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25 Cards in this Set
- Front
- Back
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Cements can work by one of three types of bonding mechanisms?
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-Non-adhesive luting
-Micromechanical bonding -Molecular adhesion |
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What is non-adhesive luting, give an example?
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-Luting has the purpose of filling the gap and prevents the entrance of fluids. ALL cement "lute"
-Example: Zinc Phosphate (no adhesion on molecular level-hold the restoration in place by engaging small irregularities on surface of both and restoration) |
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What is micromechanical Bonding, give an example?
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-Cement that work via micromechanical bonding penetrate into dsmall, deep surface pits (micromechanical require surface to be etched first before cement applied.
-Enamel need to be etched w/ phosphoric aid gel and Ceramics need to be etched w/ hydrofluoric acid -Metal need to be treated electrolytic etching, chemical, sandblasting -Example: Resin cement, Resin-modified-GC |
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What is Molecular adhesion, give an example?
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-Molecular adhesion refers to physical forces (bipolar, Van Der Waals, chemical bonds-ionic & covalent)
-Example: Polycarbonates & GI. -Thin layer of silane added to gold alloys serves as a coupling agent by bonding chemically to resin cements. This inculdes silane coupler * electroplated tin |
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Advantages and Disadvantages of Zinc Phosphate?
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-Advantage: Long clinical HX of success, Good mechanical properties, Low cost
-Disadvantage: Lack of bonding, Lack of fluoride release, Potential pulp irritation (pH= 3.5) |
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Advantages and Disadvantages of Polycarboxylate?
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-Advantage: bond to enamel (chelate to Ca2+), less pulp irritation compared ZnPO4 (Due to larger size of polyacrylic molecule = can't penetrate dentinal tubules)
-Disadvantages: Thixotropic property, high viscosity and less working time than ZnPO4, Plastic deformation (not suited for use in areas of high masticatory stresses or long span FPDs |
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Wha tis Thixotropic property?
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Substance which are thick like a solid but which flow like a liquid when a sideways force is applied
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Advantages and Disadvantages of Glass Ionomer? (Ketac-Cem)
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-Advantages: bond to tooth structure, chelates to Ca2+, bacteriostraic during setting phase, Fluoride release
-Disadvantage: pH is lower than ZnPO4 during setting, Weakened by early exposure to mositure, Desiccation produces shrinkage cracks |
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Advantages of RMGI?
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-Combines wanted properties of GI, Fluoride release and adhesion to tooth structure and the higher strength, low solubility of resin
-Less susceptible to moisture exposure -Most popular general practice |
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What are the 3 components of Resin cements?
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-Resin matrix: Bis-GMA or UDMA
-Filler particles: quartz, glass or colloidal silica of various size and shape -Silane coupling agents -Include accelerators and initiators that llow self-curingm light curing, and dual curing |
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Composite resin cement come in 3 classes?
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-Class 1: self cured materials
-Class 2: light-cured materials -Class 3: dual-cured materials |
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Advantges and Disadvantags of Resin cement?
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-Advantages: bonding capabilities, lack of solubility, higher mechanical properties, translucency of the material
-Disadvantages: Short working time, high film thickness, stress concentration, less biocompatibility (when not fully polymerized) |
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Properties of dental cements can be examined by ten aspects?
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1. Adhesion to tooth surface
2. Adhesion to restorative materials 3. Adequate strength to resist functional forces 4. Lack of solubility in oral fluids 5. Ability to achieve low film thickness under cementation conditions 6. Biocompatibility w/ pulpal tissues 7. Possession of anticariogenic properties 8. Radiopaque 9. Relative ease of manipulation 10. Esthetic or color stability |
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What are the two types of strength in cements?
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-Compressive strength (cylindrical samples)
-Diametral tensile strength (disc-like sample) |
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How is Polycarboxylate in relation to strength of cements?
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-Exhibits plastic deformation at substhreshold levels.
-Plastic behavior is undesirable in dental cement = loss of retention of cemented restorations |
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What is Fick's Law of Diffusion?
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-The greater the gap, the greater the propensity for dissolution
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Describe GI and RMGI in relation to solubility?
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-GI: quite soluble in 1st 24, after which quite resistant to dissolution
-RMGI or Resin cements: almost insoluble in oral fluids |
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Some techniques to improve teh seating of castings include:
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Internal relief of cast restoration using sandblasting, mechanical milling w/ burs
-Occlusal venting -Axial grooves -Use of die spacer -Devices for application and maintence of seating forces -Vibration during cementation |
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What is the old and new concept of Biocampatibility w/ pulpal tissues?
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-Old concept: phosphoric acid component causes pulpal infllammation
-New concept: All commonly used dental cements elicit no long-term pulpal responses -But post-cementation sensitivity remains a controversial issue (especially GI & ZNPO4) |
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What does Anticariogenic property means?
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-Does cement release fluoride
-GI cement release fluoride |
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Why is radiopacity is desirable properties?
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-Helps distinugish b/t cement line and recurrent caries, detecting cement overhangs
-Impt that luting agents have greater radiopacity than dentin = held avoids problems with interpretations |
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What is the trend of relative ease of manipulation of cements?
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-Newer materials are more technique sensitive and more critical manipulation of these materials leds to problem such as marginal leakage and pulpal sensitivity
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How does color stability related to cement?
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-Amine accelerator in dual cure luting agents may cause color change over time = change in color of restoration
-All dual cure composite cements exhibited some short and long-term color changes |
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Name an AOC for red wines from the Southern Rhone.
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Chateauneuf-du-Pape
Gigondas , Vacqueyras Cotes du Rhone , Lirac Cotes du Rhone Villages , Rasteau |
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Step by step Description of Cementation?
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-Remove provisonal cement, removal eugenol (inhibit resin polymerization). Air abrade, pumice, etch after pumicing. Air abrasion 50 um alumina or steam cleaning, ultrasonic, organic solvent (retention increase 64%).
-Apply thin coat of cement and seat restoration w/ firm rocking pressure. -Supported idea that static force and vibration produces a thinner cement firm thickness at the margins. |
