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118 Cards in this Set
- Front
- Back
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Functional Cusp bevel has what function
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Structural durability
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Seating groove has what function
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retenintion and resistance
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Occulusal reduction on teh cusp has waht function? What is the proper name for this
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Structural Durability
Planar occlusal reduction |
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Axial reduction has what function in an all metal
what about the rest of the preps |
retention and resistance
the others are R&R and Structural Durability |
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What characteristics of a crown add retention and resistance
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Axial reduction and seating groove
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What characterisitcs of a crown add structural durability
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Functional cusp bevel and planar occlusal reduction. If you didn't do this then you would have really thin metal in some parts that would lead to a fracture.
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What type of crown has a predictable restorative outcome
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Full cast crown
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what is the average lifespan of a all metal crown
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7-10 years
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How is an all metal crown better than a partial veneer
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higher resistance and retention
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In what five situations should an all metal crown be used
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when cusps need to be protected
a retainer for a FPD non esthetic zone all axial surfaces have caries the existing restoration is on 4+ surfaces |
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What is the occlusal reduction on a full metal prep
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1.5 on supporting
1.0 on non-supportin |
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Why is it important to keep the anatomy of the tooth
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so that the crown is the same thickness everywhere, which will reduce fracture
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An axial reduction of 1.0mm is seen on what type of prep
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full metal
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What odes overinclination cause
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destroys the tooth and lowers retention
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Why is it important to bevel
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to keep the anatomy so that the crown is the correct thickness. If the lab goes ahead and puts the correct thickness then the occlusion would be off and you would trim it and then have a weak cusp
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What is the correct path of insertion of a provisional?
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perpendicular to the occlusal plane.
This should be taken into account when doing the prep, if the tooth is not in alignment adjacent teeth may get in the way of placing the prep so you need to reduce it in a way that you can place the provisional |
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What type of finish line is used with a PFM, why
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shoulder (1.5) on the facial and a Chamfer (1.0)on the lingual
The facial must be larger because it has more layers as the metal is covered by and opaque, body and incisal layer of porcelain |
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What is the occlusal reduction on a PFM
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1.5 - 2.0 mm
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The lingual and Facial axial reduction of a posterior PFM crown have what function.
How is this different than a Full metal |
Retention and resistance
Structural Durability Axial reduction in a full metal does not aid in structural durability. It functions in retention and resistance. How to remember: a PFM has a different front and back thus it requires extra structural durability and it achieves this through the axial reduction |
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The Chamfer on a posterior PFM has what added function that the shoulder does not have on the same prep
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The chamfers function is in
Marginal Integrity Structural Durability Shoulder = marginal integrity |
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The occlusal reduction of a Posterior PFM is what?
What is it on the full metal |
1.5 - 2.00
Full metal = 1.0-1.5 |
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What are the five purposes of a provisional?
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Provide protection of the prep
Postitional stability Simulate definitive restoration contours (make sure you've reduced enough) Cleansibility Strength and Retention |
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What are the five different Provisional restorations?
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1. Polycarobonate Pre-fabricated Shell
2. Aluminum Pre-fabricated Shell 3. Direct Provisional aka temp filing 4. Provisional removable prosthesis 5. Custom Provisional a. indirect technique b. direct technique |
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What are the three matrix materials used with custom provisionals
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1. Biocryl matrix
2. PVS impression matrix 3. Alginate matrix |
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Of the two pre-fabricated shell crowns (polycarbonate and aluminum) what characteristics does the polycarbonate shell have that the aluminum does not
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Commonly used for anterior provisonals
No matrix needed |
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What characteristics do Polycarb and aluminum Pre-fabed shells share
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Must be trimmed to seat intraorally
must be relined with acrylic materials |
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What are the two characteristics of aluminum pre-fab shells
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unesthetic
retention of reliner material (acrylic) is an issue |
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What are the 4 benefits of Custom provisionals?
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Multiple techniques
esthetic controlled contours material options |
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What are the three material options for a custom provisional
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methyl methacrylate
ethyl methacrylate composite resin |
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Custom Provisional - BioCryl - Clear Template Technique.
What is required? What is a benefit? what are the concerns? |
Requires a pre treatment model with a dubplicated wax-up
Benefit - less expensive materials Concerns - increased lab time, distortion (occlusion and contours) |
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Indirect Technique
What is this technique used for? |
custom provisionals
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What are the material choices for the indirect technique
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ethyl methacrylate
triad methyl methacrylate |
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What are the stabilization factors of an indirect technique
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No seating pressure on the preped tooth as a cast is used.
Resistance force is needed to prevent expansion of the material |
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What method of provisonal making do we use in class
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Direct preliminary impression
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What are the down sides of direct preliminary impression technique of custom prov?
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doesn't provide opposing occlusion
interproximal embrasures must be aggresively removed no remake capability alginate is unstable |
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What custom prov technique uses stock trays
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direct preliminary impression
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what provisional technique uses alginate
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direct preliminary impression
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What are the materials used in a Custom - Direct template provisional
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Ethyl meth
Bis GMA |
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If you have a void when using bis -gma for a direct prelim prov can you add?
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small bubbles can be filled with flowable
addition to the incisal edges is possible |
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what are the characteristics of triad when used for a direct prelim prov
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small bubbles can be filled
CANNOT add to incisal - unpredictable |
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What can be done if there are voids with an acrylic prov
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easily relined and repaired
Wet the set acrylic with a monomer and then you can add more |
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what are some questions that shoudl be used when deciding the provsional technique to be used
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what is the condition of the tooth, acceptable for reproduction
whats the budget how much chair time adequeate lab facility purpose of provisional patients expectations |
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What is integrity made of - formulation
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bis gma composite resin
- minimal heat and shrinkage during polymerization |
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How long do you leave the integrity in the mouth for when doing a provisional
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1 minute
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how long do you allow integrity to self cure outside of the mouth for
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4-5 minutes
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After seating a provisional, what things shoudl you evaluate
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contact
marginal integrity contour occlusion |
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What materials are used in a final impression
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Medium and low viscosity polyvinyl siloxane (PVS)
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Why do you block out the incisor interproximal region when doing a final impression
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to prevent impression material from engaging here
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Before you begin the final impression what should you apply to the prep and surrounding tissue
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vaseline
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What is the light body (LV) PVS amterial used for
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Final impression
- it will capture the most detail so it is dispensed around the preped tooth. When adding it to the prep start at the distal and keep the tip in contact with the tooth structure, allow it to flow up over the interproximal surface then move on. |
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What is the Medium/Heavy body material used for in a final impression
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supporting the light body material in the custum impression tray, thus it is dispensed into the tray. It is darker in color
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what is the workign time of the Medium (MP) body PVS
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2.5 minutes
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How long do you seat the impression tray for during a final impression
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5 minutes, minimal
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When inspecting the final impression what are you looking for?
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material is of uniform thickness
no burn through exact representation of prep can see finish line can see tissue detail beyond the finish line |
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what is the mastercast made from
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it is the working cast that results from the pouring of the final impression. It is a positive of the prep (with much detail because we used light body PVS)
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What is the Die going to be used for?
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used to fabricate a wax for the final casting (restoration). It is the preped tooth section of the mastercast
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What are the two parts of a mastercast
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The working and the die
The working is the entire arch (+ of prep) on an articulator the die is the individual preped tooth |
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What are the two different types of mastercast system
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Working cast with a separate die
Working cast with a removable die |
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What are the two positives and one negative to a working cast with a separate die
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+'s
simple to fabricate physiological form is easily reproduced -'s distortion can occur of the wax pattern when you transfer back and forth |
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Waht are the positives and negatives to a working cast with a removable die
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+'s
reduced need to transfer wax pattern from working cast to die Distortion reduction because of one pour rather than multiple -'s error is introduced by the die not seating accurately and consistently |
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What is the two pour technique
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it is a technique used when making the mastercast and die. The first pour uses die stone like silky rock to get the arch and prep. The second pour is for the base/removable die pin, microstone is used
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What height should the initial pour be, what should it be after trimming
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stone = 2.5 cm
after trimming = 10 mm |
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What is the final set time of the silkyrock
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1 hour
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what should you do with your mastercast prior to die sectioning?
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mount the mastercast onto the whipmix articulator to acheive an accurate mounting
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Do you push or pull when removing the die from the mastercast for the first time
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push
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why do you trim the die stone up to the finish line
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facilitate proper countour development in the wax pattern
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where do u put the die spacer/relief agent
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along the die up to 1 mm of the finish line
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What is placed along the finish line of the die
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one coat of die hardener
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What is the purpose of the die hardener
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seals the die surface prior to wax pattern fabrication
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What is the viscosity of die hardening agent
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1-25 microns
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what is the viscosity of die spacer/relief afent
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4-10 microns
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What is the definition of prosthodontics
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The branch of dentistry pertaining to the restoration and maint of oral function, health, etc by the restoration of teeth with artificial substitutes
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What are the three branches of prosthodontics
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Fixed
Removable Maxillofacial |
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What is the definition of fixed prostho
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the branch of prostho concerned with the replacement and or restoration by artificial substitues that are not readily removed from teh mouth
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What is an abutment, definition
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A tooth that serves to support and retain a prosthesis, its the prep
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Where is the finish line located
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On the abutment
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Where is a margin located
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on the restoration, think open margin
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What is a retainer
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the actual restoration
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what is a pontic
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the artificial tooth in a FPD
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what is a connector
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the part that unites the pontic with the retainer (unites restoration with artificial tooth)
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What are the 5 things tooth preps are goverened by
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1. preservation of tooth structure
2. retention and resistance 3. structural durability of the restoration 4. marginal integrity 5. preservation of the periodontium |
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What is retention
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prevents removal of the restoration along the long axis of the tooth prep
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the essential element in _____ is having two opposing vertical surfaces in the same prep
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Retention
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Which is more retentive, a small or large tooth? why?
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Large, greater surface area
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what is resistance
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prevents dislodgement of the restoration by forces directed in an apical or oblique direction
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What is the term used for the prevention of movement of a restoration under occlusal forces
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Resistances
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what degree of convergence is ideal for the axial wall, clinically acceptable
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6 degrees is ideal, 16 is acceptable
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Why is the axial taper important
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improves retention
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How will adding grooves increase retention
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Increases surface area and restricts the possible paths of withdrawal or insertion
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What is the definition of structural durability
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related to the amount of restorative material necessary for that restoration to sustain occlusal loads and patient function
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what is ideal metal coping thickness
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.5-.3mm
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What is a reduction index used for?
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a guide for final contours
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What is the incisal reduction on an anterior PFM
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1.5mm
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what is the chamfer on an anterior PFM
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the lingual, 1.0mm
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What is the shoulder finish line on an anterior PFM
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on facial, 1.5mm
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What is the triple tray
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It is a direct preliminary impression technique that uses PVS and registers the opposing teeth
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What is the advantage of using the triple tray direct preliminary impression technique
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it provides for the least amount of occlusal adjustment
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What are the advantages of the Putty Matrix Direct technique
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Efficient
Can use Integrity Accurate Good for multi-unit provisionals |
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If the fit or marginal interity is questionable on a provisional what should you do
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remake it
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When using an acrylic for a provisional, if you suspect distortion what should you do
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through it out
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What are the numbers of an anterior PFM
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F- 1.5
L - 1.0 Incisal - 1.5 |
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What are the reduction numbers of a posterior PFM
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F - 1.5
L - 1.0 Supporting cusp - 2.0 non supp cusp - 1.5 |
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What are teh reduction numbers of an all metal crown
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F & L - 1.0
Supp cusp - 1.5 non supp cusp - 1.0 |
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What are the reduction numbers of an all ceramic crown
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F, L, Incisal - 1.5
* you would never use all ceramic on a posterior |
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What is the setting time of PVS
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6-8 minutes
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What is the ease of removal of PVS
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Moderate to difficult
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What is the finish line readability of PVS
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good
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What is the moisture tolerance of PVS
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poor for standard hydrophobic brands
adequate for hydrophilic brands |
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What is the pouring time of PVS
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7 days
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What is the tear strength of PVS
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Adequeate
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What is the pouring east of PVS
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hydrophobic - Poor
Hydrophilic - adequate |
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What is the mixing ease of PVS
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Hand - easy
Cartirdge system - very easy |
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What is the odor/taste of PVS
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Good
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Is PVS radioopaque
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no
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what is the shelf life of PVS
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24 months
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What are the advantages of Bis-acryl composite
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Good Marginal fit
Low exothermic heat increase Good abrasion resistance good transverse strength low shrinkage |
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What are the disadvantages of Bis-acryl composite?
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surface hardness
more likely to stain limited shades limited polishability brittle |
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Laboratory Fabrication of All-Ceramic Crowns:
o Complete prep, and make final impression; records and mater cast sent to the dental lab technician o Block out is applied to the die o Die spacer is applied to the die which provides space for the cement o Sectional impression is fabricated o Refractory/duplicate die is fabricated o The finish line is demarcated in order to know where the end of the restoration should come to o Die surface is sealed o Porcelain powder is mixed and aluminum oxide coping is applied o Particles are applied with a synthetic brush and carved to anatomical form; goes into oven where some shrinkage may occur; almost must over-apply on the porcelain o Aluminum coping is placed into a furnace and glass infiltrate is applied o Placed onto platinum foil and fired again |
read that again
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