Dental Cements Flashcards
what is a dental cement
a substance that hardens to act as a liner, base, restorative material or luting agent to bind devices and prostheses to tooth structure or to each other
what characteristics do we want a dental cement to have
- needs to be biocompatible
- needs to be inert and non-corrosive
- insoluble to acid attack
- dimensionally stable: minimal shrink upon setting and minimal expansion upon setting
- needs to set quickly
- has low surface tension
- adapts and adheres to anatomy
- insensitive to moisture during procedure
- fluoride release
- anti-microbial
- radiopaque
- cost effective
- low film thickness
- adequate strength
- low solubility
- reasonable setting time
- adequate working time
- cariostatic
- adhesion to tooth structure and restorative material
what does low surface tension mean
flows well and handles well
what low film thickness are we wanting
less than 25 micrometers
what adequate strength do we want dental cement to have
70 Mpa
what low solubility do we want dental cement to have
0.2% maximum at 24 hours
what is the reasonable setting time we want for dental cement
2.5-8 minutes
what high values do we want for cement
- high values for cyclic fatigue
- high values for thermal cycling
- high values for strength
what is cyclic fatigue
the stress, strain, and deformation induced in a material by cyclic loading
what is cyclic fatigue life
the number of loading cycles which produce a rupture or breakage in the material
what is a thermal cycle
any repetitive thermal test in which the temperature is regularly altered, touching a high temperature peak and a low temperature peak
what are the values for strength
- tensile
- compressive
- flexural strength
- shear
where do we use dental cement materials as cements
- permanent and provisional indirect restorations
- orthodontic brackets
- cementing post and core build ups
where do we use dental cement materials as a restorative material
permanent and provisional direct restorations
where do we use dental cement material as liner and bases
pulp protection in deep cavity excavation
no one cement can fill _____ but can be used _____
all applications; off label
what is adhesive bonding
accomplished through substituting inorganic tooth materials with resin monomers
- essentially minerals in the enamel and/or dentin are replaced by resin monomers
- through polymerization these become micromechanically interlocked into the porosities
how can adhesive bonding procedures can be completed
-etch and rinse and
- self etch
what is cementation
- cementation uses a good prep design and resistance to connect underlying tooth structure with a restoration
- the cement creates a hard cement layer to adhere to the 2 surfaces
- with cementation no matter how good the cement its critical that there is adequate preparation including good retention and resistance
when choosing a cement it is important to consider:
bond strength, preparation design, restorative material, ability to isolate, esthetics
what is the mechanism of action in adhesive bonding and what is the bond strength
-etched enamel leaves open the ability for resin to flow in and around the enamel rods creating resin tags
- creates micromechanical interlocking of resin with demineralized collagen of intertubular dentin
- creates a bond strength of 20-30 MPa
describe the mechanism of action of dental cement and what is the bond strength
- locking of cement into microscopic irregularities in prepared tooth surface and irregularities in the internal of the crown
- creates bond strength of 1-5MPa
how do cements work
- physical bonding
- chemical bonding
- mechanical bonding
describe physical bonding
very weak interactions with secondary bonds
- van der waals forces and hydrogen bonds
describe chemical bonding and give example
strongest bond with primary bonds
- ex: composite bond to adhesive bond agent
describe mechanical bonding
- interlocking undercuts, surface irregularities
- micromechanical retention
what are the 6 categories of dental cements
- zinc oxide
- zinc phosphate
- zinc polycarboxylate
- glass ionomer
- resin modified glass ionomer
- resin cements
what is zinc oxide at UMKC
IRM and TempBond
what dental cement is not used at UMKC
zinc phosphate
what is zinc polycarboxylate at UMKC
Durelon and Ultratemp
what is resin modified glass ionomer at UMKC
Rely- X luting
what is resin cements at UMKC
Variolink or SpeedCem
what setting mechanism does Zinc oxide eugenol use
acid-base
what setting mechanism does modified Zinc oxide eugenol use
acid-base
what setting mechanism does Zinc oxide non- eugenol use
acid- base
what setting mechanism does Zinc polycarboxylate
acid-base
what setting mechanism does Zinc phosphate
acid- base
what setting mechanism does glass ionomer
acid- base
what setting mechanism does resin modified GI use
acid base and polymerization
what setting mechanism does resin cement unfilled or filled use
polymerization
what do acid base cements use
a powder and liquid combination
what are the liquid (acid) components
- eugenol/non eugenol oils
- polycarboxylate acid
- phosphoric acid
what are the powder (base) components
- zinc oxide
- fluoraluminasilicate glass (FAS)
what are the polycarboxylic acid cements
- zinc polycarboxylate cement
- glass ionomer cement
- resin modified glass ionomer cement
what are the resin based cements
- resin modified glass ionomer cement
- unfilled resin cement
- filled resin - composite resin cement
what are the types of zinc oxide eugenol cement
- regular ZOE
- reinforced ZOE
- ZOE with ethoxy benzoic acid - increased compressive strength
what are the indications for zinc oxide eugenol cement
- temporary cement
- intermediate cement
what is the powder and liquid of zinc eugenol cement
- powder- zinc oxide
- liquid- eugenol
polymer reinforced ZOE is _____
IRM
what is the difference in compressive and tensile strength in ZOE and modified ZOE
ZOE modified has higher compressive and tensile strength
what is zinc eugenol cement made of
- ZO powder is 99% ZO and 1% radiopaque fillers
- ZOE liquid is oil of cloves (85% eugenol)
what is the zinc oxide and eugenol reaction
- zinc oxide + eugenol = zinc eugenolate
- needs water to set up
eugenol acts as a ____
sedative
ZOE is marketed as ______
TempBond
is eugenol a pulpal irritant
no
when is ZOE reinforced/IRM used as
- temporary cement if there is decreased retention or if you need more time in a temporary situation
- used as a provisional or intermediate restoration
what is the downside of eugenol in ZOE
the eugenol can inhibit the polymerization of resin products
what are the disadvantages of zinc eugenol cement
- slow setting time
- excess eugenol can be an irritant
- cement does shrink as it sets
- low strength
- high solubility
describe zinc oxide non-eugenol cements
- temporary cements
- does not have sedative effect on pulp
- eugenol is replaced with other oils
when is zinc oxide non- eugenol cements used
prior to permanent resin based cement
what is the brand name for zinc oxide non-eugenol cements and what are the characteristics of it
- TempBond NE
- slow set still
- low retention
what is the oldest cement in dentistry and when was it made
- zinc phosphate cement
- 1878
what is zinc phosphate cement made of
- zinc oxide powder + phosphoric acid (liquid)
what are the characteristics of zinc phosphate cement
- easy to manipulate
- working time is 3-6 minutes
- setting time is up to 14 minutes
- indicated for fixed pros
- high compressive strength
- low film thickness
describe the bonding of zinc phosphate cement
- creates micromechanical bond to preparation surface and crown internal surface
- bond strength 0.5-1.5Mpa
- preparation retention and reistance form is critical
when is zinc phosphate cement used and why
implant crowns due to radiographic visibility and ease of removal
what is the gold standard cement
zinc phosphate cement
describe the powder of zinc phosphate cement
- greater than 75% zinc oxide and less than 13% magnesium oxide with radiopaque fillers
describe the liquid in zinc phosphate cement
solution of 59% H3PO4, 23% Al phosphate and Zn Phosphate
describe the process of mixing zinc phosphate cement
- when mixedd, cement becomes exothermic
- must mix it on a chilled glass slab to allow for working time
- creates a stringy consistency
- remove excess cement once set
- mixed cement is acidic and can cause pulpal irritation
- once set, the cement can act as a thermal insulator
- cement is soluble in acids
what makes zinc polycarboxylate
Zn Oxide - polyacrylic acid and carboxylic acid
describe zinc polycarboxylate
- low strength overall but can form a chemical bond to tooth structure
- polyacrylic acid is less acidic than phosphoric acid, so pulpal irritation was reduced with this cement
what is the brand name for zinc polycarboxylate
UltraTemp
can zinc polycarboxylate be used prior to resin cement
yes
what is the bond strength of zinc polycarboxylate
2MPa
what is the powder and liquid in glass ionomer cements
- powder- fluoroaluminosilicate glass (FAS)
- polycarboxylic acid
glass ionomer cements are a combination of:
Ca, F, Al silicates with polycaboxylate/acrylic reactions
what is the bond strength of glass ionomer cements
3-5 MPa
what is a benefit of glass ionomer cements
releases fluoride over time
what are the downfall of glass ionomer cements
- some cases of delayed hypersensitivity with GI cements
- requires strict isolation during setting
what are glass ionomer cements used for now
mostly for ortho bands
describe how to work with glass ionomer cements
- fluidity like zinc phosphate
- needs a chilled glass slab
- do not let liquid component stand for long or it will evaporate and change your cement mixture
- remove smear layer left by burs first
- cement needs tooth to not be dry but not be wet
- cement excess should be removed immediately
what are the characteristics of glass ionomer cements
- low solubility
- can chemically bond to metal restorations
- retention strength similar to zinc phosphate
- dont dehydrate the tooth- a dry tooth combined with the initial low pH of GI cements can lead to hypersensitivity
what are the liquid (Acid) components
- eugenol/non- eugenol oils
- polycarboxylate acid
- phosphoric acid
what are the powder (base) components
- zinc oxide
- fluoroaluminasilicate (FAS) glass
what is the powder and liquid in resin modified glass ionomer cement
- powder: fluoroaluminasilicate glass
- liquid: polycarboxylate acid with resin monomers (Bis GMA or HEMA)
- also includes photo activator
what type of reaction do resin modified glass ionomer cements use
acid base and monomer polymerization via chemical, light and dual cure
what are the characteristics of resin modified glass ionomer cements
- strong cement
- bond strength 5-10 MPa
- fluoride release
- low solubility- so ideal for difficult to isolate cases
- low micro leakage- cement swells slightly upon setting to seal margins
resin modified glass ionomer cements are ideal for all restorations EXCEPT
- highly esthetic cases- the cement is bright white
- all ceramic crowns with margins less than 1mm thick. swelling of cement on setting can cause marginal fracture
- inlays and onlays
what are the steps to using the RMGI cement
- shake powder bottle
- dispense powder before liquid
- equal number of scoops to liquid drops
- hold liquid bottle vertically when dispensing
- mix powder INTO liquid within 30 seconds of dispensing
- load crown with cement
- working time once mixed is 2.5 min
- seat the crown
- maintain pressure on restoration while cement is setting
- maintain dry field duringg setting
- wait 3 minutes
- after cement has set, remove excess
describe resin cements
- high translucency
- insoluble
- high retention due to bonding
- low film thickness
- can be light cure or self cure or both
- higher incidence of post op sensitivity due to etching process and the failure to seal the dentinal tubules
when are resin cements used
inlay, onlay and all ceramic restorations
what do resin cements require
- bonding agent and an etchant
- either self etch or total etch
which cement becomes incredibly hard to remove after cured
resin cements
what does incomplete mixing result in
- weaker cement or thicker harder to seat cement which can lead to hyper occlusion
what are the problems with dental cements
- incomplete mixing
- incomplete seating
- excess drying of the tooth
- incomplete removal of excess
what does excess drying of the tooth lead to and how do you combat this
- leads to post op sensitivity
- use gluma (2x 60 second coats) prior to crown seat to decrease sensitivity
what happens if there is incomplete removal of excess
gingival bleeding, irritation, bone loss, and possible gingival surgery
what cement would you use for short prep and worried about retention
resin cement
what cement would you use for normal prep and crown seat in posterior
RMGI
what cement would you use when you are worried about recurrent decay
RMGI
what dental cement would you use with an anterior ceramic crown
resin cement
which material have the lowest film thickness to the highest
glass ionomer (Lowest) > polycarboxylate > RMGI > zinc phosphate > self adhesive resin based > resin based
which materials have the longest working time in order or longest to shortest
zinc phosphate (Longest) > RMGI > glass ionomer > polycarboxylate > resin based = self adhesive resin based
which materials have the shortest setting time in order of shortest to longest
RMGI (shortest) > glass ionomer = polycarboxylate > resin based = self adhesive resin based > zinc phosphate
which materials have the highest compressive strength in order of highest to lowest
resin based > self adhesive resin based > glass ionomer > RMGI > zinc phosphate > polycarboxylate
which materials have the highest tensile strength in order of highest to lowest
self adhesive resin based > resin based > RMGI > polycarboxylate > glass ionomer > zinc phosphate
which materials have the closest elastic modulus to dentin
zinc phosphate > glass ionomer > self adhesive resin based > resin based > RMGI > polycarboxylate
which materials cause the lowest pulpal irritation
polycarboxylate > zinc phosphate > glass ionomer = RMGI = resin based = self adhesive resin based
which materials have the lowest solubility
RMGI = resin based = self adhesive resin based > glass ionomer > polycarboxylate = zinc phosphate
which materials have the lowest microleakage
RMGI = resin based = self adhesive resin based >glass ionomer > zinc phosphate > polycarboxylate
which material is the easiest to remove excess material
zinc phosphate > polycarboxylate = glass ionomer = RMGI > resin based > self adhesive resin based
which materials have the highest retention
resin based > self adhesive resin based > glass ionomer > RMGI = zinc phosphate > polycarboxylate