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344 Cards in this Set
- Front
- Back
What are 3 indications for using impression materials?
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Diagnostic casts<div>Indirect reconstruction</div><div>Bite registration</div>
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What are some essential properties of impression materials?
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Ability to flow and wet surfaces<div>Ability to create an accurate reproduction of detail and dimension</div><div>Dimensional stability (during transition from fluid to solid and removal from mouth. Ability to maintain dimensions until poured with gypsum).</div><div><br /></div>
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What are some desireable properties of impression materials?
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Safe, easy to use<div>3-5 min working time</div><div>Acceptable taste, color, and odor</div><div>Appropriate flexibility for removal from mouth and cast</div><div>Tear resistance</div><div>Adherence to impression tray</div><div>Compatible with cast material</div><div>Color contrast between light and heavy-bodied viscosity</div><div>Reasonable cost</div><div>Radiopaque</div>
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When was alginate introduced as a dental impression material?
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1944
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When were addition reaction silicones introduced as a dental impression material?
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1980s
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What is a disadvantage of a rigid impression material?
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Cannot accurately reproduce undercuts.
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How do reversible and irreversible impression materials differ?
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Reversible (thermoplastic) - Reusable and set by termperature change<div>Irreversible (thermoset) - Not reusable and set by chemical reactions</div>
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What some reversible rigid and flexible impression materials?
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Rigid - Compound, Adaptol, Wax<div>Flexible - Agar</div>
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What are some irreversible rigid and flexible impression materials?
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Rigid - Plaster, ZOE<div>Flexible - Alginate, Synthetic rubbers</div>
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What are uses of compound and adaptol?
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Preliminary edentulous ridge impressions<div>Border molding tray for denture impressions</div>
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What are the uses zinc oxide eugenol as an impression material?
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Secondary wash impression for edentulous ridges<div>Interocclusal bite registration</div>
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What materials can be used for interocclusal bite registration?
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Wax<div>ZOE</div><div>Plaster</div><div>Hard setting PVS</div>
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What impression materials can be used for occlusal registration for articulator bite fork?
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Wax<div>Compound</div><div>Hard-setting PVS</div>
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What are the uses of impression plaster?
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It used to be used for denture impressions<div>Can currently be used as bite registration material</div>
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What are the constituents of impression plaster?
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Calcium sulfate hemihydrate<div>Potassium sulfate (accelerator)</div><div>Borax (retarder)</div><div>Starches (weakens material for separation)</div><div>Coloring agents</div>
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T or F: Impression plaster has a short working and setting time?
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True, this is to facilitate intraoral use
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What is an example of a separating media and why is it used?
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Examples - soap, varnishes, liquid alginate solutions.<div>It is used to separate impressions made with plaster by filling in the pores of the impression to aid separation.</div>
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What are some characteristics of dental compound?
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Reversible rigid impression material<div>Used for preliminary denture impressions and border moliding trays for secondary denture impressions.</div><div>Also can be used to stabalize rubber dam clamps on teeth.</div>
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What are the constituents of dental compound?
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Rosin<div>Copal resin</div><div>Carnauba wax</div><div>Stearic acid</div><div>Talc (most abundant ingredient)</div><div>Coloring agent</div>
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What are 3 impression materials used for border molding impression trays?
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Dental compound<div>Adaptol</div><div>Iso Functional</div>
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What is a disadvantage to using dental compound for border molding?
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The viscosity of compound will displace soft tissue to create an over-extended impression.
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What is the difference in physical properties of adaptol and dental compound?
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Adaptol is stickier once heated, and less rigid than compound once cooled
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Zinc oxide eugenol comes in 2 tubes, what is in each tube?
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Tube 1 (Base) - Zinc oxide, Fixed vegetable or mineral oil<div><br /></div><div>Tube 2 (Accelerator) - Oil of cloves or eugenol</div><div>gum or ploymerized rosin</div><div>Filler (silica)</div><div>Lanolin</div><div>Resinous balsam</div><div>Accelerator solution (CaCl2) and color</div>
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How can you shorten the setting time of ZOE?
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Add water - the phenol of eugenol acts as a weak acid and undergoes an acid-base reaction with zinc hydroxide to form a salt, zinc eugenolate.
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What are some advantages of ZOE impression paste?
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Accurate mucostatic (doesn't displace tissue) impression material (low viscosity)<div>Good dimensional stability - <0.1%</div><div>Inexpensive</div>
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What are some disadvantages of ZOE impression paste?
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Messiness - adheres to tissues and instruments<div>Setting time may vary due to temperature and humidity</div><div>Eugenol may be irritating to the gingiva for some patients</div>
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What is a colloid?
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A substance consisting of 2 phases<div>A type of mixture intermediate between a homogeneous solution and a heterogeneous mixture</div>
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What are dental impression colloids made from?
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Large molecules derived from seaweed dispersed in water.<div>These are known as hydrocolloids</div>
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What are the terms for a colloid material with a gas dispersion medium with a gas, liquid, or solid dispersed phase?
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Gas - no term, all soluble together<div>Liquid - Liquid aerosol (fog, mist)</div><div>Solid - Solid aerosol (smoke, dust)</div>
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What are the terms for a colloid material with a liquid dispersion medium with a gas, liquid, or solid dispersed phase?
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Gas - Foam (shaving cream)<div>Liquid - Emulsion (milk, mayo)</div><div>Solid - Sol (Paint)</div>
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What are the terms for a colloid material with a solid dispersion medium with a gas, liquid, or solid dispersed phase?
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Gas - Solid foam (styrofoam)<div>Liquid - Gel (Jelly, cheese)</div><div>Solid - Solid Sol (Cranberry glass)</div>
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What category of colloids do dental impression materials fall into?
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Sol<div>Gel</div>
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How do hydrocolloids behave in the sol and the gel state?
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The material flows freely in the sol state<div>It forms a gel when the molecules form a network of fibrils by reduction of temperature or chemical reaction</div>
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How does evaporation effect hydrocolloid impression materials?
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Hydrocolloid gels are mostly water and will lose water in an unsaturated atmosphere resulting in shrinkage and distortion of the impression.
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What percent of hydrocolloid gels are made up by water?
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66-85%
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What is syneresis?
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Exudation of a liquid film on the surface of a gel.<div>It is not pure water, it contains some of the soluble constituents of the material</div>
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What is imbibition?
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Taking up of a liquid by a gel resulting in swelling.
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What is reversible hydrocolloid also known as?
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Agar
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What are some characteristics of Agar?
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Hydrophylic<div>Thermoplastic</div><div>Elastic</div><div>Accurate enough for crown and bridge, but has been replace by rubber impression materials</div><div>Two viscosities - Light and heavy bodied</div>
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What is the composition of agar?
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A long chain polysaccharide with a molecular weight of 150,000
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What are the constituents of agar impression materials?
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Agar (8-15%) - Gelling agent<div>Borax (0.2%) - Improves strength</div><div>K2SO4 (1-2%) - Gypsum accelerator</div><div>Thymol (Trace) - Bactericide</div><div>Preservatives pigments and flavoring</div><div>Water (83%) - Dispersion medium</div>
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Describe the process of using agar as an impression material from purchase to use on the patient?
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It comes as a gel.<div>It is heat above the liquefaction point 100 C</div><div>Stored at 65 C</div><div>Cooled to 45 C when ready to use, and placed in a water-cooled impression tray.</div>
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What causes the setting reaction of Agar?
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Reducing the temperature
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What is the liquefaction temperature and gelation temperature of agar?
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100 C = liquefaction<div>37- 40 C = Gelation temp.</div>
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What are the advantages of reversible hydrocolloid (agar)?
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High flexibility - easy to remove from mouth<div>Good wettability and flow</div><div>Inexpensive materials after initial cost of water bath.</div>
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What are some disadvantages of reversible hydrocolloid?
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Long working and setting time - temperature dependent<div>Low tear resistance</div><div>High dimensional change if not poured immediately</div><div>Patients may experience discomfort with extremes of heat and cold</div>
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What are some characteristics of alginate?
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Thermosetting<div>Hydrophilic</div><div>Elastic</div><div>Most used impression material</div>
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What are some reasons alginate impressions are used?
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Study models<div>Casts for opposing occlusion</div><div>Removable partial dentures</div>
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What is the composition of alginate powder?
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Sodium alginate - 18%<div>Calcium sulfate dihydrate - 14%</div><div>Sodium phosphate - 2%</div><div>Silicate powder 56%</div><div>Pigments and flavoring</div><div>Glycols - make powder dustless</div>
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What is the role of sodium alginate in alginate powder?
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Gelling agent
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What is the role of calcium sulfate dihydrate in alginate powder?
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Reactant
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What is the role of sodium phosphate in alginate?
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Retarder
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What is the role of silicate powder in alginate?
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Filler
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What are the 2 steps in the setting reaction of alginate?
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1. Sodium phosphate retards setting of calcium sulfate with potassium alginate by preferentially reacting first with the calcium sulfate.<div><br /></div><div>2 Na3PO4 + CaSO4 ---> Ca3(PO4)2 + 3 Na2SO4</div><div><br /></div><div>2. Sodium alginate reacts with calcium sulfate to form an insoluble calcium alginate.</div><div><br /></div><div>2 Na-Alg + CaSO4 ----> Na2SO4 + Ca-Alg2</div>
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Describe the setting of alginate?
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Setting occurs when the calcium provides cross-linkage from one long alginate molecule (fibril) to another, restricting movement.
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In lecture agar and alginate are compared to the setting of 2 foods, which foods are they?
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Agar - Like the setting of Jell-O<div>Alginate - Like the setting of instant pudding</div>
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What is the typical alginate set time?
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From start of mixing until material is no longer tacky:<br /><br /><div>Type I (fast set) - 1-2 min</div><div>Type II (normal) - 2-4.5 min</div>
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What are 2 ways to lenghten the setting time of alginate? Which is the preferred method?
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1. Increase water to powder ratio<div>2. Lowering water temperature</div><div><br /></div><div>Lowering the water temperature is preferred because increasing the water to powder ratio weakens the gel.</div>
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What is the correct proportion of water for 15 grams of alginate powder?
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40 mL to 15 grams
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How long should alginate be held in place in the mouth to set?
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3 minutes - this will enhance the strength.
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Why should alginate be removed with a quick snap?
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To reduce distortion and tearing.<div>Tear strength is greater with rapid loading.</div>
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Which type of alginate has the best tear strength? worst?
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Identic has the highest tear strength<div>Supergel has the lowest tear strength</div>
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Which type of alginate has the highest strain percentage (higher = more flexible)? Lowest?
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COE Alginate = most flexible<div>Triphasix = Least flexible</div>
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Which type of alginate has the best wettability? Worst?
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Jeltrate - best wettability<div>Identic - worst wettability</div>
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Most alginate brands have a recovery from deformation percentage of what?
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96-98%
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What is thought to be the reason for compatibility of gypsum products with alginate?
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Amount of sodium phosphate/sulfate (retarder) in the alginate
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What is discide ultra?
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A quarternary ammonium disinfectant.
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What are some advantages of alginate?
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Short working and setting time<div>High flexibility - easy to remove from mouth</div><div>Good wettability</div><div>Inexpensive</div><div>Good patient acceptance</div>
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What are some disadvantages to alginate?
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Low resistance to tear<div>High dimensional change if not poured immediately</div><div>Adequate reproduction accuracy - good enough for some things, not for others</div>
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What is the likely reason for an alginate mix with a grainy appearance?
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Improper mixing<div>Prolonged mixing</div><div>Excessive gelation</div><div>Water/powder ratio too low</div>
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What are some likely reasons for tearing of alginate?
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Inadequate bulk<div>Moisture contamination</div><div>Premature removal from mouth</div><div>Prolonged mixing</div>
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What are some reasons an alginate impression may have external bubbles?
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Undue gelation preventing flow<div>Air incorporated during mixing</div>
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What are some reasons for irregularly shaped voids on an alginate impression?
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Moisture or debris on tissue
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What are some reasons for a rough or chalky stone model?
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Inadequate cleansing of impression<div>Excess water left in impression</div><div>Premature removal of the impression</div><div>Model left in impression too long</div><div>Improper manipulation of stone</div>
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What are some reasons for distortion of an alginate impression?
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Impression not poured immediately<div>Movement of tray during gelation</div><div>Premature removal from mouth</div><div>Improper removal from mouth</div><div>Separation from tray from not using adhesive</div>
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What are 3 types of non-aqueous impression materials?
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Polysulfide<div>Silicone (Condensation, Addition)</div><div>Polyether</div>
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What are some characteristics of elastomeric non-aqueous impression materials?
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1. Most commonly used materials for crown and bridge impressions.<div>2. More hydrophobic than hydrocolloids</div><div>3. High degree of elastic recovery</div><div>4. Set by chemical reaction of two components</div><div>5. Made from synthetic polymers</div><div>6. Temperature will affect setting time</div><div>7. High degree of dimensional stability</div><div>8. High degree of tear resistance</div><div>9. Less flexible than hydrocolloids</div><div>10. Relatively expensive ($0.20-0.67/ml)</div>
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What are the setting mechanisms of synthetic rubbers?
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Chain lengthening<div>Crosslinking </div><div>Continued polymerization</div>
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Describe the condensation method of polymerization?
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Two molecules unite forming a larger molecule and a small molecule is released as a by-product.
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How do by-products effect stability of a condensation material?
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The material is less stable because the reaction includes the formation of a by-product
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What are 2 examples of materials that undergo condensation reactions?
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Polysulfide rubber<div>Condensation reaction silicone</div>
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Describe the addition reaction of polymerization?
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The joining of 2 molecules to form a larger molecule. No by-products are formed so it is more stable.
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What are 2 examples of addition reaction materials?
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Polyether<div>Addition reaction silicone</div>
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What is accuracy of an impression dependent on?
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Amount of elastic recovery and polymerization shrinkage
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Polymerization shrinkage causes the model of the teeth to be larger or smaller than the actual tooth?
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Larger - The model ends up larger than the original because shrinkage of the impression material occurs toward the tray, or away from the tooth.
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Which materials have the highest percentage of shrinkage after 24 hours?
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Polysulfide (0.7%)<div>Condensation silicone (0.5%)</div>
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What is the polymerization shrinkage of polyether and addition silicone after 24 hours?
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Polyether - 0.1%<div>Addition silicone - 0.04%</div>
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How can you reduce shrinkage of acrylic used in making a custom tray?
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Reduce the thickness of impression material
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What are the distinct advantages to low viscosity and high viscosity non-aqueous elastomeric materials?
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Low viscosity flows well and captures detail<div>High viscosity has more filler and less polymeric material, which reduces shrinkage.</div>
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Why is timing of light-body and heavy-body mixing and insertion critical in a dual mix - single impression technique?
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The different viscosities do not always bond together well
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T or F: The direction of tray seating may affect the flow of heavy body material in a dual mix-single impression technique?
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True
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What are some causes of lack of flow of impression material?
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Contour of teeth<div>Directionof seating tray</div><div>Viscosity of impression material</div>
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Describe a dual mix - two impressions technique?
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1. Heavy-bodied initial impression on study cast with relief to create a custrom tray from a stock tray.<div>2. Secondary or wash impression with light-bodied material to capture detail.</div>
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What are the advantages of the monophase-regular bodied impression technique?
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Quick<div>No delamination problems</div>
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What are the viscosities of non-aqueous elastomeric impression materials and their uses?
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Light-bodied - delivered by syringe<div>Regular-bodied - syringe or alone in single mix</div><div>Heavy-bodied - tray material to provide stability</div><div>Putty - Tray material to provide stability</div>
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What are 3 ways in which non-aqueous elastic impression materials are mixed?
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Hand mix<div>Static mix (Auto mix) - pastes from cartridgens mixed through baffled tip by force from plunger</div><div>Dynamic mix - motorized mixer</div>
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When you are mixing impression materials with an automix gun, why should you extrude a small amount out first?
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To make sure flow is even
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What do you do if impression material does not polymerize?
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Place cartridge in sterilization bag and mark on the bag that it did not set and turn it into the dispensary. The manufacturer will replace the cartridge.
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T or F: Addition silicone is pseudoplastic and thins during expression through a baffled tip?
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True
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What is the recommended use for closed-mouth impressions (e.g. triple tray)?
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Single crowns or 2 single crowns in quadrant with a terminal natural tooth in occlusion
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Why is high tear strength so important when taking impressions for a crown or other fixed prosthesis?
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To minimize tearing of thin areas around the margins upon removal of the impression.<div><br /></div><div>Amount of distortion is important to, polysulfide has the highest tear strength, but may stretch and distort.</div>
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What are some causes of distortion?
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Deflection of impression material and rebound after removal from mouth.<div>Seating an impression after the material has begun to set</div><div>Polymerization shrinkage</div><div>Loss of condensation reaction by-products</div><div>Thermal contraction (oral to room temp)</div><div>Absorption of water or disinfectant</div><div>Incomplete recovery because of viscoelastic behavior</div><div>Incomplete recovery from plastic deformation</div>
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What are some reasons an impression distorts upon removal from the mouth?
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Undercuts - because the material is subjected to shear, compression and tensile forces<div>Failure to achieve adhesion of the impression material to the tray</div>
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How does bulk of material in the tray help prevent distortion from an undercut?
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If there is enough thickness, the strain can be minimized because there is support of the material in the area deflected.
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What is in the base pase of polysulfide rubber?
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Polysulfide polymer<div>Filler (titanium dioxide)</div>
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What is in the accelerator paste of polysulfide rubber?
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Lead dioxide (catalyst)<div>Non-reactive oils</div><div>Sulfur</div>
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What is the setting mechanism of polysulfide rubber?
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Lead oxide causes condensation of the terminal and pendant SH groups on the polysulfide molecule.
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What are the by-products of the setting of polysulfide rubber?
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Water and lead by-products
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What are the advantages of polysulfide?
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High flexibility - easy to remove<div>High tear resistance</div><div>Good flow</div><div>Low cost</div>
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What are the disadvantages of polysulfide?
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Unpleasant taste and odor<div>Only fair stability, custom acrylic tray should be used for best results</div><div>Less wettable than polyether or hydrophylic addition silicone</div><div>Lead dioxide will stain clothing</div>
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What is in the base paste of condensation silicone?
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Polymer - hydroxy terminated poly(dimethyl siloxane)<div>Crosslinker - orthoalkylsilicate</div><div>Filler 30-40% for paste; 75% for putty</div>
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What is in the catalyst paste of condensation silicone?
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Catalyst - metal organic ester, tin octoate<div>Carrier - oily dilutent</div>
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Describe the setting reaction of condensation silicone?
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Tin octoate catalyzes the reaction<div>Chain lengthening occurs by condensation of terminal OH groups of the siloxane</div><div>Ortho alkylsilicate cross-links the polysiloxane chains with alcohol as a by-product.</div>
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What are the advantages of condensation silicone?
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Pleasant taste and odor<div>Relatively clean</div><div>Relatively inexpensive</div>
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What are the disadvantages of condensation silicone?
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Only fair stability<div>Medium tear resistance</div><div>Least wettable of the synthetic impression materials</div>
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What is in the base paste of polyether?
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Prepolymer-low molecular weight polyether with ethylene-imine terminal groups<div>Filler</div>
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What is in the accelerator paste of polyether?
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Catalyst- aromatic sulfonic acid ester<div>Fillers and plasticizer</div>
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Describe the setting reaction of polyether?
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Aromatic sulfonic acid ester catalyzes the pre-polymers<div>Addition polymerization through ring opening of ethylene-imine group and chain extension</div>
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What are the advantages of polyether?
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Highly accurate<div>Good dimensional stability</div><div>Stock, custom or dual-arch trays</div><div>Good surface detail</div><div>Pour within one week</div><div>Multiple casts</div><div>Good wettability</div>
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What are the disadvantages of polyether?
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Cost ($124/200 ml cartridges) <div>Short working time</div><div>Bitter taste (improved with impregum soft)</div><div>Low tear strength</div><div>Absorbs water (changes dimension, don't store with alginate or wet paper towels)</div><div>Rigid (difficult to remove from undercuts, thinners may be added to delay set and increase flexibility)</div>
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What is the composition of addition silicone?
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Prepolymer - vinyl terminated siloxane<div>Prepolymer - siloxane with hydrogen side groups</div><div>Catalyst - Chloroplatinic acid</div>
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Why were surfactants added to PVS?
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Increase wettability<div>Yields fewer bubbles</div>
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Describe the reaction of PVS materials?
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H2PtCl6 catalyses the reaction<div>Propagation occurs as the vinyl groups reacts with the hydrogen side groups.</div>
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What is the setting time of PVS?
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3 to 7 minutes.<div>Setting time may be delayed by refrigeration</div>
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Why do some manufacturer's add Pt and Pd to PVS?
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To scavenge hydrogen so that it doesn't cause bubbles. Materials without these metals should not be poured up until 1 to 2 hours has passed to allow the hydrogen to dissipate
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Why should you not use latex gloves with PVS?
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Sulfur from latex gloves may poison the catalytic reaction when mixing putty and prevent setting.<div>Remove gloves and wash hands or wear vinyl gloves when mixing putty.</div><div><br /></div><div>The same concern exists when using ferric sulfate hemostatic agents because the sulfur will hinder the setting reaction.</div>
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What effect can PVS and sulfur from hemostatic agents have on ceramic crowns?
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It may cause gray staining through all ceramic crowns at the gingival 1/3
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What are some hemostatic agents used at UNLV?
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Viscostat clear - Aluminum chloride<div>Viscostat Brown - Ferric sulfate (more effective)</div><div>Also consider injecting anesthetic (w/epi) in papilla for hemostasis.</div>
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What are the advantages of addition silicone?
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Excellent stability and accuracy<div>Clean and easy to use</div><div>Neutral taste and odor</div>
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What are some disadvantages of addition reaction silicone?
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Medium resistance to tear<div>Posssible hydrogen release</div><div>Cost</div><div><br /></div>
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Which non-aqueous elastic material releases gas?
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PVS
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Which non-aqueous elastic impression materials can produce multiple casts per impression?
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Polyether<div>Addition silicone</div>
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What are some ways to deal with anatomical undercuts on the patient when taking an impression?
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1. For patients with large interproximal spaces or gingival recession use blockout material or rope wax.<div>2. For buccal exostoses, use alginate applied in undercut area</div><div>3. If unable to remove an impression from the patient's mouth, you may have to section the impression tray</div>
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What are some strategies to avoid breakage of stone when separating stone from the impression?
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Wait 24 hours to separate - cast will be stronger<div>If there are large undercuts, cut away impression material in non-critical areas</div><div>Section the impression tray.</div>
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What is alginot?
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A polyvinyl siloxane impression material used as an alginate substitute.<div>Not for use on crown and bridge impressions</div>
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What is an advantage to alginot?
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Can pour multiple casts<div>Not super expensive</div>
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What is blu-mousse commonly used for?
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Bite registration<div>It is a PVS material</div>
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What are some criteria for bite registration materials?
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1. Set quickly<div>2. Be reasonably stiff on application, resist flow - mousse-like</div><div>3. Hard set, but flexible enough to remove from undercuts</div><div>4. Trim easily - not brittle</div>
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What are some characteristics of blu-mousse?
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Initially low viscosity, sets to 80% the hardness of plaster of paris<div>Classic - sets in 90-120 seconds intraorally</div><div>Radiopaque</div><div>Resists slumping and flow</div><div>Can be used as an impression material instead of putty</div><div>Compatible with other PVS materials</div>
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What is fit checker used for?
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Check for areas inside restorations that interfere with complete seating.<div><br /></div>
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What material is fit checker made out of?
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White and black are condensation silicone<div>II NDS is addition silicone</div>
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How do you use fit checker?
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Mix and place in crown<div>Seat and allow to set (40 sec)</div><div>Can show the fit at margins - the thickness of fit checker will be the thickness of cement</div><div>Look for grayness at margins</div><div>Also can be used for partial denture frameworks</div>
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What is Comprecap used for?
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It is used adjunctively with retraction cord prior to taking impression<div>Patient bites down on it for 3-5 minutes compressing gingiva, aiding retraction.</div>
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What is the advantage to the BFC "transfer" syringe for impression materials?
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Intraorally, smaller and easier to manipulate than a large dual cartridge gun.
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Which light body PVS material has the highest tear strength?
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Aquasil
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What does a higher strain in compression value of an impression material mean?
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It is more flexible.
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Which light bodied PVS impression material is the most flexible?
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Flexitime
|
|
How is the elastic recovery test performed on PVS products?
|
20 mm sample compressed 30% and measured within one second.<div>All materials exceeded the standard of 96.5%</div>
|
|
How is the detail of reproduction test done?
|
25 mm long v-shaped grooves of 20 microns in width must be duplicated by light-bodied and 50 micron groove duplicated by heavy-bodied material.<div><br /></div><div>All PVS materials achieved the standard</div>
|
|
What does the shark fin test find?
|
Flow of elastomeric impression materials
|
|
How is gypsum compatibility test performed?
|
Impression of 50 micron groove must be reproduced in gypsum model.<div><br /></div><div>All PVS products exceeded the standard..</div>
|
|
What is the test for linear dimensional change before and after disinfection?
|
Maximum dimensional change measured at 24 hours, 7 days, and 14 days under controlled conditions. <div>Change cannot exceed 1.5%</div><div>All materials achieved the standard.</div>
|
|
Which impression material has the greatest tear strength?
|
Polysulfide, followed by addition silicone and polyether
|
|
Tor F: Most studies found that dual arch impressions using closed mouth technique were clinically acceptable?
|
True, However, Dr. Walker noted that this may not be conclusive
|
|
What was a problem with the studies on triple tray use?
|
Most had small numbers in the sample groups, with large standard deviations.
|
|
What is the prevalence of triple tray use in dental schools?
|
21 schools teach it<div>21 dont</div><div>18 didn't respond</div>
|
|
What is the composition of resin based composite?
|
<div>1. Diacrylate monomers:</div><div><br /></div>Bis-GMA - Bisphenol A glycidyl methacrylate<div>Urethane dimethacrylate</div><div>Diluent and cross-linking monomers</div><div>Photo sensitive initiators</div><div><br /></div><div>2. Filler particles</div>
|
|
What is the photoinitiator in RBC? Accelerator?
|
Diketone (Camphorquinone)<div>Amine (DMAM) </div>
|
|
How does the photopolymerization of composite work?
|
Light reacts with Camphorquinone and the Amine <div>The activated amine reactes with Bis-GMA to initiate polymerization</div><div>The end of the Bis-GMA molecule reacts with other Bis-GMA molecules in a step called propagation</div>
|
|
What is the absorption wavelength of Camphorquinone?
|
470 nm
|
|
Why are additional photoinitiators added to some resin based composites?
|
To minimize the yellow of camphorquinone and maximize the percent conversion.
|
|
What are 2 photoinitiators added to resin-based composite in addition to camphorquinone?
|
Phenylpropanedion (PPD)<div>Lucirin TPO</div>
|
|
T or F: Camphorquinone is not as efficient as other photoinitiatorss?
|
True, but its absorption range is 380-520 nm, which matches halogen lights.
|
|
What are 3 light sources used for curing RBC?
|
Quartz-tungsten-halogen (QTH) - Traditional and Fast<div>Plasma arc (Xenon short arc) (PAC)<br />LIght emitting diode (LED)</div>
|
|
In what units is light intensity measured?
|
mW/cm^2
|
|
Of the total energy output of QTH lights, how much is useful for photo-curing?
|
0.5%<div><br /></div><div>Most of the energy is infrared and must be filtered</div><div>There is a fan in QTH lights to reduce the heat.</div>
|
|
What are some characteristics of the Optilux 501 light?
|
<div>QTH light</div>80 Watt bulb<div><div>With 8mm turbo 900 tip, boost 1050 mW/cm^2</div><div>With 11mm 700, boost 825 mW/cm^2</div></div>
|
|
What wavelengths will QTH lights emit?
|
380-500 nm - This will activate all dental photoinitiators
|
|
What are the advantages of QTH lights?
|
Wide spectral range<div>Cures all RBC</div>
|
|
What are some disadvantages to QTH lights?
|
Light has shorter life span than LED<div>Power cord</div><div>Less efficient than LED</div><div>Harmful UVA emissions</div>
|
|
What are some characteristics of plasma arc curing units?
|
Electric arc started, light emitted from a glowing plasma, which is a gaseous mixture of ionized moleculed and electrons.<div>Power density up to 1775 mW/cm^2</div>
|
|
What are some characteristics of Sapphire Plus light?
|
Plasma arc light<div>$4,000</div><div>Power - 9mm tip 1775 mW/cm^2, 11mm 1175 mW/cm^2</div>
|
|
What are some characteristics of the Demi Plus curing light?
|
LED<div>Lithium ion battery</div><div>Fan</div><div>8mm tip - 1,200 mW/cm^2</div><div>11mm tip - 600 mW/cm^2</div><div>Does not cure all materials</div>
|
|
What are some characteristics of Paradigm curing light?
|
LED<div>No docking station, cannot be used while charging</div><div>10mm tip - 1150 mW/cm^2</div><div>Does not cure all materials</div>
|
|
What are some characteristics of the Fusion curing light?
|
LED<div>Changeable tips - Reg, White light, UV for bleach shades</div><div>Lenses - wide angle and focused</div><div>Removable lithium ion battery</div><div>Regular tip - 1,650 mW/cm^2</div><div>Can cure all materials based on which tip you are using</div>
|
|
What are some characteristics of the Valo Corded curing light?
|
LED<div>Standard power: 1,100</div><div>High: 1,400</div><div>Plasma: 3,000</div><div>Cures all materials</div>
|
|
What are the characteristics of the Valo Cordless curing light?
|
LED<div>2 replacable 3.2v LiFePO4 batteries</div><div>Standard power: 1,200</div><div>High - 1,428</div><div>Plasma - 3,000</div><div>Cures all materials</div>
|
|
What are some general characteristics of LED curing lights?
|
1. Extremely long life<div>2. Light intensity comparable or higher than QTH, but concentrated in the 440-480 nm range.</div><div>3. May not cure every product as effectively unless poly-wave light emissions utilitzed</div><div>4. Typically light guides are tapered and approx. 8 mm in diameter</div><div>5. Energy efficiency permits battery power</div><div>6. Simpler LEDs may not cure beyond 3-4 minutes, and lack timers</div>
|
|
Which photoinitiators may not be activated by LEDs?
|
PPD <div>Lucerin TPO</div>
|
|
How does a poly-wave (2 peak or dual peak) LED work?
|
A violet LED is added to the array to cover all photoinitiators
|
|
What are some characteristics of the Ultra-Lume 5 curing light?
|
Corded<div>Dual peak LED</div><div>403 nm and 450-470 nm</div><div>No radiometer</div>
|
|
What is the temperature of the tip of the Ultralume 5 light?
|
60 C or 140 F<div>The others hang around 30-45 C</div><div><br /></div>
|
|
In a study on monkey teeth, what was the temperature increase of the pulp from light curing that caused some pulpal necrosis?
|
An increase of 5.5 C caused 15% pulpal necrosis
|
|
What are some measures of polymerization?
|
Percent conversion of double bonds to single bonds<div>Hardness test</div><div>Depth of cure test</div>
|
|
What percent of conversion of double bonds to single bonds is considered ful polymerization?
|
55-65%
|
|
What score on the Knoop hardness test is considered full polymerization?
|
75-85 for hybrid composite<div>30-40 for microfill composite</div>
|
|
What is considered an adequate cure of the bulk of composite using the hardness test?
|
If the bottom of the mass has a score that is 80% or greater the hardness score at the top, then the cure is adequate
|
|
How does a scrape test work?
|
After curing in a metal mold 8mm deep, the soft material is scraped away.<div>If 1/2 the depth is solid, the cure is considered adequate</div>
|
|
What is the ISO standard depth of cure using the scrape test?
|
A minimum of 1.5 mm should be polymerized
|
|
T or F: There is only moderate correlation between Knoop's Hardness Scale and percent conversion?
|
True
|
|
How can you test your own curing light?
|
Use a compule of composite.<div>Cut off the tip and light cure</div><div>Then cut off the other end and remove the uncured material</div>
|
|
What are some factors in resin-based composite polymerization?
|
1. Constituents of the resin-based composite<div>2. Visible light-curing unit</div><div>3. Clinical factors</div>
|
|
How does shade and translucency effect polymerization?
|
Opaque, low value, high chroma shades absorb more light and cure less deeply.<div><br /></div><div>White cures better</div>
|
|
How much light is transmitted through a mass of composite at the surface, 2mm, and 3mm?
|
The surface receives 100% of the light<div>At 2mm only 10% is transmitted</div><div>At 3mm only 3% of light is transmitted</div>
|
|
Why do microfills cure less deeply than hybrids?
|
The more resin, the more photoinitiators and amine accelerators to yellow.<div>To prevent yellowing, microfills have less photoinitiators and amine accelerators than hybrids, so they cure less deeply.</div>
|
|
What is the concentration of initiator and accelerator in composite?
|
0.03%-0.09% diketone<div>0.04% aliphatic amine, or 0.1% aromatic amine</div>
|
|
T or F: Resin based composites with only camphorquinone have better polymerization with a monowave light?
|
True, but when other photoinitiators are added, curing is better with a polywave light.
|
|
What are the peak wavelengths and mW/cm^2 for the Bluphase G2 (poly), Valo (poly), Bluephase (mono) LED lights?
|
Bluphase G2 - 461 and 410 nm - 1310 mW/cm<div>Valo - 459 and 410 nm - 1233 mW/cm</div><div>Bluphase - 455 nm 1775 mW/cm</div>
|
|
What are some concerns with inadequate polymerization?
|
Weak restoration<div>Increased wear</div><div>Recurrent decay</div><div>Leaching monomers, initiators, and accelerators</div>
|
|
What are some consequences of polymerization of RBC?
|
1. Shrinkage - with insufficient bond, shrinkage can cause microleakage, sensitivity, and recurrent decay<div>2. Stress - If bond is insufficient, force could lead to post-op sensitivity or fractured tooth. </div>
|
|
What is polymerization stress dependent on?
|
Shape of cavity preparation<div>Stiffness of composite</div><div>Amount of shrinkage</div>
|
|
What is C-factor?
|
Configuration factor - The ratio of bonded surfaces to unbonded surfaces.
|
|
How does C-factor affect stress?
|
The higher the C-factor, the more stress created during polymerization shrinkage
|
|
In what direction does composite shrink?
|
Unbonded composite shrinks toward the center of the mass<div>Bonded composite creates stress at bond interface</div>
|
|
T or F: The higher the modulus of elasticity (stiffness) of RBC, the higher the stress during polymerization?
|
True, this is C-factor dependent. Greater shrinkage leads to greater stress.
|
|
What are some strategies used to minimize contraction stress?
|
Low shrinkage composite<div>Thicker or 2 applications of bonding agent</div><div>Incremental cure vs. bulk cure</div><div>Placement of RMGI liner</div><div>Soft or ramp curing with curing light.</div>
|
|
T or F: Tooth deflection, sensitivity, marginal fracture-white lines, debonding, and recurrent decay are all outcomes associated with RBC contraction stress?
|
True, but no clinical evidence exists to support a cause effect relationship between contraction stress and clinical failure or longevity
|
|
Light intensity X time yields what units?
|
J/cm^2 - This is the curing energy or energy density
|
|
How much energy density is needed to cure 2 mm of RBC?
|
24 J/cm^2 has been found by 2 studies to be the answer<div>Other studies vary from 12-36 J/cm^2</div>
|
|
How does shade affect energy density required to cure composite?
|
Lighter shades require less.<div><br /></div><div>A1 can be cured at 12J/cm^2</div><div>A4 requires 24 J/cm^2</div>
|
|
What are some characteristics of bulk fill Resin-based composite?
|
Introduced to reduce curing time<div>Limited shade selection</div><div>More translucent</div><div>Two different viscosities of material</div><div>Similar shrinkage and stress to hybrids</div>
|
|
Which bulk fill RBCs were shown to have significantly lower depths of cure than they claimed?
|
Sonic Fill - Kerr: Claimed 5, Results - 3.67mm<div>Tetric Evo Ceram Bulk Fill - Claimed 4, Results - 3.32mm</div><div>Alert-Condens. Pentron - Claimed 5, Results - 2.53 mm</div>
|
|
Which bulk fill composites can be used on the occlusal surface?
|
High viscosity bulk fills:<div><br /></div><div>Sonic Fill</div><div>Tetric Evo Ceram</div><div>X-traFil-VoCo</div><div>Alert-Condens Pentron</div><div>Quixx-Dentsply/Caulk</div>
|
|
What are some disadvantages to Bulk Fill composites?
|
Cure still does not reach deep preps<div>Flowables not used on occlusal surface</div><div>Making tight contacts may be difficult</div><div>Preventing voids is unpredictable</div>
|
|
What are some clinical factors affecting polymerization?
|
Diameter of light guide<div>Tapered (turbo) tip, or straight</div><div>Divergence of light from light guide or LED</div><div>Distance of light guide from material</div><div>Duration of cure</div>
|
|
How do non-tapered light guides that are larger than the exit port affect intensity?
|
They reduce intensity
|
|
How large must a light guide be in order to fully cure the occlusal surface of an entire molar?
|
At least 11 mm
|
|
How much does angling the curing light from a perpendicular position reduce light energy?
|
A 30 degree angle reduces light energy by 26%<div>45 degree angle - 56%</div><div>60 degree angle - 81%</div>
|
|
How much did instruction to operators on light guide placement improve energy delivered?
|
63%
|
|
What are some curing light factors that effect polymerization?
|
Cleanliness and condition of tip<div>Diameter of light guide</div><div>Tapered light guides</div>
|
|
How wide must the tip diameter be in order to obtain 11mm light emission?
|
13 mm tip
|
|
How does a tapered light guide affect intensity?
|
A decreased diameter of 1.4X may increase irradiance by 2X at the tip end.
|
|
How does distance of light guide from material affect intensity?
|
The greater the distance from the subject, the less intense the light and the less depth of cure
|
|
Changing the curing distance from 2mm to 9 mm had what effect on light intensity?
|
19% to 68% depending on the light
|
|
What factors result in shorter curing time?
|
Higher irradiances - plasma arc, fast halogen, fast LED<div>Hybrid RBC</div><div>High value shades</div><div>Translucent shades </div><div>Close distance</div><div>Good collimation</div>
|
|
What factors result in longer curing time?
|
Lower irradiance - moderate halogen, moderate LED<div>Microfil RBC</div><div>Low value shades</div><div>Opaque shades</div><div>Greater distances</div><div>Poor collimation</div>
|
|
What is 4th generation etch and rinse adhesives?
|
3 step system<div><br /></div><div>Etchant</div><div>Primer in one bottle</div><div>Adhesive in the other</div>
|
|
What is 5th generation etch and rinse adhesive?
|
Two step system<div><br /></div><div>Etchant</div><div>Primer and adhesive combined in one bottle</div>
|
|
Describe dentin bonding?
|
It involves:<div><br /></div><div>1. tooth structure (adherend)</div><div>2. an intermediate layer (adhesive)</div><div>3. restorative material (adherend)</div>
|
|
What are some benefits of dentin bonding?
|
Aids in retention<div>Reduces marginal leakage, decreasing staining, sensitivity,and caries</div>
|
|
What is the primary bonding mechanism of resin-based composite?
|
Mechanical bonding - retentive interlocking through replacement of minerals from hard tissue by resin monomers
|
|
What part of the tooth bonds most predictably in a composite restoration?
|
Enamel because it:<div><br /></div><div>is more homogenous in structure</div><div>Higher in inorganic content</div><div>Higher surface energy</div>
|
|
Why does resin bond less predictably with dentin?
|
Higher variability<div>Higher organic content</div>
|
|
What is the composition of enamel?
|
Mostly hydroxyapatite - 86%<div>Water - 12%</div><div>Organic - 2%</div>
|
|
What does etching enamel do?
|
Creates micropores - 5-50 microns deep<div>Increases surface energy</div><div>Increases wettability</div>
|
|
What is in bonding agents?
|
Diacrylates with low-viscosity monomers:<div><br /></div><div>1. Bis-GMA</div><div>2. UDMA</div><div>3. TEGDMA</div><div>4. HEMA</div>
|
|
What is the bond strength of bonding agent with enamel?
|
20 MPa
|
|
What are some characteristics of dentin?
|
Dentin contains mineral, collagen fibrils, water<div>Tubule structure</div>
|
|
What is the composition of dentin?
|
Inorganic - 50%<div>Organic - 25%</div><div>Water 25%</div>
|
|
How can the structure of dentin vary?
|
Person to person<div>In teeth within the same arch</div><div>As a function of depth within the same tooth</div><div>With degree of mineralization</div>
|
|
What is the dentin smear layer?
|
A layer of debris from tooth preparation of 1-3 microns in depth
|
|
T or F: Dentin was not etched prior to the 4th generation bonding agents?
|
True
|
|
What is used as the etchant, primer, and adhesive in the 3-step (4th generation) bonding systems?
|
Etchant - Phosphoric acid, 32-37%<div>Primer - Hydrophylic monomer - HEMA</div><div>Adhesive resin - Hydrophobic monomer - Bis-GMA, TEGDMA</div>
|
|
What are some examples of 4th generation (3-step) etch and bonding systems?
|
Scotchbond multi-purpose<div>Optibond FL</div><div>All Bond 2</div>
|
|
What are the results of a 15 second etch?
|
Chemical alteration of the surface by phosphoric acid<div>Removes dentinal smear layer to expose collagen fibrils</div><div>Simultaneous enamel etch</div>
|
|
After the etchant has been on for 15 seconds, what is the next step?
|
Rinse and dry, but keep dentin a little moist.
|
|
What does the primer do?
|
Displaces water<div>Promotes infiltration into collagen fibrils</div>
|
|
What is in primer, and why do you air dry the primer?
|
Hydrophylic monomers dissolved in acetone, alcohol, or water.<div>Air drying drives off solvents and excess water</div>
|
|
What does a bifunctional monomer like HEMA do?
|
Links hydrophilic collagen to hydorphobic resin
|
|
What does adhesive resin do?
|
Stabilizes the hybrid layer<div>Fills up remaining pores</div><div>Makes resin tags</div><div>Links primer to resin-based composite</div>
|
|
What is in adhesive resin?
|
Unfilled or lightly-filled monomers - Bis-GMA, UDMA, TEGDMA
|
|
What is the hybrid layer?
|
Collagen infused with resin
|
|
Why are 5th generation etch and rinse bonding systems more technique sensitive?
|
Higher solvent to monomer ratio, resulting in risk of applying too thin.
|
|
What are some examples of 5th generation (2 step) bonding systems?
|
Gluma Comfort Bond + Desensitizer<div>Optibond Solo Plus</div><div>One-Step Plus</div><div>Prime&Bond NT</div>
|
|
Optibond Solo Plus is based with what solvent?
|
It is alcohol based
|
|
What is a good shear bond strength for dentin bonding?
|
A 12 study average of 20 MPa was found
|
|
What is a good tensile dentin bond strength?
|
10 MPa
|
|
What is the usual micro tensile bond strength?
|
60 MPa
|
|
What are some causes of dentin sensitivity and pulp irritation with dentin bonding?
|
Nanoleakage - poorly hybridized resin tag<div>Internal gap - No resin tag in tubule (likely to cause dentin sensitivity)</div><div>Bacteria - External gap via open margin (may result in pulpal irritation)</div>
|
|
What are the pros of total etch systems (4th and 5th generations)?
|
Separate acid etch - good enamel etch pattern<div>Multiple long-term clinical studies available</div>
|
|
What are the cons of total etch bonding systems?
|
Potential to over-etch dentin resulting in leakage<div>Post-conditioning rinse necessary</div>
|
|
What are the self etch adhesive types?
|
6th generation - 2 step: Self-etching primer, Adhesive resin<div>7th generation - 1 step: Self-etching primer/adhesive</div>
|
|
What are some examples of 6th generation bonding systems?
|
Clearfil SE Bond<div>Optibond XTR</div><div>All-Bond SE</div>
|
|
What are some considerations for using Clearfil SE Bond?
|
Keep refrigerated, bring to room temperature for use.<div>Uncut enamel must be etched with phosphoric acid</div>
|
|
What are the steps for using Clearfil SE Bond?
|
Self-etching primer applied for 20s<div>Do not rinse</div><div>Dry with mild air (water based)</div><div>Apply bond and thin with mild air flow</div><div>Cure for 10 seconds</div>
|
|
What are some examples of 7th generation One-step with Mix (conditioner and primer and adhesive)?
|
Adper Prompt-L-Pop<div>Clearfil Liner Bond 2V</div>
|
|
What are some examples of 7th generation One-step, no mix?
|
G-bond<div>Bond Force</div><div>Xeno IV</div>
|
|
What are the constituents of self-etch adhesives?
|
1. Self-etch adhesive monomer - HEMA phosphate<div>2. Diacrylates and Cross-linking monomer - BisGMA, UDMA, TEGDMA</div><div>3. Monofunctional monomers - HEMA</div><div>4 Additives - Photoinitator, solvents (aqueous acetone or alcohol), stabilizers and fillers</div>
|
|
What does the TEGDMA do in self-etch adhesives?
|
Decreases viscosity and creates polymer network
|
|
What does HEMA in self-etch adhesives do?
|
Improves miscibility and solubility
|
|
Which etchants are the most effective? Least?
|
Most - Etchants in the Total etch systems - pH of 0.1-0.8<div><br /></div><div>Least - Etchants used in self-etching adhesives</div>
|
|
What is the problem with hydrolytic degradation of self-etching bonding agents (7th gen)?
|
<div>Causes voids on the adhesive interface</div>Failure of the restoration over time.
|
|
Why does 2 step self-etch work more effectively than 1 step self etch?
|
Adhesive layer decreases permeability and hydrolysis of bonding agent, permitting better bond.
|
|
What are the pros of self-etch bonding agents?
|
Good dentin conditioning - simultaneous infiltration of bonding components<div>Reduction in post-op sensitivity</div><div>No post-conditioning rinse - </div><div>Reduced application time with some products</div>
|
|
What are some cons to self-etch bonding agents?
|
Must refridgerate - Components are subject to hydrolysis in acid environment.<div>Some require multiple layers and agitation</div><div>Enamel etching may be suspect</div><div>Many not compatible with self-cured RBC</div>
|
|
Define occlusal fissure?
|
Cleft formed from imperfect fusion of enamel or adjoining dental lobes
|
|
Define occlusal pit?
|
A small depression in enamel, usually located in a developmental groove where two or more enamel lobes are joined.
|
|
What is pit and fissure sealant?
|
A resinous material designed for application to occlusal surfaces of posterior teeth to prevent ingess of oral fluids, bacteria, and debris in order to preven caries.
|
|
What is the most popular sealant on the market?
|
Ultraseal by Ultradent
|
|
Which sealant materials are used at UNLV?
|
Ultraseal by Ultradent<div>Embrace by Pulpdent</div>
|
|
What are some characteristics of Bisphenol A (BPA)?
|
1. BPA poses health risks due to endocrine-disrupting and estrogenic properties.<div>2. Main sources are contaminated food, drinking water from PVC pipes, and copy paper.</div><div>3. Dental materials may be a source (Sealants, RBC)</div><div><br /></div>
|
|
What percent of carries in young US patients occur in pits and fissures?
|
90%
|
|
What are the best predictors for caries risk?
|
1. Prior caries experience<div>2. Fluoride history</div><div>3. Fissure anatomy</div><div>4. Oral hygiene</div>
|
|
What are the general indications for sealants?
|
1. High caries risk<div>2. Incipient lesions</div>
|
|
What are some general contraindications for sealants?
|
Low caries risk<div>Well-coalesced pits and fissures</div><div>Frank caries</div>
|
|
What is the international caries detection and assessment system (ICDAS)?
|
A 6 point scale ranging from a sound tooth (1) to extensive distinct cavity involving more than half the tooth.
|
|
When should a tooth be sealed?
|
After the entire occlusal surface is visible because it is difficult to get isolation of a partially erupted tooth.
|
|
What are sealant materials composed of?
|
Bis-GMA or Urethane diacrylate
|
|
How are sealants cured?
|
There are autopolymerizing sealants or light cured sealants
|
|
How do retention rates of filled sealants compare to unfilled sealants?
|
Retention rates are similar
|
|
How does the strength of filled vs. unfilled sealants compare?
|
Filled - Compressive strength = 170, Tensile strength = 31<div>Unfilled - Compressive strength = 130, Tensile strength = 24</div>
|
|
T or F: Transparency or opacity is not determined by fillers?
|
True
|
|
What is an advantage to both opaque and translparent sealant?
|
Opaque - More visible, which aids inplacement<div>Transparent - Leakage (staining under sealant) may be detected earlier</div>
|
|
What are the steps of sealant application?
|
1. Clean pit and fissure surfaces<div>2. Isolation of teeth</div><div>3. Etch enamel</div><div>4. Rinse and dry teeth</div><div>5. Apply sealant</div><div>6. Evaluation</div><div>7. Periodic evaluation</div>
|
|
Why do you clean pit and fissure surfaces prior to placing a sealant?
|
To remove groww plaque and debris that may interfere with etching or sealant penetration
|
|
What are some methods to cleaning pits and fissures?
|
Ruber cup or brush and pumice<div>Explorer tip and rinsing</div><div>Toothbrush w/ toothpaste</div><div>Dry tooth brush, Air polishing</div><div><br /></div><div>They all have similar retention rates</div>
|
|
How does air polishing work?
|
Bicaronate of soda is sprayed on the tooth.
|
|
T or F: Air polishing with bicarbonate soda benefits retention of sealant?
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Both T and F: In vitro studies sho benefit. In vivo study showed no difference in retention rate.
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Which isolation technique is better for sealants, rubber dam or cotton rolls?
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They both have comparable sealant retention rates.
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What are the differences in gel and liquid etchant? Which is better for sealants?
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Gel - offers more control on placement and is easily visible<div>Liquid - flows easily and covers the entire occlusal surface.</div><div><br /></div><div>Neither is better, they have similar sealant retention rates</div>
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How is gel etchant applied? Liquid?
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Gel - syringe<div>Liquid - Brush, Cotton or foam pellet</div>
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Where should etchant be applied when doing sealants?
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All susceptible pits and fissures<div>Extend up cuspal inclines 2 mm beyond anticipated margin of sealant.</div><div><br /></div><div>Avoid contacting soft tissue - If contact occurs, rinse and suction</div>
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Why would you agitate the etchant after placement?
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It is thought to expose new acid to the surface of the tooth.
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How are sealants retained?
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Resin flows into depressions caused by etching, forming resin tags
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How long should etchant be left on tooth when doing a sealant?
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15-20 seconds.
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Why must you dry the tooth prior to placing sealant?
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Sealant is hydrophobic, so the surface must be dry in order to bond well.<div><br /></div><div>An exception to this rule is Pulpdent Embrace</div>
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How does a dried etched tooth look?
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Chalky and frosted appearance
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T or F: Salivary contamination during or after etching may have an adverse effect on sealant bond to enamel?
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True, if contamination occurs, rinse, dry and re-etch
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What is an optional step in placing a sealant?
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Applying primer from dentin bonding systems<div>A reason to do this is that the primer acts as a wetting agent to improve adhesion in moist environment.</div>
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What are some instruments used for applying sealant?
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Dispensers<div>Brushes</div><div>Metal instruments</div>
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What is the application technique for sealants?
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Apply only in the depths of the pits and grooves.<div>Do not extend beyond the etched area.</div>
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How can you remove bubbles in sealant material prior to curing?
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With an explorer. If you don't remove bubbles, the defect will concentrate stress during function and likely fracture.
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What is the curing technique for light cured sealants?
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20 second light cure<div>Tip within 2mm of tooth</div><div>11-13 mm diameter curing tip</div><div><br /></div>
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How many teeth can be sealed with on drop of Universan and Catalyst do?
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2-3 teeth.
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When using chemically activated sealant, how long do you leave sealant on before checking it?
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2 min. - you can check set of residual sealant in well to check if it is done.
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What are the criteria for visual and tactile inspection of sealant?
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Coverage of pits and fissures<div>Absence of voids</div><div>Fused interproximal areas</div><div>Occlusion</div>
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T or F: When using Embrace, you should leave the tooth slightly wet prior to placing sealant.
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True
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What are some techniques to correct defects in sealants?
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Small voids can be repaired by adding new material<div>Remove sealant in interproximal space with a scaler</div>
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What percent of sealants need to be repaired or replaced each year?
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5-10%
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What is the success rate of sealants with routine recall and replacement?
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80-90% success rate for 10 years or more.
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Why would you seal incipient lesions?
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Sealing incipient lesions will prevent progression as long as the seal remains in tact.
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What is a PRR?
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A conservative restoration of an active cavitated lesion in a pit or fissure that does not extend into dentin. Also includes placement of sealant in any non-carious radiating fissures or pits
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What is the UNLV fee of sealant vs. prr?
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Sealant - $15<div>PRR - $50</div>
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What is the difference in a PRR and a class I restoration?
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Class I is used to restore a carious lesion into dentin. It is not a preventative procedure
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What have studies shown about retention fo sealants in buccal and lingual pits?
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There is no difference in retention between buccal/lingual and occlusal sealants if dentin primer and adhesive is used.
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T or F: No anticaries benefit has been shown with resin sealants containing fluoride?
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True
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What was found in a study about using self-etching primer and adhesive with sealants?
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Less retention than the standard. It is not recommended.
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What is tooth pain form dentin/cementum sensitivity commonly due to?
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Cold stimulus - air, cold liquid<div>Touch - dental instrument, finger nail, etc.</div><div>Pain is usually short-lived, ending with termination of the stimulus</div>
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How is gingival pain distinguished from dentin/cementum sensitivity?
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Redness, bleeding and swelling present with gingival pain
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How is a toothache distinquished from dentin/cementum sensitivity?
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Spontaneous, constant pain occuring without stimulus describes a toothache.
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What is the prevalence of hypersensitive dentin/cementum?
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Clinical occurrence of 8.9-14.5% depending on age/sex make-up of group studied and stimuli used.
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What is the proposed etiology of dentin/cementum sensitivity?
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Hydrodynamic theory of pain<div>Bacteria and pulpal inflammation</div>
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What is the hydrodynamic theory of dental pain?
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Temperature, osmosis, dryness, and tactile sensation induce fluid flow in dentinal tubules and stimulate nerve fibers.
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What may be the causes of pulpal inflammation?
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Open tubules and bacteria<div>Traumatic occlusion</div><div>Abrasion/erosion</div>
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What is the cause of hypersensitive dentin?
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Open tubules at the surface due to:<div><br /></div><div>Traumatic occlusion - flexure abfractions</div><div>Plaque accumulation/low pH - erosion</div><div>Abrasion/erosion - Toothbrush and diet</div>
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Which surface is most commonly affected by non-carious cervical lesions?
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Buccal surfaces of posterior are most common.<div>These are often associated with hypersensitivity</div>
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What are some additional causes of dentin/cementum hypersensitivity?
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Post-op sensitivity<div>Tartar control toothpastes (pyrophosphates)</div>
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What are the primary rationales for treating hypersensitive dentin?
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Sealing dentinal tubules<div>Reduction/elimination of inflammation</div><div>Alter neural pain transmission</div>
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What are some treatment approaches to dentin hypersensitivity?
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Occlusal treatment - adjustment or nightguard - reduce hyperemia and periodontal inflammation<div>Toothpastes - Potassium nitrate - alters neural conduction</div><div>Fluoride - Blocks tubules</div><div>Anti-inflammatory agents - reduces inflammation</div><div>Precipitation of compounds - blocks tubules</div><div>Dentin bonding agent - blocks tubules</div><div>Restorative resins - blocks tubules</div><div>Ionophoresis - blocks tubules</div><div>Laser - blocks tubules</div>
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Other than toothpaste, what is another way potassium nitrate may be used to control dentin sensitivity?
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Using potassium nitrate gel in a bleaching tray.
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Why should prescription fluoride toothpastes to limit dentin sensitivity not be used by children under 6?
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To prevent dental fluorosis
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What are some anti-inflammatory agents used to inhibit dentin sensitivity?
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1. Locally applied corticosteroids - not commonly used today<div>2. Protein preciptiation with silver nitrate, zinc chloride, strontium chloride, and formaldehyde - Not commonly used today</div><div>3. Oxalate precipitation - Monohydrogen-monopotassium oxylate reacts with ionized calcium in dentinal fluid to occlude tubules.</div><div>4. One bottle primer - places film over dentin surface - e.g. HEMA, Gluma</div>
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How does ionophoresis work?
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Electircal current may enhance ion uptake by dentinal tubules - used with fluoride solution
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T or F: Treatment for dentin hypersensitivity may be transient?
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True, long-term treatment demands attention to causative factors. e.g. occlusion, oral hygiene, toothbrushing technique, choice of toothpaste, diet, habits
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