Dental Material

• Biomaterials


  Materials used in the treatment and prevention of dental diseases and the interactions of these materials with tissues of the face and mouth

  
• Importance of studying dental materials for dental professionals

  • Keep up with requirements for delivering optimal health care
  • Deliver minimally invasive dentistry
• The study of dental materials covers the evolution, development, properties, manipulation, care, and evaluation of biomaterials used in dentistry

  
• Evidence-based dentistry (EBDM)


  An approach to oral health care that requires the judicious integration of systematic assessments of clinically relevant scientific evidence, relating to the patient's oral medical history, with the dentist's clinical expertise and the patient's treatment needs and preferences
• Evidence-based dentistry helps the clinician make decisions about what is relevant to incorporate into practice
• Questions to ask when incorporating EBDM into a practice

  • How does your practice make decisions about techniques, technology and products being used?
  • How do you analyze scientific research to ensure your product provides clinical benefit to your client?
  • Do you try product samples before giving them to your clients?
  • How does your office stay informed about newest advances in dentistry?
  • How do you incorporate client's needs and choices into your decision making process?
• Importance of EBDM


  • Increases the potential for successful client care outcomes by understanding the cause and effect relationship between biomaterials and selected treatment
  • Increases the success of the treatment rendered
• The ADA's Council on Scientific Affairs and ADA staff scientists review dental drugs, materials, instruments, and equipment for safety and effectiveness
• The ADA seal outlines a broad spectrum of requirements that must be met to qualify for the ADA Seal of Acceptance
• The ADA Seal of Acceptance is available for consumer products, not professional products
• FDA classifications of medical/dental devices

  • Class I (lowest risk, good manufacturing standards)
  • Class II (required to meet performance standards set by FDA or ADA)
  • Class III (most regulated, support or sustain human life, require FDA approval)
• The ISO and ADA represent the standards used to develop specifications and testing at the international level
• Impression materials


  Materials used to make replicas (models / casts) of teeth restorations and preparations made for restorative treatments and other supporting oral tissues both hard and soft

  
• In Canada, dentistry manufacturers must provide a valid certificate showing that their quality management system complies with the ISO standard for quality systems
• Impression materials record hard and soft tissue relationship
• Future developments in dental biomaterials

  • Advances in periodontal surgery, restorative dentistry, and implant therapies - teeth retention
  • Demand for esthetics - increase demand for whitening systems, esthetic restorations and orthodontic procedures
  • Advances in tissue regeneration, implant therapies, esthetic adhesion and biomechanics
  • Current research is concentrating on bringing technology to the dental office, making dental appointments faster, minimally invasive, and more comfortable for the client resulting in optimum client-centered oral health care
• Impression


  A negative reproduction of the oral structure
• Diagnostic cast (study models)


  Positive replica of the teeth and surrounding oral tissue

  
• Die


  The replica of a tooth that has been prepared for a restoration

  
• Ideal properties of impression material

  • Ease of manipulation
  • Reasonable cost
  • Appropriate setting time and characteristics
  • Accuracy in clinical use
  • Sufficient mechanical strength
  • Dimensional stability
  • Non-toxic or irritating
  • Acceptable to the client
  • Readily disinfected
  • Compatible with die and cast materials
  • Good shelf life

  
• Types of impressions


  • Preliminary impressions
  • Final impressions
  • Bite registration (occlusal impressions)
• Types of impression materials

  • Elastic materials: hydrocolloids (agar & alginate), polyvinyl siloxane (PVS), polyether
  • Inelastic materials: older impression materials, seldom used (impression plaster, zinc oxide eugenol, impression wax)

  
• Hydrocolloids


  Water based colloids that function as elastic impression materials
• Types of hydrocolloids


  • Reversible hydrocolloids
  • Irreversible hydrocolloids
• Sol


  Liquid state in which colloidal particles are suspended, by cooling or chemical reaction it can change into a gel
• Gel


  A semisolid state in which colloidal particles form a framework that traps liquid (Example: Jell-O)
• Reversible hydrocolloid


  • Accurate impressions of teeth and tissue with undercuts
  • Main use for impressions of operative and crown and procedures

  
• Agar


  Reversible hydrocolloid material that has properties of reversing its physical state that is reusing material for multiple number of impressions
• Components of agar


  • 80% - H2O
  • 8 - 15% - agar-agar (extracted from seaweed)
  • Colorants
  • Flavors
  • Potassium sulfate
  • Borax
  • Alkyl benzoate
• Irreversible hydrocolloid (alginate)


  • Most widely used impression material
  • Change from a sol phase to a gel phase via chemical reaction cannot be reversed
  • Not accurate enough for final impressions
  • Do not capture fine detail
  • Do not flow well into embrasures or occlusal surfaces

  
• Components of alginate


  • Calcium sulfate
  • Diatomaceous earth
  • Colorant
  • Flavor
  • Inhibitors
  • Potassium sulfate
  • Trisodium phosphate (controls setting rate)
• Advantages of irreversible hydrocolloid (alginate)

  • Good for subgingival impression
  • Working in a "wet" environment
  • Pouring models
• Disadvantages of irreversible hydrocolloid (alginate)

  • Shrinkage - syneresis
  • Swelling - imbibition
  • Poor tear strength
  • Client care - burning "tissues"
• What alginate impressions are used for

  • Patient treatment planning
  • Part of the patient's permanent record
  • Preliminary impressions
  • Final impressions
  • Bite registration
  • Pouring models
  • Subgingival impressions
  • Working in a "wet" environment

  
• Criteria for an acceptable alginate impression

  • All teeth present
  • Frenum attachments present
  • Free of voids/air bubbles
  • Good detail and definition
  • Free of distortion/drag areas
  • Adequate generalized mucobuccal fold
  • Attached firmly to tray (no tears)
  • Centered
  • Smooth, glossy texture
  • Maxillary tuberosity/retromolar pad
  • Not overseated/underseated (no metal showing and a peripheral roll)

  
• Taking an alginate impression

  1. Tray Selection

  2. Dispensing

  3. Mixing - wet material and then rotate bowl

  4. Loading

  5. Glazing

  6. Seating

  7. Removal

  8. Handling
• Smear alginate in areas that you feel will result in insufficient alginate when taking the impression
• Over-seating tray: see plastic or metal tray
• Under-seating tray: lack alginate in the vestibular area (MBF)
• Tray selection for alginate impressions

  • Manufactured in several form stock trays: Rim Lock, Perforated and Custom Made stock trays
  • Variety of sizes
  • Perforated trays allow for the flow of alginate through the perforations and lock alginate into the tray but can cause gag reflex
  • Using incorrect tray size will result in an unacceptable impression
  • Utility wax may be used to extend the tray