EL MAESTRO PART 2, EL MAESTRO PART 1

QUESTION: Ductility - gold's ability to be

worked into different shapes

How do you bevel occlusal floor (gave list of instruments) • 13, 8 • 15, 80 (GMT) • 15, 95

• 15, 80 (GMT)

Bur used that converges F and L walls? #245, 7901, 169 (tapered bur, 0.9 diameter)

- If 169 is not thre, pick 245.

QUESTION: Main difference and advantage of using GMT instead of Enamel hatchet? a. bi-angled cutting surface b. angle of the blade c. push/pull action instead of

angle of the blade

What is the correct method of excavation of deep caries? a. Large bur from periphery to the center b. Large bur from center to periphery c. Small bur from periphery to center d. Small bur from center to the periphery

. Large bur from periphery to the center - use the largest bur that fits, and go around the periphery and then towards the deepest

Axial pulp should be? ______ mm into DEJ

0.2 - 0.5 into DEJ

QUESTION: Diameter of 245 bur?

0.8 mm

Position of incisal portion of matrix band? # mm above adjacent marginal ridge

1 mm above adjacent marginal ridge.

What bur do you use to shape convergent walls for amalgam ->

169

Rotary high speed, how many round per min?

200,000 RPM - slowspeed goes 20-30k average, endo = usually 800

What bur use for amalagam retention in class II? 245 or 330

245

Which is best for occlusal convergence in a prep?

245 (169 is better for occlusal)

Example of pear shape bur: 329, 330, 245 (330L)

245 (330L) 245 = 330L = pear and elongated bur (tip is a cone)

Placing pin in amalgam restoration, Amt in tooth/restoration/angulation = #mm

2mm

Proper pulpal floor depth using Bur 245?

3mm, so half of it is 1.5 mm which is proper pulpal floor depth

What is the hardest (most rigid) gold? Gold Type #

4

Reason for using porcelain for posterior onlay (bond to dentin, to correct occlusion, etc)

????

Which bur do you use for peds? A.245 B.18 C.51

A.245

What is the reason to burnish gold to the margin?

Acute angle of gold margin

Material to use for best interproximal contact of a CLASS II is

Admix Amalgam (others Spherical amalg., Composite w/ and w/o filler) - Admix materials = better for proximals contcts b/c of higher condensation forces

Overtriturating amalgam? sets too fast, decreases setting expansion, increase compressive strength

All of the above

Which is a characteristic of a gold inlay?

Axial walls converge toward the pulpal floor (axial pulpal walls = divergent prep) - From facial to lingual, the axiopulpal line angle of an onlay preparation is longer than the axiogingival line angle (if it were not, the preparation would be undercut and the onlay would not seat). For an MOD onlay prep, the axial walls must converge from the gingival walls to the pulpal wall (for the same reason, the onlay would not seat if they diverged).

Most likely for amalgam to fail? Outline cavity design, poor condensation

Outline cavity design,

What is wrong about retention pin? Better retention with bigger pin. follows axial, 0.5mm in DEJ.

Better retention with bigger pin.

What's the difference between an enamel hatchet & gingival marginal trimmer?

Both chisels but GMT has curved blade and angled cutting edge while Enamel HA has cutting edge in plane of handle

You did a prep with high speed + diamond bur and tooth is sensitive, what is it about bur and handpiece that it caused sensitivity? A) Desiccation B) Traumatized dentin C) Heat

C) Heat

Bur used for polishing -

Carbide have more threads, STEEL FOR POLISH

When prepping the amalgam, which is incorrect? Cavo surfaces is _______ than 90 degrees

Cavo surfaces is greater than 90 degrees - Ideal cavo margin (margin between tooth and your prep) is 90 degree

Chisel vs spoon application:

Chisels are intended primarily to cut enamels, but spoons remove caries & carve amalgams

BWX, Tooth #18 has mesial amalgam restoration with overhang and very light contact. What lead to this? A wedge was not placed right poor adaptation of matrix band

poor adaptation of matrix band

Zinc in amalgam, what is used for?

Decreases oxidation of other elements (deoxidizer) Zinc acts as a deoxidizer, which is an O2 scavenger that minimizes the oxides formation of other elements in the amalgam alloys during melting.

If there is water while you are condensing amalgam, what happens? severe expansion, corrosion delayed expansion decreased compressive strength

Delayed expansion

What happen to amalgam with moisture contamination? delayed .....

Delayed expansion

deform (without fracture) under tensile strength; ability to stretch into wire - greatest ductility to least: gold, silver, platinum, iron, nickel, copper, aluminum, zinc, tin, and lead.

Ductility -

Gold casting wrong? Due to hygroscopic expansion or setting expansion

Due to hygroscopic expansion - Plaster expands during casting so gold casting will be smaller than expected

What instrument would not be used to bevel the gingival margin of an MOD prep?

Enamel Hatchet

Advantage of inlay over amalgam?

Esthetics, less tooth reduction

Recently placed gold inlay on upper tooth is opposing lower amalgam, what is the most common reason for pain afterwards? __________ shock

Galvanic shock - Galvanic shock Sensitivity - choose this if only question says opposing dissimilar metal.

QUESTION: MOD amalgam with hole why?

poor condensation - condensation removes mercury (gamma mercury removed)

divergent walls (2-50 per wall), 300 bevel margins for better fit, skirt - extend beyond line angle - resistance/retention: 2-50 of taper per wall as tall as possible. - Primary retention is from wall height & taper. - Secondary retention is from retention grooves, skirts, and groove extensions.

Gold inlay/onlay Prep:

QUESTION: Reduction dimension for functional/non-functional cusps in gold and PFM Gold: functional = non-function = PFM =

Gold: functional = 1.5, non-function = 1. PFM = 1.5-2mm

Most common reason for Amalgam fracture occuring in a primary tooth: Inadequate ......

Inadequate cavity prep (especially the isthmus area)

How far do you extend the pulpal floor in class I amalgam cavity on primary dentition? - 1mm into dentin - Just into dentin

Just into dentin (total prep should 1.5 mm so 1 mm for enamel & ~ 0.5 mm for dentin

QUESTION: When do use base metal opposed to gold?

Long span bridges (FPD) - need it be more rigid = more base metal

Mercury poisoning effects?

Loss of hair was a choice (I looked it up, and I think that is the answer)

deform (without fracture) under compressive strength; ability to form a thin sheet - Greatest malleability to least: gold, silver, lead, copper, aluminum, tin, platinum, zinc, iron, and nickel

Malleability -

What is true of amalgam within a year after placement Marginal leakage increases as restoration ages Marginal leakage decreases as restoration ages No marginal leakage

Marginal leakage decreases as restoration ages - b/c it gets filled with corrosion products

Burs for smoothing out preps? More flutes and shallow more flutes and deeper less flutes and shallow less flutes and deeper

More flutes and shallow (this is what red burs are)

Is the isthmus the same for inlay and amalgam ->

NO - isthmus is convergent for amalgam & divergent for inlay.

Where is it acceptable to leave unsupported enamel?

Occlusal wall of class V amalgam - It's not a bearing surface so you can leave unsupported enamel in class V

From pt images, which amalgam filling has the lowest Copper content?

One that looks corroded.

Which high speed bur gives a smoother surface?

Plain cut fissure bur = best cross cut fissure have a higher cutting efficiency

QUESTION: Greatest wear on enamel of the opposing tooth: amalgam, porcelain, microfill, hybrid composite, Porcelain (zirconia)

Porcelain (zirconia)

Two class III lesions adjacent to each other (kissing lesion). Which one do you prep first & which will be filled first?

Prep larger 1st Restore smaller 1st

Which is the only surface not beveled for an onlay?

Pulpal

QUESTION: What's the best way to prevent proximal dislodgement/fracture of class II amalgam filling? • Retentive grooves (for proximal resistance) • converging axial walls (B&L walls) • depth of prep

Retentive grooves (for proximal resistance) • converging axial walls (B&L walls)

Proximal retention in class II box for amalgam?

Retentive grooves, convergence of facial lingual walls, bevel on axiopulpal line angle, all of the above, none of the above

More # of blades on carbide burs:

SMOOTHER, DECREASED CUTTING EFFICIENCY

How to remove a gold inlay?

Section isthmus and remove in 2 pieces

Amalgam large condenser with lateral condensation is used in:

Spherical

What type of amalgam needs to be condensed more?

Spherical

What do u not use when beveling gingival margins?

Tapered diamond - Causes enamel fracture

Patient had occlusal amalgam on tooth #30 few weeks ago, one day the dude went to Chinatown and was having lunch with his hommies. He bit down on something and the amalgam broke off. He came back to your office demanding how could this happen with a new filling. What should be crossing your mind?

The prep was not deep enough.

What would cause displacement of odontoblastic processes? Thermal Dessication Mechanical Chemical

Thermal

What is the most accurate pulpal test to determine vitality of a tooth with a full-gold crown? Electric testing Percussion test Palpation test Thermal test

Thermal test

What causes displacement of odontoblastic nuclei in the dental tubules? Thermal, mechanical, chemical, caries, dessication

Thermal, - related to hydrodynamic theory I think so I put thermal

Put wedge in (before or after) matrix

after

Huge MOD in posterior -> restore with ......

amalgam

Restoration of class 2 for posterior with heavy occlusion amalgam, composite, microfill

amalgam,

Resistance form for amalgam prep: bevel in the...

bevel in the axiopulpal line angle to reduce stress and increase RESISTANCE form. - resistance = keeping the restoration from fracturing, "ways to resist stress" - smooth floor & line angles. Flat walls are right angles of tooth's long axis.

QUESTION: Weakest part of the gold mod inlay is?

cement layer (cement = weakest part of cast gold restoration)

Pt w/ onlay, 3yrs later sensitivity-

cement wash out?

How to account for mesial concavity on maxillary 1st premolar when restoring with amalgam: custom wedge acrylic within matrix normal matrix create overhang and recontour

custom wedge

QUESTION: Main Disadvantage of gold inlay a. deforms under load b. wear opposing c. cement is soluble (not soluble) d. possible attrition

deforms under load since it is high noble gold and softer, it may have higher creep

What type of Mercury is in the dental office? Inorganic elemental

elemental

QUESTION: What do you not use to bevel an inlay prep? a. enamel hatchel b. ging marg trimmer c. flame diamond bur d. carbide bur

enamel hatchel

QUESTION: Only advantage of porcelain over gold:

esthetics.

QUESTION: Why do we bevel the edge of gold-

finish margins better, marginal stability & better adaptation

Zinc phosphate can be used for

gold. - Zinc phosphate is used as a cement for gold & PFM (basically metals). Zirconia can't bond to it so we use GI.

Most common pulpal damage from cavity prep -

heat, dentin dessication

Most common reason for failed amalgam moisture contamination improper prep design - not enough depth improper titrutration

improper prep design - most likely depth (first), than outline form

Differences between 245 and 330 burs: All other dimensions the same except for length shape what angle they form.

length 245 bur is 3mm in length 330 is 1.5mm.

Which tooth will the matrix band be a problem with when placing a two surface amalgam? to give an idea of the anatomy of the region:

mesial on maxillary first molar b/c of the cusp of carabelli also - mesial Of max 1st premolar (MOST DIFFICULT due to mesialdevelopmental grove, contact is harder) > Distal of max molar

For amalgam, the most toxic mercury is: Elemental mercery, ethyl mercury, methyl mercury (organic mercury)

methyl mercury (organic mercury)

Type of mercury most hazardous to dentist health: methyl mercury, ethylmercury, inorganic mercury, elemental mercury

methyl mercury,

Acute mercury toxicity for dentists or subacute mercury poisoning symptoms, the first signs is: , other are

nausea, other are muscle weakness (hypotonia) and hair loss.

You have an amalgam that is deficient at the margin by 0.5mm (concavity) and no signs of recurrent decay. What do you do: remove and replace, observe/monitor, repair with amalgam

observe/monitor,

Isthmus of MOD prep extends over 1/3 of intercuspal dimension, how to treat? amalgam, crown, onlay, inlay crown

onlay, - Inlays when less than 1/3 intercuspal dimension is prepped

Picture of a deep amalgam w/ overhang: What is wrong with marginal ridge of DO amalgam of #29? All of the following except ? Occlusal wear, over carving, wedge not placed right, overcarved

overcarved

Increasing intercuspal space affects ...... form

resistance

Marginal ridges help with....... form

resistance

Loss of marginal ridge affects ........

resistance and retention

Removing cusp affects ........ form

retention

Removing cusp affects......... form

retention

QUESTION: Dentist has to reduce a weak cusp during onlay preparation is to: a) outline form b) resistance form c) retention form

retention form - Cuspal coverage - retention form

QUESTION: Effects burnishability in gold - yield .....

strength

What happens to amalgam if it is contaminated with water/moisture? Decrease in .....

strength

More corrosion of amalgam is in which phase?

tin-mercury phase (gamma 2 phase) -Noble metals (gold, pd, platinum) are CORROSION RESISTANT while silver & tin erode - most common corrosion products found with conventional amalgam alloys are oxides and chlorides of tin - silver tarnish but copper & tin corrode

When is onlay indicated?

when cuspal coverage is needed or when cusp is undermined by not enough dentin