Fixed Q4 Flashcards by Tim Agee

What is worse, an open margin or an over-contoured crown?

Over contoured

plaque trapped underneath

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What is the most critical and neglected aspect of occlusion?

Lateral excursive movements

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Most errors in crown contours are found where?

Embrasure spaces

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If crown is deficient, how would you add matl IP or occlusally?

Ceramic - stack low fusing porcelain

Metal - solder

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What type of luting material needs anesthesia?

What type strengthens restorative material?

Bonded Resins

for both

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What is the advantage to a Luted crown?

What is the disadvantage of a Bonded crown?

sectioned and removed easily

prepped off

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What type of cement will increase the flexural strength of glass ceramic crowns?

Adhesively bonded resin

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T/F

You can bond zirconia and metal

False

*crystal/metal won’t adhere to bonding agent

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For emax, would you lute or bond if you lacked resistance form?

bond

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For emax, if you can’t isolate, would you lute or bond?

lute

*adhesive cement very difficult if can’t isolate

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T/F

Bonding strengthens, holds over time better but if you have retention/resistance you often don’t need it

True

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T/F

Bonding is very difficult to remove and more technical to apply

True

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Name 3 advantages to luting with RMGI:

postcementation sensitivity minimal

higher strength than normal GI

strength similar to resin luting agents (but not really)

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Zinc Phosphate has a film thickness of ___ um, is easy to clean, and has a long track record of success

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What has better biocompatibility than Zinc Phosphate b/c polyacrylic acid molecule is large and does not penetrate into the dentinal tubules?

Zinc Polycarboxylate

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What luting agent is superior to Zinc Phosphate and Zinc Plycarboxylate and is susceptible to moisture?

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What luting agent is extremely biocompatible but has mechanical properties inferior to other cements?

Zinc Oxide Eugenol

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Why are resin cements susceptible to incomplete seating?

High film thickness

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2 goals of provisional cements?

seal margin

prevent leakage/pulpal irritation

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What type of provisional cement does ASDOH use?

tempbond NE - zinc oxide bases cement

*NE stands for Non-Eugenol

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Why is Eugenol bad in resins?

free radical scavenger that can inhibit resin setting

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Normal Provisional cement we use is tempbond NE, what is the stronger one we use?

What type of cement is it?

Durelon

Polycarboxylate

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Sequence of check when seating a crown:

Margins

Occlusal

Contour

Esthetics

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If crown isn’t seated all the way and you adjust the occlusal contacts, you will be in…

Hypo-occlusion

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Check IP contact with...

accufilm

A removeable die system is set in Type ___ gypsum, and it can abrade the IP contacts so adjustments are made on another poured up non-removeable system

You can't get an explorer in all IP contacts, so what to do? If you don't have adjacent teeth, do you still need to take a radiograph?

Radiograph NO - not if detectable with an explorer

How thick is accufilm?

21 microns - fold over technique to see how much to grind (by measuring adjacent teeth to the one in hyperocclusion)

Sequence to bond a veneer:

Veneer HF Silane Bonding (No primer) luting Bonding (w/ primer) HPO4 Veneer prep

What is the purpose of a primer? Why don't use on veneer?

Hydrophilic to hydrophobic no dentin - no need

We can't use adhesive bonding if the Intaglio is...

Metal or Crystal *so no zirconia, no PFM

Would we lute or bond empress?

Bond -will increase strength

Would we lute or bond emax?

Either - if min. occlusal thickness bond - if good retention/resistance lute

Why do we add grooves and boxes to a gold crown prep?

Irregularities help luting agent - and prevents leakage

Brand name of the RMGI we use to lute in clinic:

FujiCEM * increases strength, lowers solubility * RMGI is still considered luting

In an endo tooth - If 3 or more walls have a 1mm thickness following crown prep, do what?

Chamber retained core buildup

When should a post be used in an endo tooth?

Retention inadequate *two walls or less

To put Amalgam in a core buildup, how thick should the wall be after a prep is made?

1 mm

What type of build up is used for multi-rooted teeth that have gone through endo?

Chamber retained core build up *has dentin thickness and pulp chamber adequate

The height of a core build up has to be at least what?

4 mm *either height of pulp chamber or into root canal

As a core material composite has a _____ CTE ____ modulus of elasticity Bonding to denting that is _____

high low not strong

What is the disadvantage of GI as a core material?

Strength *also moisture sensitive and low tensile strength

What is the purpose of a Post? What does it NOT do?

retain core build up reinforce tooth

A post should only be considered to retain core build up when?

all other forms of retention are inadequate *only two walls

A post is ideally ____ the length of the root An apical seal of at least ___mm of GP is to remain

2/3 4mm

What is more important, 4mm of GP remaining when placing post or it being 2/3 of the length of root?

4mm

Post diameter should be limited to ____ the root diameter

1/3

T/F | Strength of an endo treated tooth is directly related to bulk of dentin structure

True

What type of post leads to higher fracture rates?

Active *screwed in

What type of Post has enhanced esthetics, excellent biocompatibility, mechanical properties similar to dentin, easy to use/remove, firm retention with adhesive, and lower radiopacity than a metal post?

Fiber reinforced

Two types of Posts:

Fiber and Metal

How is a Metal post placed? Fiber?

Luted Bonded

What type of Post is one piece, high cost, and technique sensitive?

Cast

How big should a ferrule be?

2-3mm

What is the function of a ferrule?

reduces tooth fracture

Mechanical loading will produce cracks that progress in what direction?

Coronal to Apical

Fatigue failure is more catastrophic in what type of tooth?

Nonvital *complete root fracture may occur

Libman Nichols found that Ferrule length worked better at 1.5mm than 2mm - why?

2mm had to cut tooth structure down, lowering C/R ratio

Ideal Crown to Root ratio: Minimum:

2: 3 1: 1

If we have less than 1:1 Crown to Root ratio, what type of occlusal trauma will ensue?

Secondary - reduced peridontium

In upper anterior teeth, what wall is the most critical in reducing load fracture?

Palatal

We want how many mm of Ferrule above the margin?

2mm

T/F | Ferrule effect is for resistance/retention

False *designed to prevent tooth splitting

2 techniques to gain adequate tooth structure:

Crown lengthening Orthodontic extrusion

Crown to Root ratio better with extrusion and crown lengtheing

Yes?

Junctional Epithelium + Connective Tissue

Biologic Width

On average we want __ mm from the bone to where the core material starts

5 *2 bio width +1 sulcus +2 Ferrule

One article concluded that a post doesn't strengthen a tooth, but weakens it

True

Do you have to crown a tooth that has been endo treated?

Endo Tx teeth last how long?

1-25 years

Sorensen et al concluded that _____ didn't significantly improve that rate of clinical success for Mx and Mb teeth

Coronal coverage of anterior teeth

Sorenson et al concluded that intracoronal reinforcement (a post) didn't do what?

increase resistance to fracture

The purpose of a post:

Retain core build up

Bridge, aka

FPD - fixed partial denture

FPD, dummy tooth: Crowns: Crown prep: between dummy tooth and crowns:

Pontic Retainer Abutment connector

Ante said that the combined pericemental area (root structure) should be greater than or equal to the area of the teeth being replaced

True *all root area

Does an FPD have to fulfill Ante's Law?

No * most don't and are fine * now it's more like Ante's Guideline

an FPD only one side of which is attached to a retainer

Cantilever

Why is a Cantilever not ideal?

Doesn't direct forces along long axis of the tooth *why generally don't do and recommend implants instead

Greatest failure rate in Sorensen study was pulpless (endo Tx) teeth with?

No crown

3 reasons a tooth needs a crown:

Tooth structure Improve esthetics change contours

A crown that supports a removable partial denture (RPD)

Survey Crown

RPD abutments fail 2x as often as FPD

True

A Post will decrease the success rate of an FPD

True

What tooth should be prepped 1st in FPD?

Smaller | premolar rather than molar - errors can be corrected w/ greater tooth structure

What instrument can detect undercuts when prepping an FPD?

Surveyor Instrument *also CEREC