Upload
navya-anil
View
1.234
Download
66
Embed Size (px)
Citation preview
Good morning...
Dental Dentalwaxeswaxes
Dental waxes Dental waxes
• Waxes have several applications indentistry.
Components of dental waxes Components of dental waxes
Natural wa xes
Synthetic w axes
Additives
•Mineral•Plant•Insect•Animal
•Acrawax C• Aerosol O T•Castorwax• Aldo 33
• Stearic acid•Oils•Colorants•Resins
Natural waxes Natural waxes
Complex combination of organic compound s of high molecular weights.
Two principle groups of organic compounds contained in waxes are-
HYDROCARBONS &ESTERS
Natural waxes Natural waxes
• Mineral waxes-distillation product of petroleum • Parrain• Microcrystalline• Barnsdahl• Ozokerite• Ceresin• Montan
Plant waxesEg)carnaubua wax-occurs as fine powders on leaves of certain tropical plants
Insect waxEg –bee wax
Synthetic waxes Synthetic waxesNatural waxes are not consistent in their
composition and properties, so to overcome this synthetic waxes are used.
• They are highly refined Acrawax C• Eg)• Aerosol OT• Castorwax• Aldo 33
Wax additivesWax additives• Fats• Oils• Resins• Gums- to improve the properties of
wax
FatsFats• Increase the melting range and the ha
rdness of compound waxes.
OilsOils• Hydrocarbon oils - soften mixture of w
axes.
• Silicone oils - improve the ease of poli shing with waxes.
ResinsResins
• Most natural resins are obtained from trees and plants.
• improve toughness, hardness, meltin g range of waxes
Properties Properties of of waxes waxes
Melting range Melting range
• They have melting range rather than m
elting point.• Mixing of waxes change their melting
range
Thermal expansion Thermal expansion
• Expand when temp. is risen
• Contract when temp. is decreased
• Dental waxes have the largest coefficient of thermal expansion.
Mechanical properties Mechanical properties
• The elastic modulus, proportional limit and compressive strength of waxes are low compare with those of other materi
als and these properties depend strong ly on the temperature.
FlowFlow• Flow is dependent on the temp. of the
waxes.
• Flow is greatly increase as the melting point of the wax is approached.
DuctilityDuctility
• Ductility increase as the temp of a wax is increase
• Waxes with lower melting temp. have a g reater ductility.
• The highly refined waxes is quite brittle
- Dental wax Classification - Dental wax Classification
• Pattern waxes• Processing waxes• Impression waxes
Pattern wax Pattern wax• An artificial dental restoration is first made
with pattern wax,whch is later replaced with permanent material eg)cast gold alloys, co-cr-ni alloys or poly methyl methacrylate resin
1)1) Pattern wax Pattern waxeses
1. Inlay waxes
3. Baseplate waxes2. Casting waxes
2)2) Processing wax Processing wax
• Used primarily as auxillary aids in th e construction a variety of restoratio
ns and appliances either clinically or in the laboratory
Processing waxes Processing waxes
1. Boxing waxes
2. Utility waxes
3. Sticky waxes
4. Carding waxes
3)3) Impression waxes Impression waxes
• Used for taking impression within the mouth.
– Bite registration waxes– Corrective waxes
Korecta wax
Alu wax
1. Inlay waxes
Inlay wax Inlay wax :: CCompositionomposition
Paraffin (major portion)
Microcrystalline waxCeresin
CarnaubaCandelillaBeeswax
Inlay waxes generally are produced in deep blue , green , or purple rods or sticks.
The flow can be reduced by adding more carnueba wax o r by selecting
higher melting paraffin waxes.
Inlay pattern wax Inlay pattern wax
• A pattern of the wax is first constructed in inlay wax .
Inlay pattern wax Inlay pattern wax
• The pattern then is embedded in a gyp- sum silica investment material to form
a mold with an ingate or sprue leading from the outer surface of the investme
nt mold to the pattern.
Inlay pattern wax Inlay pattern wax
• The wax is subsequently eliminated by h eating & softening and the mold is furthe
r conditioned to receive the molten metal.
Inlay pattern wax Inlay pattern wax
Inlay waxes : Properties Inlay waxes : Properties
ANSI/ADA Specification No. 4 for denta l inlay casting wax.
Type I wax = a hard wax that is prescribe d for forming direct patterns in the mouth.
Type II wax = a softer wax that is used as an indirect technique wax.
FlowFlow The working temperature for making direc
t wax pattern must not to be so high as to cause damage to the vital tooth structure.
At mouth temp., direct inlay wax must hav e essentially no flow to minimize the possi
bility of distortion of the pattern during re moval from the tooth cavity.
Casting wax Casting wax
The pattern for the metallic framework of r emovable partial denture and other similar structures is fabricated from the casting wa
xes.
Casting wax : Casting wax : CCompositionomposition
The ingredients are similar to tho se found in inlay waxes.
Baseplate wax Baseplate wax
Baseplate wax derives its name fro m its use on the baseplate tray in th
e technique for complete denture r estoration.
It’s normally pink color.
Baseplate wax Baseplate wax
Baseplate wax : Baseplate wax : CCompositionomposition
- 70 80 % paraffin or ceresin small quantities of other waxes & additi
ves. typical composition
– - 80 12% ceresin % beeswax– 25. % carnuaba– 3% natural or synthetic resins– 25. % microcrystalline or synthetic wax
Baseplate wax : Baseplate wax : PPropertiesroperties
ANSI/ADA Specification No.24– Type I - Soft, building contours and
veneers– Type II - Medium, patterns in mouth, normal climates– Type III - Hard, patterns in mouth,
in tropical climates
Linear thermal expansion from 25o-40oC < 08. %
Softened sheets shall cohere readily witho ut becoming flaky or adhering to fingers No irritation of oral tissue
trim easily with a sharp instrument at 23oC
Practical requirements Practical requirements
Smooth surface after gentle flaming No residue on porcelain or plastic teeth
Coloring shall not separate or impregnat e plaster during processing
No adhesion to other sheets of wax or se parating paper on storage
Practical requirements Practical requirements
Beading &Beading & Boxing wax Boxing waxUsed to build up vertical walls around the
impression,in oder to pour the stone and make the cast
ADVANTAGES OF BEADING & BOXING
1)Preserves the extensions & landmarks
2)Controls the thickness of borders
3)Controls the form and thickness of the base of cast
4)Conserves the artificial stone
Boxing wax: Boxing wax: WW orking properties orking properties
- -Federal specification No U W 138 Smooth, glossy surface on flaming
Pliable at21o C , retain shape at35
o C
Seals easily to plaster with hot spatula
Utility wax Utility wax
Used in numerous instance most likely consists of beeswax, petrola
tum and other soft waxes
Used to adjust contour of perforated tray for the use with hydrocolloid(to raise flange height, to extend the tray posteriorly and to raise palatal portion of the tray in case of deep palate)
Sticky wax Sticky wax
It is sticky when melt and adheres closely t o the surface on which it is applied. It is firm, free from tackiness and brittle at
room temp. Rosin & yellow beeswax are the usual majo
r constituents.
Used for assembling/joining metal parts before soldering and for joining fragments of broken repair procedure
Corrective impression wax Corrective impression wax
Used as a wax veneer over an original imp ression to contact and register the detail o
f the soft tissue .To record posterior palatal seal in dentures
Formulated from hydrocarbon waxes such as paraffin,ceresin & beeswax and may co
ntain metal particles
The flow at37o
C is 100%
Corrective impression wax Corrective impression wax
Bite registration wax Bite registration wax
Used to record the relationship bwn upper and lower teeth .this is necessary to mount cast correctly in articulator
Formulated from beeswax or hydro carbon waxes such as paraffin or ce
resin and contain alumina or coppe r particle
Bite registration wax Bite registration wax
• Alu wax
Bite registration wax Bite registration wax
• Occlusal indicator wax