4. Waxes Flashcards
Dental Waxes Compositions Three general components • \_\_\_\_ waxes: – \_\_\_\_ – Plant – \_\_\_\_ - Insect • \_\_\_\_ Waxes • \_\_\_\_
natural mineral animal synthetic additives
COMPOSITIONS Natural Waxes • Mineral Waxes (\_\_\_\_, Ceresin) From \_\_\_\_- mixture of \_\_\_\_ • Wide range of molecular \_\_\_\_ and \_\_\_\_ ranges • Partly \_\_\_\_ • Flaky, not \_\_\_\_ or glossy surface
paraffin ceresin petroleum hydrocarbons wt. melting crystalline smooth
COMPOSITION Natural Waxes Plant Waxes (\_\_\_\_)
- ____, Acids, Alcohols, resins
- Hard and ____, high ____ range
- Used to ____ the melting range and hardness of ____ waxes.
carnauba esters brittle melting increase paraffin
Plant waxes - Carnauba
From a Brazilian ____ - they pick the leaves, crush and ____ until the wax kind of flakes off the surface. Contributes to the glossy ness of the mineral waxes
Plant waxes - Candelillia
Found in ____ from Mexico, tend to be used in cosmetic industry. Extracted from ____ the plant to separate the wax (floats to the top) from the plant material.
palm tree
dry
shrubs
boiling
COMPOSITIONS Natural Waxes
Animal Waxes (____)
• ____, and unsaturated hydrocarbons
• Modifies ____
• Spermaceti wax is the coating for ____ from sperm whale
spermaceti
esters
properties
dental floss
COMPOSITIONS Natural Waxes • Insect (\_\_\_\_) Main component of \_\_\_\_ . Esters, Sat. and Unsat. \_\_\_\_, and organic acids . Brittle but becomes \_\_\_\_ at body temp.
This is the wax that you should stabilize your ____ with after you take a model, it becomes brittle so if the models ever shift from the articulation the wax will be brittle and dislodge
beeswax
sticky wax
hydrocarbons
plastic
impression
COMPOSITION Synthetic Waxes
- ____ from batch to batch
- Similar properties to ____ waxes
- Limited ____ with other waxes
Synthetic waxes include:
• ____ waxes, wax esters
• ____ glycol waxes
• ____ and hydrogenated waxes
Synthetic waxes are usually consistent and are usually used as ____ materials. They increase rigidity and modify the ____ of the wax
consistent
natural
compatibility
polyethylene
polyoxoethylene
halogenated
impression
crystallinity
COMPOSITIONS
Additives
• Gums : viscous, ____, harden on exposure to ____
• Fats : tasteless, ____, colorless, feel greasy. Increases ____ range and ____
• Resins : produce ____ products
Gums: since they are amorphous they have no definite ____ shape
Amalgam restorations used to be lined with something called a copalite and it was made from a resin called ____ (a naturally brittle resin dissolved in an organic solvent) and was thought to decrease ____ Only placed with ____ NOT resin bc it prevented them from curing
amorphous air odorless melting hardness harder
crystalline
copa
sensitivity
amalgam
Properties of Waxes • \_\_\_\_ Range • Thermal Expansion • \_\_\_\_ Properties • Flow • \_\_\_\_ Stress • Ductility
melting
mechanical
residual
PROPERTIES OF WAXES
Melting Range
• Waxes contain different types of molecules so they have melting ____ instead of melting ____.
• Most waxes contain ____ wax and ____ wax. When combined in a 75% to 25% mixture the ____ range dramatically increases
The graph is how it changes the melting of the waxes.
“At the beginning with just the mineral wax the melting range is very small, but as you increase the contribution of the plant to mineral wax the melting range increases”
ranges
points
paraffin
carnauba
PROPERTIES OF WAXES
Thermal Expansion
- Waxes ____ when subjected to a rise in temp and ____ as temp decreases.
- Dental waxes have the largest coefficient of ____ than any other dental material.
- Many waxes have at least ____ rates of expansion between ____ and ____o C . The changes occur at ____ points.
- That is very important bc all of the cast restorations are waxed up, so you want to make sure that you invest it and cast it and not let it sit for an extended period of time, bc the ____ change after its sat for a while. You will learn this when making a gold crown in GRD 2. If you make up and inlay or a PFM and dont invest and cast it in time then changes can occur and the final restoration may not fit
expand contract thermal expansion 2 22 52 transition
properties
PROPERTIES OF WAXES
Thermal Expansion
Clinical consequence of High ____
Changes in wax patterns after critical dimensions are set may be a major contributing factor to ____ of the finished restoration.
expansion
inaccuracy
PROPERTIES OF WAXES
Mechanical Properties
- Elastic Modulus, Proportional Limit and Compressive Strength are ____
- Dependent on ____
- The modulus of the inlay wax is important in the ____ of casting investment in which the wax pattern is subjected to stresses resulting from the expansion of investment during setting.
Elastic modulus - elasticity, when the impression is subject to ____ or compression
Proportional limit - greatest stresses the material can sustain before ____
Compressive strength - ____, especially within the forces of mastication in registration wax
low temperature hygroscopic expansion tension deviation resistance
PROPERTIES OF WAXES
Flow
• ____ of molecules over each other. Flow is dependent on the ____ of the wax
• Direct inlay wax technique
– ____ flow required a few degrees above ____ temp.
- instead of preparing a tooth for a class 1 amalgam you would prepare it for a class 1 inlay then melt the wax directly in you prep and set at mouth temp so you could remove it without ____ in any way. So this property of the flow of wax became very important
slippage temp high mouth deforming
PROPERTIES OF WAXES Flow
• Direct inlay wax technique
– At mouth temp. An inlay wax must have no ____ to prevent ____ of the pattern during removal from the tooth cavity
flow
distortion
PROPERTIES OF WAXES Residual Stress (____ Effect)
• Residual stress exists in a completed pattern due to ____ from adapting the wax
Why not just soften the wax in the preparation and have the pt bite down? This is memory effect (residual stress), if you force it into the cavity and take the impression but once you remove it and the external walls aren’t there to hold it in it tends to ____ again bc of all of the molc that were forced in there originally
memory
pressure
expand
PROPERTIES OF WAXES
Ductility
- Like flow, ductility increases as the ____. of the wax specimen is increased
- Waxes with ____ melting temps have a greater ductility at any given temp than those with higher melting temps
- Generally highly refined waxes are ____
- Ductility of mineral waxes increases if appreciable amounts of occluded ____ is present
All of the properties of wax are ____ dependent.
2. When you use beading wax you can mold it just from the heat of your ____, compared to something like inlay wax that you have to melt in order to flow and stretch
Ductility is defined as the ability of the material to be ____ deformed
temp lower lower brittle oils
temp
hands
plastically
Classification
Pattern: ____, inlay, ____
Processing: ____, boxing, ____
Impression: bite, ____
Classification based on ____ and ____
Pattern waxes have 2 important properties: 1. the thermal changes that occur in ____ (meaning its temp sensitive). 2. There is a tendency for the waxes to warp or distort on ____. You cant let it set for an extended period of time.
Processing waxes are used as auxiliary aids. What i said about beading wax and boxing wax so that you can pour up a model within an area as opposed to the double pour technique where you pour the model in the impression and make a patio on the desk of your red rubber cast formers. What you would do instead would bead of use the red utility wax to surround the impression then use the boxing wax to surround the utility wax and you can pour your model the ideal way. This was the air bubbles rise up as compared to a 2 pour technique where you flip the impression over onto a patio on the desk and air bubble rise to the occlusal surface as opposed to the base of the cast (listened to this 3x she is pretty wordy here idk rambles a ton)
Impression waxes used if you know that the pt has an ____ (especially for a denture) you can make the impression using a bite or corrective type wax to be able to remove it from the undercut easily
casting
baseplate
utility
sticky
use
application
dimesnion
standing
undercut
