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344 Cards in this Set

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  • Back
What are 3 indications for using impression materials?
Diagnostic casts<div>Indirect reconstruction</div><div>Bite registration</div>
What are some essential properties of impression materials?
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. &nbsp;Ability to maintain dimensions until poured with gypsum).</div><div><br /></div>
What are some desireable properties of impression materials?
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>
When was alginate introduced as a dental impression material?
1944
When were addition reaction silicones introduced as a dental impression material?
1980s
What is a disadvantage of a rigid impression material?
Cannot accurately reproduce undercuts.
How do reversible and irreversible impression materials differ?
Reversible (thermoplastic) - Reusable and set by termperature change<div>Irreversible (thermoset) - Not reusable and set by chemical reactions</div>
What some reversible rigid and flexible impression materials?
Rigid - Compound, Adaptol, Wax<div>Flexible - Agar</div>
What are some irreversible rigid and flexible impression materials?
Rigid - Plaster, ZOE<div>Flexible - Alginate, Synthetic rubbers</div>
What are uses of compound and adaptol?
Preliminary edentulous ridge impressions<div>Border molding tray for denture impressions</div>
What are the uses zinc oxide eugenol as an impression material?
Secondary wash impression for edentulous ridges<div>Interocclusal bite registration</div>
What materials can be used for interocclusal bite registration?
Wax<div>ZOE</div><div>Plaster</div><div>Hard setting PVS</div>
What impression materials can be used for occlusal registration for articulator bite fork?
Wax<div>Compound</div><div>Hard-setting PVS</div>
What are the uses of impression plaster?
It used to be used for denture impressions<div>Can currently be used as bite registration material</div>
What are the constituents of impression plaster?
Calcium sulfate hemihydrate<div>Potassium sulfate (accelerator)</div><div>Borax (retarder)</div><div>Starches (weakens material for separation)</div><div>Coloring agents</div>
T or F: &nbsp;Impression plaster has a short working and setting time?
True, this is to facilitate intraoral use
What is an example of a separating media and why is it used?
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>
What are some characteristics of dental compound?
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>
What are the constituents of dental compound?
Rosin<div>Copal resin</div><div>Carnauba wax</div><div>Stearic acid</div><div>Talc (most abundant ingredient)</div><div>Coloring agent</div>
What are 3 impression materials used for border molding impression trays?
Dental compound<div>Adaptol</div><div>Iso Functional</div>
What is a disadvantage to using dental compound for border molding?
The viscosity of compound will displace soft tissue to create an over-extended impression.
What is the difference in physical properties of adaptol and dental compound?
Adaptol is stickier once heated, and less rigid than compound once cooled
Zinc oxide eugenol comes in 2 tubes, what is in each tube?
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>
How can you shorten the setting time of ZOE?
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.
What are some advantages of ZOE impression paste?
Accurate mucostatic (doesn't displace tissue) impression material (low viscosity)<div>Good dimensional stability - &lt;0.1%</div><div>Inexpensive</div>
What are some disadvantages of ZOE impression paste?
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>
What is a colloid?
A substance consisting of 2 phases<div>A type of mixture intermediate between a homogeneous solution and a heterogeneous mixture</div>
What are dental impression colloids made from?
Large molecules derived from seaweed dispersed in water.<div>These are known as hydrocolloids</div>
What are the terms for a colloid material with a gas dispersion medium with a gas, liquid, or solid dispersed phase?
Gas - no term, all soluble together<div>Liquid - Liquid aerosol (fog, mist)</div><div>Solid - Solid aerosol (smoke, dust)</div>
What are the terms for a colloid material with a liquid dispersion medium with a gas, liquid, or solid dispersed phase?
Gas - Foam (shaving cream)<div>Liquid - Emulsion (milk, mayo)</div><div>Solid - Sol (Paint)</div>
What are the terms for a colloid material with a solid dispersion medium with a gas, liquid, or solid dispersed phase?
Gas - Solid foam (styrofoam)<div>Liquid - Gel (Jelly, cheese)</div><div>Solid - Solid Sol (Cranberry glass)</div>
What category of colloids do dental impression materials fall into?
Sol<div>Gel</div>
How do hydrocolloids behave in the sol and the gel state?
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>
How does evaporation effect hydrocolloid impression materials?
Hydrocolloid gels are mostly water and will lose water in an unsaturated atmosphere resulting in shrinkage and distortion of the impression.
What percent of hydrocolloid gels are made up by water?
66-85%
What is syneresis?
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>
What is imbibition?
Taking up of a liquid by a gel resulting in swelling.
What is reversible hydrocolloid also known as?
Agar
What are some characteristics of Agar?
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>
What is the composition of agar?
A long chain polysaccharide with a molecular weight of 150,000
What are the constituents of agar impression materials?
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>
Describe the process of using agar as an impression material from purchase to use on the patient?
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>
What causes the setting reaction of Agar?
Reducing the temperature
What is the liquefaction temperature and gelation temperature of agar?
100 C = liquefaction<div>37- 40 C = Gelation temp.</div>
What are the advantages of reversible hydrocolloid (agar)?
High flexibility - easy to remove from mouth<div>Good wettability and flow</div><div>Inexpensive materials after initial cost of water bath.</div>
What are some disadvantages of reversible hydrocolloid?
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>
What are some characteristics of alginate?
Thermosetting<div>Hydrophilic</div><div>Elastic</div><div>Most used impression material</div>
What are some reasons alginate impressions are used?
Study models<div>Casts for opposing occlusion</div><div>Removable partial dentures</div>
What is the composition of alginate powder?
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>
What is the role of sodium alginate in alginate powder?
Gelling agent
What is the role of calcium sulfate dihydrate in alginate powder?
Reactant
What is the role of sodium phosphate in alginate?
Retarder
What is the role of silicate powder in alginate?
Filler
What are the 2 steps in the setting reaction of alginate?
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 ---&gt; 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 ----&gt; Na2SO4 + Ca-Alg2</div>
Describe the setting of alginate?
Setting occurs when the calcium provides cross-linkage from one long alginate molecule (fibril) to another, restricting movement.
In lecture agar and alginate are compared to the setting of 2 foods, which foods are they?
Agar - Like the setting of Jell-O<div>Alginate - Like the setting of instant pudding</div>
What is the typical alginate set time?
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>
What are 2 ways to lenghten the setting time of alginate? Which is the preferred method?
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>
What is the correct proportion of water for 15 grams of alginate powder?
40 mL to 15 grams
How long should alginate be held in place in the mouth to set?
3 minutes - this will enhance the strength.
Why should alginate be removed with a quick snap?
To reduce distortion and tearing.<div>Tear strength is greater with rapid loading.</div>
Which type of alginate has the best tear strength? worst?
Identic has the highest tear strength<div>Supergel has the lowest tear strength</div>
Which type of alginate has the highest strain percentage (higher = more flexible)? Lowest?
COE Alginate = most flexible<div>Triphasix = Least flexible</div>
Which type of alginate has the best wettability? Worst?
Jeltrate - best wettability<div>Identic - worst wettability</div>
Most alginate brands have a recovery from deformation percentage of what?
96-98%
What is thought to be the reason for compatibility of gypsum products with alginate?
Amount of sodium phosphate/sulfate (retarder) in the alginate
What is discide ultra?
A quarternary ammonium disinfectant.
What are some advantages of alginate?
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>
What are some disadvantages to alginate?
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>
What is the likely reason for an alginate mix with a grainy appearance?
Improper mixing<div>Prolonged mixing</div><div>Excessive gelation</div><div>Water/powder ratio too low</div>
What are some likely reasons for tearing of alginate?
Inadequate bulk<div>Moisture contamination</div><div>Premature removal from mouth</div><div>Prolonged mixing</div>
What are some reasons an alginate impression may have external bubbles?
Undue gelation preventing flow<div>Air incorporated during mixing</div>
What are some reasons for irregularly shaped voids on an alginate impression?
Moisture or debris on tissue
What are some reasons for a rough or chalky stone model?
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>
What are some reasons for distortion of an alginate impression?
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>
What are 3 types of non-aqueous impression materials?
Polysulfide<div>Silicone (Condensation, Addition)</div><div>Polyether</div>
What are some characteristics of elastomeric non-aqueous impression materials?
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>
What are the setting mechanisms of synthetic rubbers?
Chain lengthening<div>Crosslinking&nbsp;</div><div>Continued polymerization</div>
Describe the condensation method of polymerization?
Two molecules unite forming a larger molecule and a small molecule is released as a by-product.
How do by-products effect stability of a condensation material?
The material is less stable because the reaction includes the formation of a by-product
What are 2 examples of materials that undergo condensation reactions?
Polysulfide rubber<div>Condensation reaction silicone</div>
Describe the addition reaction of polymerization?
The joining of 2 molecules to form a larger molecule. &nbsp;No by-products are formed so it is more stable.
What are 2 examples of addition reaction materials?
Polyether<div>Addition reaction silicone</div>
What is accuracy of an impression dependent on?
Amount of elastic recovery and polymerization shrinkage
Polymerization shrinkage causes the model of the teeth to be larger or smaller than the actual tooth?
Larger - The model ends up larger than the original because shrinkage of the impression material occurs toward the tray, or away from the tooth.
Which materials have the highest percentage of shrinkage after 24 hours?
Polysulfide (0.7%)<div>Condensation silicone (0.5%)</div>
What is the polymerization shrinkage of polyether and addition silicone after 24 hours?
Polyether - 0.1%<div>Addition silicone - 0.04%</div>
How can you reduce shrinkage of acrylic used in making a custom tray?
Reduce the thickness of impression material
What are the distinct advantages to low viscosity and high viscosity non-aqueous elastomeric materials?
Low viscosity flows well and captures detail<div>High viscosity has more filler and less polymeric material, which reduces shrinkage.</div>
Why is timing of light-body and heavy-body mixing and insertion critical in a dual mix - single impression technique?
The different viscosities do not always bond together well
T or F: &nbsp;The direction of tray seating may affect the flow of heavy body material in a dual mix-single impression technique?
True
What are some causes of lack of flow of impression material?
Contour of teeth<div>Directionof seating tray</div><div>Viscosity of impression material</div>
Describe a dual mix - two impressions technique?
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>
What are the advantages of the monophase-regular bodied impression technique?
Quick<div>No delamination problems</div>
What are the viscosities of non-aqueous elastomeric impression materials and their uses?
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>
What are 3 ways in which non-aqueous elastic impression materials are mixed?
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>
When you are mixing impression materials with an automix gun, why should you extrude a small amount out first?
To make sure flow is even&nbsp;
What do you do if impression material does not polymerize?
Place cartridge in sterilization bag and mark on the bag that it did not set and turn it into the dispensary. &nbsp;The manufacturer will replace the cartridge.
T or F: &nbsp;Addition silicone is pseudoplastic and thins during expression through a baffled tip?
True
What is the recommended use for closed-mouth impressions (e.g. triple tray)?
Single crowns or 2 single crowns in quadrant with a terminal natural tooth in occlusion
Why is high tear strength so important when taking impressions for a crown or other fixed prosthesis?
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>
What are some causes of distortion?
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>
What are some reasons an impression distorts upon removal from the mouth?
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>
How does bulk of material in the tray help prevent distortion from an undercut?
If there is enough thickness, the strain can be minimized because there is &nbsp;support of the material in the area deflected.
What is in the base pase of polysulfide rubber?
Polysulfide polymer<div>Filler (titanium dioxide)</div>
What is in the accelerator paste of polysulfide rubber?
Lead dioxide (catalyst)<div>Non-reactive oils</div><div>Sulfur</div>
What is the setting mechanism of polysulfide rubber?
Lead oxide causes condensation of the terminal and pendant SH groups on the polysulfide molecule.
What are the by-products of the setting of polysulfide rubber?
Water and lead by-products
What are the advantages of polysulfide?
High flexibility - easy to remove<div>High tear resistance</div><div>Good flow</div><div>Low cost</div>
What are the disadvantages of polysulfide?
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>
What is in the base paste of condensation silicone?
Polymer - hydroxy terminated poly(dimethyl siloxane)<div>Crosslinker - orthoalkylsilicate</div><div>Filler 30-40% for paste; 75% for putty</div>
What is in the catalyst paste of condensation silicone?
Catalyst - metal organic ester, tin octoate<div>Carrier - oily dilutent</div>
Describe the setting reaction of condensation silicone?
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>
What are the advantages of condensation silicone?
Pleasant taste and odor<div>Relatively clean</div><div>Relatively inexpensive</div>
What are the disadvantages of condensation silicone?
Only fair stability<div>Medium tear resistance</div><div>Least wettable of the synthetic impression materials</div>
What is in the base paste of polyether?
Prepolymer-low molecular weight polyether with ethylene-imine terminal groups<div>Filler</div>
What is in the accelerator paste of polyether?
Catalyst- aromatic sulfonic acid ester<div>Fillers and plasticizer</div>
Describe the setting reaction of polyether?
Aromatic sulfonic acid ester catalyzes the pre-polymers<div>Addition polymerization through ring opening of ethylene-imine group and chain extension</div>
What are the advantages of polyether?
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>
What are the disadvantages of polyether?
Cost ($124/200 ml cartridges)&nbsp;<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>
What is the composition of addition silicone?
Prepolymer - vinyl terminated siloxane<div>Prepolymer - siloxane with hydrogen side groups</div><div>Catalyst - Chloroplatinic acid</div>
Why were surfactants added to PVS?
Increase wettability<div>Yields fewer bubbles</div>
Describe the reaction of PVS materials?
H2PtCl6 catalyses the reaction<div>Propagation occurs as the vinyl groups reacts with the hydrogen side groups.</div>
What is the setting time of PVS?
3 to 7 minutes.<div>Setting time may be delayed by refrigeration</div>
Why do some manufacturer's add Pt and Pd to PVS?
To scavenge hydrogen so that it doesn't cause bubbles. &nbsp;Materials without these metals should not be poured up until 1 to 2 hours has passed to allow the hydrogen to dissipate
Why should you not use latex gloves with PVS?
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>
What effect can PVS and sulfur from hemostatic agents have on ceramic crowns?
It may cause gray staining through all ceramic crowns at the gingival 1/3
What are some hemostatic agents used at UNLV?
Viscostat clear - Aluminum chloride<div>Viscostat Brown - Ferric sulfate (more effective)</div><div>Also consider injecting anesthetic (w/epi) in papilla for hemostasis.</div>
What are the advantages of addition silicone?
Excellent stability and accuracy<div>Clean and easy to use</div><div>Neutral taste and odor</div>
What are some disadvantages of addition reaction silicone?
Medium resistance to tear<div>Posssible hydrogen release</div><div>Cost</div><div><br /></div>
Which non-aqueous elastic material releases gas?
PVS
Which non-aqueous elastic impression materials can produce multiple casts per impression?
Polyether<div>Addition silicone</div>
What are some ways to deal with anatomical undercuts on the patient when taking an impression?
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>
What are some strategies to avoid breakage of stone when separating stone from the impression?
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>
What is alginot?
A polyvinyl siloxane impression material used as an alginate substitute.<div>Not for use on crown and bridge impressions</div>
What is an advantage to alginot?
Can pour multiple casts<div>Not super expensive</div>
What is blu-mousse commonly used for?
Bite registration<div>It is a PVS material</div>
What are some criteria for bite registration materials?
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>
What are some characteristics of blu-mousse?
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>
What is fit checker used for?
Check for areas inside restorations that interfere with complete seating.<div><br /></div>
What material is fit checker made out of?
White and black are condensation silicone<div>II NDS is addition silicone</div>
How do you use fit checker?
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>
What is Comprecap used for?
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>
What is the advantage to the BFC "transfer" syringe for impression materials?
Intraorally, smaller and easier to manipulate than a large dual cartridge gun.
Which light body PVS material has the highest tear strength?
Aquasil
What does a higher strain in compression value of an impression material mean?
It is more flexible.
Which light bodied PVS impression material is the most flexible?
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. &nbsp;<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: &nbsp;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) &nbsp;</div>
How does the photopolymerization of composite work?
Light reacts with Camphorquinone and the Amine&nbsp;<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: &nbsp;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, &nbsp;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&nbsp;<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: &nbsp;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 &nbsp;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: &nbsp;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.&nbsp;</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: &nbsp;The higher the modulus of elasticity (stiffness) of RBC, the higher the stress during polymerization?
True, this is C-factor dependent. &nbsp;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: &nbsp;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. &nbsp;
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&nbsp;</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: &nbsp;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&amp;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 -&nbsp;</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: &nbsp;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: &nbsp;Air polishing with bicarbonate soda benefits retention of sealant?
Both T and F: &nbsp;In vitro studies sho benefit. &nbsp;In vivo study showed no difference in retention rate.
Which isolation technique is better for sealants, rubber dam or cotton rolls?
They both have comparable sealant retention rates.
What are the differences in gel and liquid etchant? Which is better for sealants?
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>
How is gel etchant applied? Liquid?
Gel - syringe<div>Liquid - Brush, Cotton or foam pellet</div>
Where should etchant be applied when doing sealants?
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>
Why would you agitate the etchant after placement?
It is thought to expose new acid to the surface of the tooth.
How are sealants retained?
Resin flows into depressions caused by etching, forming resin tags
How long should etchant be left on tooth when doing a sealant?
15-20 seconds.
Why must you dry the tooth prior to placing sealant?
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>
How does a dried etched tooth look?
Chalky and frosted appearance
T or F: &nbsp;Salivary contamination during or after etching may have an adverse effect on sealant bond to enamel?
True, if contamination occurs, rinse, dry and re-etch
What is an optional step in placing a sealant?
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>
What are some instruments used for applying sealant?
Dispensers<div>Brushes</div><div>Metal instruments</div>
What is the application technique for sealants?
Apply only in the depths of the pits and grooves.<div>Do not extend beyond the etched area.</div>
How can you remove bubbles in sealant material prior to curing?
With an explorer. &nbsp;If you don't remove bubbles, the defect will concentrate stress during function and likely fracture.
What is the curing technique for light cured sealants?
20 second light cure<div>Tip within 2mm of tooth</div><div>11-13 mm diameter curing tip</div><div><br /></div>
How many teeth can be sealed with on drop of Universan and Catalyst do?
2-3 teeth.
When using chemically activated sealant, how long do you leave sealant on before checking it?
2 min. - you can check set of residual sealant in well to check if it is done.
What are the criteria for visual and tactile inspection of sealant?
Coverage of pits and fissures<div>Absence of voids</div><div>Fused interproximal areas</div><div>Occlusion</div>
T or F: When using Embrace, you should leave the tooth slightly wet prior to placing sealant.
True
What are some techniques to correct defects in sealants?
Small voids can be repaired by adding new material<div>Remove sealant in interproximal space with a scaler</div>
What percent of sealants need to be repaired or replaced each year?
5-10%
What is the success rate of sealants with routine recall and replacement?
80-90% success rate for 10 years or more.
Why would you seal incipient lesions?
Sealing incipient lesions will prevent progression as long as the seal remains in tact.
What is a PRR?
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
What is the UNLV fee of sealant vs. prr?
Sealant - $15<div>PRR - $50</div>
What is the difference in a PRR and a class I restoration?
Class I is used to restore a carious lesion into dentin. &nbsp;It is not a preventative procedure
What have studies shown about retention fo sealants in buccal and lingual pits?
There is no difference in retention between buccal/lingual and occlusal sealants if dentin primer and adhesive is used.
T or F: No anticaries benefit has been shown with resin sealants containing fluoride?
True
What was found in a study about using self-etching primer and adhesive with sealants?
Less retention than the standard. &nbsp;It is not recommended.
What is tooth pain form dentin/cementum sensitivity commonly due to?
&nbsp;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>
How is gingival pain distinguished from dentin/cementum sensitivity?
Redness, bleeding and swelling present with gingival pain
How is a toothache distinquished from dentin/cementum sensitivity?
Spontaneous, constant pain occuring without stimulus describes a toothache.
What is the prevalence of hypersensitive dentin/cementum?
Clinical occurrence of 8.9-14.5% depending on age/sex make-up of group studied and stimuli used.
What is the proposed etiology of dentin/cementum sensitivity?
Hydrodynamic theory of pain<div>Bacteria and pulpal inflammation</div>
What is the hydrodynamic theory of dental pain?
Temperature, osmosis, dryness, and tactile sensation induce fluid flow in dentinal tubules and stimulate nerve fibers.
What may be the causes of pulpal inflammation?
Open tubules and bacteria<div>Traumatic occlusion</div><div>Abrasion/erosion</div>
What is the cause of hypersensitive dentin?
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>
Which surface is most commonly affected by non-carious cervical lesions?
Buccal surfaces of posterior are most common.<div>These are often associated with hypersensitivity</div>
What are some additional causes of dentin/cementum hypersensitivity?
Post-op sensitivity<div>Tartar control toothpastes (pyrophosphates)</div>
What are the primary rationales for treating hypersensitive dentin?
Sealing dentinal tubules<div>Reduction/elimination of inflammation</div><div>Alter neural pain transmission</div>
What are some treatment approaches to dentin hypersensitivity?
Occlusal treatment - adjustment or nightguard - reduce hyperemia and periodontal inflammation<div>Toothpastes - Potassium nitrate &nbsp;- 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 - &nbsp;blocks tubules</div>
Other than toothpaste, what is another way potassium nitrate may be used to control dentin sensitivity?
Using potassium nitrate gel in a bleaching tray.
Why should prescription fluoride toothpastes to limit dentin sensitivity not be used by children under 6?
To prevent dental fluorosis
What are some anti-inflammatory agents used to inhibit dentin sensitivity?
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>
How does ionophoresis work?
Electircal current may enhance ion uptake by dentinal tubules - used with fluoride solution
T or F: &nbsp;Treatment for dentin hypersensitivity may be transient?
True, long-term treatment demands attention to causative factors. e.g. occlusion, oral hygiene, toothbrushing technique, choice of toothpaste, diet, habits