What is cement for?
- A cement is a solid paste, which implies that some sort of setting reaction takes place.
- Bonding:
o Ceramics/resin-based material bonding to tooth structure
o Needs to be decided case by case
o Do you have enamel, dentine, how much dentine do you have
o Thickness is key for the crown, need light to pass through if curing photopolymerization
What tissues are involved for cementation?
o DENTINE, ENAMEL
o Materials abutment are made of (zircona, resin, etc)
o Interfaces need to be compatible
What potential materials are involved in cementation?
o Ceramics, etc
o Surface energy of substrate (dentine or enamel), surface tension of liquid (cement, adhesives, primer, etc)
o Need to increase surface energy of substrate, so need to etch, air abrasion, to make surface to be active. Need cement to have low surface tension.
What do you need for CAD/CAM materials like lithium disilicate glass ceramic?
o If has glass in composition, need fluoride in the cement +etch to increase surface energy
o Zirconia needs silica or air abrasion + primer
What is the chemical or mechanical process involved in cementation?
o Seals the interface between the tooth and the restoration
o Acts as a barrier against bacterial microleakage
o Holds the tooth and the restoration together through some form of surface attachment.
What are the general steps for luting cement manipulation?
- Smear layer removal
- Temporary cement removal
- Powder/liquid ratio
- Mechanical mixing speed.
- Seating force/vibration
- Moisture control
What are the ideal properties a luting cement has? (4)
- Biological properties
- Mechanical properties
- Aesthetic properties
- Working properties
What are the biological properties of an ideal luting cement?
o Biocompatibility
o Little/no interaction with oral fluids/tissues
o Non-toxic
o Low allergic potential
o Inhibition of caries and/or biofilm
o Prevention of microleakage
What are the mechanical properties of an ideal luting cement?
o Strength (compressive, tensile, flexural)
Crown is compressive strength and flexural
Bridges are flexural stress.
Ceramics are good under compressive and flexural strength but not good under tensile strength
Filler and particles give resistance to materials in resin-based cements
o Modulus of elasticity
o Fracture toughness
o Hardness:
High hardness materials have resistance to penetration.
o Solubility
o Water sorption
o Adhesiveness
o Wear resistance
o Setting stresses.
What are the aesthetic properties of an ideal luting cement?
o Colour stability
o Radiopacity
What are the aesthetic properties of an ideal luting cement?
o Film thickness
o Viscosity (particle size).
What is the classifications for permanent luting cements?
- Water based
- Resin-based
What are some examples of water based permanent luting cements?
Zinc polycarboxylate
Zinc phosphate
Glass-ionomer cement (GIC):
* Conventional GIC
* Resin-modified GIC
What are some examples of resin-based permanent luting cements?
Self-curing/light-curing/dual-curing
Adhesive/self-adhesive.
What are the classifications for temporary luting cements?
- Oil-based
- Oil-free
What are some examples of oil-based temporary luting cements?
Zinc-oxide eugenol
Temporary GIC
What is an example of an oil-free temporary luting cement?
Zinc-oxide non-eugenol
What is zinc phosphate?
- Acid-base reaction
- Powder (90% ZnO, 10% MgO)
- Liquid (67% phosphoric acid buffered with aluminium and zinc).
- Water content (33%) controls ionisation of the acid and rate of setting reaction.
- Film thickness <25 micrometres
- Ideal mixing and seating technique for optimum result.
- Last a very long time but smell bad after time.
- Cement strength almost linearly dependent on powder : liquid ratio (more powder = better strength)
- Compressive strength 80-110MPa.
- Tensile 5-7MPa
- Set cement extremely stiff, modulus of elasticity 13 GPa.
- Does not chemically bond to tooth structure.
- Long clinical track record.
What are the uses for zinc phosphate?
o Long term luting of well fitting,
- prefabricated and cast posts,
- metal inlays,
- onlays,
- crowns,
- fixed bridges,
- aluminous all-ceramic crowns to tooth structure, amalgam, composite, or GIC cores.
What are glass ionomer cements?
- Acid-base reaction
- Introduced as luting agents in early 1970’s
- Acid-base reaction between aluminium fluorosilicate glass particles and a liquid consisting of copolymers of weak polyalkenoic acids.
- Adherence to tooth structure.
- Compressive strengths 90-230 MPa.
- Reduced microleakage over non-adhesive type cements.
What are resin-modified glass ionomer cements?
- Acid-base reaction
- Setting reaction leads to formation of a metal polyacrylate salt and a polymer.
- Harden by:
o Acid-base reaction (fluoroaluminosilicate glass powder + aqueous solution of polyalkenoic acids modified with pendant methacrylate groups).
o Photo/chemically initiated free radical polymerisation of methacrylate units. - Compressive and diametral tensile strength > Zn phosphate, polycarboxylate and GIC, but < resin composite.
- Adhesion to enamel and dentine and fluoride release as GIC.
- Less soluble than GIC, more resistant to water attack during setting
- Adequately low film thickness.
- Addition of resin not significantly reduced dehydration of GIC component.
- Hydrophilic nature of polyHEMA results in increased water sorption and plasticity and hygroscopic expansion.
- Potential for substantial dimensional change.
- Biocompatibility due to free monomer.
- Not significantly affected by eugenol containing temporary cements.
What are the uses of resin-modified glass ionomer cements?
- Uses: Metal/MC crowns/bridges to tooth, amalgam, resin composite, GIC cores:
o Risk of expansion induced root fracture if used in non-vital teeth to cement posts. - High caries risk should use GIC or RMGIC as cement, rather than normal resins.
What is RELY-X?
Resin-modified glass ionomer cement
o Two setting reactions:
Acid-base reaction
A free radical polymerisation of the pendant
o Methacrylate groups of the polymer and HEMA.
o But, the free radical polymerisation reaction takes place without the need for light activation (a methacrylate dark cure) via the same water-activated redox catalyst system found in 3M Vitremer materials.
o Tell patient to not drink coke in the first 30 minutes or to eat for 30 minutes to allow cement to have best polymerisation
What is GC FujiCEM?
Resin-modified glass ionomer cement.
o The first RMGIC offered in a paste/paste formulation.
o (Claimed to) possess higher dentin and enamel bond strengths and lower film thickness than any competitive glass ionomer cement (Conventional or resin modified).
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Revision of endodontic principles27
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Success/failure in endodontic treatment12
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Restoring endodontically treated teeth26
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Extra coronal restorations - crowns and laboratory stages17
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Principles of tooth preparation16
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Shade selection in dentistry26
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Impression techniques and soft tissue management27
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Extra-coronal restorations - treatment planning17
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Temporary crowns18
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Elastomeric impression materials37
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Crown fitting and cementation36
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Periapical pathology33
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Medical devices (MDR) regulations23
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Jaw movements and articulators36
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The TMJ32
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An introduction to partial dentures 131
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Materials for cementation31
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Partial dentures 2 - clinical and laboratory stages34
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Partial dentures 3 - partial denture design34
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Partial dentures 4 - impressions and recording the occlusion35
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Partial dentures 5 - anterior saddles and aesthetics20
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Fixed bridges25
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Partial dentures 6 - managing free-end saddles, try in and fit22
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Partial dentures 7 - Denture polymers27
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An introduction to oral surgery30
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Fascial spaces and the spread of infection30
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Clinical occlusal investigations12
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Occlusal factors in restoration failures9
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Complications of extractions in oral surgery32
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Abnormal bleeds21
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Inlays/onlays31
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Materials for crown and bridgework25
