irregularity for micromechanical retention and exposes –OH groups for chemical bonding with silane coupling agents.

No, CAD blocks are not indicated for multi-unit FPDs.

Condensation reactions with silanol (SiOH) groups generated by hydrolysis of the alkoxy (or methoxy) group (RO3Si-).

Advantages include homogeneous blocks with fewer porosities leading to microcracks and better margins.

Because hydrofluoric acid (HF) has no effect on Al2O3.

Zinc phosphate is a good choice because it is cheap, easy to use, and suitable for crowns that are already opaque.

Bruxism/clenching and deep overbite, especially in the elderly.

PFM crown, as the material needs to resist firing with metal.

A 1 mm margin for aesthetics (non-stress-bearing area) and 1.5 mm occlusally for force-bearing areas. If there are no opposing teeth, a more conservative approach can be taken.

Advantages include simplicity, durability, homogeneity (reduced microcracks), different aesthetic options, superior accuracy, and the availability of chairside options.

Posterior regions and substructures to mask dark underlying metal/discolouration.

Zirconia has a notable opacity in dental restorations.

The steps involved in bonding glass-based ceramics are: 1) Air abrasion, 2) Etching with HF, 3) Silane treatment, 4) Etching the tooth with 37% orthophosphoric acid, 5) Applying resin-based composite luting material.

It minimizes operator-dependent errors.

95%

Contemporary cements include resin cements, resin-modified glass ionomer cements (RMGIC), self-adhesive composite resins, and compomers.

Single tooth restorations.

Shrinkage with firing is a common issue with dental ceramics.

Disadvantages include a limited number of burs which limits the finish, margin and fit to prep not being great, and higher costs (though improved with current technology).

Bleaching can extract alkaline ions from within ceramics, potentially causing surface roughening.

Chemical and micromechanical bonding via 4-MET and MDP, which are acidic functional monomers that demineralize and penetrate the dentine and enamel.

The elastic modulus of hybrid ceramics is ~30 GPa, which is lower than conventional ceramics but similar to dentine.

By pressure casting at 450-550°C for less than 1 hour to initiate enucleation, then cooling to room temperature.

Fabrication defects such as voids created during processing and sintering, and internal surface cracks that develop during firing and cooling.

Subgingival placement of the margins.

A combination of mechanical and chemical pre-treatments.

CAD/CAM materials have a lower survival rate than PFM due to a higher incidence of veneer chipping.

The machining process may create stresses in the material.

Melt infiltration, solvent infiltration, and initiator infiltration.

700 MPa

Highly translucent and allows for controlled shade (polychromatic).

Hybrid ceramics are ceramic-resin materials created to combine the Young’s modulus of resin-based composites with the aesthetics of ceramics.

Firing is associated with 2% shrinkage, which CAD accounts for by synthesizing an expanded restoration to compensate.

Legacy cements refer to traditional cements such as zinc polycarboxylate, zinc phosphate, and conventional glass ionomer cement (GIC).

70%

High abrasion resistance and chemical inertness.

Compare the mechanical integrity of different types of CAD/CAM materials and discuss their reinforcement strategies, such as those used for zirconia.

92%

e.max restorations can now be done with a 1 mm reduction.

Cohesive failure within the veneer.

They are low-strength etchable glass-based ceramics made by injection-moulding under heat and pressure, resulting in reduced shrinkage and increased flexural strength (~160 MPa).

Posterior crowns, copings over dark underlying teeth, and monolithic bridges.

They start in a blue state composed of metasilicate and lithium disilicate nuclei, with flexural strength prior to firing of ~130 MPa.

Yttria (yttrium oxide, Y2O3) is used to stabilize the tetragonal zirconia polycrystal (3Y-TZP), maintaining its structure at room temperature and opposing the opening of cracks by creating compressive stresses.

To know their oral hygiene habits.

Considerations include how the papilla comes together, gingival margins, adjacent teeth, color of the underlying tooth, and the cementation system.

Frameworks of fixed partial dentures (FPDs) and metal-free super-structures on implant abutments.

Silanise porous ceramic.

To overcome polymerisation shrinkage, reduce size and number of defects, and reduce monomer release.

Weak (FS 60-70 MPa), excessive shrinkage, and microporosities leading to inhomogeneity.

Hybrid ceramics have a flexural strength of 150-160 MPa, which is higher than feldspathic glass (70-100 MPa).

CAD/CAM systems have similar survival rates to conventional crowns.

Because young patients have large pulp chambers.

Higher glass content in glass-based ceramics provides better aesthetic properties such as translucency, which mimics the optical properties of enamel and dentine.

Glass-based ceramics are not sufficiently strong for posterior crowns but can be used anteriorly, with fracture loads comparable to natural teeth in the premolar area.

Inlays made from glass-based ceramics showed survival rates of 94.7% after 5 years, 90.6% after 8 years, and 85.7–89% after 10 years.

Glass ceramic enriched with 10% zirconia by weight.

Improved mechanical properties, less risk of shrinkage, and they are translucent and aesthetic.

Colour stability, translucency, and polishability.

By developing compressive strength in the surface of the materials through methods like chemical bonding with adhesive resin cements and thermal tempering.

There are distinct differences between the various types of ceramics used.

Young patients with large pulp chambers, high aesthetic demands, patient request, and metal allergy.

By using air abrasion to improve bonding.

They have higher strength due to a densely-packed crystalline network.

Abrasive wear can be reduced by glazing the crown, although leucite used to enhance strength and optical properties can aggravate this effect.

Repairs require hydrofluoric acid, silane, and composite, but the finish is never as good as the original.

Free radicals are formed that react with functional groups of the silane coupling agent and resin monomer to form a covalent polysiloxane (-Si-O-Si-) network.

Zirconia has higher flexural strength (900-1200 MPa) and high fracture toughness (9-10 MPa m-1), which hinders the propagation of cracks.

460 MPa

They offer high translucency for aesthetics in anterior regions, low translucency for discoloured teeth, and polychromatic blocks that are good for anterior teeth because the incisal edge is more translucent.

MO (for discoloured prep), LT (posterior restorations), MT (brighter than LT but more translucent), and HT (inlays/onlays/veneers).

Because they are brittle and have inferior tensile strength, which can lead to microcracks.

Careful preparation and crown design should minimize stress concentration, minimize tensile forces, and use shoulder and chamfer finishing lines to minimize oblique forces in the margins.

Cementation is technique-sensitive because it requires good technique and moisture control, and all steps must be followed to achieve a good result.

Phosphate-modified composite resin (MDP) cement.

Largely through micromechanical means, as the tooth is etched as normal.

Silane treatment acts as a coupling agent, bonding dissimilar materials by establishing a bond between ceramic and composite resin, and improving wetting.

They are not really used anymore due to advancements in other methods.

97%

Vita Enamic is a polymer-infiltrated ceramic network (PICN) with an inorganic ceramic network (leucite-based glassy phase and zirconia-reinforced) and an organic acrylic polymer infiltrate (e.g., UDMA and TEGDMA).

Transformation toughening is a process where external stresses cause a metastable tetragonal phase to transform into a stable monoclinic phase, resulting in volumetric expansion that can compress crack tips. Zirconia benefits from this process.

Glass-based ceramics are mainly used for veneers.

The flexural strength of glass-based ceramics like Vita TM Mark II is 100 MPa.

Exposure to HCl significantly increases roughness in ceramics compared to zirconia.

Leucite filler dissolves preferentially in etching, creating micromechanical retentive features.

Crown, core material, veneer, inlay/onlay.

Equipment-heavy and time-consuming.

The lithium disilicate crystallizes as the lithium metasilicate reacts with the silicate, resulting in 70% lithium disilicate by volume, higher crystallinity, and altered grains.

Adding filler to glass-based ceramics improves their mechanical properties such as strength, thermal expansion, and contraction by interspersing small crystals in the ceramic structure, which impedes the propagation of cracks.

97% after 5 years and 93.5% after 10 years.

Hybrid ceramics have lower fatigue-resistance compared to zirconia, LD, and In-Cerams.

It can withstand 350-450 MPa, with increased fracture toughness and flexure strength relative to leucite.

The polymeric component allows hybrid ceramics to undergo slight plastic deformation, which improves resistance to fracture.

Propensity to fracture, which is related to the size, distribution, and nature of the crystalline phases.

Placing dental ceramics in a potassium nitrate salt tank cooler than the glass transition temperature causes Na+ ions on the ceramic's surface to exchange with K+ ions from the salt tank, compressing the silicate system.