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33 Cards in this Set
- Front
- Back
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When do we place crowns on teeth?
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Whenever the tooth needs strength and protection.
-when we can't expect the tooth to function overtime given the occlusion. - the more tooth structure that is missing, the higher the likelihood of needing a crown. |
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What would the size of the existing restoration or carious lesion be to indicate a crown?
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when the width becomes more than a third of the distance between the cusp tips, it is most likely to need a crown.
When its this distance, we feel like the cusp will fracture. |
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Where must the margin for the crown prep be?
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Must be in sound tooth structure.
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How is endodontic treatment related to needing a crown?
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Teeth needing any endo esp posterior teeth will need to be crowned afterward. Anteriors may need crowns, but since the forces of occlusion are different here, there may be other options.
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Cracked tooth syndrome..
Tooth hurts. What question do you ask? |
Sensitive to hot and cold?
when eating? Certain times of day? Biting on it in a certain way? Patient answers yes ot pain on eating. Pt has cracked tooth, and test it out with a temporary crown. If symptoms go away, make the actual crown. If symptoms do not go away, this may indicate endo. |
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Cracked tooth that is asymptomatic
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may happen with old restorations. do we wait until its symptomatic before it needs a crown? Its up to the patient after you explain all the options.
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Cracked tooth with a fractured root
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Discomfort as they chew in a certain area; swelling of gum tissue. Probing tooth and in one area drops all the way down. Crack runs on tooth surface, all the way down. This is NOT restorable and they will lose the tooth.
May also sent pt to periodontist to ensure that it is a fractured root. Won't show up on xray. |
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Crown vs. onlay
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If tooth needs a lot of retention, it will need a crown.
-if tooth will be an abutment for a partial denture. -Aesthetics are better with a crown. -Fixed bridge work can be indicated if we lose a tooth. You could do implants as well. Really depends on neighboring teeth. If other teeth need to be restored also, fixed bridge is good. If neighboring teeth are healthy, do an implant. |
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First thing you want to look at when you look in patient's mouth?
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Oral hygiene
- in general, does it look clean or dirty? |
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2nd thing you look at?
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Condition of restorations
-when were they done and how do they currently look? |
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Alginates - what are 2 important properties?
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Syneresis - tendency of aliginate to dry out. take damp paper towel and wrap the aliginate and place in ziploc bag.
Imbibition - tendency of aliginate to absorb water |
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What is arch integrity?
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The way in which teeth hold their positions in the mouth. When teeth are lost, you lose arch integrity and teeth begin to shift and tip. Teeth may become angled incorrectly, and supra erupt. Study models are the best way to look at this.
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Full mouth x rays?
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Use these to look at anything else in the mouth you cannot directly see. Look at quality of bone, roots, small cavitated lesions.
Next, you create a treatment plan |
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2 important points for fixed partial dentures. Two things that we are most concerned about?
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-most concerned about abutments
-path of insertion teeth that support the denture are called abutments. |
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Crown on either end are called? What are all the parts of the fixed denture?
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The retainer.
The replacement tooth is a pontic. Space in between is called a connector. |
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What are the 5 requirements of the abutment teeth?
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1. Periodontal teeth must be sound even if they are endodontically treated for the abutments.
2. root configuration -oval on premolars is good support. roots going in different directions and flare out is good for resistance. root fusion is not good. 3. periodontal surface area / root surface area: amount of surface area of the tooth held in the bone. has to do with how strong its held in place (multi rooted better than single) least: lateral incisor maxillary crown to root ratio = how much tooth is present in the bone vs. how much bone is below the tissues. Ideal: 2:3. Normal: 1:1. Need a reasonable about of bone support. 4. length of span - how much space between abutment teeth. rapidly evaporating with implants. -2 abutments for 2 pontics. missing 3 teeth, then need 3 abutments: Tillman's Rule -Anti's Law- root surface of the abutment teeth should surpass that of the teeth being replaced with pontics. 5. Opposing occlusion |
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Biomechanical considerations of the length of span
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-The longer anything it is, the more prone to flexion.
Flexing of the span increases directly. Q^3. Height will decrease the flex, but there's only so much height you can add occlusogingivally. Adding buccolingually is not as dramatic as occlusogingivally. |
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Double abutting?
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Add a second retainer on a second abutment tooth if you are concerned with heavy occlusal forces.
-with flexion, the secondary abutment must be very retentive. |
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Occlusion
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1. think about each patient individually and on their bite. How tough or soft it is.
2. how deep the bite is. overbite is very large. with greater overbite, the more force there is and the more likely the restorations will fail eventually. |
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What if you are missing your incisors?
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Any time the replacement teeth may carry outside inner axis abutment line. Will create a lever on the abutments.
wider arc is more likely to need double abutting. |
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Pure abutment?
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Missing a few teeth and in the middle, theres a single tooth. since tooth has a little movement there's tendency for bridge work to teeter totter.
-look at how strongly the periodontal support is. -can add an interlock or precision attachment connector to distal of pure abutment |
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Tilted molar?
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-Natural path of insertion doesn't match well.
-if its tipped a great deal, could do molar uprighting and orthodontically straighten it out: increase span, molar is higher in occusal plane. -modify prep to make half crown -forces redistribute along a different axis. -Another thing is a telescopic prepping. outside of coping corrects the path, which is made of gold. Building a mini crown underneath and the mini crown can lift the whole plane. |
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Canine replacement bridge?
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Canines hold a lot of force.
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Cantilever
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Hang a replacement tooth off of another tooth. Very challenging to to do successfully.
-Huge amount of torquing force on neighboring teeth, and failure rate is higher. -Look for areas where there's less force - canine, lateral incisor. Never make the cantilever bigger than the size of a premolar. -Not for endodontically treated tooth. -As you move forward , they are better but overall don't do them . they tend to fail. |
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Flexi post?
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Active post are usually a bad idea since they place stress inside the tooth.
-has sharp threading inside. |
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For a crown prep, what do the following factors do for resistance and retention form?
1. decrease taper 2. increase surface area 3. increase length |
1. increase resistance an d retention
2. increase retention 3. increase resistance |
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What are some indications for going sub gingival for the prep?
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1. subgingival decay, fracture or existing restoration
2. retention to increase occlusal gingival height of preparation 3. esthetics 4. break contact |
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If you are going to go sub gingival, where should the finish line be?
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A min of 0.5 mm coronal to the periodontal attachment.
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What type of finish line should be avoided completely?
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Feather or knife edge - holding diamond burr parallel to surface of tooth removing only enough to scribe a faint demarcation.
-increase degree of difficulty w/ indirect procedures |
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What finish line is made for porcelain?
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Chamfer. Created w round end tapered diamond bur. removes axial depth to depth of 1/2 bur diameter.
PFMs mostly |
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What finish line is used for porcelain jacket crwosn nd veneered crowns w/ porcelain butt margin
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Shoulder - created by using a flat ended taper diamond bur, preparing a shelf thats greater than 90 degrees to the axial wall.
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What are two slight variations for chamfer and shoulder finish line?
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beveled version of each. Beveled chamfer is good for full gold crown, and is better at marginal
Beveled shoulder - full metal crowns, with better marginal seal. |
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Name 5 advantages for FGC, and 2 disadvantages
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-strength of complete cast
-greater conservation of tooth structure -max protect from caries -good for those with brutism -similar hardness to opposing teeth Disadvantages -lack esthetics -accurate vitality test can't be obtained |
