آخر محاضرة

• Why is it important to study failure in dental materials?

  To prevent failures that can occur in dental materials.
• What type of failure is described as preventable?

  Preventable failure
• What type of failure is described as unavoidable?

  Unavoidable failure
• What is a key question regarding failure in dental materials?

  How to deal with failure?
• What are the main types of dental materials?

  • Metal
  • Polymer
  • Ceramic
  • Composite

  
• What are the two categories of dental materials based on their function?

  • Restorative
  • Auxiliary
• What are the four types of properties that dental materials can have?

  • Physical
  • Mechanical
  • Chemical
  • Biological
• What are the types of failure in dental materials?

  • Corrosion
  • Wear
  • Craze
  • Fracture
  • Fatigue
  • Creep
  • Solubility
  • Adhesion failure
  • Staining
  • Microleakage

  
• What is one type of failure in dental materials?

  Corrosion

  
• What is another type of failure in dental materials?

  Wear
• What is another type of failure in dental materials?

  Craze
• What is another type of failure in dental materials?

  Fracture
• What is another type of failure in dental materials?

  Fatigue
• What is another type of failure in dental materials?

  Creep
• What is another type of failure in dental materials?

  Solubility
• What is another type of failure in dental materials?

  Adhesion failure

  
• What is another type of failure in dental materials?

  Microleakage
• What is tarnish in dental materials?

  Surface discoloration on a metal or slight loss of surface finish.
• What is corrosion in dental materials?

  It is an electrochemical process causing metal deterioration.
• What are some effects of corrosion in dental materials?

  It causes metal deterioration and pulpal pain.
• What is the fundamental basis of chemical (dry) corrosion?

  It occurs in the absence of water and involves direct combination of elements.
• What is electrochemical (wet) corrosion?

  It requires water and an electric current for the corrosion process.
• What is oxidation in the context of electrochemical corrosion?

  It is the loss of electrons by a metal.
• What are the components of an electrochemical cell?

  • Anode: surface where oxidation occurs
  • Cathode: surface where reduction occurs
  • Electrolyte: supplies ions and carries away corrosion products
  • External circuit: conduction path for electric current
• What are the forms of electrochemical corrosion?

  1. Dissimilar metals
  2. Heterogeneous surface composition
  3. Stress corrosion
  4. Concentration cell corrosion
• What happens when dissimilar metals are in direct contact?

  It can result in galvanic shock and sharp pain.
• What is stress corrosion?

  It occurs when mechanical stress and a corrosive environment are present.
• What is concentration cell corrosion?

  It occurs due to variations in the composition of electrolytes.
• What is the definition of wear in dental materials?

  It is the removal of constituents from a material's surface due to mechanical action.
• What are the factors influencing wear of dental materials?

  • Surface roughness
  • Temperature
  • Moisture
  • Diet
• What is craze in dental materials?

  Craze refers to fine cracks in polymers under tensile load.
• What is creep in dental materials?

  Creep is time-dependent plastic deformation under constant load near melting point.
• What is fatigue in dental materials?

  Fatigue is failure due to repeated application of loads below the elastic limit.
• What is solubility in dental materials?

  It measures how much a material dissolves in a fluid.
• What is the clinical significance of solubility in restorative dental materials?

  Restorative materials should have no solubility in the oral cavity.
• What is failure of adhesion in dental materials?

  It refers to the inability of materials to bond properly.

  
• What is microleakage in dental materials?

  It is the drawing of bacteria and debris into gaps between tooth and restoration.

  
• What are the potential consequences of microleakage?

  It can lead to secondary caries, sensitivity, and pulp irritation.

  
• What are the causes of microleakage?

  Debonding, inadequate bonding, and polymerization shrinkage.

  
• What is the solution to microleakage?

  Adequate bonding and sealing of dentinal tubules.