types of crowns - the audss

FIXED PROSTHODONTICSTypes of Crowns

Dr Elena Hotinski BDSc (UWA), DClinDent (Pros)

Specialist Prosthodontist @drelenahotinski

Types of Crowns1. Full Gold Crowns (FGC)

2. Metal Ceramic Crowns (PFM / PBM)

3. All Ceramic Crowns

• Lithium Disilicate / Glass Ceramic (e.g. E.max)

• Monolithic Zirconia

• (PBZ)

4. (Partial Crowns / Inlays / Onlays / Veneers)

5. Endocrowns

6. Vertical Crown Preparations

7. Surveyed Crowns

Types of Crowns1. Full Gold Crowns (FGC)

2. Metal Ceramic Crowns (PFM / PBM)

3. All Ceramic Crowns

• Lithium Disilicate / Glass Ceramic (e.g. E.max)

• Monolithic Zirconia

• (PBZ)

4. (Partial Crowns / Inlays / Onlays / Veneers)

5. Endocrowns

6. Vertical Crown Preparations

7. Surveyed Crowns

Not covered in this lecture

Full Gold Crowns• Used for teeth that require full coverage and

aesthetic demands are low

• Can mask very dark / black underlying tooth structure

• Retainer for posterior bridgework

• Abutment teeth for partial dentures (surveyed crowns)

• Extremely long lasting

• Excellent for high load situations (e.g. bruxers) as they can’t fracture

Full Gold Crowns

• Advantages:

• Superior strength

• Longevity superior to all other fixed restorations

• Conservative preparation

Full Gold Crowns• Disadvantages:

• Not tooth coloured (‘inferior’ aesthetics)

• Any type of crown preparation involves removal of healthy tooth structure

• Potential adverse effects on the pulp and periodontium

• Shouldn’t be carried out if a more conservative restoration is possible (e.g. onlay)

Preparation of Full Gold Crown

Supplementary retention groove can be added for very short teeth (either on mesial /

distal or buccal / lingual)

FULL GOLD CROWNS

Indications Contraindications Advantages Disadvantages

Posterior, high load locations (e.g. bruxers)

Anterior teeth / any teeth visible in smile

Superior strength, longevity, and marginal fit

‘Inferior’ aesthetics / display of metal

RCT’d teethIntact thick buccal or lingual

wall (more conservative restoration may be possible)

Can mask very dark / black underlying tooth structure

Very expensive (high lab costs)

Partial denture abutment teeth (surveyed crown) No chipping / fractures

Single teeth or posterior bridgework

Metal Ceramic Crowns• Used for teeth that require full coverage and

aesthetic demands are significant but an all ceramic crown is not appropriate

• Very deep sub gingival margins (use of metal margins in these areas often best)

• Very dark / black underlying tooth structure

• Long span or posterior bridgework

• Abutment teeth for partial dentures (surveyed crowns)

Metal Ceramic Crowns• Advantages:

• Combines strength of an all metal crown with the aesthetics of ceramics

• Can be used in high stress situations (e.g. parafunction) with metal occlusal surface

• Can look very natural and aesthetic with a good lab technician

• Easier preparation than partial crowns

• Proven longevity with a large amount of supporting literature

Metal Ceramic Crowns• Disadvantages:

• Significant amount of tooth reduction required

• Buccal margin often has to be placed subgingivally for aesthetic reasons

• Aesthetics not as good as all ceramic crowns

• Can appear slightly greyish and more opaque (not as translucent)

• Difficult shade selection

• Need good laboratory support

Preparation of Metal Ceramic Crown

“Winged” Preparation “Wingless” (Preferable)

METAL CERAMIC CROWNS


Moderate aesthetics required Large pulp chamber on vital tooth

Superior aesthetics compared to full gold crown

Removal of substantial tooth structure required

Very deep sub gingival margins

Intact thick buccal wall (consider onlay)

Can mask very dark / black underlying tooth structure

Veneering porcelain is brittle and subject to fracture

RCT’d teeth that are severely discoloured

When more conservative restoration is possible Well established track record Shade selection can be

difficult

Partial denture abutment teeth Inferior aesthetics compared to all ceramic crown

Long span / posterior bridgework Expensive / high lab costs

Very difficult to polish once porcelain has been adjusted

(lab needs to reglaze)

All Ceramic Crowns• Highly aesthetic

• No underlying metal

• Most closely resemble natural tooth structure in colour and translucency

• Final appearance of glass ceramics (e.max) can be influenced by the colour of the core, the colour of the underlying tooth structure, and different coloured cements

• Main disadvantage is susceptibility to fracture

• This risk is reduced with modern resin bonding and higher strength materials

All-Ceramic Crowns - e.max

• Advantages:

• Superior aesthetics due to excellent translucency

• Lack of metal reinforcement means slightly more conservative prep than metal ceramic

All-Ceramic Crowns - e.max

• Disadvantages:

• Reduced strength without metal substructure**

• More significant tooth preparation required on proximal and lingual aspects

• Material is unforgiving if tooth is under prepared

• Can fracture due to brittleness or sharp internal line angles

• Colour may be incorrect if underlying tooth structure shines through

• If ceramic is adjusted and not polished properly, can cause wear of opposing teeth over time

All Ceramic Crowns

• Modern Methods of Fabrication:

1. Heat Pressing

2. Slip Casting

3. Milling

Method of Fabrication e.max press

https://www.youtube.com/watch?v=ooRPBw4Zj60



Preparation of All Ceramic Crown

ALL CERAMIC CROWNS - E.MAX


High aesthetic requirementWhen superior strength is

warranted and metal ceramic crown is more appropriate

Best aesthetics Reduced strength compared to metal ceramic crowns*

Heavily restored teeth, preferably with remaining

enamel

Thin teeth bucco-lingually or very short teeth

Good tissue response, even with sub gingival margins

Proper preparation extremely crucial

RCT’d teeth with post/cores but not severely discoloured

Insufficient coronal tooth structure for support

Slightly more conservative of buccal wall than metal

ceramic crownsBrittle nature of material

Favourable distribution of occlusal load

Unfavourable distribution of occlusal load / bruxism

Can only be used for single crowns or anterior 3-unit

bridges

All-Ceramic Crowns - Monolithic Zirconia

• Very high flexural strength, fracture toughness, and modulus of elasticity compared to other ceramics

• Very opaque material

• Core material and cement colour have no effect on final appearance

• Can mask discoloured underlying tooth structure

• Monolithic = one solid piece of material

• No veneering material therefore no problems with fracture of the veneering ceramic


• Advantages:

• Can have very good aesthetics

• Extremely high strength and fracture toughness

• No veneering ceramic over the top therefore no problems with chipping

• Can be a very conservative preparation


• Disadvantages:

• Very opaque (limited translucency)

• If you need to do chair side adjustments, MUST polish it properly otherwise can be very abrasive to opposing tooth

• Can’t be bonded to tooth structure as reliably as glass ceramics

• Still awaiting long term studies on performance

All Ceramic Crowns

• Modern Methods of Fabrication:

1. Heat Pressing

2. Slip Casting

3. Milling

Method of Fabrication Monolithic Zirconia

Preparation of Monolithic Zirconia Crown

Minimum 0.5mm

0.3mm -

• Margins:

• 0.3-0.5mm shoulder or heavy chamfer

• Occlusal:

• 1mm non-functional cusps

• 1.5mm functional cusps

• Absolute minimum 0.5mm

https://www.southerncrossdental.com.au/useful-information/tooth-preparation

ALL CERAMIC CROWNS - ZIRCONIA


Posterior crowns with aesthetic requirement

Insufficient coronal tooth structure for support

Good aesthetics with experienced technician

Very opaque and monochromatic

When superior strength is warranted but not enough space

for metal ceramic (short teeth)Need superior aesthetics? Good tissue response (very

biocompatible) Proper polishing crucial

RCT’d teeth that are moderately discoloured

More conservative preparation than metal ceramic crowns

Single crowns or bridgework Superior strength

Unfavourable distribution of occlusal load / bruxism Very cheap / low lab cost

Shade Taking for Glass Ceramics

Must take a natural die / stump shade for any e.max restorations.

Different shades of resin cement are available to make minor changes to the final colour of all ceramic (e.max) restorations. There are equivalent shades of try in pastes to test first before final bonding.

- Transparent - Yellow - Opaque - White

Shade Taking for Glass Ceramics

Endo Crowns• Alternative option for restoring very broken down root canal

treated molars using the pulp chamber for extra macro-mechanical retention

• Fabricated from a single block of ceramic material (usually e.max) that is bonded with resin cement (micro-mechanical retention)

• Useful in very short, broken down molars where there is limited interocclusal space

• Not suitable for anterior teeth or premolars

• Easier clinical procedures (preparation / impression) than normal crowns but can be more difficult to temporise

Sedrez-Porto et al. 2016; Biacchi et al. 2013

Preparation of Endo Crown

Einhorn et al. 2019

90° butt joint margin

Smooth internal line angles (can block out undercuts with composite)

Occlusal reduction at least 2-3mm

Supragingival enamelmargins wherever possible

6° internal taperof pulp chamber

Flat pulpal floor withsealed radicular spaces

(not mandatory to extend into root canals)

Vertical Crown Preparations

• Also known as “vertipreps”

• Crown preparation without a defined margin or finish line

• Finished to a knife edge or feather edge, also called ‘shoulderless’

• Lab technician chooses where to put the margin in close consultation with the dentist

Vertical Preparation

Agustin-Panadero et al. 2016

Prepare supra-gingival finish line

15° angulation to eliminate first 1mm of

crown emergence

Creation of vertical plane between crown

and root

Vertical Crown Preparations• Advantages:

• Preservation of more tooth structure in cervical area

• Therefore often used for periodontally compromised teeth

• Seemingly more simple, faster preparation and impression procedure

• Final margin can be finished at various different levels without compromising fit of margins

• Often guided by level of gingival tissues

• Less prone to have a micro gap at margin

Vertical Crown Preparations• Disadvantages:

• No long term evidence to support supposed benefits

• Small number of lab studies and case reports only

• Extremely technique sensitive

• Need excellent laboratory support and communication between dentist and technician

• Technician cannot differentiate between tooth structure and core material on model

• Often end up with crown margin finishing on filling material

Surveyed Crowns• Teeth that are planned to serve as abutments for a new partial CrCo dentures are sometimes

prepared for crowns before the commencement of denture fabrication

• Indications:

• Necessary to restore a broken down tooth to serve as partial denture abutment OR

• Natural tooth that is to be a partial denture abutment cannot be altered to provide:

• Suitable path of insertion

• Adequate retentive area

• Favourable contour (reciprocal area or guide plane)

• Rests in desired areas

• Favourable occlusal relationship

• Final crown incorporates a guide plane, rest seat and undercut based on partial denture design

• Need to dictate the location of each of these features on lab form

• Usually metal ceramic crowns with partial denture features in metal

Chandler, Brudvik & Fisher 1973

Questions?

types of crowns - the audss

Documents