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47 Cards in this Set
- Front
- Back
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What must the depth of the pulpal floor be for an amalgam prep?
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No less than 1.5 mm. Can go deeper depending on where the caries is.
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What must the width be for an amalgam prep?
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only enough to remove the caries, and for extension for prevention
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What do you need a matrix for?
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any time there is a mesial, buccal, distal, or lingual prep.
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What does a matrix do?
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provides a wall, tight rigid container so that when you pack amalgam, it is well condensed.
1. matrix band 2. matrix retainer 3. wedge |
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5 important criteria that matrix must accomplish
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1. rigid container - in order to aggressively condense amalgam into the prep.
2. No gap at gingival margin - we don't want a lot of extra amalgam interproximally against soft tissue 3. no trauma to tissue - want to allow full recovery 4. high enough? must be higher than the amalgam that you pack into it. 5. logical shape? |
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what;s an overhang?
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amalgam is overextended gingivally.
consequences: bone loss, secondary caries, raises potential for periodontal disease. |
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What is an open contact?
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adjacent teeth that are supposed to touch each other, don't touch.
due to poor matrix band placement inadequately condensing the amalgam. |
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Confluent?
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surface of natural tooth and restoration are smooth and flow together.
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1. Purpose of retainer?
2. Properties of the matrix band? 3. block 4. U |
1. retian the matrix band. tighten or loosen the matrix band.
2. 0.0015 inches thick, but different sizes available. #1 universal band, other shapes are available. 3. the screw is contianed here. as you tighten it, it keeps the matrix in the container. 4. Open end of the U always goes to the gingiva. closed end goes to the occlusal surface. Top end of the loops is wider than the gingival end. smaller diameter goes to the gingiva. |
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Wedge?
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Base of the wedge always goes towards the gingiva. It pushes the metal against the tooth below the gingival margin.
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What side of the matrix band should be on the gingiva?
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The narrow dimater should be toward the gingiva.
The retainer should be toward the buccal. Matrix must be higher than the adjacent tooth's marginal ridge |
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In GV black's time frame, what was the old way of making amalgam?
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Use silver coins and grind it into fine powder that can be compressed
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What was gallium and indium used for?
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Newer materials that are placed into amalgam to aid in bonding.
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What is amalgam composed of currently?
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alloy powder of Ag, Sn, Cu and mercury. Hygiene of mercury is very important.
Can be present in spherical powders. Must be aggressively mixed. |
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Describe the unique setting (hardening) of amalgam.
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Not a snap set, it slowly gets harder. At first its pretty easy to mix, with a very gradual setting. It allows you to carve it and shape it before it gets too hard.
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Working time of amalgam?
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Has an adequate working time; Time that you're given to do the shaping and placement of amalgam.
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What's one of the biggest problems w/ amalgam?
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1) poor edge strength- the thinner it is, the more likely it is to break under tension. Need to remove a lot of tooth structure for the retention.
2) very brittle, no elasticity. But if you try to push amalgam, it does well (good compressive) |
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What is a huge advantage of amalgam?
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has very good compressive strength if its done well. can push on amalgam without effecting its structure too much.
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What the single biggest predictor of success w/ amalgam?
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Operator variability (how it's used).
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What is amalgam stored in? What are the advantages of this?
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Pre-portioned capsule (not free mercury powder, etc.)
-Good since we need to consider mercury hygiene, and safety. -Standardized proportions by the manufacturer w/ careful calibration. -no free mercury -easy to use -color coding (size and type) -Don't throw in trash! |
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What's a pestle?
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A mixing aid that helps in the agressive mixing. Some capsules have this little white object.
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Trituration?
Trituration time? What happens if you lower this? |
The mixing of amalgam. Today's its done on a machine called amalgamator. It aggressively mixs the powder and mercury in the capsule. Every single powder particle is being coated with mercury. There shouldn't be any free mercury in the mix, if its properly mixed. each brand of amalgam has a diff. trituration time.
wiggle bug amalgamator - ex. took 20 min. In this school, it takes 7 sec for each capsule. Lowering the time means you have more time to work the material. But if you decrease it, it won't be a well mixed amalgam and there will be free mercury! |
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What happens after there is adequate trituration time?
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Drop the mixed amalgam into the amalgam well, and pick out the pestle. Use an amalgam carrier to carry amalgam from the well into the pts mouth. Come in variety of sizes.
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Wha tis the purpose of the piston of the amalgam carrier?
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Pushes the filled amalgam out of the tube and into the area. Load i very quckly.
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Condensation?
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Pushing the mass of the amalgam such that it gets volumetrically smaller, and you get rid of the air bubbles. On a lower tooth, you must raise the pts jaw.
Goals -no voids -no free mercury -work-hardening- metal can be treated w/ heat or deformed. Gets to be a better material when its heat treated or work hardened -tooth separation - force must be firm such that tooth is slightly sep from adjacent tooth. |
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As you get towards teh top of the tooth, what must you do?
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switch to larger condensers. Must firmly condense before you go o the next insturment.
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Why is it important to over pack the amalgam?
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aka overcondesation. Shaping of final restoration is a substractive process. Acheived by carving excess amalgam away. Must start w/ more than you're going to need.
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Condensation tips!
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1. start immediately
2. small increments 3. small pluggers 4. work into corners 5. work against band 6. overpack with big pluggers |
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What do you do after you over-pack the amalgam?
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You'll want to do what's called burnishing. You're still within the working time of this amalgam, all instruments should be ready and lined up to be very efficient.
Burninshing = taking a ball burnisher. position it in the middle of amalgam and push it laterally against the margins. This increases the hardness, strength, and supercondenses the margins. The surface of the restoration must be as hard and strong as possible, and margins must be as gap free as possible. Use a cominbation of the small and large ball burnishings. |
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What do you do after the burnishing?
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Carving! You remove just the right amt of excess. If you take away too much, you cannot add more.
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What's the 1st instrument you use in carving?
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#23 explorer. Position it so that its 45 degrees to the long axis of the tooth. Tip of explorer touches the matrix band to create an occluslal embrasure and marginal ridge. Confluence is important since it must be confluent with the surrounding tooth structure.
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What's the 2nd instrument you use in carving? What are 2 methods of using this instrument?
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Discoid-cleoid. Discoid looks like a disc and cleiod looks like a claw. Discoid has a nice sharp edge, so position it parallel to the margin, you end up with amalgam that is confluent to the natural tooth structure.
2nd way is to drag the tool from te tooth structure down into the amalgam. Here, don't put too much pressure or else you get under-contour. Never start with amalgam and carve toward the tooth structure (end up with a little edge) |
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Ditching?
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surface of amalgam that is lower than the tooth structure.
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What's the 3rd instrument you use in carving?
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Anatomical burnisher (acorn). Has a blunted pointed end. can be used to put primary groove anatomy. Don't want to be very agressive here, still want to maintain the 1.5 mm depth. Good for burnishing into the 2ndary grooves too.
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What do you do to remove the remnants of amalgam?
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take a pellet of cotton, and buff the surface so it looks nice and smooth.
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What happens if you wait too long the remove the band?
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it will be too difficult to remove any excess that passes the gingival margin, and the buccal and lingual will be hard to carve away.
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What's the proper way to remove the band?
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remove the wooden wedge first. Loosen the smaller nut, remove the retainer from the band. Slide the matrix out from the opposite side of the restoration. Then slowly lift the back surface of the matrix and in an arch sufarce like motion.
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What do you do to carve away the excess amalgam on the proximal surface?
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3 instruments you use:
1) half hollenback and position it so that when you drag it, part of the instrument is on the tooth structure and part of it is on the amalgam. 2) Wiland carver (similar looking to sickle scaler) - ver sharp internal edge. Sneek it into the gingival edge and slowly slide up toward the surface. Critical to assess the contact before you take the rubber dam off. |
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How do you critically assess your amalgam restoration?
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Critical to asess if its clinically acceptable.
-take dental floss and slowly snap it out. this will check for contact and flash. Flash = excess amalgam causes shredding or snagging of floss. Open contacts mean you need to start over again. |
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How do you check the occlusion?
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Articulating paper - double inked paper ( blue is easiest to read). Put it between the upper and lower teeth where you did your restoration.
-don't bite down hard, relax your jaw and very gently bring your back teeth together in a normal bite. -need to check MIP (hypo, hyper, or normal occlusion). If you see a lot of blue spots, the best scenario is when you have normoocclusion. hyperocclusion - restoration is the only thing that touches. can't acheive MIP since the filling is in the way. |
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Normocclusion
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if there are any spots on the amalgam, the blue spots are in the same exact spots as it is on the natural teeth in the mouth. Spot is equal in intensity on the amalgam as it is on the other teeth in the mouth.
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Conformative occlusion
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restoration you're placing conforms to the pts existing occlusion. Never want to change the occlusion with a single restoration.
Goal is to get normo conformative occlusion. |
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Slight hypo-occlusion?
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There's a spot that only on the marginal ridge, then you take a carver and remove it. The spot is removed now, but its on all the natural teeth.
-not perfect but its safe. This is considered acceptable. You either want nothing on amalgam, or equal intensity of spots. |
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Hyper occlusion?
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Not good. Restoration is higher than it needs to be = malocclusion. This results in breakage of restoration or some level of discomfort.
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excursions?
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Done only after you check the occlusion. swing the jaw left to right, and side to side.
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What happens when you have hyperocclusion?
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take a discoid-cleiod and carve away a little bit more until all the blue spots appear at the normal contact points. You don't want any excursive interferences or contacts.
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Goal of carving?
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do an amalgam restoration that if you were to take spray paint, you wouldn't be able to tell whcih tooth you restored. If you took a study model, you wouldn't be able to tell which tooth was restored.
Put into the mouth what should have been there in the first place. Need to reflect the amalgam of the surrounding teeth. |
