cementation in fixed prosthodontics
TRANSCRIPT
Cementation in Fixed ProsthodonticsBY : ABDEL RAHMEN M. ABDEL HAMEED
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Clinical importance
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Bonding Mechanisms
Mechanical bonding
Molecular Adhesion
Micromechanical bonding
Bonding Mechanisms
Mechanical bonding
Molecular Adhesion
Micromechanical bonding
Mechanical bonding:
Bonding Mechanisms
Mechanical bonding
Molecular Adhesion
Micromechanical bonding
Molecular Adhesion
Molecular adhesion include the use of chemical
bonding between tow materials. Such as chemical
bonding, occur between the COOH group of the zinc
polycarboxylate and glass ionomer (GIC) cements
and the tooth structure.
Silane coupling agent is another example for
molecular bonding mechanism
Bonding Mechanisms
Mechanical bonding
Molecular Adhesion
Micromechanical bonding
Micromechanical bonding
This mechanism use the microstructure of the tooth structure to provide retention.
The bond strength of micromechanical bonding mechanism sometimes
exceed the cohesive bond of enamel.
Ceramics can be etched with hydrophloric acid and silanated, before using
resin cement with it. Metals also can be prepared by electrolytic etching,
chemical etching or sandblasting before using the resin cement with it.
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Classification of luting cements
According to the duration in
clinical performance
definitive
Provisional
According to reaction
mechanism
acid base reaction
polymerization reaction
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Ideal criteria of luting cements
Physical properties
Biocompatibility
Sealing and Anticariogenic Activity
Adhesion
Mechanical properties
Fatigue strength
Fracture toughness
Elastic Modulus
Wear
Handling and radiopoacity
Ease of use
long working time
short setting time
Radiopoacity
Esthetic
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cements:Resin cementsResin modified glass ionomer
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cements:Resin cementsResin modified glass ionomer
Zinc phosphate cement
Compressive strength (st): 96-110
Mpa
Tensile st: 9.3 Mpa
PH during cementation: 3.5
Film thickness: 10-20 um
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cements:Resin cementsResin modified glass ionomer
Zinc polycarboxylate cement
Compressive st: 50-80 Mpa
Tensile St: 7-10 Mpa
Bond strength to tooth structure: 9
Mpa for Enamel and 3.3 Mpa for
Dentin.
PH during cementation: 4.8
Film thickness: 13-20 um
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cements:Resin cementsResin modified glass ionomer
Glass Ionomer cements
Compressive st: 127 Mpa
Tensile st: 8Mpa
Bond st to tooth structure: 9 Mpa for enamel and 3 Mpa for
dentin
Film thickness: 9.5 – 16 um
advantages
fluoride
Bond to tooth structure
good esthetic properties
less soluble than zinc phosphate cement
GIC is 65% more retentive than zinc phosphate cement.
disadvantages
high acidity
sensitive to both moisture and dehydration
. GIC is translucent
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cements:Resin cementsResin modified glass ionomer
Zinc oxide eugenol cements:
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cementsResin cementsResin modified glass ionomer
Resin cements
Compressive st: 200-250 Mpa
Tensile st: 40-50Mpa
Film thickness: 25 um
Solubility in water: Insoluble
Resin cements are composed of organic matrix such as BISGMA or UDMA and inorganic fillers
Advantages
high mechanical properties
good seal abilities
good bond strength
no solubility
excellent esthetic
disadvantages
polymerization shrinkage
pulpal irritation
difficulty of removing the hardening
excess cements.
Classification of resin cement
According to the adhesive
scheme
Self-etching Self-adhesive
Total etching
According to the mode of
polymerization
Chemical cure Light cure Dual cure
Total etching resin cements
use three step bonding technique
Acid etching
Bonding
Cement application
Self-etching
The bonding agent is applied directly to
the tooth structure and cured, and then
the resin cement is applied.
Self-adhesive resin cements
The adhesive resin cement can be applied
directly to the tooth structure. It provide the
best retention with dentin.
Cement selection
Zinc phosphate cementZinc polycarboxylate cementGlass Ionomer cementsZinc oxide eugenol cementsResin cementsResin modified glass ionomer
Resin modified glass ionomer
Compressive st: 150 Mpa
Tensile st: 25-35 Mpa
Film thickness: 20 um
Resin modified glass ionomer combine the strength and the insolubility advantages of the resin cements and the fluoride release of the GIC
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Cementation
Cementation with Zinc phosphate cementCementation with Zinc polycarboxylate cementCementation with glass ionomer cementsCementation with resin cements
Cementation
Cementation with Zinc phosphate cementCementation with Zinc polycarboxylate cementCementation with glass ionomer cementsCementation with resin cements
Cementation with Zinc phosphate cement
tips for cementation :
Complete isolation is necessary during the whole process.
Vital teeth ---> two layers of varnish or bonding agent should be applied first.
Non-vital teeth ---> No need for varnish.
Liquid/Powder Proportions: six drop of liquid for each crown.
Do not dispense the liquid until just before mixing.
Divide the powder in small increments each of 3 mm thickness.
Mixing time is 10-20 seconds for each increment.
Mix in circular motion. Mix over wide area of the glass slab introduce the powder slowly in to the liquid check the consistency Bruch the cement inside the fitting surface
grooves, pins, and inlays ---> fill them before seating the restoration
If necessary use the retraction cord in the sulcus.
seat the restoration ask the patient to close over a plastic wafer Leave the cement to fully set then remove
the excess.
Cementation
Cementation with Zinc phosphate cementCementation with Zinc polycarboxylate cementCementation with glass ionomer cementsCementation with resin cements
Cementation with Zinc polycarboxylate cement
Tips for cementation: Isolation wash the restoration and clean it with
alcohol sandblast the fitting surface coat the outer surface with petroleum Powder/Liquid Proportion : according to
manufactures instructions
working time: 30 seconds
brush the cement inside the restoration,
seat the restoration, ask the patient to bite
over aplastic wafer
setting time: 3 minutes
Remove the excess either before or after the
cement become rubbery.
Cementation
Cementation with Zinc phosphate cementCementation with Zinc polycarboxylate cementCementation with glass ionomer cementsCementation with resin cements
Cementation with glass ionomer cements
tips for cementation isolation coat outside the restoration with petroleum Clean the tooth with brush and pumice. don’t
use acid etch for this step Don not use varnish Powder / Liquid proportions : one scoop of
powder/ two drops of liquid working time: 60 seconds setting time : 3 minutes
mix rapidly until the mix become creamy
capsule form is now available in the market
Brush the restoration with the cement; seat the restoration, ask the patient to occlude over the plastic wafer.
Wait until the cement become brittle but before complete setting and remove the excess cement.
Coat the crown margin with varnish or petroleum
Cementation
Cementation with Zinc phosphate cementCementation with Zinc polycarboxylate cementCementation with glass ionomer cementsCementation with resin cements
Cementation with resin cements
Tooth preparation : isolation ( rubber dam is a must) clean the tooth with pumice and brush, clean and
dry if total etching system is used :
apply the acid etch ( phosphoric acid 37% ) 30 seconds for enamel and 10 seconds for dentin
wash and dry ( don’t dissipate dentin) apply the bond with brush, wait for 1 minute, cure
for 20 seconds
if self-etching system is used
apply the self-etching bond , wait for 1 minutes and
cure
If total etching system will be used the tooth not
need any preparation more than cleaning with brush.
treatment of the fitting surface of the restoration :
The fitting surface of the restoration is treated before receiving the resin cement by two ways Roughening the surface to increase the surface
area and create a microspores In the restoration surface
Increase the wettability of the restoration surface with silane coupling agent.
Roughnining of the fitting surface can be achieved by various techniques depending on the type of the restoration.
Content
Clinical importance
Bonding mechanismsClassification of luting cementsIdeal criteria of luting cementsCement selection
Cementation
Special consideration:
Special consideration:
Cementation of ceramic restorationsBonding of resin to zirconia: Cementation of posts Cementation of partial coverage restorationCementation of the gold alloy:
Special consideration:
Cementation of ceramic restorationsBonding of resin to zirconia: Cementation of posts Cementation of partial coverage restorationCementation of the gold alloy:
Cementation of ceramic restorations
tooth preparation
restoration preparation differ according to the type of the ceramic material: Feld spathic porcelain ( HF + S )
Lucite reinforced ceramics (IPS Empress): ( sand + S )
Lithium disilicate (IPS Emax( ( Sand + HF + S )
Zirconia Lava ( Silica )
Cercon ( Silica + MDP )
other types such as IPS Emax zircad and Ketana (Phosphoric acid monomer containing primer)
Special consideration:
Cementation of ceramic restorationsBonding of resin to zirconia: Cementation of posts Cementation of partial coverage restorationCementation of the gold alloy:
Bonding of resin to zirconia:
sandblasting and silanation of zirconia
Plasma spraying
Porcelain particles infusion
Special consideration:
Cementation of ceramic restorationsBonding of resin to zirconia: Cementation of posts Cementation of partial coverage restorationCementation of the gold alloy:
Cementation of posts
Metallic posts
Fiber posts
Special consideration:
Cementation of ceramic restorationsBonding of resin to zirconia: Cementation of posts Cementation of partial coverage restorationCementation of the gold alloy:
Cementation of partial coverage restoration
Special consideration:
Cementation of ceramic restorationsBonding of resin to zirconia: Cementation of posts Cementation of partial coverage restorationCementation of the gold alloy:
Cementation of the gold alloy: