Prosthetics II.
Fixed dentures nlay, root canal inlay
Fixed dentures
> Cemented (fixed) on/in pilots, abutment teeth.
> Inlays (inlays, onlays, overlays, partial crowns).
> Crowns
> Bridges
Fixed dentures
Cemented on the teeth - crowns, bridges, inlays
Fixed bridge
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Fixed dentures
Material - metal alloy, ceramics
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Removable dentures
Partial
Complete (fu
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Procedures
> In dental surgery
> In dental laboratory
> Special instruments
> Basic (main) materials
(metal alloys, ceramics,polymers)
> Auxilliary (accessory) materials
(impression, carving, die, insulating investing, grinding, polishing)
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Manufacturing of dentures
Model of gypsum (plaster) - model of a denture (wax pattern).
Model of a denture (wax pattern) directly in the mouth - rarely.
Denture is formed without a wax pattern in the dental lab.
lenka.roubalikova@tiscali.cz
Manufacturing of dentures
Model of gypsum (plaster) - model of a denture (wax pattern).
lenka.roubalikova@tiscali.cz
Impressions of the jaw - negativ
The impression is filled with a casting material (gypsum) - poured into
Model (various purpose)
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Models
> Working model - the denture is produced on this model (special procedures)
> Opposing model (antagonal) - necessary for the recognition of intermaxillary relationship
> Bite regitration - wax
lenka.roubalikova@tiscali.cz
Manufactoring of dentures principle of lost wax method
>The denture (not the denture itself but the model of the denture) is produced on the working model.
>The model of the denture is made of the carving wax.
>The wax is replaced by the main (base) material.
lenka.roubalikova@tiscali.cz
Fabrication of dentures
The model (wax) of the denture is invested
The wax is removed from the form and the base material is placed into the form.
Wax removal:
The wax is burned out (for metal alloys) or removed by hot water (for polymers)
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Manufacturing of dentures
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Manufacturing of dentures
Direct method
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Manufacturing of dentures
Direct method
No impression The model of the denture is made directly in the mouth
For inlays only
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Rigid fillings
Manufactured in a dental lab
Direct or indirect method
Direct method rarely
Indirect method most common
■ Crown inlay - a part of a clinical crown is replaced
Root canal inlay
The inlay is cemented into the root canal and replaces a crown (abutment tootlw stump, snag)
Crown inlay
Material
> Composit
> Ceramics
> Metal Alloys
r
Angle of convergence
>0° - maximum > 6° - very good >15°- acceptable >20° - insuficient
Optimum 6° -15'
Crown inlays
Indikations
A big lost of dental tissues Big interdental spaces
Next to the crowns and bridges made of metal alloy
Contra - indication
Crown inlays
7. Too small - shallow (flat) cavities
2. High caries risk
3. Frontal area (metallic)
Partial crown
Retention of rigid fillings
Whitstand capability aaainst axial forces:
Geometry of the preparation Quality of the luting material
(facilitating shape)
Rau G. 1994
Retaining areal
Surface of contact
Inlay or crown (internal, outer, combined)
Stability of rigid fillings
Whitstand capability aqainst horizontal
forces
Angle of convergence Axial length contact surface
Basic rules of cavity preparation
>Box
> No undercuts
> Light divergence of the walls (facilitating shape)
• ■
t3
Box
Undercuts
Simple box Facilitating form
nlay of metal alloy
Direct method
Indirect method
nlay of metal alloy
> Direct method
Direct modellation in the mouth Special wax - casting wax, (special polymers) Sprue pin Investment
Method of the lost wax
nlay of metal alloy
Direct method
> Central cavities (class I., classs V.)
> Root canal inlays
nlay of metal alloy
Indirect method
Taking of the impression Model
Modellation of the casting wax, (special polymers) Sprue pin Investment
Method of the lost wax
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Dokončená preparace
Nasazená rekonstrukce
Aesthetic inlays - composite materials, ceramics
Special procedure
Indirect method always
Root canal filling
Root
Root canal inlay
Core
Crown
Indication :
Root canal inlay
Restoration for teeth with lost crown
(cca 2/3 of the crown)
It is anchored in the root canal
(the tooth must be endodontically treated)
The coronal part is formed as a stump for the crown
It enables to treat this teeth with crown
Contraindication
Teeth that cannot be treated endodontically
Decay of the root or coronal part of the crown
Less than 1 mm hard dental tissues supragingivally
Destruction of root canal walls circulary
Root canal inlay - preparation
Removal of the root canal filling (2/3), 4 mm of the root canal filling must be left.
The third rule
Direct method
Isolation
Modellation - casting wax, heated, flowing
Sprue pin with reservoir
Sprue cone
Investment
Lost wax method
(burntout in the special oven)
Indirect method
Impression
Model
Modellation - casting wax, heated, flowing
Sprue pin Investment Lost wax method
(burntout in the special oven)
Indirect method
Impression material
Model
Insulation
Model lation
/
Indirect method
Impression
Model
Modellation - casting wax, heated, flowing
Sprue pin Investment
Method of the lost wax
(burntout in the special oven)
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Cementation
Zinkoxid phosphate cement Lentulo
Vaseline
Removal of access of the cement