Dental Materials Flashcards
(25 cards)
What does alginate contain?
Seaweed extract
What are the advantages of alginate?
Easy to use
Can be used for all types of impressions
Can be withdrawn from undercut areas without distortion, tears or fractures
Cheap
What are the disadvantages of alginate?
Impressions can distort; specific handling required to prevent distortion
Best models are obtained by casting up immediately
What needs to be used with alginate when taking impressions?
(Tray +) tray adhesive
What is the ratio used with alginate?
1 scoop : 1 “cup” of water
Why do we mix alginate?
Remove air bubbles and lumps
How do we clean up after mixing alginate?
Wipe bowl and spatula clean with paper towels (clinical waste)
What do we do after taking an impression with alginate?
Rinse impression under running water
Place in perform for 10mins
Rinse again (decontamination)
Wrap in damp gauze and place in airtight sealable bag
What does IRM consist of?
(Intermediate restorative material)
Zinc oxide and eugenol
What is the ratio used with IRM?
2 scoops : 3 drops
What is IRM used for?
Temporary fillings
Non-irritant linings for deep cavities
Sedative dressings for painful various teeth
What are the advantages of using IRM?
Soothing and non-irritating to pulp
Can be used as a sedative lining under permanent restorations
What are the disadvantages of using IRM?
Too soft and slow-setting to use as a foundation for a permanent filling in one visit
Not compatible with composite fillings
Some patients may be allergic to preparations containing eugenol
What are the ratios for polycarboxylate cement?
2 scoops : 1 drop of water for thick mix
1 scoop : 2 drops of water for lining mix/cementing
What are the advantages of using polycarboxylate cement?
Less irritant than other cements
More adhesive to dentin than other cements
Can be used to cement inlays, crowns and orthodontic bands
What are the disadvantages of using polycarboxylate cement?
Difficult to manipulate as it is adhesive to instruments
Very difficult to remove from instruments when dried
What do you mix IRM on?
Cellulose mixing pad/thin glass slab
How do you handle the components of IRM?
Invert bottle/shake to loosen powder and tap top to prevent puff of dust on opening
Level scoops
Divide powder into 4 sections
Dispense liquid separate from powder by holding bottle in palm of hand
Wipe spatula immediately after mixing with a wet paper towel
What are the two types of glass ionomer?
Fuji 2 (light cure)
Fuji 9 (chemical cure)
What is glass ionomer made of?
Glass-like powder mixture of aluminosilicates
Liquid contains polyacrylic acid
What is glass ionomer used for?
Restorations
Linings
Fissure sealants
Adhesive cements
What are the outstanding properties of glass ionomer?
Releases fluoride - prevents further caries development around cavity
Bonds directly to enamel, dentin and cementum without acid etching
What are the advantages of using glass ionomer?
Adheres to enamel, dentin and cementum
Ideal for class V cavities
Excellent marginal seal
Releases fluoride over time
Aesthetically better than amalgam
What are the disadvantages of using glass ionomer?
Lower strength than amalgam and composites
Very exact handling required for correct placement
Easily ruined by moisture contamination
Mix must have exact proportions to produce optimal set
