Restorative Materials Quiz - Composite Properties
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Questions and Answers

What is the ideal radiopacity of a composite used as a posterior restorative material?

  • Lower than dentine
  • Higher than enamel
  • Non-radiopaque
  • Equal to enamel (correct)

    • Which type of discoloration is primarily caused by a gap between the restoration and tooth tissues?

  • Bulk discoloration
  • Surface roughness discoloration
  • General surface discoloration
  • Marginal discoloration (correct)

    • What is a significant challenge when interpreting compressive strength of composites?

  • It is a direct indicator of tensile strength
  • Easy measurement techniques are available
  • Compressive strength is always higher than tensile strength
  • Various failure modes can affect results (correct)

    • Why is tensile strength measurement considered more meaningful than compressive strength for restorative materials?

    <p>Restorations fail more commonly under tension.</p> Signup and view all the answers

    Which method can help mitigate general surface discoloration in composite materials?

    <p>Polishing with a graded process</p> Signup and view all the answers

    What is a common result of long-term chemical breakdown in amine-cured composites?

    <p>Yellowing effect</p> Signup and view all the answers

    What makes measuring tensile strength in brittle materials like composites difficult?

    <p>Internal flaws and cracks in the surface</p> Signup and view all the answers

    Which of the following is not a type of discoloration that composites may experience?

    <p>Thermal discoloration</p> Signup and view all the answers

    What is the primary reason for water absorption in composite resins?

    <p>Resin content</p> Signup and view all the answers

    What intrinsic water sorption range is suggested for resins?

    <p>40-45 µg/mm³</p> Signup and view all the answers

    Which composite type generally has a higher coefficient of thermal expansion?

    <p>Micro-filled resins</p> Signup and view all the answers

    What effect does increasing filler loading in composite resins have on thermal expansion?

    <p>Decreases thermal expansion coefficient</p> Signup and view all the answers

    Which factor can lead to excess water absorption in composite resins?

    <p>Air voids within the material</p> Signup and view all the answers

    What is the purpose of using thin samples for water sorption measurements?

    <p>To obtain accurate water sorption measurements</p> Signup and view all the answers

    What composite resin has the highest reported intrinsic water sorption according to the data?

    <p>P-30 (3M Dental)</p> Signup and view all the answers

    What is the coefficient of thermal expansion for enamel?

    <p>11.4 ppmx.°C⁻¹</p> Signup and view all the answers

    What is the primary use of the diametral tensile test in dental materials?

    <p>To determine the tensile strength of a material</p> Signup and view all the answers

    Which type of wear involves two surfaces rubbing together directly?

    <p>Abrasive wear</p> Signup and view all the answers

    What factor may impact the wear resistance of dental composites according to early studies?

    <p>The hardness of the material</p> Signup and view all the answers

    What is a common challenge in measuring wear in dental materials?

    <p>Variation in patient-specific conditions</p> Signup and view all the answers

    Which statement best describes fatigue wear?

    <p>It involves cracking due to repeated loading.</p> Signup and view all the answers

    What type of wear is associated with chemical attacks through hydrolysis or acid-induced erosion?

    <p>Corrosive wear</p> Signup and view all the answers

    Why may laboratory tests not accurately predict in vivo wear of dental composites?

    <p>In vitro tests cannot simulate real-life patient variability.</p> Signup and view all the answers

    Which restorative material has the highest diametral tensile strength according to the provided data?

    <p>P-30 (3M Dental Products)</p> Signup and view all the answers

    What is one of the limitations of using hardness as an indicator of wear resistance in composites?

    <p>There are inconsistencies with varying filler loadings.</p> Signup and view all the answers

    What factor is suggested to be crucial for reliably evaluating wear mechanisms in composites?

    <p>Combination of lab results, clinical experience, and patient-specific data</p> Signup and view all the answers

    What can increasing the filler loading in resin composites lead to?

    <p>Crumbly and cracking composite</p> Signup and view all the answers

    Which method is NOT mentioned as a way to increase viscosity in resin composites?

    <p>Adding plasticizers</p> Signup and view all the answers

    What is the purpose of acid etching with phosphoric acid when using composite resins?

    <p>To improve adhesion to enamel and dentin</p> Signup and view all the answers

    Which type of composite was developed to improve marginal adaptation?

    <p>Flowable composites</p> Signup and view all the answers

    What are flowable composites primarily used for?

    <p>Small preparations and margin repairs</p> Signup and view all the answers

    What is a limitation of packable composites?

    <p>They can be difficult to control due to low viscosity</p> Signup and view all the answers

    Which component is primarily associated with cytotoxic reactions in composite resins?

    <p>Low-molecular-weight monomers</p> Signup and view all the answers

    Why are high-molecular-weight monomers considered less problematic?

    <p>They are less likely to leach out</p> Signup and view all the answers

    What is a common drawback of the resin composite materials in terms of caries?

    <p>They progress rapidly with these materials</p> Signup and view all the answers

    What improvement do contemporary handling characteristics achieve with resin composites?

    <p>Better manipulation and sculpting</p> Signup and view all the answers

    What is the primary function of fluoro-alumino-silicate glass in a polyacid-modified resin composite?

    <p>To provide a source of fluoride</p> Signup and view all the answers

    Which component is responsible for forming the resin matrix in a polyacid-modified resin composite?

    <p>Dimethacrylate monomer (e.g., UDMA)</p> Signup and view all the answers

    What triggers the acid-base reaction that helps release fluoride in a compomer?

    <p>Water absorption from the oral environment</p> Signup and view all the answers

    What is a key difference between compomers and standard composite resins?

    <p>Compomers include a source of fluoride</p> Signup and view all the answers

    What role do hydrophilic monomers play in polyacid-modified resin composites?

    <p>They help transport water and fluoride ions</p> Signup and view all the answers

    In which type of composite do methacrylated polycarboxylic acid copolymers play a role?

    <p>Resin-modified glass-ionomer cements</p> Signup and view all the answers

    What initiates the curing process in compomers?

    <p>Blue light activation</p> Signup and view all the answers

    What distinguishes compomers from resin-modified glass-ionomer cements (RMGICs)?

    <p>Compomers are modified from composite resins</p> Signup and view all the answers

    Which component is critical for the continuous release of fluoride in compomers?

    <p>Water</p> Signup and view all the answers

    What does the copolymerization process involve in compomers?

    <p>Mixing an acidic monomer with dimethacrylate monomer</p> Signup and view all the answers

    What is a primary advantage of indirect composite restorations?

    <p>They address polymerization shrinkage issues effectively.</p> Signup and view all the answers

    Which type of fiber-reinforced composite is known for having high flexural strength?

    <p>Fibre-reinforced composites (FRCs)</p> Signup and view all the answers

    What is the main reason composite restorations are preferred for anterior applications?

    <p>Excellent aesthetic properties.</p> Signup and view all the answers

    What type of fiber form is used in the 'Stick-Net' composite product?

    <p>Mesh</p> Signup and view all the answers

    What concern remains with composite restorations despite lab curing?

    <p>Unreacted methacrylate groups.</p> Signup and view all the answers

    In which application are FRCs primarily utilized?

    <p>Dental splints and bridges</p> Signup and view all the answers

    Which of the following statements about posterior restorations is true?

    <p>They may present marginal seal issues when not in enamel.</p> Signup and view all the answers

    What is a characteristic of particulate-filled composite resins?

    <p>Insufficient strength for certain dental applications.</p> Signup and view all the answers

    What is the primary issue with large composite restorations compared to amalgam restorations?

    <p>They suffer more from polymerization shrinkage.</p> Signup and view all the answers

    What can happen as a result of poor adhesion to dentin in composite restorations?

    <p>Results in gaps and sensitivity.</p> Signup and view all the answers

    What is the average particle size of filler particles in small-particle hybrid composites?

    <p>Less than 1 µm</p> Signup and view all the answers

    Which factor complicates the bonding of composites to heavily compromised teeth?

    <p>Limited enamel for bonding.</p> Signup and view all the answers

    What benefit do smaller sized filler particles provide to composites?

    <p>Smoother surface finish</p> Signup and view all the answers

    Why are composites more susceptible to wear in posterior restorations?

    <p>They face higher occlusal forces.</p> Signup and view all the answers

    In which fields has nanotechnology had a significant impact?

    <p>Materials science and medicine</p> Signup and view all the answers

    What role does moisture control play in composite restorations?

    <p>It improves the adhesive bond strength.</p> Signup and view all the answers

    What can occur if composite restorations are placed in patients with habitual bruxism?

    <p>Wear and potential damage may occur.</p> Signup and view all the answers

    How do complementary particle size distributions benefit filler loading?

    <p>They reduce overall filler size and increase packing density</p> Signup and view all the answers

    What is the resolution limit of visible light compared to surface irregularities from small filler particles?

    <p>0.38 µm to 0.78 µm</p> Signup and view all the answers

    What is a disadvantage of composite materials in comparison to glass ionomer cements (GICs)?

    <p>Composites lose fluoride release over time.</p> Signup and view all the answers

    What is a consequence of inadequate marginal adaptation in deep gingival preparations?

    <p>Higher chance of microleakage and sensitivity.</p> Signup and view all the answers

    How does thermal expansion mismatch affect composite restorations?

    <p>It can lead to separation from tooth tissues.</p> Signup and view all the answers

    What is the primary strength factor of composite restorations?

    <p>Adhesive bond to the tooth tissues.</p> Signup and view all the answers

    What is a significant characteristic of fluoride release in compomers?

    <p>It provides a constant release over time.</p> Signup and view all the answers

    What is necessary for compomers to adhere to enamel and dentin effectively?

    <p>A standard dentin adhesive.</p> Signup and view all the answers

    In terms of polymerization shrinkage, how does compomer compare to composite resins?

    <p>It has similar volume shrinkage.</p> Signup and view all the answers

    What limits the applications of compomers in dental procedures?

    <p>Their mechanical properties are not suitable for high-stress situations.</p> Signup and view all the answers

    What distinguishes the mechanical properties of compomers from composite resins?

    <p>Compomers generally have inferior mechanical properties.</p> Signup and view all the answers

    How does the water absorption of compomers compare to that of composite resins?

    <p>Compomers absorb water more quickly.</p> Signup and view all the answers

    What is one potential issue with compomers due to their hydrophilic resin matrix?

    <p>Excessive hydrolytic expansion.</p> Signup and view all the answers

    In which situations are compomers considered a good alternative to glass ionomers?

    <p>Temporary restorations in permanent teeth.</p> Signup and view all the answers

    What can improve the performance of certain compomer products?

    <p>Proprietary adhesives with self-etching primer characteristics.</p> Signup and view all the answers

    What is a common clinical outcome reported for compomers after 3-4 years of use?

    <p>Successful clinical results.</p> Signup and view all the answers

    Study Notes

    Radiopacity

    • When composites are used as posterior restorative material, their radiopacity is of utmost importance.
    • A non-radiopaque composite is virtually impossible, and would allow the caries process to continue undetected for too long.
    • Some composites fall short of the radiopacity requirement, and should not be used for posterior restorations.

    Color Match

    • The aesthetic qualities of composites are well recognized.
    • Composites can suffer from discoloration in one of three ways:
      • General surface discoloration
      • Marginal surface discoloration
      • Bulk discoloration
    • Marginal discoloration is usually due to the gap between the restoration and the tooth.
    • Debris penetrates the gap and leads to an unsightly marginal discoloration.
    • Employing an acid-etch technique, it is possible to overcome this problem by bonding with the enamel.

    Mechanical Properties

    • Compressive strength and a number of composites are comparable with those of enamel and dentine.
    • It is interesting to note that an anterior composite can have a similar compressive strength to that of an enamel and dentine.
    • However, the indications for their use as posterior restorations are quite different.
    • It is important to know the compressive strength of a material.

    Wear Resistance

    • Chemical attack on composites can occur as a result of a corrosive attack of the resin due to acid.
    • Wear is the process by which material is displaced or removed by the interfacial forces which are generated as two surfaces rub together.
    • Two-body abrasion occurs when the harder of the two surfaces rub together in the mouth.

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    Description

    Test your knowledge on the properties and behavior of composite materials used as restorative materials in dentistry. This quiz covers topics such as radiopacity, discoloration, tensile and compressive strength, and other characteristics affecting composite performance. Perfect for dental students and professionals looking to refresh their understanding.

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