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See all Premium member Presentation Transcript CRITERIA FOR SELECTION OF IMPRESSION MATERIALS FOR THE PARTIALLY DENTATE PATIENTS : CRITERIA FOR SELECTION OF IMPRESSION MATERIALS FOR THE PARTIALLY DENTATE PATIENTS BY RABIA MUNIR D-515 What are impression materials? : What are impression materials? “impression materials are used to obtain a true replica of teeth and mucosa” Different types are available: Types of impression materials: : Types of impression materials: RIGID IMPRESSION MATERIALS THERMOPLASTIC IMPRESSION MATERIALS ELASTIC MATERIALS: IRREVERSIBLE HYDROCOLLOIDS: : IRREVERSIBLE HYDROCOLLOIDS: Selection of trays : Selection of trays Classification of impression trays: Stock trays Custom trays Depending on the perforations they are either Perforated or non-perforated Stock trays: used to make preliminary impressions. Plastic stock trays with handles : Plastic stock trays with handles Metal stock trays : Metal stock trays Slide 8: For alginate: perforated tray is preferred For agar: rim lock trays For impression compound: non perforated trays are preferred For elastomers: retention of the material is achieved by an adhesive material. Min (2-3mmclearance )btw stock tray and ridge,* 5-6mm for impression compound Tray adhesive being applied : Tray adhesive being applied CUSTOM TRAYS : CUSTOM TRAYS Fabricated on a preliminary cast, made from preliminary impression of the patient. Used to make final impressions Materials used: acrylic, shellac, tray compound Acrylic customized tray : Acrylic customized tray Primary impression materials: : Primary impression materials: These include Impression compound (mucocompressive) Tray compound stick compound Alginate (mucostatic) Secondary impression materials: : Secondary impression materials: Alginate Rubber base Waxes used to make impression for distal extension partial dentures silicone impression material CRITERIA FOR SELECTION: : CRITERIA FOR SELECTION: KENNEDY’S CLASS 1 Bilateral edentulous areas located to posterior to natural teeth IMPRESSION MATERIALS: Impression compound can be used to record the edentulous area (mucocompressive) Wash impression is taken with alginate Slide 15: Elastomers i.e. silicone and Thiokol can be used for secondary impression ONE STAGE IMPRESSION: Light bodied material is placed in syringe and placed on areas where high detail req. some is then squirted on heavy bodied material loaded on tray. Impression is then taken as normal. KENNEDY’S CLASS 2 : KENNEDY’S CLASS 2 Unilateral edentulous area posterior to remaining natural teeth IMPRESSION MATERIAL: Impression compound is used in a similar manner Wash impression is then done with alginate elastomers KENNEDY’S CLASS 3 : KENNEDY’S CLASS 3 Unilateral edentulous area with natural teeth both anterior and posterior to it IMPRESSION TECHNIQUE: Alginate can be used to take the primary impression Elastomers can also be used KENNEDY’S CLASS 4 : KENNEDY’S CLASS 4 A single, but bilateral edentulous area located anterior to remaining natural teeth IMPRESSION MATERIAL: Alginate can be used for the primary impression Elastomers CLASS2 modification 1 : CLASS2 modification 1 Preliminary impression can be done with impression compound to record the edentulous area, excess is scraped off Wash impression with alginate Elastomers can be utilized, light bodied for injection by syringe, and medium & heavy bodied for use on tray Alginate impression : Alginate impression Maxillary arch impression : Maxillary arch impression IMPRESSION MATERIAL FOR SEVERE UNDERCUTS: : IMPRESSION MATERIAL FOR SEVERE UNDERCUTS: Reversible hydrocolloid Alginate can tear on removal from severe undercuts Siliconised alginates have superior resistance to tearing Slide 24: Chief use of elastomers is in impressions for partial dentures when undercuts are so severe that alginate would tear Slide 25: Polyether impression material is the stiffest and most difficult to withdraw over undercuts IMPRESSION PLASTER: In the presence of undercuts it will fracture on removal from mouth Flabby ridge : Flabby ridge Window technique: Preliminary impression is taken using alginate loaded in a stock tray. impression is poured, customized tray constructed. Customized tray has window over the area corresponding to flabby ridge. Impression is taken in low viscuosity silicone. Once this has set it is left in place & medium Flabby ridge area marked with indelible pencil: : Flabby ridge area marked with indelible pencil: Slide 28: Viscuosity is injected over flabby ridge&allowed to set and removed as one impression. Flabby ridge impression: : Flabby ridge impression: Impression material for partially dentate patients with cleft palate: : Impression material for partially dentate patients with cleft palate: GUTTA PERCHA: It softens at 60-65c At mouth temperature the material will flow if pressure is applied to it It can be used for impression taking in cleft palate patients being moulded for a no of days by contact with moving soft tissue. Slide 31: Alginate can also be used to take the impression. references : references Mc cracken (partial denture) Philips’ dental materials Ec combe Jaypee prosthodontics www.dentistry.bham.ac.uk www.detalresource.org You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.