dental cements and cementation Flashcards
dental cements
1) indirect restorations crown, bridge, inlay, onlay
2) liners and bases
3) temp restoration material
luting
1) viscous material placed between the tooth and prosthesis that hardens through chemical reaction
- firmly attaches
properties for performance
1) high compressive ,tensile, and bond strength
2) withstand forces immediately
3) low viscosity and solubility
4) adequate fracture toughness to resist stresses at the restoration/tooth
5) good seal
6) color stability
7) provide good seal
8) biocompatibility
mechanisms
1) non adhesive
2) molecular adhesive
3) micromechanical
non-adhesive
1) zinc phosphate cement
2) material hardens and acts as a wedge
- friction
molecular adhesion
1) glass ionomers and RMGI
2) true chemical rxn to tooth
3) involves van der waals forces
4 )conventional cementation
- ionic bonds
- technically not “bonding process”
micromechanical
1) pitted tooth enamel
2) enamel is etched with phosphoric acid
3) ceramics except zirconia are etched with hydrofluoric acid
4) metals and zirconia are sandblasted internally
choices for cement
1) zinc phosphate
- powder is MgO and liquid is phosphoric acid
- lots of sensitivity
2) poly carboxylate
- less acidic polyacrylic and more bonding
- hard to work with
3) GI
- lowest post op sensitivity
- takes weeks to fully react
4) RMGI*
- resin is a scaffold for rxn to finish
5) resin cements
RMGI
1) fuji Cem
2) range of resin vs GI
3) acid base rxn
4) photo cure
5) chemical polymeization
fuji cem 2
1) traditional cementation
2) FVC, PFM, FZ, gold
3) not recommended for LDS
- due to setting expansion and LDS needs to be bonded
4) longer working time
resin cements
1) solubility is least
2) much stronger
3) micromechanically
- etched ceramic restorations (5-10% hydrofluoric acid)
- etched enamel (40-340% phosphoric acid)
resin cement classification
1) polymerization
- light (NX3, Variolink, RelyX veneer)
- dual (NX3 dual cure, RelyX unicem)
- chemical (Panavia, C&B)
2) adhesive scheme
- total etch (relyX ARC, variolink II)
- self etch (RelyX unicem, panavia)
relyX unicem
1) dual cure
2) self-adhesive
light cured
1) use photo initiators
2) ex. NX3 light cure, variolink veneer, Relyx veneer
3) can be used with LDS < 2 mm thick
- esthetic zone, thin ceramic
4) extended working time, setting on demand
5) color stability due to the absence of TERTIARY AMINE component
dual cure
1 )ex. NX3 dual cure, relyx unicem
2) the tertiary amine + benzoyl peroxide
3) under restorations that attenuate light (thick zirconia)
4) color darkens with time due to tertiary amine
chemical cure
1) Panavia, C&B
2) two paste system
3) used under PFM crows and cementing posts