Impression  materials
Upcoming SlideShare
Loading in...5
×
 

Impression materials

on

  • 25,408 views

 

Statistics

Views

Total Views
25,408
Slideshare-icon Views on SlideShare
25,408
Embed Views
0

Actions

Likes
13
Downloads
854
Comments
2

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel

12 of 2

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
  • We are Manufacturer & Supplier of Surgical, Dental, Orthopedic & Laparoscopic instruments.

    We want offer our quality product supply services with highly competitive prices.

    Fo more information, please visit http://www.alispo.com.pk

    Waiting prompt reply.

    Best regards,

    Syed Hammad Raza
    Export Executive

    ALISPO SURGICAL SUPPLIES'
    P.O. BOX-2872,
    RORAS ROAD, MUZAFAR PUR,
    SIALKOT 51310 PAKISTAN.

    Tel: +92-52-3572427 Fax: +92-52-3572570 Mob: +92-300-8 717 212
    E-MAIL: info@alispo.com, info@alispo.com.pk
    Skype: asad.alispo
    Are you sure you want to
    Your message goes here
    Processing…
  • ;->10X
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • bibin

Impression  materials Impression materials Presentation Transcript

  • Impression materials
    by
    Bibinbhaskaran
  • Impression materials
    Definition :- (GPT):
    A negative likeness or copy in reverse of the surface or object.
    2) An imprint of the teeth and adjacent structures for use in dentistry
  • Impression material:-
    Any substance or combination of substances used for making an impression or negative reproduction.
    Impression technique:-
    A method and manner used in making a negative likeness.
  • classification
  • Classification
    Based on rigidity : Rigid
    egPlaster,Zincoxideeugenol
    impression compound
    Elastic
    egAlginate,polyether,silicone
    Based on setting of the material: 1.) Chemical reaction(irreversible)
    eg plaster of paris,zincoxideeugenol
    alginate,additon and condensation silicones
    2 ) Physical change of state(reversible)
    eg agar
  • Based on viscosity : Mucostatic
    eg impression plaster,agar,
    light body elastomer
    Mucocompressive
    eg Impression compound,alginates
    Pseudoplastic
    eg addition silicones
  • Based on interaction with saliva
    and water : Hydrophobic
    eg polysulfide ,condensation
    silicones
    Hydrophilic
    egputty,impression plaster
    Based on use :
    Primary
    impression material
    eg impression compound,alginate
    Secondary
    Impression material
    egZoe,medium bodied elastomers
    Duplicating
    material
    eg agar
  • Based on
    Chemical composition : impression plaster
    impression compound
    metal oxide(zinc oxide eugenol)
    pastes
    agar hydrocolloid
    alginate hydrocolloid
    polysulfides
    condensation silicones
    addition silicones
    polythers
    light curing polyether
    (urethane dimethacrylate)
  • Desirable qualities
    Pleasant odor taste and color
    Absence of toxic irritants
    Adequate shelf life
    Economical
    Easy to use
    Setting that meet clinical requirements
    Satisfactory consistency
  • Readily wet oral tissues
    Elastic
    Adequate strenght
    Dimensional stability
    Compatiblity with cast and die materials
    Accuracy
    Disinfection
  • Impression plaster
  • Impression plaster
    The impressions are very accurate
    Being hydrophilic it has got intimate contact with oral tissues by absorbing surface moisture
  • Impression compound
  • Impression compound
    Fusion temperature of impression compound is 43.5 degree celesius
  • Zinc oxide eugenol impression material
  • Zincoxideeugenol impression material
    Non eugenol pastes-
    One of the chief disadvantages of Zoe pastes is the possible burning sensation caused by eugenol.orthoethoxybenzoic acid (EBA) is a valuable substitute for eugenol in this regard.
  • Alginate
  • Alginate
    Gelation reaction-
    2Na3P04 + 3CaSo4----- Ca3(Po4)2+3 Na2SO4
  • Recent advances in alginates
    Dust free alginates-
    De-dusting agent (glycerin or glycol)
    Siliconized alginates-
    silicon polymers are added to strengthen the material
    Alginates containing disinfectants-
    eg quaternary ammonium salts or chlorohexamine are added to alginate powder.
    Hard and soft set alginates-
    by adjusting the amount of fillers
  • Reversible hydrocolloid-AGAR
  • Agar
    Gelation-
    Gelation is accomplished by circulating cold water of approximately 18-23 degree for not less than 5 min.
  • Elastomeric impression materials
    Classification :-
    Based on viscosity-
    Class 1 heavy body heavy viscosity
    Class 2 regular body or medium body
    Class 3 light body or low viscosity
    Based on chemistry-
    Polysulfides
    Condensation silicones
    Additional slilicones
    Polythers
    Visible light curable polyether
  • POLYSULFIDES
  • polysulfides
    Polysulfide is one of the least stiff or highly flexible of elastomeric material
    For accurate polysulfide impressions-
    The cast should be poured immediately after taking impression
    Minimise the amount of material used to take impression by using custom made acrylic trays
  • Condensation silicones(Double mix type)
  • Condensation silicones
    It is also called room temperature vulcanising silicones(RTV)
    Uses –
    It is widely used in recording dentulous impressions in preparation of crowns,bridges,inlays,onlays and to some extent for partial dentures
    It is also used to record edentulous impressions in preparation of complete denture
  • Putty type
    Advantages –
    No custom tray required
    No special equipment required
    Moderate strength in deep sulcus
    Pleasant odor
    Adequate shelf life
    Disadvantages –
    Should be poured shortly after removal
    Hydrophobic
    Difficult to electroplate
    Easily distorted
  • Addition silicones(Double mix type)
  • Addition silicones
    Addition polysilicones are the most stable of all the existing materials
    It has an excellent recovery of 99.93%
    It exhibits pseudoplasticproperties.it can be used both as syringe and tray materials
  • Putty type
    Advantages –
    No custom tray
    No special equipment
    Good shelf life
    Can be poured more than once
    Disadvantages –
    Extremely hydrophilic
    More difficult to pour
    Most expensive
  • Polyether materials
  • Polythers
    Uses-
    For recording impression in preparation of crowns and bridges
    Cavity preparation for inlays and onlays
    For construction of partial and complete dentures
  • Visible light cured polyether
  • Light cured polyether
    It has excellent elasticity
    It has infinite working time and short setting time
    The impression can be stored upto two weeks
  • Disinfection
    Most manufacturers recommend a specific
    disinfectant,such as iodophor,bleach,orglutaldehyde,for disinfection.
    Certain disinfectants may result in gypsum casts that have a lower surface hardness or diminished surface detail.
    The current protocol for disinfecting hydrocolloid impressions recommended by the centre for disease control is to use house hold bleach(1 to 10 dilutions),iodophor or synthetic phenols as disinfectants
    An alternate disinfection method is by immersion,but this should not exceed 10 min.
  • Duplicating materials
    Duplicating is required for two reasons:-
    1, The cast on which the wax pattern of the metal frame work is to be formed must be made from refractory investment because it must withstand the casting temperatures required for gold or base metal alloys
    2, The original cast is needed for checking the accuracy of the metal frame work and for processing the denture base portion of the partial denture
    The most common duplicating materials are agar hydrocolloid compounds, The primary advantage of agar is their set is reversible.the disadvantage is it is subject to dimensional change.The best storage condition is 100% humidity.
  • Tissue conditioners
    Tissue conditoners are soft elastomers used to treat an irritated mucosa supporting a denture.it is used to provide time for healing of soft tissues
    Tissue conditioners are composed of powder containing poly(ethyl methacrylate)and a liquid containing an aromatic ester – ethyl alcohol.
    The properties that make tissue conditioners effective are-
    1,viscous behavior which allows adaptation to irritated denture bearing mucosa
    2,viscoelastic behavior which cushions the cyclic forces of mastication and bruxism
  • References
    Zardiackas.L.D , Dental materials,Dentla clinics of morthamerica,July 2007,vol 51,pg 629-643 .
    O’Brien.W.J, Dental materials and their selection, 3rd edition, Quintessence publications.
    Craig.R.G, Dental Materials, 12th edition, Elsevier publications.
    Anusavice, Phillip’s Science of Dental Materials, 11th edition, Saunders publications. Impression materials.