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98 Cards in this Set
- Front
- Back
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Dental Cements
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re used & have multiple uses
doctor chooses type (6 types) |
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uses of dental cements
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pulpal protection
luting- cementation restorations surgical dressing |
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what causes pulpal protection
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bacterial effects of caries.
response to chemicals of restorative materials. thermal conductivity of metal restorations placed near pulp. dentin remaining over the pulp is too thin to withstand compressive, tensile and shearing stress |
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cavity varnish
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acts as protective barrier between preparation and restoration
natural copal or synthetic resins dissolved in a solvent like alcohol or chloroform applied in 2-3 layers to allow evaporation not often used, washes out at margin |
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liner
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low strength base
calcium hydroxide is used used when dentin no longer covers pulp (direct pulp cap) stimulates reparative dentin alkaline pH 9-11 |
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high strength base
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provides thermal insulation
support for restorations cements mixed to a base are mixed to thick putty-like consistency in preps with 2mm or less dentin base is recommended |
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buildup
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placing a cement buildup reinforces the remaining tooth structure
like high-strength base, provides mechanical support for a restorative material when an excessive amount of tooth structure is removed or missing |
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luting cementation
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used for permanent or temporary luting of fixed prostheses, ortho bands, and pins and posts
must have good wet ability & flow to provide a thin film thickness |
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tooth-restoration interface
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when tooth structure & fixed prostheses are in intimate contact, a microscopic space exists
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luting
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primary purpose is to fill the interface
mixed to primary consistency must have thin enough viscosity to be able to flow into a film thickness of 0.25 or less |
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how are dental cements used for restorations
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only as a secondary consistency for their sedative effects for provisional & intermediate restorations
the exception is glass ionomer cement that is used at the cervical portion of a tooth cements are not frequently chosen as restorations because of their lower strength and wear resistance & higher solubility |
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how are cements used for surgical dressing
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cements are used to provide protection and support for the surgical site
provides patient comfort and help control bleeding mixed to soft putty-like consistency that hardens when placed over the tissue chemical or light cured |
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what is the strongest cement?
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resin cements
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what is the weakest cement?
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zinc oxide eugenol
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solubility
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tendency to dissolve in oral fluids leading to microleakage
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what dental cement is the closest to insoluble as possible?
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resin cement
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primary consistency...
secondary consistency... |
mixed thin (like honey)
putty like state |
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adhesion
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bonding of dissimilar materials by the attractive forces of atoms or molecules
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mechanical adhesion
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based on the interlocking of one material with another
makes the restoration highly retentive and resistant to microleakage |
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types of dental cements
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zinc oxide eugenol
zinc phosphate polycarboxylate glass ionomer resin hybrids |
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zinc oxide eugenol
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IRM, temp rest, high/low strength bases, root canal sealers, periodontal dressing
acts as a sedative to the pulp, kind to tissue (ph 7) weak cement, low strength high solubility obtundant paste/paste, powder/liquid |
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zinc phosphate
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permanent luting agent, cementation of ortho bands
w/ additional powder can provide thermal insulation for high strength base MIXED ONLY ON GLASS SLAB! oldest dental cement not widely used today powder/liquid ph 4.2 acidic pulpal irritation high solubility |
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what is the oldest cement
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zinc phosphate
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zinc polycarboxylate
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primarily used for final cementation of indirect restoration, can be used as high strength bases, thermal insulator, bond ortho brackets
1st cement with an adhesive bond powder/liquid system high viscosity high solubility low strength short working time non irritating to pulp strong bond to tooth |
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glass ionomer
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luting agents, restorative materials, thermal insulator, core build up, crowns, bridges, veneers
available as pre measured capsule esthetic restoration of anterior teeth (light cure) (self cure) permanent luting agents use chemical adhesion low to moderate strength includes fluoride ion produce postoperative sensitivity strong bond to tooth non irritating to pulp |
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resin based cements
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modified composites
bond ceramic indirect restorations, conventional crowns, and bridges, and to indirectly bond orthodontic brackets (light, dual, self cured) |
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resin cement- light cured
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used to lute metal free restorations, porcelain veneers, ortho retainers, peril splints
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resin cement- dual cured
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used to lute porcelain or resin restorations
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resin cement- chemical cured
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used to lute metal based restorations, posts, and porcelain/ resin restorations
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hybrid ionomer
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similar to glass ionomer
modified with additional resin (light cure) improved bond strength compressive strength tensile strength insoluble includes a fluoride ion not recommended for ceramic restoration |
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define obtundent
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a metrical that reduces irritation
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which dental cement acts as an obtundent
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zinc oxide eugenol
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which dental cement is the most difficult to mix?
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zinc phosphate
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which dental cement is most irritating to the pulp
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zinc phosphate
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which dental cement forms a bond with the enamel of the tooths surface
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polycarboxylate & glass ionomer
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what are the types of powders used for different dental cements
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zinc oxide, powdered glass
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what are the liquids used for dental cements
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phosphoric acid
polyacrylic acid eugenol |
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which dental cement is supplied as a paste/paste system
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zinc oxide eugenol
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what is the number of the cement spatula
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#24
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Calcium hydroxide is a cavity liner, what does this mean?
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a thin layer of calcium hydroxide is placed in the area of the cavity preparation that is close to the pulp to stimulate additional dentin
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what chemical action does calcium hydroxide has on the tooth
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promotes the growth of secondary dentin
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which dental cements is considered to be temporary
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zinc oxide eugenol
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which dental cement takes the longest to set
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zinc phosphate
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direct placement materials
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placed directly into the cavity prep or bonded directly onto the tooth surface (in the mouth)
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esthetic materials
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tooth colored
composite resin glass ionomer cement resin-modified glass ionomer (hybrid) compomer |
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composite resin
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mixture of 2 or more materials that has properties superior to any single component
tooth colored (used ant or post) organic resin matrix & inorganic fillers joined by a silane coupling agent that sticks the particles to the matrix has initiators and accelerators that cause materials to set |
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resin components
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thick liquids made up of 2 or more organic molecules
reduce viscosity & allow the loading of filler particles, a low molecular weight monomer is added Bis-GMA is most commonly used resin for matrix comp. UDMA is another type |
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filler particles
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added to organic resins to make them stronger
added to control handling characteristics reduce shrinkage made up of inorganic particles like quarts, silica, glass higher the filler content= stronger material particle size affects the wear resistance & polish-ability of material |
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particle size
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amount of filler & amount of resin between particles relate to how the material wears
large particles= finish restoration appears dull & rough small particles= smoother surface |
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coupling agent
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stronger bond between organic fillers & resin matrix
silane reacts with surface of the inorganic filler good adhesion of the 2= minimal loss of filler particles & reduces wear |
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polymerization
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chemical reaction that occurs when low molecular weight molecules (monomers) join to form long-chain high molecular weight molecules (polymers)
initiators & activator chemicals cause polymerization |
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what are the 3 types of composite materials used in dentistry? what are the advantages/disadvantages
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chemical cure (self cured): 2 paste system, supplied in jars or syringes , limited work time, must be a homogenous mix, air can cause voids
light cure: most common, ample work time, set w/ curing light dual cure: use both chemical & light cure, 2 paste system or syringe, initial set by curing light, chemical reaction finishes process |
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how are fillers available?
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macrofilled: 1st gen composite resin, large filler particles, greater strength, dull rough surface, absorbs stains
microfilled: smaller particles, not as strong as macro filled materials, glossy finish, doesn't absorb stains easily hybrid: contains both, easily polished, greater strength than microfilled, high wear resistance micro hybrids considered newest gen, combo of small & microfine particles |
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flowable composite
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low viscosity
light cured resin, lightly filled can be delivered directly into the preparation by small needles on syringes used in conservative type procedures |
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pits & fissures sealants
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low viscosity resins vary in filler size
prevents caries contains little or no filler similar to flowable composites |
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biocompatibility
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when tubules are sealed by dentin bonding agents or a base is placed which reduces sensitivity and prevents inflammation to the pulp
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polymerization shrinkage
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shrinkage that occurs when composite resin is cured
when cured matrix usually shrinks away from cavity walls curing small increments decreases shrinkage |
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thermal conductivity of composite
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composite resin is a biologically protective material for the pulp
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elastic modulus
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stiffness of composite & is determined by the amount of filler
greater the volume of the filler, the stiffer & more wear resistant is the restoration |
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which composite materials have greater water sorption
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microfills & flowables
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radiopacity
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metals like lithium, barium or strontium are added to filler to make restoration more opaque when viewed on radiograph
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how would you choose what material should be used for anterior teeth in non stress bearing areas?
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select based on color matching & ability to finish to a natural glossy appearance
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how would you choose what material should be used for stress bearing areas?
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use stronger hybrid or micro hybrid materials
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physical properties of glass ionomers
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biocompatible
bond to tooth structure releases flouride ion high water solubility thermal expansion similar to natural teeth good insulators moderate compressive & tensile strength wear faster radiopaque |
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compomers
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composite resins that have been modified with polyacid
release fluoride but not the same as glass ionomer good color matching ability polish well medium wear rate |
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indirect restorations
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fabricated outside of the mouth
inlays onlays veneers crowns with porcelain or ceramic facings |
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bonding
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attaching restorative materials to the tooth by adhesion
prepare surface or tooth for restoration (remove decay, plaque, debris) tooth is etched or conditioned with 10% to 42% solution of phosphoric acid (provides rough surface to bond to) |
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what is primary bonding?
secondary bonding? |
primary or chemical bond occurs through adhesion when the bonding agent & the composite resin material adhere to each other, it is stronger than a secondary or physical bond
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what type of wetting material is used for bonding agents
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typically made of low viscosity material
etching increases the ability of the bonding material to wet the tooth surface by creating a high surface energy, good wetting increases the contact of the material and the tooth |
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smear layer
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made up of debris on tooth surface resulting from the cutting of tooth structure during cavity preparation
must be removed before bonding procedure |
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dentin etching
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phosphoric acid dissolves the smear layer first
portions of the hydroxyapatite crystals from dentin create a porous surface & expose collagen fibrils that are part of the dentin matrix opens dentinal tubules leaving a rough porous surface dentin has a lower mineral content, etch only 10 secs |
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bonding agents
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low viscosity resins dissolve in solvents (acetone/ ethyl alcohol)
penetrate porosities in the tooth surfae created by etching |
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what type of bonding agent is required for enamel?
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low viscosity liquid
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what ape of bonding agent is required for dentin?
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primer and bond
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what is on the surface of the polymerized bonding resin
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a thin coat of uncured resin
resins used for composites & sealants form this layer |
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when is polymerization inhibited?
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when the surface is exposed to oxygen in the air
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clinical application of bonding
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porcelain: stronger retention if bonded rather than cemented
metal:used to create a stronger bond before cementation of a crown or bridge amalgam:helps seal out microleakage |
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how does bonding play a part in ortho?
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brackets have repaved bands, cements can't be used so the crackers must be bonded
cements are difficult to cure through brackets, dual cure is used |
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endodontic posts
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placed within the roots of endodontically treated teeth to retain material & build up missing tooth structure
metal or nonmetal bonded with bonding agents and resin cements |
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sealant composition
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chemically similar to composite resin
resin component is based on bis-GMA polymerization occurs by self reaction light activation |
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sealant working time
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self cured sealants polymerize to final set within 2 mins from start of mixing
light cured sealants allows operator to manipulate material does require 20 sec application of curing light |
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dental amalgam
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alloy-mixture of two or more metals
alloy in amalgam is mostly silver but contains copper, tin & zinc when silver based allow is mixed with mercury, the reaction is amalgamation |
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lathe cut alloy particles
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formed by shaving fine particles off an ingot of the alloy with the use of a lathe
particles are shifted to separate them into fine & ultra fine particles |
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spherical alloy particles
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produced by spraying molten alloy into an inert gas
formed as the atomized droplets cool |
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admixed particles
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consist of a mixture of lathe-cut & spherical particles
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alloy composition
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considered to be high copper confer (10%-30%)
compared with their predecessors (2% to 4%) silver (40%-70%) tin (12%-30%) mercury (43&-50%) |
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silver in amalgam
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setting expansion
increases strength corrosion resistance |
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copper in amalgam
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setting expansion
increases strength corrosion resistance |
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tin in amalgam
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setting contraction
decreases strength corrosion resistance |
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zinc in amalgam
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reduces oxidation of other metals
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gamma phase
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silver alloy phase
it is the strongest phase and involves the least corrosion |
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gamma 1 phase
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consists of mercury reacting with silver
strong and corrosion resistant |
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gamma 2 phase
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consists of the faction of mercury with tin
weak and corrodes easily |
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tarnish
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results from contact with oxygen chlorides, & sulfides in the mouth
causes dark dull appearance that is not destructive to amalgam |
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corrosion
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chemical reaction between amalgam & substances in saliva or food that results in oxidation
2 dissimiliar metals interact in a solution that contains electrolytes an electrical current is generated between the metals (galvanism) |
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creep
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gradual change in shape of the restoration resulting from compression by the opposing dentition
associated with gamma 2 phase, seen with low copper alloys & results in deterioration of the margins |
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what is the strongest directly placed restorative materials
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amalgam
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high copper alloys
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has higher 1 & 24 hour compressive strengths than admixed
24 hours admixed & spherical high-copper shrinks slightly whereas low copper expands |
