Phillips Dental Material Impression Materials Flashcards
According to Phillips Dental Materials: What is agar/reversible hydrocolloid?
An aqueous impression material used for recording maximum detail
According to Phillips Dental Materials: What is alginatre/irriverasable hydrocolloid?
An aqueous impreesion material used for recording minimal detail
According to Phillips Dental Materials: What are characteristics of ZOE impression paste?
Cannot be removed past undercuts without distortion Impressions become rigid Inelastic Do not compress the tissue during seating Hard tissue structures of the mouth
According to Phillips Dental Materials: What are characteristics of elastic impression material?
Can be stretched or compressed slightly Can rebound without permanent deformation Accurately reproduce hard and soft tissue structures of the mouth
According to Phillips Dental Materials: What are characteristics of Elastomeric Impression Materials?
Rubbery polymers which are either chemically or physically cross-linked Cross-linked by either condenstaion or addition reaction
According to Phillips Dental Materials: What are the 4 sub -types of Elastomeric Impression Materials based on viscosity classes?
1 light body 2 medium body 3 heavy body 4 putty
According to Phillips Dental Materials: What are the 4 main types of Elastomeric Impression Material?
1 Polysulfide 2 Condensation Silicone 3 Addition Silicone 4 Polyether
According to Phillips Dental Materials: What type of impression material is VPS (vinyl polysiloxane)
Addition Silicone
According to Phillips Dental Materials: What characteristics does VPS have?
Addition reaction polymer is terminated with vinyl groups and is cross-linked with hydride groups activated by a platinum salt catalyst
According to Phillips Dental Materials: Does VPS reaction cause by-products?
No, it is addition polymerization NOT condensation
According to Phillips Dental Materials: During the VPS reaction what can occur during a secondary reaction between moisture and residual hydrides of the base polymer? What can be added to decrease this?
Development of hydrogen gas, this results in tiny bubbles to form in the stone if it is poured immediately A noble metal such as platinum or palladium can act as a scavanger for the released hydrogen gas
According to Phillips Dental Materials: Is VPS hydrophillic or hydrophobic? What is added to changes this?
Hydrophobic by nature A nonionic surfactant is added to render the surface of the impression hydrophilic
According to Phillips Dental Materials: What is the material in natural latex and some vinyl gloves to inhibit the setting of VPS impression material?
Sulfur contamination
According to Phillips Dental Materials: Working time is measured at what temperature? Setting time is measured at what temperature?
Working time= room temperature Setting time= mouth temperature
According to Phillips Dental Materials: As viscosity increases what do working and setting times do?
Decrease
According to Phillips Dental Materials: Which of the 4 types of elastomeric impression materials suffer the greatest and the least amount of linear contraction?
Condensation Silicone is the most Addition Silicone is the least
According to Phillips Dental Materials: What is the chief active ingredient of alginate?
Soluble Aginates such as sodium, potassium or triethanolamine alginate
According to Phillips Dental Materials: What is “dustless” alginate?
“Dustless” Alginate has incorporated glycerine on the alginate powder to prevent airborne fine silica poarticles that can pose a health hazard after long term exposure
According to Phillips Dental Materials: What is the sol-gel reaction of alginate?
The reaction of soluble alginate with calcim sulfate and the formation of an insoluble calcium alginate gel
According to Phillips Dental Materials: Why is a thrid water-soluble salt added to the solution for alginate?
To extend working time, the third salt is known as a retarder
According to Philips Dental Materials: What are two factors that commonly influence setting time?
Temperature of the water Contaminates such as gypsum can acclerate the set
According to Phillips Dental Material:
What are the advantages and disadvantages of VPS?
According to Phillips Dental Materials: What are the advantages and disadvantages of alginate?
