3

WELCOME

3

TO

FIXED PROS

Daily Lab Projects 50% Quiz, Midterm, Final 50%

You must pass both the lab and the written independently

Do not be late

YOU HAVE 5min FOR EACH ESSAYEACH QUESTION IS 2PTS

50 QUESTIONS TOTAL: 15 QUIZ

15 Midterm20 final

Some of you

Will........

Fail

Worse situations exist

What happens when I fail?

remediation90 crown preparations

and a 3hr 10 preparation practical

Perfection

CAD-ucation

Save Dental Education

Of students will have over $100,000 of debt

2000 2004 2008 2012

85K

105K

160K

240k

Of female dental students Cost of tuition

Pre-clinical Curriculum

Of classes that are not dental

The NEW wayGrading

“Vision trumps all other senses.

DR. JOHN J. MEDINA

”

30%70% 0%

PFM Gold All-Ceramic

7 years ago30%70% 0%

PFM Gold All-Ceramic

7 years ago30%70% 0%

PFM Gold All-Ceramic

7 years ago30%70% 0%

PFM Gold All-Ceramic

7 years ago30%70% 0%

PFM Gold All-Ceramic

7 years ago30%70% 0%

PFM Gold All-Ceramic

7 years agoDental School Private Practice

3%MOSTLY 2ND

MOLARS

0.5mm chamfer878K 016

Gold Preparation

3-6° taper

1mm supra-gingival

1mm axial

1-1.5 occlusal reduction

Functional cusp bevel

B L

Posterior PFM

Ceram metal Restorati ns

(PFM, PBM)

Incisal Porcelain

Dentin Porcelain

Opaque

Metal Coping

1950's by Dr Abraham Weinstein

in 1997 they made up 80% of all crowns and bridges

2016 they made up 10% of all crowns and bridges

replaced by all-ceramic crowns

PFM crowns as seen here can have metal exposed in unestetic areas to allow for more conservative reduction in those areas

(1mm vs 1.5mm)

metal occlusals are perfect for bruxers

Ceram metal Restorations

(PFM, PBM)

1mm

2mm

B L

Rule: Do not want >2mm

porcelain unsupported

Porcelain fracture from the metal framework

Porcelain fracture from the metal framework

1mm heavy chamfer878K 018

3-6° taper1mm supra-gingival unless in esthetic zone may

place 0.5mm sub-gingival using cord for controlled margin lowering

1.5mm axial

1.5-2mm occlusal reduction

or

847kr 018

PFM Preparation

1mm round shoulder

follow reduction for gold if you have areas that you want to keep

in metal

Functional cusp bevel

B L

l

Things to avoid with Finish Line design

“lipped”

When you use greater than 1/2 the diameter of a chamfer diamond or greater than the entire

diameter of a shoulder diamond. Therefore it is easier to lip a finish line with a chamfer diamond

than a shoulder diamond.

BeveledShoulder

We do not use a beveled shoulder at MUSC

chamfer lip shoulder lip Do not over reduce

over reduced

Things to avoid

over taper

arbitrarily placing sub-gingival finish lines

Bridges

PFM alloys: usually

phosphate bound

investment

High noble: ≥ 60% with ≥ 40% goldNoble: ≥ 25% nobleBase: < 25% noble

Porcelain bonds through covalent chemical bond to oxide layer. Must add tin indium iron or gallium for

oxide to form.

Must have CTE of metal>ceramicwant melt temp 300-500 > porcelain fusing temp

Ante’s Law

In 1926 Ante suggested that is was unwise to provide a fixed partial denture when the root surface area of the abutment was less than the

root surface area of the teeth being replaced.

never more than 3 pontics, even 2 is

risky

CEMENT

Zinc Phosphate: Classic cement, long track, Low PH (sensitivity without varnish?) No Bond,

Mixed on frozen glass slab to increase working time. Not pop anymore

Glass Ionomer Chemical bond to tooth, FL release, Good strength, sensitive to moisture/

desiccation during placement, CTE same as tooth

Zinc Polycarboxylate weak but present bond to tooth esp enamel through calcium chelation, kind

to pulp

RMGILike GI but lower solubility, higher strength. Bad CTE, contradicted for all

ceramics.

ResinGood mechanical properties and high bond, ideal for all-ceramic restorations

Terminology

Fixed Partial Denture

Retainer: 1:2 ratio ideal, 1:1 very minimum and must be small span(1

pontic)

Soldering Flux: dissolves oxides and Increase flow and Wets melts 150 below fusion temps.

Sodium PyroborateBoraxSilica

0.25mm

Strength depends on SA but Height most important

anti- Flux: graphite, limits area of flux

double width, strength doubleddouble height strength cubed!

Ridge lap, (Saddle)

Modified Ridge lap

Bullet (Heart, Conical)

Ovate

Sanitary, (Hygienic)

Saddle Pontic (ridge lap)

plaque accumulation

Chronic inflammation

Modified Ridge Lap

eliminate concavity

Posterior

Anterior

Tissue contacting crest of ridge.

Hygienic Pontic (sanitary)

Hygienic Designs

conventional

Perel

Bullet Pontic (heart shaped)

Ovate Pontic

No “black triangles”

Bridges may have rigid connectors …

… or non-rigid connectors

(Ideal)

(Contraindicated for mobile retainers)

Posterior Ceramic

All Ceramic

6-10° taper In Posterior preserve enamel at margins!

1.5mm axial

1.5-2mm occlusal reduction

1mm round shoulder

more rounded

Functional cusp bevel

Round internal line angle

847kr 018

1.0mm

“Measure Twice Cut Once”

preserve enamel

B L

Non-anatomical Reduction!

Non-anatomical does not mean Flat!

M

B

D

B L

Non-Anatomical

Anatomical

Non anatomic reduction improved crown adaptation

Anatomic reduction increased gap, thinner ceramic

Heavy Chamfer

No undercuts

No prepsLeaning

1mm

1.5mm

Smooth Margins???

Rounded Shoulder

Rounded Shoulder

Lipp

ed

Clinical Case

Anterior PFM

“No form of Nature is inferior to Art; for the arts merely imitate natural forms” Marcus Aurelius

imitate nature

Laboratory Technique

body (dentine) porcelain

incisal (enamel) porcelain

PFM (cross-section)

opaque

metal coping

Pros1. Strong 2. Can be esthetic 3. Can be used for Bridges 4.Can have metal on occluding surfaces

ConsExpensive

1. Usually not esthetic 2. Prep must have retention 3.Porcelain breaks off over time 4. Must hide unaesthetic

margins below tissue

margins exposed

margins exposed

not natural

not natural

"If I had eight hours to chop down a tree, I'd spend six sharpening

my axe." — Abraham Lincoln

Get a good look at the natural tooth

Visualize the prep before you start

Visualize prep within tooth

1.5mm

2mm

1mm

F L

1mm

1.3mm

1.5mm1mm

0.5mm

"measure twice and cut once."

Inadequate facial reduction

HEAVY facial reduction

Lingual wall undercut

correct incorrect

B BL L

Inadequate lingual reduction

Shoulder

(variations)

Sloped Shoulder Beveled

ShoulderShoulder

(rounded internal line angle)

Heavy Chamfer Chamfer Feather

Terminology Variations

Beveled ShoulderChamfer Feather

Metal Only

Beveled Shoulder

60%sub-gingival margins will be exposed within

2 yearsShillingburg, Jr, DDS, Herbert T.. Fundamentals of Fixed Prosthodontics, 3rd Edition. Quintessence Publishing (IL), 011997. 25.3.4)

No Metal Collar

00 cord will lower the tissue 0.25-0.5mm

Shoulder

(variations)

Sloped Shoulder

Beveled Shoulder

Shoulder (rounded internal line angle)

Heavy Chamfer

Chamfer Feather

Terminology Variations

Avoid a lipped margin

“lipped”“lipped”chamfer lip

shoulder lip

Avoid a lipped margin

greater than 1/2 the

diameter of a chamfer diamond

greater than 80% the

diameter of a round shoulder

diamond

1.5mm

1. mm

0.5 mm

1. Describe a PFM crown preparation on an anterior tooth including mm of reduction, planes of reduction, reduction for metal lingual vs ceramic lingual and finish line design.

2. Describe a PFM crown including layers, thickness of layers, composition of

ceramic, bonding mechanism

0.5mm chamfer878K 016

Gold Preparation

3-6° taper

1mm supra-gingival

1mm axial

1-1.5 occlusal anatomical reduction

Functional cusp bevel

B L

1mm heavy chamfer878K 018

3-6° taper1mm supra-gingival unless in esthetic zone may place 0.5mm sub-gingival using cord for controlled margin

lowering

1.5mm axial

1.5-2mm anatomical occlusal reduction

or

847kr 018

PFM Preparation

1mm round shoulder

follow reduction for gold if you have areas that you want to keep in

metal

Functional cusp bevel

B L

All Ceramic

6-10° taper1mm supra-gingival unless in esthetic zone may place 0.5mm sub-gingival finish line using cord for controlled

finish line lowering. In Posterior preserve enamel at margins!

1.5mm axial

1.5-2mm occlusal reduction

0.8-1mm round shoulder

non-anatomical=smooth and rounded

Functional cusp bevel

Round internal line angle

847kr 018

1.0mm

“Measure Twice Cut Once”

preserve enamel

B L

847kr 018

2mm2mm

At MUSC we must achieve a circumferential 2mm

vertical ferrule effect where the

finish line is on solid tooth structure cervical to a

filling or core.

3mm 3mm

It is important to maintain biologic width where 3mm is

needed between the margin of the crown and the crest of

the ridge. If this is in violation, or predicted to be in violation,

a perio consult for crown lengthening is mandatory.

Critical errors that may result in an automatic failure

“lipped”

When you use greater than 1/2 the diameter of a chamfer diamond or greater than the entire diameter of a shoulder diamond. Therefore it is easier to lip a finish line with a chamfer diamond than a shoulder diamond.

BeveledShoulder

We do not use a beveled shoulder at MUSC

chamfer lip shoulder lip Do not over reduce

over reduced

1.0mm

847kr 018

over taper

arbitrarily placing sub-gingival finish lines

Critical errors that may result in an automatic failure