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26 Cards in this Set
- Front
- Back
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Elastomeric impression materials are generally hydrophobic in nature (T/F)
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True
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The further the margin is located sub-g, the easier it is to obtain an accurate impression (T/F)
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False: Further maring located sub-g, the more difficult it is to obtain an accurate impression
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What are the requirements of the impression?
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-Prep. area
-Extensions -Imperfection-free |
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In the pt, mouth, ___ ___ is one of the most impt. aspects of successful impresison making.
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-Moisture control: any moisture introduced will results in a void
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What increases the width of the gingival sulcus to uncover the sub-g margins by creating a space b/t the prep. and inner aspect of gingival epithelium?
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-Gingival retraction cord
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What method is accped as gingival retraction?
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-Mechanical: Unmedicated cord it
-Mechano-chemical which aid in homeostasis retraction -Electrosurgical -Laser |
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What are the type of cords?
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-Twisted cords
-Braided cords -Knitted cords |
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What is the problem with Twisted cords?
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-Easily separate under packing pressure
-Easily catches on burs |
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Describe Braided cords?
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-Will not separate easy
-Firmer = Less absorbent -Maintian braid during packing -2 Types (Filled-core, Hollow-core) |
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Describe Knitted cords?
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-more compressible than braided or twisted
-Hold 2.5X more solution -Cut more than catch on a bur -Easy to remove from sulcus |
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With most impression amterials, ___ mm of retraction provide adequate clearance to reproduce
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0.5 mm
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What can larger cord result in?
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-Less compressible cords can result in tissue tearing, hemorrhage and postoperative tissue recession
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What is used in non-chemical containg/Plain retraction cords?
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-Distilled water-mechanical
-Hemoeostatic agents (mechanochemical) -Astringents (mechnochemical) |
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What is an example of chemical/medicaments used in retraction cords?
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-Vasoconstrictors: Epinephrine: 1 inch string 0.5% Epi = 0.5 mg of epi = safe and is strong enough to get desired effect
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What is the contraindications for epi-containing retraction cord use?
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-HX of cardiovascular disease
-Hyperthyroidism -Hypersensitivity to Epi -Pt. taking Rauwolfia, ganglionic blockers -Glaucoma -Lacerated gingival tissues |
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What is the Epi. Syndrome?
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-Tachycardia
-Increased respiration -Increased BP -Nervousness -Headache -Fright and postoperative depression |
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What is the advantages and Disadvantages of Epi?
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-Advantages: Kind to gingival tissues, good tissue diplacement, good hemostasis, provide clean sulcus when removed, minimal tissue los , no tissue discoloration
Disadvantages: adverse cadiovascular effects, Risk of epi. syndrome, don't use when CT is exposed, don't use w/ ferric sulfate |
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Describe Ferric Sulfate?
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-Astringedent or Visco-stat
-Kinder than Aluminum Chloride (1-3 min packing & safe up to 30 min) |
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What is the advantages and disadvantages for Ferric sulfate?
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Advantages: excellent hemeostasis, inlcuding cutting tissue, minimal tissue loss, moderate displacement, extend working time, compatible w/ Aluminum Chloride
-Disadvantages: Tissue discoloration, Moderate tissue trauma, unpleasant taste, not compatible w/ epi, interferes w/ setting of some addition RXN impression materials |
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Describe Aluminum Chloride?
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-Hemodent
-most products supplied as buffered solution to reduce pH -Buffered soln. 10% - 25% -Recommended TX time for 10 min |
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What is the advantages and disadvantages for Aluminum Chloride?
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-Advantages: moderate homeostasis, moderate tissue displacement
-Disadvantages: Moderate tissue loss, localized tissue destruction if soln. over 10% is used |
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Serrated ends work best w/ what type of cord?
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-Fimer cords: to reduce slipping of cord, offer more control to pink cords into tight gingival sulcus, less likely to puncture through retraction cord, or damage gingival tissues
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What type of instrument is used for soft twisted or braided cords?
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-Smooth-ended packing instrument
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When is a single cord-technique used?
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-Single cord is palced in the suclus and removed before the impression is mad .
-Used for shallow to moderate sulcular depth |
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When is a double-cord technique used?
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-Deep suclus, tissue can collapse over the top of cord, restricting impresison material access to retracted sulcus.
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Describe the double-cord technique?
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-1st cord is smaller is packed under prep. margin to control gingival seepage and hemoorhage
-2nd cord is larger, is placed above the 1st cord and removed before impression is made. This allow good access for impression material |
