Intermediary Materials And Cements Flashcards
What are dental cements used for?
To lute (glue/cement) inlays, crowns bridges and other restorations in place
Ideal properties of a dental cement
Strong/hard Protect pulp Insoluble in saliva Stable Adhesive Non-porous Biocompatible Easy to manipulate Not affected by thermal changes
Film thickness
Dental cement should have a film thickness of .25 micrometers
Viscosity
Resistance of liquid to flow
Setting time
Time required for a material to polymerize or harden
Strength
Ability of a prosthesis to resist induced strength without fracture or permanent deformation
Solubility
The amount of a substance that will dissolve in a given amount of another substance
Other terms for dental cements
Limiting agents Base Filling material Temporary restoration Intermediate restoration Periodontal pack Temporary cement
Three basic categories of dental cements
Water based
Resin based
Oil based
Water based cements
Rely on acid base setting reaction. Do not bond well. Some release fluoride and have low film thickness
Ex. Glass ionomer cements, zinc phosphate
Resin based cements
High bond strength. Many use adhesives. Some have monomers or use primers so that they will bond to dental alloys and ceramics
Ex. Resin modified ionomer cements, copomers)
Oil based cements
Used for luting restorations. Most contain eugenol but there are some oil free cements. These are thicker and have lower mechanical properties
Ex. Zinc oxide eugenol, non-eugenol cements
What forms do glass ionomer cements come in? Are they water or resin-based?
Can be both water-based and resin-based
Come as a powder and liquid and even as a single dosed capsule
What kind of sudden reaction do water-based cements have? How do they bond, how are they mixed and what is the working time?
Acid based reaction
Bind chemically to enamel and dentin
Can be mixed on a glass slab or paper pad
Working time is approximately 2 min
How are resin modified glass ionomer cements cured, what form are they available in?
They are both self cure and light cured
Available in powder and liquid, paste and encapsulated
What are resin modified glass ionomer cements used for?
Permanent cementation, ceramic metal crowns, bridges, metal in leas, Onley‘s can also be used for luting
Material of choice for cementing permanent crowns. They are the strongest and least soluble
What is zinc phosphate used for?
“Traditional” crown and bridge cement
How is zinc phosphate supplied? What type of reaction results from the mixing process?
Supplied as a liquid and powder which begins the setting reaction when you start mixing.
Results in an exothermic reaction because of the acid in the mixture. Must be mixed on a cool glass slab. Mix slowly
What is a major component of Resin-based/composite cements? What are they used for?
Major component is silica or glass.
Used for crowns, bridges, restorations, bonding brackets
Characteristics of resin based cements
Have superior bonding strength Manipulation is critical to performance Tooth surface must be edged with acid Tooth must be cleaned and isolated Can be used for veneers
What are copomers?
Poly acid modified composites
Used for cast alloy crowns, bridges, ceramic and metal crowns and bridges, gold inlays, onlays and veneers
What are the two oil based cements?
Zinc oxide eugenol and non-eugenol cements
What are oil based cement used for?
Temporary restorations, soft tissue pack, root canal sealer‘s
Non- eugenol can be used if a patient is sensitive
What is the mixing process for oil based cements?
2 paste
disperse equal length of each onto a paper pad. Mix until uniform in color
What are the four types of oil based cements? What is the range of setting time?
Type I- temporary cement
Type II- permanent cement
Type III- filling materials and bases
Type IV- cavity liners
Setting time ranges from 15 minutes to 12 hours
What is a common type of cavity varnish?
Copalite
What do cavity varnishes do?
Act as a barrier against irritants Reduces oral fluid into Dentin Do not bond to tooth Not used with composite restorations Many are used with zinc phosphate cement
What is one type of dental bonding agent? What does it do?
Gluma primer bonding agent is being used as a varnish
Helps bond the amalgam with the tooth structure
What are cavity liners/bases used for?
To create a secondary Dentin when applied to pulp exposures
High strength bases provide thermal protection for pulp
What is the primary cause of failure?
Washout. Which means cement loss, which means leakage
Why does leakage occur?
Secondary decay
