How do you make an impression with polysulfide?
– One technique using polysulfide impression material for a full-denture impression is to mix a drop of water with the material to accelerate the setting. – Polysulfide impression material is often used with custom trays to increase the accuracy of the impression.
What is the difference between polyether impression and polysulfide impression?
The hydrophilic nature of polyether impression material is manifested in carbonyl (C=O) and ether (C-O-C) groups, whereas polysulfide material has hydrophilic disulfide (-S-S-) and mercaptan (-S-H) groups .
What is the common name for polysulfide?
– Often, polysulfide materials are called “rubber” or “rubber base” materials, even though polyether and silicone materials are also rubber materials. Polysulfide, polyether, and silicone materials are also called non aqueous elastomeric impression materials.
Can you use polysulfide impression for crowns?
– With proper handling, polysulfide impression materials can be used for inlays, crowns, and bridges. – However, they are not as accurate as other non aqueous elastomeric materials. – A polysulfide impression should be poured within several hours after mixing.
What is polysulfide used for?
Applications of Polysulfide Modified Epoxy Adhesives Aircraft fuel tank sealants. Industrial tank liners. Electrical potting. Corrosion protection of offshore structures.
What is polysulfide material?
The polysulfide sealing compound is a kind of even ointment sealing material which uses the LP liquid polysulfide rubber as the base material mixed with curing agent, plasticizer and filler through the treatment of blending. From: Building Materials in Civil Engineering, 2011.
Is polysulfide a rubber base?
If you need a dental impression material that can remain accurate even if there is moisture like saliva or blood, polysulfide is a good choice. Also known as Rubber Base, this soft material allows for base impressions that can be easily removed from the mouth.
Is polysulfide an elastomeric?
BRIEF HISTORY OF ELASTOMERIC IMPRESSION MATERIALS Polysulfides were the first elastomeric impression materials. For over 30 years, these remained the primary elastomeric material of choice until polyethers burst on the scene with their improved hydrophilicity.
What is polysulfide coating?
Polysulfide sealants are designed for joints that need to withstand prolonged immersion in liquids. Typical applications include swimming pools, fountains, cooling towers, fuel and chemical storage tanks, wastewater treatment and petrochemical plants.
What is the difference between polysulfide and polyurethane sealant?
Polysulfide sealant is a type of sealant designed for joints that have to withstand prolonged immersion in liquids. Polyurethane sealant is a type of sealant having single-component elastomeric sealant properties that tend to dry at humidity and at room temperature.
What is the disadvantage of using a polysulfide material?
Polysulfides have a long working and setting time, which is an advantage when impressions are being taken of multiple preparations, but a disadvantage when only one or two teeth have been prepared.
What is true polysulfide?
Polysulfides are a group of chemical compounds made up of sulfur atom chains which posses solvent, chemical, and weather resistance in addition to flexibility and tensile strength. These compounds are primarily used as additives in the production of rubbers, sealants, and adhesives.
How is calcium polysulfide made?
Calcium polysulfide is produced by reacting lime with sulfur in boiling water. The resultant solution is highly alkaline (pH 11.5-11.8) and corrosive.
Why is lead added to polysulfide?
According to the manufacturer, the polysulfide polymer has a low molecular weight, comprising terminal and pendent mercaptan groups. The lead dioxide catalyzes the condensation of the terminal and the pendent groups with -SH groups in other molecules, lengthening and cross-linking the chain.
What are the different types of elastomeric impression materials?
Four types of elastomeric impression materials are available in the market: addition silicone, also known as polyvinyl siloxanes (PVS), condensation silicone, polyether, and polysulfide.
What is non aqueous elastomeric impression material?
WHAT IS NON-AQUEOUS ELASTOMETRIC IMPRESSION? They are synthetic polymers with rubber properties after setting. Used to make the final impressions for indirect restorations and implants. All teeth in the arch and the soft tissues immediately surrounding the tooth preparation must be reproduced in the impression.
Which type of bite registration material is most popular?
Addition silicones are popular as dental impression materials and are used in bite registration procedures.
How is light bodied material placed around a prepared tooth?
A special syringe, or extruder, is used to place the light-bodied material on and immediately around the prepared teeth.
Is polyvinyl siloxane hydrophobic?
Vinyl Polysiloxane Impression materials (VPS) are most frequently used as the impression material in fixed prosthodontics. As VPS is hydrophobic when it is poured with gypsum products, manufacturers added intrinsic surfactants and marketed as hydrophilic VPS.
What is the relationship between dental impressions and silicones?
Relationship of Properties and Clinical Application. Accuracy, the ability to record detail , ease of handling, and setting characteristics are of prime importance in dental impressions. Silicones generally have shorter working times than polysulfides but somewhat longer times than polyethers.
What are elastomeric impressions?
Elastomeric impression materials such as polysulphide, the silicones and polyether ( Chap. 7) are supplied in collapsible tubes (much like toothpaste). These are to be proportioned for mixing according to the length of the extruded ‘rope’, either of one part when the other reactant is in a liquid to be dispensed by counting drops, or for both parts in ‘paste-paste’ systems. The basic difficulty here is that the width of the extruded material depends on both the rate of extrusion (how hard one squeezes the tube) and on the speed of movement of the tube. It is notoriously difficult to achieve the requisite balance. It is not helped by the fact that the viscosities of the two components are often different, requiring a different amount of effort. The tube nozzles are usually of different sizes when the volume proportions are not 1 : 1, i.e. the rope thickness is supposed to be adjusted to give equal lengths when the ratio is correct. This may make judgement more difficult because of the conceptual conflict between volume and length.
How long does it take for elastomeric impressions to recover?
Insignificant elastic recovery occurs after 20 to 30 minutes; therefore, dies should be prepared promptly after that time for greatest accuracy. Addition silicones that release hydrogen are an exception to this guideline.
Why are elastomeric impressions not as accurate as the first?
Second pours of gypsum products into elastomeric impressions produce dies that are not quite as accurate as the first, because the impression can be deformed during the removal of the first die; however, they are usually sufficiently accurate to be used as a working die.
How does deformation affect the accuracy of an impression?
The accuracy of the impression may be affected when the percentage of deformation and the time involved in removing the impression are increased . In both instances, permanent deformation increases, the amount depending on the type of elastomeric impression material.
Which is more potent, hydrogen sulfide or polysulfide?
Polysulfides have recently gained attention for their importance in the brain and other tissues, where they activate transient receptor potential channels even more potently than hydrogen sulfide.
Is polysulfide a chemical?
However, the existence of polysulfides in the biological environment is only partially compatible with their known chemical properties since polysulfides are usually not resistant to reducing conditions and high concentrations of thiols (e.g., glutathione) as they contain a highly reactive sulfane sulfur [40,46].
What is permlastic impression?
Permlastic is a polysulfide, condensation-cured, elastomeric impression material in three viscosities. Regular Permlastic is recommended for partial- or full denture impressions because it has a high degree of flow that will register the finest detail.
What is heavy body permlastic?
Heavy-Bodied Permlastic is formulated for use whenever a stiffer material is indicated. The heavy body consistency results in optimum compression of the Light-Bodied Permlastic in a double-mix, copper-band impression.
