Impression Material

IMPRESSION MATERIALS, TYPES and TRAYS Impression are negative reproduction of teeth and surrounding structure Preliminary Impression done by the assistant poor dimensional stability stock impressions trays Final Impressions done by the doctor only good dimensional stability stock impressions trays /custom trays

Preliminary Impression Material Irreversible Hydrocolloid/Alginate Thermo-dots Polyvinylsiloxane Condensation material Uses: Diagnostic models Opposing arch models Fabrication of custom trays Fabrication of provisional restorations

IMPRESSION TRAYS Full arch custom made preformed plastic perforated rim lock max/mand Quadrant Triple Tray quadrant sextant take upper and lower in one Sextant Tray custom made preformed plastic perforated rim lock ant/post

INITIAL IMPRESSIONS Negative is poured in gypsum to create a positive model. Models can be articulated together, articulator recreates the TMJ. Models can be used as opposing for bite registration

FINAL IMPRESSIONS Negatives poured in gypsum to create positive model Models are articulated together and the prep tooth is cut out of the model to create a die A die is a replication of the prepared tooth or teeth or the edentulous mouth

CUSTOM TRAYS Acrylic light cured or self cured resin material need a polymer and monomer polymerization = setting

CUSTOM TRAYS Vacuum formed custom trays resin sheets are heated and formed over the initial impression using heat and vacuum

CUSTOM TRAYS Thermoplastic tray material beads or buttons that are pliable when heated

Preformed rim lock Locks impression material into tray

Preformed Plastic Need tray adhesive

Triple Trays Takes final impression, opposing impression, and bite registration

CUSTOM TRAYS Acrylic resin tray Much like the thermoplastic beads Needs spacer and stops because of the custom fit Spacer can be pink wax, aluminum foil or wax paper

ELASTOMERIC MATERIALS Rubberlike qualities Used when precise duplication is needed No distortion, great dimensional stability Supplied in a two paste system base and catalyst Supplied in either a two tube system or extruder gun Can be one or multiple body types

Polysulfide Advantages good stability,accuracy sharpness in detail light = syringe, wash medium, heavy = tray material long shelf life used for crown, bridge, partial, denture impressions Disadvantages stains, tastes bad and stinks ten minute setting time

Polyether Advantages excellent accuracy great dimensional stability medium body only, used as both syringe and tray material used for crown, bridge, denture and partial impressions Disadvantages only one body type

Silicone Polysiloxane Polyvinylsiloxane Condensation – putty used for bite registration, custom tray Polyvinylsiloxane addition silicone advantages high degree of accuracy and dimensional stabilty three body types disadvantages expensive

Bite Registration Polysiloxane bite registration material open bite (shown) closed bite Wax bite registration material pink wax horseshoe wax bees wax aluwax

Preparation for Impression Mix syringe material, deliver to provider Mix tray material, place in tray and deliver to provider Remove impression. disinfect and evaluate Prepare provisional if necessary Select material Select type of tray or trays Obtain an opposing arch, if necessary Apply adhesive as directed to impression tray

What to send to Lab Lab slip Final Impression Opposing arch Bite registration It is important to give the lab tech everything they will need to produce a quality product

Deliver Appointment Prosthetic should be due two days before appointment. Any adjustments can be done outside the mouth before cementation or placement Final adjustment of cemented appliance can be done in the mouth Oral hygiene instructions