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
total etch
1) 30-40% phosphoric acid to dentin and enamel
2) relyx arc, variolink II, NX3
self-etch
1) self-etching primer to prepare the tooth
2) can be in one or two steps
3) rely x unicem !!!
when you use self-etch, does it stay acidic
1) weak acid gets buffered
self-adhesive
1) need tooth structure for this
2) acidic monomers need to be neutralized
- solubility issue would be an issue
3) so SARC cannot be used if the core is amalgam or other metals
when to use what types of cements
1) strength of material
a) weaker material (empress)
- BOND will make it stronger
b) stronger materials (PFM, metal, zirconia, LDS)
- cement or bond
2) retention
a) retentive
- RMGI, SARC, either bond or cement
b) nonretentive
- bond it
bond strength
1) RMGI < self-adhesive < adhesive
cementation of #19
1) using RelyX unicem2
- can also use Fuji Cem 2
2) a resin based cement
- self-adhesive
- no need to etch, but you can selectively etch the enamel
- cannot use with large restoration as buildup (bc it is a SARC)
- cannot be used with veneers (tertiary amine)
- material is not that strong
using relyX unicem 2
1) if metal, PFM, zirconia
- sandblast intaglio
2) if LDS
- phosphoric acid to clean surface (NEVER for zirconia)
3) prepared tooth
- remove temporary and clean cement
- clean with pumice
- dry (no over dry)
4) cementation
- initial bleed
- apply inside restoration
- firmly sit with finger pressure
- dual cure so you can light cure each surface for 20 seconds
- 6 minute setting time
restoration pre-treatment
1) sandblaster is used to increased surface intaglio
2) aluminum oxide is the medium
3) the device delivers a small stream
4) good for all metal and zirconia
- not for silica (LDS)
5) microetching using siljet
- necessary for preps without retention that need to be bonded
- introduce silica to intaglio, which enhances dental adhesive
clinic protocols for the relyx unicem 2
1) clean tooth with pumice
2) bleed rely x unicem 2
- bleed tip again
3) seal restoration and remove excess
4) tack cure 1-2 seconds
- remove excess
5) fully cure
microporosities
1 )silica
- hydrofluoric acid
2) zirconia and metal
- sandblasting
3) tooth
- phosphoric acid
remove cement
1 )floss with double knots
- pull floss from buccal
for # 9 LDC bonding
1) dual cure resin cement
- NX3 Nexus (ARC)
2) non light accessible (assume >2 mm)
3) non retentive LC, MZ, PFM, PFZ, allow, all ceramic inlays, onlays
NX3 nexus
1) stronger bond
2) multiple shades with try in paste
3) light cure
- low strength, thin
4) dual cure
- high strength or when light is not accessible, and prep is non-retentive
in addition to Dual cure Nx3 Nexus
1) hydrofluroic acid
2) silane
- couple resin with silica
3) prelude
*applied to restoration
4) if you have enough enamel, you can selective etch with phosphoric acid
hydrofluoric acid
1) LDS restorations
2) if not pre-etched
silane
1) good for silica based materials like LD
2) coupling agent for the two dissimilar materials
teflon tape
1 )for protecting adjacent teeth
preparation of #9
1) silane 60 seconds
- air dry
2) apply bonding (black)
- do not cure
- place under UV shield box
3) do not need primer (yellow)
4) polish tooth with pumice, apply teflon
5) add yellow
- 15 seconds scrub
- 10 secs air dry
6) dispense link on both (Red)
7) apply nexus 3
cementation options for our two crowns
1) #9 LDS >2 mm
- nexus dual cure
2) #19 monolithic zirconia
- fuji cEM 2
- relyx unicem 2
- panavia
nexus 3 light cure
1 )good for veneers and thin LDS
2) pre-etched
3) silane to internal surface for 60 seconds
4) do not need the LINK
- apply prelude adhesive to internal surface of restoration
- OR SCOTCHBOND BECAUSE ITS BETTER!!!
cementation clinical tips
1) always work under isolation
- anesthetize as needed
2) keep working time in mind
3) hold down with fingers after seating
4) be very quick to floss the interproximal areas right after seating
5) clean up as much excess as possible before final curing
6) after set, verify contacts and margin closure
seating failures
1) tall preps
- be careful
2) incomplete seating can be due to overfilling
- seated too slow
3) place thin wall on axial surface
4) work quickly
5) check margins immediately
temporary cements
1) zinc oxide eugenol
- ex IRM, tempbond, tempbond NG
- must be cleaned off COMPLETELY before final crown
2) zinc polycarboxylate
- ex. durelon, ultratemp (non-retentive preps)
mixing tempbond
1) base and accelerator
2) smash and mix
3) just line the walls (do not need to fill it all up)
know these cements
1) fuji cem
2) rely x unicem 2
3) nexus nx3 dual cure
4) nexus nx3 light cure
5) all the temporary cements
- tembond, IRM, ultratemp, durelon
