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63 Cards in this Set
- Front
- Back
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how does the adhesive prep. for a class 2 resin composite differ from black's traditional amalgam design
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1. prep is shallower. this is b/c the retention is probided through bonding to tooth structure raterh than mechanical undercuts
2. narrower outline form: allows less occlusal contact and reduces wear 3. rounded internal angles: this conserves tooth structure, dec. stress 4. No extension for prevetion used: occlusal fissures are included only if carious tooth structure dictates |
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what are 2 properities of resin composites that allow less sensitivity than amalgam
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1. low thermal conductiviy: b/c they do not readily transmit temp. changes, and there is an insulating effect
2. elimination of galvanic currents: resin composite does not contain metal so it will not initiate or conduct galvanic currents |
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radiopaque restorative materials are necessary to allow the dentist to distinguish restorationfrom caries, from sound tooth structure. What is the requirement by ADA to be claimed as radiopaque
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material has a radiopacity greater than that of an equal thickness of aluminum which has a radiopacity approx. = to dentin
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how has amalgam become less attractive to dental professionals
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govt. agencies consider classifying it as hazardous waste = offices need to install expensive systems to remove mercury from wastewater
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what are some of the causes of post-op sensitivity
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1. polymerization shrinkage: this shrinkage results in formation of a gap
2. gap allows bacterial penetration and fluid flow within it. the bacteria or the noxious prods. may enter dentinal tubules and cause pulpal inflammation and tooth sens. OR the outflow of dentinal fluid through gap is interpreted as pain by the pulp 3. cuspal deformation from the contraction forces of shrinkage result is cracking 4. flexure of resin composite under an occlusal load may be transmitted to odontoblastic processes |
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what is the correlation btw. patients who experience postop. pain and success of restoration
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those who experience post-op sensitivity w/in one month are 2X's more likely to habe that restoration fail within 5 yrs.
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it has been shown that the marginal gap formed at the gingival margin as a result of polymerization shrinkage allows the ingress of cariogenic bacteria. why is this
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levels of S. mutans are significantly higher in the plaque adj. to prox. surfaces of posterior resin restoration than either amalgam or glass ionomer
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true or false less secondary caries occurred in all classe of amalgam restoration combined than in resin composite restorations
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true!
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I am one of the types of wear that resin composites undergoes. I am generalized wear that occurs across the entire occlusal surface of the composite as a result of the abrasive action of particles during mastication
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abrasion
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I am a type of wear that resin composite undergoes. I am the result of direct contact with opposint tooth surfaces in the occlusal contact areas of the restoration
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attrition
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what type of filled composites are more subect to attrition
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microfilled are more subject to attrition while more heavily filled hybrid resin composites are more resistant
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what type of resin composites have a significantly higher abraion wear
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larger mean particle size. this is due to the loss of the larger filler particles
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what are some clinically relevant wear factors
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1. the size of the restoration: as the SA and length of cavosurface margins inc. so does the exposre to occlusal forces = inc. wear
2. location of restoration in the arch: th more posterior a tooth the greater the masticatory forces = more rapid wear 3. the occlusal load it must withstand: proximal surfaces are subjected to forces of abrasion during fxn as well due to indiv. tooth movement 4. how well the resin composite is cured |
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true or false? there are some resin composites tha have been shown to exhibit less wear than amalgam
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FALSE!
some studies indicate that resin has acceptable wear for up to 17yrs. while other report significantly higher wear rates than amalgam |
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gen. the more closely the mechanical prop. of a restorative material simulate those of enamel and dentin the better the restoration's longevity. In what aspects do resin NOT compare to tooth structure
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1. low fracture toughness: in comparison to metallic restorative material
2. high deg. of elastic deformation: 6-8 X's that of amalgam. this is assoc. with high bulk fracture, microcrack foramtionand low resistance to occlusal loading 3. coefficient of thermal expansion: it is higher than that of tooth structure = expands and contracts more than enamel and dentin when exposed to variations in temp. |
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how does water sorption effect the performance of resin composits
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water is absorbed into the resin component of resin composite materials and water content is inc.
-due to the swelling of the resin matrix from water sorption the filler particle bone to resin is weakened |
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what is hydrolytic breakdown
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is when resin water sorption occurs. water is absorbed into the resin. due to swelling the filler particle boned to resin is weakened. If the stress is greater than the bond strength the resulting debond = hydrolytic breakdown
* incompletely cured resin composite will exhibit more water sorption and greater hydrolytic degradation |
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how does the amount of cross-linking in polymerization (deg. of conversion) relate to mechanical properties and wear
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As the amt deg. of conversion or polymerization increases the mechanical properties improve.
-with reduced polymerization there is significant inc. in wear **But polymerization shirnkage also inc. with more crosslinking |
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does resin compostie restoration placed in coolusal surfaces of molars fare worse or better than pre-molars
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worse.
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do resin composite fare better in class 1 or class 2 restorations
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Class 1 restorations fare better (pit and fissure)
remember class 2 are proximals of posteriors |
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do resin composite restorations fare better or worse under high masticatory forces
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under high masticatory forces resin fares worse than those under lesser forces
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true or false? large restorations fare better than small to moderate sized restorations
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false large restorations fare worse than smaller sized restoratinos.
-thus limiting the size of the outline form and ensuring that the occlusal load are absorbed by the tooth structure are important |
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what type of technique would be best to use with margins in thin enamel near the cementoenamel junction or on cementurm or dentin
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open sandwich technique: provides significant protection of the toothe structure neear the gingival margin against deminerlaization
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what is PARQ
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Procedures, Alternatives, Risks, Questions
informed consent -100% of patients wanted the dentist to tell them about all aspects of alternative restoative materials -75% of patients preferred a written explanation rather than simply an oral explanation -82% of patients would NOT choos a posterior resin composite restoration to replace an amalgam restoration |
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what is the primary advantage of autocure vs. light cured resin composites
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primary advantage is that it can be placed in bulk, saving tiem
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although VLC composites are more time consuming what are the advantages of its uses over autocured resin composites
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VLC's achieve:
-more complete polymerization resulting in superior mechanical properties and they exhibit better color stability -autocured incorporate voids as a result of mixing 2 paste systems and inc. porosity dec. tensile strength and smoothness * mixing also interrupts the polymerization process |
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at what rate do sealants tend to fail
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at a rate of 5-10 % per year
this is significant b/c the caries rate for teeth in which sealants are partially or totally lost inc. significantly - the key to sealan success in preventing caries is total retention of the sealant |
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true or false? sealants placed on mandiublar teeth show higher retention rates than maxillay teeth; premolars show higher retention than molars
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TRUE
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How do bonding agents help to improve sealant retention
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bonding agents used prior to sealant placement helps to wet fissures, improves sealant penetration into fissures, inc. bond strength, improve sealant adhesion to saliva contaminated enamle = improved retention
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how does the slight mechanical prep. of fissures with a sm. bur or air abraison enhance sealant penetration and attachment
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dec. bubble formation, improves marginal adaptation, dec. marginal leakage,
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how do RMGI sealants compare to resin sealants
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they have poor mechanical retention compared to resin sealants
but flowable resin composite materials have been shown to perform well as fissure sealants |
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what is PRR
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preventive resin restoration: restoration that max. the benefits of conservative adhesive dientistry. It limits prep. to pits and fissures that are carious. once the lesion is eliminated no further prep. is performed
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true or false if you place a PRR and leave some carious lesions by accident you will follow up to find a giant cavitated lesiont
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false! If caries lesion is inadvertently allowed to remain in or at the base of sealed fissure it will NOT progress b/c the seal prevents nutrients from supplying cariogenic bacteria
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in facial and lingual proximal margins why is it necessary for the cavity prep. to form an obtuse angle with the external tooth surface
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b/c the enamel rods exit the tooth at approx. rt. angles to the external tooth surface it is necessary for the cavity prep. to form obtuse angle to expose the ens of the enamel rods
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true or false? the gingival margin should ALWAYS be beveled
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FALSE!
should be beveled only iof the margin is in enamel well away from the cementoenamel junction and an adequate band of enamel remains. -when the prep. approaches within approx 1mm of the cementoenamel junction why? b/s as it nears the junction the enamel layer is thinner than in other regions of the crown and beveling the prep. inc. the potential for removing the little enamel that remains |
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True or false: avoidance of bevels on the occlusal surface prevents the loss of sound tooth structure, dec. the SA of the final restoration, lessens the chance of occlusal contact on the restoration
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true!
placement of occlusal bevels has demonstrated no benefit to the longevity of class 2 resin composit restorations |
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what types of cases indicate the use of a calcium hydroxide liner
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it should be limited to those areas of the prep. that are believed to be very close to the pulp or when there is minute pulpal exposure
- placement of calcium hydroxinde liner over an extensive area of dentin provides no benefit to the pulp and dec. the SA of dentin available for adhesion. Also dissolution of the liner during acid etching can interfere with a sound bond to enamel and dentin |
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what are the advantages of using a glass-ionomer liner under posterior resin composite restorations
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glass ionomer materials bond to both tooth struct. and overlying resin composite.
-they introduce less polymerizationstress into tooth structure than resin composite -releases fluroide into adj. tooth structure may dec. secondary caries - dec. marginal leakage and improves marginal integrity |
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what are 2 advantages of the glass ionomer liner that should encourage a clinician to consider the use of a glass ionomer liner even if an adequate band of enamel surrounds the entire prep
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glass ionomer liner on dentin cavity surfaces has been shown to sign. reduce postoperative sensitivity compared to the use of dentin adhesive alone and
glass ionomer liners can reinforce the prep. walls by adhering to dentin and minimizing cuspal deformation und load. glass ionomers also reduce the rise in pulpal temp. associated with curingin increments |
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If the gingibal margin of a class 2 prep is in enamel but w/in 1mm of the cementoenamel junction or if it is in dentin an alternative restorative material cannot be used. What must be used
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an RMGI in a open sandwich/bonded bases technique due to reduced marginal leakage, good antibacterial activity the reduced post operative sensitivity and reduce in vivo demineralization adj. to gingival margin
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when using an RMGI due to your prep's gingival margin of the proximal box extending below the cementoenamel junction onto dentin. What level should your RMGI stick to
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the RMGI should remain apical to the proximal contact
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why is it important that the layers of adhesive resin are not too thick
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layers of adhesive resin that are 42 micrometers thick or greater can be detected on bite wing radiographs and might be mistaken for a marginal defect or caries lesions
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what are the benefits and downfalls of a clear matrix
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advantage: allows penetration of the curing light from multiple directions. allowing curing from proximal and gingiva directions rather than from the occlusal only
* it also allow form more favorable direction of the polymerization shrinkage downfall: thicker than the thinnest metal matrices and its lack of rigidity makes placement through tight interprox. contacts difficult |
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what are the benefits of the ring system
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-provide wedging to ensure good interproximal contact,
-better proximal contours -simplify matrix placement for a single proximal surface |
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why is the placement of the first increment in resin composites so critical
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b/c of the tendency for microleakage to occr in the gingival margin
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true or false all increments should be no thicker than 2.0mm
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False!
the first incremental lalyer should be no thicker than 1 mm placed against the gingival wall. a thin first layer will ensure proper light irradiation throughout the increment |
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thicker consistency resin composites have significantly inc. cavity wall voids compared to med. or thinner viscosity materials BUT flowable resin composites have up to 3X's greater polymerization shrinkage. what can you do to alter thicker composites or apply flowable resin
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- to enhance the flow of thick resin composite into a cavity prep. you can warm it prior to injection
-flowable resin hold promis when applied in a snowplow technique: initial thin increment of flowable composite is placed over gingival and/or pulpal floors. then an initial increment of heavily filled restorative resin composite is syringed or pushed into the unset flowable resin coposite * in this technique most of the flowable resin is displaced by the restorative composite and is removed. = diadv. chara. removed |
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what technique can be used as an alternative to layering techniques
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conical light curing tip; wedged into resin composite. used to apply press. to matrix band and push against adj. tooth
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what type of instrument do you wan to use to add your final increment
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a rounded, cone-shaped instrument, slightly moistened with resin adhesive or a low visco. resin sp. designed to prevent sticking of resin compostie to the instrument before curing
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what is the successive cusp build up technique
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method for replacing occlusal anatomy: stop placing oblique layer at a point juged to be the base of the pit and fissure anatomy for the final restoration
-the final increments of resin composite are positioned and adapted to replace the missing portions of inner inclines of the cusps one cusp at a time |
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name some other polymerization techniques
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-argon laser units:
- plasma arc curing (PAC) units: generate notably higher irradiance levels than do standard halogen units. purpose for inc. intensity is to inc. the resin composite polymeriazation rate. but the inc. rate of cure doesNOT enhance adhesion of resin composite to cavity walls and inc. microleakage with poorer margina adaptation -LED curing units |
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what are the advantages and disadvantages of LED curing lights the most recently dev. alternative polymerization techniques
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LED curing units: wavelength is closely matche to caphorquinone. more energy efficient and a lifespan approx. 1000 times longer than the typical halogen bulb
disadv:narrow wavelength limiting their usefulness in curing any materials that do not use camphorquinone as the photoinitiator |
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true or false the term condensabe is appropriate for packable resin composites b/c by definiton it denotes an inc. in density as occurs when dental amalgam is condensed inot a cavity prep
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False! such a volume reduction does not occur with resin composites when they are pushed into a prep.
-packable resin composites used to inc. viscosity and impart a consistency that more closely mimics dental amalgam |
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what type of instrument do you wan to use to add your final increment
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a rounded, cone-shaped instrument, slightly moistened with resin adhesive or a low visco. resin sp. designed to prevent sticking of resin compostie to the instrument before curing
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what is the successive cusp build up technique
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method for replacing occlusal anatomy: stop placing oblique layer at a point juged to be the base of the pit and fissure anatomy for the final restoration
-the final increments of resin composite are positioned and adapted to replace the missing portions of inner inclines of the cusps one cusp at a time |
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name some other polymerization techniques
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-argon laser units:
- plasma arc curing (PAC) units: generate notably higher irradiance levels than do standard halogen units. purpose for inc. intensity is to inc. the resin composite polymeriazation rate. but the inc. rate of cure doesNOT enhance adhesion of resin composite to cavity walls and inc. microleakage with poorer margina adaptation -LED curing units |
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what are the advantages and disadvantages of LED curing lights the most recently dev. alternative polymerization techniques
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LED curing units: wavelength is closely matche to caphorquinone. more energy efficient and a lifespan approx. 1000 times longer than the typical halogen bulb
disadv:narrow wavelength limiting their usefulness in curing any materials that do not use camphorquinone as the photoinitiator |
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true or false the term condensabe is appropriate for packable resin composites b/c by definiton it denotes an inc. in density as occurs when dental amalgam is condensed inot a cavity prep
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False! such a volume reduction does not occur with resin composites when they are pushed into a prep.
-packable resin composites used to inc. viscosity and impart a consistency that more closely mimics dental amalgam |
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true or false? the best method for finishing is to minimize the need for finishing and polishing
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true: finishing and polishing procedrues are inherently destructive to the restoration surface and may result in the formation of microcracks at and bleow the surface
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true or false? finishing of resin composite earlier as compared to later does not matter
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false: delaying finishing for 10-15 mins. will allow approx. 70% of max. polymerization to occur during "dark curing" early finishing has been shown to sign. inc. microleakage
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what types of disks when used from coarse to very fine render some of the smoothest finishes to resin composites
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aluminum oxide disks on lingual and proximal embrasures = flat or convex contours
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true or false: abrasive disks are perfect for finishing occlusal surfaces
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false: carbide finishing burs perform or diamond burs. best results with rubber or silicne disks, points, cusps, and brushes with aluminum oxide, silicon dioxide, or diamond particles work well.
Do not finish with burs with 18 or fewer flutes = rough surface |
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why is rebonding of the final cure recommended
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b/c finishing procedrues are dstructive to resin composite. rebonding application of a low viscosity resin to the finished surface and margins of a restoration improves marinal integrity, reduces microleakage, and stainign
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