Studied by 3 people
NOT ALL
Clinical Products
include bite registration wax, disclosing wax (also known as pressure-indicating paste), utility waxes for altering and adapting impression trays, and low-melting type I inlay waxes used in the mouth for direct-waxing processes for pattern production
Laboratory Products
include boxing wax, baseplate wax, sticky wax, beading wax, utility wax, and hard, medium, and soft type II inlay-type waxes for making patterns on patients’ models using the indirect wax technique
Synthetic Waxes
are chemically synthesized from natural molecules; most synthetic waxes are homogeneous than pure natural waxes
Natural Waxes
are derived from mineral, vegetable, and animal origins
40-60%
most dental waxes contain ___-___% paraffin by weight, which is derived from high-boiling fractions of petroleum
Paraffin Wax
→ flakes when trimmed
→ does not produce a smooth, glossy surface, which is a desirable requisite for an inlay wax o thus, other waxes and natural resins must be added as modifying agents
Gum Dammar or Dammar resin
→ natural resin
→ added to the paraffin to improve the smoothness in molding and to render it more resistant to cracking and flaking
→ increases the toughness of the wax and enhances the smoothness and luster of the surface
Carnauba Wax
→ occurs as a fine powder on the leaves of certain tropical palms
→ very hard, has a relatively high melting point and has an agreeable odor
Candelilla Wax
→ provides the same general qualities as carnauba wax but its melting point is lower and it is not as hard as carnauba wax
Ceresin
→ white wax extracted from ozokerite, a waxy mineral mixture of hydrocarbons that is colorless or white when pure, but it has a somewhat unpleasant odor
→ may replace part of the paraffin to modify the toughness and carving characteristics of the wax
WAX PATTERN REMOVAL
→ Wax pattern should be removed from the die without any distortion of wax → Any motion that might distort the wax pattern should be avoided during removal
SPRUE DIAMETER
→ Select a sprue former with a diameter that is approximately the same size as the thickest are of the wax pattern
SPRUE POSITION
→ The position of the sprue former attachment is often a matter of individual judgment and intuition, based on the shape and form of the wax pattern
greatest bulk
→ Ideal position for the sprue formes is the point of _____________ in the pattern to avoid distorting thin areas of wax during attachment to the pattern and permit complete flow
SPRUE ATTACHMENT
→ The sprue former should be directed away from any thin or delicate parts of the pattern because the molten metal may abrade of fracture investment in the area and result in a casting failure
SPRUE LENGTH
→ The length of the sprue former depends on the length of casting ring. Sprue too short = wax pattern will be removed from the ring due to porosities
→ Gypsum bonded – 6 mm from the top; phosphate bonded – 3-4 mm
Phosphate-Bonded
these investments are designed primarily for alloys used to produce copings or frameworks for metal-ceramic prosthesis and some base metal alloys; it can also be used for pressable ceramics
Ethyl Silicate-Bonded
investments used principally for the casting of removable partial dentures made from base metals (Cobalt and Nickel based alloys)
Gypsum-Bonded
-based materials type represent for the traditionally used conventional casting of gold alloy inlays, onlays, crowns, and larger fixed dental prostheses (FDPs)
High Heat Casting Technique
1 min. can pass without noticeable change
Low Heat Casting Technique
the alloy should be cast right after removal from the oven
Clay Crucibles
crown and bridge alloys, such as the high noble and noble types
Carbon Crucibles
high noble crown and bridge alloys but also for the higher-fusing gold-based metal-ceramic alloys
Air Supply for the Lower Frame
→ incomplete combustion and a lower temperature will result → this type of flame is likely to be favored by the beginner because the roaring sound that accompanies this flame adjustment “sounds” hot
Upper Brush Flame
→ indicates the proper adjustment for maximal efficiency and temperature
Non-Combustion Zone
→ no heat is present
Combustion Zone
→ green and immediately surrounding the inner cone
→ the gas and air are partially burned
→ this zone is oxidizing and should always be kept away from the molten alloy during fusion
Reducing Zone
→ dimly blue and located just beyond the tip of the green combustion zone
→ this is the hottest part of the flame and it should be kept constantly on the alloy during melting
Oxidizing Zone
→ outer cone is the area in which combustion occurs with the oxygen in the air
→ under no circumstances should this portion of the flame be used to melt the alloy
→ not only is its temperature lower than that of the reducing zone but it also oxidizes the alloy
base metal alloys
the highest temperatures are required for
750 C to 1030 C
burnout temperatures for phosphate-bonded investments range from
