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Sequences of operations
Fixed dentures:
Full crown
Made of metal alloy (gold or chromcobalt)
1. Phase in dental office
Preparation
Reduction 0,5 mm around, occlusaly 1 mm
Preparation border – shoulderless or very slight round shoulder,
located subgingivally 0,5 mm.
Taking impression
Elastomeric impression materials
Polysulfid, silicon, elastomers.:
Before the impression the retraction cord is applied around the tooth – subgingivally in
order to open gingival sulcus and take an exact impression of this area.
Dual viscosity technique.
a) Dual viscosity technique – double impression or
b) Simultaneous dual viscosity technique.
Antagonal impression of alginate
Occlusal registration (wax)
1. Phase in dental lab.
Making the cast (model) of gypsum (pouring the impression).
There are three types of base raw materials derived from partial dehydratation of gypsum
rock:
Plasters – fluffy, porous, least dense.
Hydrocal – hihger density, more crystalline
Densite – densest of the raw material.
Plasters----- model plaster, lab plaster
Hydrocal----dental stone
Densite ------high strength dental stone
High strength dental stone is used for fixed dentures.
Wax pattern
Lost wax method. – investment and casting, finishing.
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2. Phase in dental office
Try of the crown and its cementation.
Metal ceramic crown
Made of metal alloy ( usu chromcobalt) and ceramics which covers completely the metal
framework
These crowns are fully covered with ceramic material.
1. Phase in dental office
Preparation
Reduction 1 mm around, occlusaly 1, 5 mm.
Preparation border - rounded shoulder located subgingivally 0,5 mm.
Taking impression
Elastomeric impression materials
Polysulfid, silicon, elastomers.:
Before the impression the retraction cord is applied around the tooth – subgingivally in
order to open gingival sulcus - an exact impression of this area is necessary.
Dual viscosity technique.
a) Dual viscosity technique – double impression or – two phases
b) Dual viscosity technique – one phase
Antagonal impression of alginate
Occlusal registration (wax)
1. Phase in dental lab.
Making the cast (model) of gypsum (pouring the impression).
There are three types of base raw materials derived from partial dehydratation of gypsum
rock:
Plasters – fluffy, porous, least dense.
Hydrocal – hihger density, more crystalline
Densite – densest of the raw material.
Plasters----- Model plaster, lab plaster
Hydrocal----dental stone
Densite ------High strength dental stone
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On the model the technician makes wax pattern of the metal framework of the
metalceramic crown.
The wax is changed with the metal alloy used the lost wax method. – investment and
casting,
After casting follows the finishing of the framework
2. Phase in dental office
Trying of the metal framework and choice of colour
2. Phase in dental lab
Making of the ceramic coat (fully covered crown)
special procedure – firing in a special oven in several phases.
3. Phase in dental office
Trying of the crown and cementation
Facette crown
This crown is made of the metal alloy (golden or chromcobalt), partially covered with
composite or methylmethacrylic resin. Resin covers the metal framework on the vestibular
side.
1. Phase in dental office
Preparation –
Reduction 1 mm vestibulary, orally 0,5 mm, occlusally 1 mm
Preparation border: rounded shoulder located 0,5 subgingivally
Taking impression
Elastomeric impression materials
Polysulfid, silicon, elastomers.:
Retraction cord around the tooth
Dual viscosity technique.
a) Dual viscosity technique – double impression or – two phases
b) Dual viscosity technique – one phase
Antagonal impression
Alginate
Occlusal registration (wax, elastomeric materials)
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2. Phase in dental lab.
Making the cast (model) of gypsum.
There are three types of base raw materials derived from partial dehydratation of gypsum
rock depending on on the nature:
Plasters – fluffy, porous, least dense.
Hydrocal – hihger density, more crystalline
Densite – densest of the raw material.
Plasters----- Model plaster, lab plaster
Hydrocal----dental stone
Densite ------High strength dental stone
On the model the technician makes
Wax pattern
Lost wax method. – investment and casting, finishing of the framework
3. Phase in dental office
Trying of the metalframework and choice of the colour
3. Phase in dental labe
Making of veneer (partially covered crown)
There are two possibilities:
If the facette is made of the composite material – the material is applied directly on the
metal framework and cured.
If the facette is made od methylmetacrylic resin – te facette is modelled of wax, put into
the flask (two parts) with plaster, after the plaster has been set, the wax is removed with
hot water and replaced with resin dought, closed again and the resin is polymerized in hot
water.
The procedur eis principally the same as with jackette crown made of methylmetacrylic
resin.
Jackette crown – ceramics, resin, composite
1. Phase in dental office
Preparation –
Reduction 1 mm around, incisally 1, 5 mm
Preparation border – rectangle shoulder
Located subgingivally 0,5 mm.
Taking impression
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Elastomeric impression materials
Polysulfid, silicon, elastomers.:
Retraction cord around the tooth
Dual viscosity technique.
a) Dual viscosity technique – double impression or – two phases
b) Dual viscosity technique – one phase
Antagonal impression
Alginate
Occlusal registration (wax, elastomeric materials)
1. Phase in dental lab.
Making the cast (model) of gypsum.
There are three types of base raw materials derived from partial dehydratation of gypsum
rock depending on on the nature:
Plasters – fluffy, porous, least dense.
Hydrocal – hihger density, more crystalline
Densite – densest of the raw material.
Plasters----- Model plaster, lab plaster
Hydrocal----dental stone
Densite ------High strength dental stone
On the model the technician makes
Wax pattern – not of the casting wax, but of modelling wax (pink colour)
The model must be isolated.
The wax model of the crown is put into a flask (two parts), after the plaster has been set,
the wax is removed with hot water and replaced with resin dought, the flask is closed and
the resin is polymerized in hot water.
2. Phase in dental office
Try and cementation.
REMEMBER! BEFORE TAKING THE IMPRESSION THE GINGIVAL SULCUS
MUST BE OPEN USING THE RETRACTION CORD!
The cord is emoved after the imperssion with the thick materiál before the impression
with cream is used.
If one phase technique of the impression is used, the retraction cord is removed before
taking the impression.