Cements Flashcards
What types of permanent/definitive cements are there? What categories are they divided into?
Contemporary
- GIC
- RMGIC
- Resins
- Adhesive resin
Traditional
- Zinc phosphate
- Zinc polycarboxylate
What types of temporary/provisional cements are tehre?
Zinc oxide eugenol
Zinc oxide non eugenol
Resin
What are the ideal properties of cements?
Patient benefits
- Biocompatible
- Anticariogenic
- Shade options
- Strength, high wear resistance, low setting stress
- Good marginal seal
- Aesthetic/colour stability
Operator benefits
- Sufficient working time
- Low film thickness
- Radiopacity
- Ease of use
Durability:
- Low solubility
- Good comp;ressive + tensile strength
- Adhere to tooth structure and restorative materials
What are the methods of action of cement?
Mechanical + micromechanical
-Physical interlocking with surface irregularities
Chemical bonding
-Adhesive chemical bond can sometimes be formed between tooth and cement or cement and restoration
How can micromechanical retention be enhanced? What sort of restorations is this most effective on?
-Surface roughening via:
-Air abrasion
-Acid etching
Most effective on restorations with high tensile strength such as resin and RMGIC
What brands of GIC cement are available in clinic?
- Ketac Cem
- Fuji I
What brands of RMGIC cement are available in clinic?
Fuji Plus
Fuji Cem
What resin cements are available in clinic? What are their cure and bonding properties?
*Self adhesive=self etch
- MaxCem Elite
- Dual cure
- Self adhesive
- Rely X Unicem II
- Dual cure
- Self adhesive
- Nexus III
- Dual and light cure
- Total etch
- Panavia F 2.0
- Dual cure
- Adhesive resin (monomer contains component that bonds to precious and semi precious metals)
What Zinc polycarboxylate cements are available in clinic?
-Poly F plus
What Zinc phosphate cements are there (note not available in clinic)
- Fleck’s
- Hy-Bond
What are the components of GIC cements?
Powder:
- Calcium aluminosilicate glass
- Fluoride powder (controls cement formation and modifies physical properties)
Liquid:
- Dilute polyalkenoic acid (e.g. polyacrylic acid)
- Maleic acid
- Itaconic acid
What are some properties of GIC?
Handling:
- Sensitive to early moisture contamination and dessication
- Water absorption can cause degradation of cement, loss of translucency, decreased cement hardness
- Dessication can cause crazes and cracks if left for more than 10minutes–>cohesive failure
- Low film thickness + constant viscosity after mixing–> good seating
- Working time 2 - 3.5 minutes
Durability
- Low modulus of elasticity
- High compressive strength
- Poor wear resistance
- Use in caution in areas of high occlusal load
Effect on structures:
- Has chemical adhesion to tooth structure due to chelation with calcium and phosphate ions in dentine and enamel
- Slow, long term fluoride release–>cariostatic
Aesthetics
-Good translucency
For Ketac Cem, what are:
- Working time
- Setting time
- Steps in using
Above what temperature is setting time accelerated
Work time: 3 minutes
Setting time: 7 minutes
Steps:
- Clean and dry tooth and restoration
- Condition cavity for 20 seconds, rinse and gently air dry, avoid further saliva contamination
- Depress Aplicap, place in activator and activate once
- Mix in high frequency mixer Capmix (10 seconds) or Rotomix (8 seconds)
- Apply thin coat of cement to internal surface of restoration
- Seat restoration with firm pressure
- Remove excess after set
- Setting time accelerated above 23 degrees
- Longer mixing times=shorter working times and vice versa
What are RMGIC cements composed of?
- Hydrophilic monomers or polymerisable resin added to conventional GIC
- Also contains polymerisation inhibitors and moderators
- Hence setting reaction both acid base as in GIC and chemical/light initiated of resin
- Also include other di-methacrylates such as ethylene glycol methacrylate and glycidol methacrylate
- Also contains Bis-GMA
What are the properties of RMGIC cements?
Handling:
- Less moisture sensitive vs GIC
- Susceptible to dehydration shrinkage for up to several months post insertion–> cracks at exposed tooth cement restoration interface
- Film thickness similar to GIC (low)
Dimensional stability:
- Curing shrinkage (due to resin component)
- Volumetric expansion (over long term due to hydrophilic nature of added resin causing water sorption)–>unsuitable for veneers, all ceramic crowns, posts ( as ceramic weak to tensile forces which expansion applies)
Durability/longevity
- Higher compressive and tensile strength vs. GIC but lower vs resins
- Less soluble vs GIC
- However, concerns over long term stability
Effect on structures
- Some fluoride release
- Adhesion to tooth structure similar to GIC
What is the working and setitng time of Fuji Plus GC? (RMGIC) What are the steps in using it?
Working time: 2.5 minutes
Setting time: 4 minutes (autocure)
- Clean and dry tooth + restoration
- Condition tooth with 10% polyacrylic acid for 20 seconds
- Rinse and gently dry tooth and restoration, avoid saliva contamination
- Place capsule in activator and depress once, mix in rotational mixing device for 8 seconds
- Apply to internal restoration surface
- Seat on tooth within 30 seconds
- Remove excess after 1 minute while at gel stage
- Maintain isolation until set
What is the working and setting time for Fuji Cem GC? (RMGIC). What are the steps for usage?
Working time 2 minutes
Setting time 4.5 minutes (autocure)
- Clean and dry tooth + restoration
- Condition tooth for 20 seconds with 10% polyacrylic acid
- Rinse + gently air dry
- Dispense and mix Fuji Cem RMGIC in mixer for 10 seconds (it is hand mixed)
- Apply to internal restoration surface and seat within 30 seconds
- Remove excess after 1.5 minutes
What are resin cements composed of?
- Bis-GMA dimethacrylate or urethane demethacrylate based
- Fillers: 20 - 80% by weight (colloidal, silcat, barium glass)
What systems do resin cement come in?
- Powder/liquid
- Capsulated
- Paste/paste systems
What are the two ways of categorising resin cements? What are the types in each category?
Mechanism of cure:
- Self/auto
- Light cure
- Dual cure
Mechanism of bond:
- Total etch
- One step etch and bond (self-etch)
- Adhesive resin