Cementation Flashcards
What are the 3 classifications of cements?
- Liners and bases
- Temporary cements
- Permanent cements
Example liner/ bases?
Glass ionomer cement
Properties of RMGIC
- Ease of use/ bulk fill
- Command set w/ light cure
- Possibility of subsequent etching to establish strong adhesive bond w/ dentine bonding agent
- Adhere to unetched hard tissue
- Sustained F- release
What must temporary cements be able to do?
Must remain cemented between prep and definitive restoration for 1 week - several months
Sometime necessary long term provisionals - assess pulp health, gingival health and evaluation aesthetic and function
What can the loss/ failure of temporary cement lead to?
Pain
Overeruption - loss of space
Drifting proximal teeth
Damage to core prep
PODD
What are the ideal functions of temporary cement?
Provide seal - protect marginal leakage
Prevent plural irritation
Low strength - easy to remove
Protect prep
SPSP
Ideal properties of temporary cement?
Seal against oral fluids Low solubility Biocompatible Chemical compatibility w/ provisional Ease of use/ ease of removal Easy eliminate excess Adequate working and setting
E-CABLES
What materials are used as temporary cement?
Fine particle zinc oxide eugenol cement = TempBond
Non-eugenol cement = TempBond NE
What materials should not be used as temporary cement?
Zinc phosphate, zinc polycarboxylate, GIC
Too high strength
What are the adv/ disadv of ZoE cements?
Adv
- Easy removal, acceptable sealing, obtundent effect pulp, easy use
Disadv
- Free eugenol act as plasticiser of methacrylate resin - reduce surface hardness and strength
- Eugenol interfere w/ bond strength resin cement - inhibit polymerisation
What is purpose of permanent cement?
Fill micro gap between tooth structure and restorative material to assist in retention
- Proper resistance and retention from preparation is most important for successful retention
Types of permanent cement?
- Total etch adhesive resin cements: self cured resin, light cured resin, dual cured resin
- Self etching resin cements
Properties of ideal cement?
Adequate working time - rapid set Low film thickness Low solubility High compressive and tensile strength Low viscosity Adhesion to tooth and restorative material Biocompatible Cariostatic Translucent or opaque Radiopaque
CRAVATS CBF
What is RMGIC?
Hybrid resin and GIC
Insoluble oral fluid
Bond inorganic phase dentine
Disadv of using RM-GIC as permanent cement?
Adhesion to tooth or ceramic not as strong
Hydroscopic expansion can lead to fracture of ceramic - contraindicated w/ ceramic
When is it acceptable to use RM-GIC as permanent cement?
Metal-based inlay, onlay, crowns or bridges
Mechanism of RM-GIC?
Contain acid-soluble glass, poly acid polymer and polymerising dimethacrylate
Polyacid polymer react w/ calcium in glass filler and dentine
Dimethacrylate polymerise into solid resin
Composition and setting of RMGIC?
Powder - ion leachable glass
Liquid - bisGMA enable polymerisation reaction, poly acid reacts powder acid-base reaction, HEMA enable resin and acid to co-exist in solution, water allows for ionisation
Advantages of RMGIC as permanent cement?
Adequate compressive, tensile and flexural strength - less than composite Easy manipulation and use Low film thickiness F- release Polymerisation not significantly affected eugenol-materials Minimal post-op sensitivity Some adhesion enamel/dentine Resistance marginal leakage
CRAMPS AFF
Disadv of RM-GIC as permanent cement?
Dehydration shrinkage
Can create stress fractures
HEMA responsible increase water sorption - cause hydroscopic expansion
Cement bulk very hard to remove
How to use total etch adhesive resin cement?
Pre tx-tooth w/ 37% phosphoric acid and dentine bonding agent prior to application
Ceramic fit surface etched HF acid - micro mechanically retentive surface
Resin cement used conjunction silence applied HF-etched crown
Form micro mechanical bond to both tooth strcuture
Need ideal moisture control
When can total etch method be advantageous?
Tooth wear case w/ less ideal cervico-incisal height
May require additional bond strength
Advantage of total etch method?
Superior compressive and tensile strength
Insoluble oral fluid
Adhesive
Micro-mechanical bond enamel, dentine, glass-ceramic
Wide range shade, translucencies
Disadv of total etch method?
Technique sensitive
High film thickness
Marginal leak due polymerisation shrinkage
Pulp reaction if on vital dentine
No F- release
Low elasticity - can’t support long span prosthesis
Hard to remove hardened resin inaccessible area
