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56 Cards in this Set
- Front
- Back
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Class 3 composites?
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Smooth surface caries on the proximal surface.
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Composite resin (resin- based composites)
curing and polymerization |
composite - polymerization. setting reaction for composite resin.
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What are 2 ways to start polymerization?
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auto curing/chemically curing
- composite requires 2 things to be mixed together -then you have limited working time before it sets. -like amalgam, you have enough working time to place it, then you wait for it to get hard. - has a manufacturer determined wait time but today most use light or photo curing- when you want it to cure, you use a curing light. surface will set pretty quickly but deeper than that usually takes a little longer. Dual curing - both chemical and light curing. |
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Micromechanical adhesion
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what makes composite radically diferent than amalgam.
composite will stick to tooth structure unlike amalgam which only requires mechanical adhesion. |
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Before 1970?
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Restorative dentistry was revolutionized with composites.
earliest composites - not as good as what's out there today. -tehy were NOT adhesively bounded. they were just like amalgam, and waited for it to set. shapeed with diamonds and burrs. -earliest composities were unbonded. |
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What did michael bonaour do?
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used the components of adhesion in industry to dental use. Earlier than that, the composites were only enamel bonded (no dentin).
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When was light curing introduced?
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short while after enamel bonding.
nuva light / nuva system: used UV light. light source was very expensive. beginning of a revolution in dentistry. Replaced by much safer, blue light. Blue light cures composite. |
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What happened after light curing was introduced?
What will happen to composites over the next 10 years? |
Came up with dentin and enamel bonding. Enamel bonding - 1980s.
Since then, things are getting better. composite will continue to et better over the next 10 years. Amalgam - will not. |
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What happens during polymerization?
What is the 'brown line'? |
Mass shrinks a little bit. Contraction gap - occurs at the margins when composite shrinks.
Very early composites had brown lines before there was effective enamel bonding. |
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What types of particles were the oldest composites made of? What was the method of curing?
What was a problem with autopolymeriation? |
larger macrofil particles.
autopolymerzing. No shade selection, only universal shade. -chemically polymerized. Several minutes working time. Autopolymerized resin turned darker color = amine discoloration. Light curing does not go through amine discoloration. |
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The technique for composite - first step?
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1. shade selection - use the shade guide and individual things are shade tabs.
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When to select the shade?
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At teh beginning of the appointment. Dehydrated tooth can be several shades lighter than a hydrated tooth.
Crtical that you select shade at right time. To rehydrate teeth, it takes several hours. |
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What is an important factor in how the color of the shade appears?
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The right light - or light source.
Metamerism: color is interpreted based on the light rays that are hitting it. |
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What should light source should you used in shade selection?
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full spectrum light bulb.
Sunlight may be good but impractical. |
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Isolation..why eight holes?
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You can much better isolation if you go to at least 1 posterior tooth. Don't need to use a rubber dam clamp, you can simply use 2 wedgets.
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shade selection….
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beginning of appointment
full spectrum light arm’s length good eyes (color acuity) use a good shade guide shade AND opacity multi-shade, multi-opacity |
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For anterior teeth, why is it crucial to invert the dam? What must you do in order to achieve this?
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Isolation is much more important for composites than it is for amalgam. Composites cannot tolerate water, blood, or saliva contamination.
Must be inverted properly and to maintain a tight seal. May need to ligate the tooth because of the shape on the lingual side. No height of contour. Typically ligate th tooth you work on and the one adjacent to it. |
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What is magnification more important for? Amalgam or composite?
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composite
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Describe facial or lingual "access".
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Get to the anterior lesion either through facial or lingual direction.
historically a lingual access was always recommended. Today, facial or lingual are acceptable. composites in the past were not as matchable to the natural tooth structure. Lingual access will hide the restoration. |
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How do you determine whether to come from facial or lingual access?
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It depends on which way will preserve the most healthy tooth structure.
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After you decide between the facial/lingual access, what do you do next?
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Decide where the lesion is incisal or gingival. You can do a periapical xray or transillumination = phenomenon where you can see the lesion with you eye using light shining on one side and your mirror on the other side. You should see a shadow.
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What burr do you use for anteriors?
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Can use a #329 = similar to 330 but smaller dimensions.
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Describe the 4 steps involved in the preparation for class 3
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1) locate lesion
2) decide access 3) get to the lesion (MID) 4) remove soft dentin |
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Is it important to remove unsupported enamel for anterior composites?
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sometimes. For amalgam, its always important. The facial wall almost never has dentin attached to it, therefore its unsupported. However, there won't be any forces applied to the unsupported enamel. Therefore, for class 3 lesion, facial enamel does NOT need to be removed. You can leave unsupported enamel here. It gives you a much better aesthetic result.
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For class 3, what type of unsupported enamel must you remove?
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incisal edges. otherwise, class 3 will turn into class 4.
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What about extension for prevention? Must you break contact?
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as long as all the margins are in enamel, enamel to composite margins should never allow microleakage. margins aren't vulnerable unlike in enamel.
Don't need to worry about it for anterior teeth. |
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What's the best cavo surface margin for composite? Why?
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its about 45 degrees. bevel - when 2 planes come together, at an angle that is less than or greater than 90 degrees. 45 degree bevel will etch better.
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What does etching cause? how is this related to 45 degree cavo surface angle?
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selective dissolution of enamel rods so you can create microporosities (small holes).
If you etch the sides of enamel rodes, you dont get a good etching pattern. |
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What creates a microporous surface?
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application of 30-37% phosphoric acid for 15 sec on beveled enamel will create a microporoous surface.
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Where does the best etching happen?
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On the cut ends of enamel rods. This is why is occurs best on rods hat are beveled at 45 degrees.
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How do you "bevel"?
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flame shaped diamond burr. Position the instrument, the width for class 3 should only be 1/2 mm.
Use the Wieland carver to chip away part of the enamel. The hole will have a slight 45 degree enamel on all enamel margins. |
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Internal line and point angles for class 3?
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All internal line and point angles should not be sharp. Composite materials aren't condensed, so they have problems adapted to a sharp corner. Must make certain that the composite adapts well.
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Is there retention form for composite?
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Yes, the etching on the enamel surface is the retention form. Once adhesive works its way into the holes, there's micromechanical retention.
You never intentionally converge walls. |
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Is there resistance form for anterior composites?
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forces are much less and there are no heavy occluding forces. Impossible to get an occlusal contact. Resistance form isn't important for anterior composites.
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Class 3 composite matrix band?
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clear plastic strip, Mylar strip.
There's 3 components: 1. clear plastic strip - allow light to pass throgh 2. wooden or plastic wedge 3. your finger to hold the mylar in place gingival most part of the plastic strip must be on gingival most part of the tooth. Good to put a subtle curve on the clear plastic strip. Don't need a rigid container. |
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Matrix purpose?
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Good shape and good to reduce amount of excess. Its good to place the matrix, and then the acid etch. Plastic strip will minimize etching of adjacent tooth too.
Sline in and go below margin. Us e finger during curving. Minimizing excess is a practical thing to do so you can't carve it away once its set. |
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The "bonding agent"?
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aka adhesive. Sits between the prep and the composite that goes over it. Responsible for composite to stay in place to toohth structure.
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Who is Michael Buonocore?
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Invented adhesive dentistry around 1955. He introduced the concept.
in early days, adhesive dentistry was just for enamel bonding now we use enamel for enamel and detin bonding. |
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Step 1
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acid etch. 35% phosphoric acid blue colored gel. used to be a clear liquid, and use to etch everywhere since you couldn't see it. Colored gel makes it easier for placement and for rinsing it off.
Total etching = dentin and enamel are etched at the same tiem wit the same solution. old days, we only etched enamel. You want to go slightly beyond the margin too. gentile aggitation is okay. remove excess water, but don't dessicte. Should be slightly damp The effects of etching are reversible. This will remineralize. We don't want to etch for more than 15s. After that, rinse with water. You don't want to etch dentin for mre than 15 sec. Ensure that all of the blue is gone. Etching will take away phosphates, ca, from the surface. After that, it looks slightly chalky. |
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What happens when you etch dentin?
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You can see holes of dentinal tubules and spaces between the collagen fibrils.
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What happens after etching i.e. what state is the tooth left in?
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microporous enamel
no smear layer spaces between dentin, collagen lots of holes smear layer - must be removed on every prep. |
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Describe priming
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enamel and resin blend very wel toether. When you apply any resin to enamel, it adapts very well and flows into the spaces. For dentin, it simply sits on the surface and doesn't penetrate wel.
primer - makes dentin attractive to resin, since otherwise it wouldn't be. collagen is resin phobic and needs to be primed to be made resin |
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Step 3? What 3 things do all resins do?
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Penetration of low viscosity of resin into the smaller holes.
All resins do hte following 1. make lots of holes 2. dentin needs to be made attractive to the penetrating 3 use low viscosity resin to make it onto the porosites. |
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Describe the process of sealing the adhesive..
What's the oxygen inhibited layer? |
1. etched and rinsed (at least for 15 s)
2. primed 3. sealed (infiltration of the holes) 4. light cured 5. reactive surface - now its able to bind to whatever is placed on top of it. Oxygen inhibited layer = reactive surface: any composite never fully polymerizes on the surface. As long as teh surface is exposed to air, it will never fully polymerize so there's lots of reactive chemical sites. once bonding agent is applied, you have lots of reactive sites. This is what makes incremental curing possible. Its importnat not to contaminate this air inhibited layer. If you do, you won't get a good bond. |
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What are 2 ways of getting composite into the tooth?
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1. compules - single use containers of composite. This goes into a squeeze gun.
**what we have is in a syringe. |
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placement instrument?
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Very small thin, and flexible. Has a thin paddle shape.
Finger placement is important, must be placed on the facial surface to make sure you don't have a lot of excess on the front. |
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Can composite be mchanically compressed into place?
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With amalgam, it stays where you push it.
Composite - relatively sticky to instrument, can't push it down or else it will stick. You need to simply "swipe" into into place. it’s NOT condensation use paddle-shaped instruments unset material is sticky wipe into prep, avoid voids! watch out for overhead light cure well from both sides |
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Visible light curing
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designed to shine 480 nm (blue light).
Functions: 1. triggers polymerization **light must hit the entire depth Notes: -get close but not too close - need to get tip as close to it as possibl but don't touch it. -don't under-cure (time) almost impossible to overcure composite. much better to cure for longer than shorter.. - check your light on a regular basis. |
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3 types of curing lights..
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1. Halogen lights
2. LED lights -- more popular now. 3. plasma arch curing light - not used that much. cures very quickly Difference in halogen vs. LED: halogen one has no cord. LED light has a bulkier cord halogen - very powerful light, generate a lot of heat. emits all other colors of light. Lamp has filters that filter everything except for the useful light. get blue light in 480 nm. Huge waste of energy! Much of it is goes to heat LED - much mroe efficient use of energy. hardly any heat. don't need a fan, or base unit. Much easier to use and more portable. earlier versions of LED - wouldn't cure the very light or very dark shades. but now they cure everything. higher quality - better depth of cure. |
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What is depth of cure? What affects it?
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cures below the surface. you want a 2,3,4 mm depth of cure for a curing light.
Determinations: 1. quality of light source 2. color of composite - translucent, very light shades will have easier penetration that dark ones. 3. opacity of composite - light translucent shades may cure about 3 mm below surface. darker ones maybe only 1 or 2. 4. closeness - don't want scatter. 5. time- takes a while for light to penetrate. 6. cure through tooth - sometimes has an unimpeded tooth structure. 7. why is it so important? can't afford to have deep unpolymerized resin. |
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Radiometer?
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Place light tip on this instrument, and you can measure how much blue light is actually being emitted from the tip.
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Bulk curing vs. incremental curing
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bulk : cure all at once. its very easy, and good for a shallow preps. bulk filling should only be done on shallow preps to make certain that the deepest layer is polymerized.
depth of cure - anytime you're more than 2 mm deep for the prep, you should use incremental curing esp if your light has a pure depth of cure. incremental curing: good way to minimize polymerization stress. can get a better aesthetic result. good to cure against a plastic strip. once air inhibited layer has been contaminated, you have a hard time placing a second layer over this. |
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What do you NOT want a lot of for composite, unlike amalgam?
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You dont want a lot of excess because you're not carving it after its cured.
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Purpose of "finishing". What must be used?
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Finishing - getting the contours right!
use sof-lex disks. ultra thin disks with varying degrees of grit. The disks snap on to the mandrel - usually goes into a slow speed handpiece and things are attached to the mandrel - placed in slow speed. coarsest to middle coarse - used for finishing light coarse to lightest coarse- polishing - very smooth surface. |
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#12 scalpel blade
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good instrument for removing gingival flash (the only one), and getting gingivial embrasure contour perfect.
Looks like a big hook with the inside as a very sharp blade. |
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Finishing strips?
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Once you remove gingival flash, you use this which is like a thin piece of sandpaper. 2 sides, slide it through contact and "shoe shine" it.
should finish with the dam still on. Don't do final finish and polish before you adjust the occlusion. |
