Tissue Management & Impression Technique
Post on 24-Dec-2014
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DESCRIPTIONOverview of final impression and soft tissue management technique for excellent impressions.
- 1. Tissue Management and Impression Techniques and Material
- Parag R. Kachalia DDS
- Jessie V. Vallee, DDS
Preclinical Fixed Prosthodontics Class of 2011 2.
- If the restoration is to fit precisely, the cast on which it is made must be as nearly an exact duplicate of the prepared tooth as possible
Impression Musts! 3.
- High potential for improper use of material
- Much variation from material to material
- Accurate impressions have been destroyed due to incorrect handling
- Have also been destroyed due to delays between removal from the mouth and pouring
- Exact duplicate of the prepared tooth and enough tooth structure below the margin for accurate definition of the finish line
- Other teeth must accurately be reproduced in order to articulate the casts correctly
- It must be free of bubbles and voids (especially in the area of the finish line)
Impression Must Meet Following Requirements 5.
- Your choice is based on:
- 1) personal preference
- 2) ease of manipulation
- 3) strength and shelf life
- 4) predictability
- 5) economics
- 6) accuracy
Comparison of Impression Materials 6.
- Final Impressions:
- 1) Polysulfides
- 2) Reversible Hydrocolloids
- 3) Condensation Silicone
- 4) Polyvinyl Siloxane*
- 5) Polyether*
- * - used at UOP
Choice of Materials 7.
- Can be described as ease of pouring with gypsum products
- Classified as readily wettable (hydrophilic), resistant to wetting (hydrophobic)
- Hydrophilic Materials:
- Irreversible Hydrocolloid (alginate)
- Reversible Hydrocolloid
Love it or leave it
- Hydrophobic Materials:
- Polyvinyl Siloxane
- Condensation-Reaction Silicones
- Shear Thinning- a materials viscosity decreases as it is expressed through a syringe, yet maintains its body when left alone.This allows for a monophasic material to respond differently under different conditions
- This type of material may also be termed thixotropic
- Materials on todays market range from 2.6 pounds of pressure required to express through a syringe to 112 pounds of pressure (polysulfide through a small diameter syringe)
- Should not be considered as a primary factor in impression material selection
- Least expensive impression found is a polysulfide in custom trays (average of $5.50 in 1998)
- Most expensive impression found is a polyvinyl siloxane in stock metal trays (average of $13.50 in 1998)
- Todays average cost of a final impression is approximately $15.00
- In use for over 60 years
- Sold in a semi-solid state
- Liquefied by placing in boiling water, then cooled in two stages
- Cool tap water is circulated through the tray
- Material is 85% water
- Inexpensive and can be removed in 3 minutes!
- What then are the drawbacks of this material?
- Can only be poured once
- Quite temperature dependent
- Potential injury to the patient
- If left exposed, can begin to distort readly
Reversible Hydrocolloids 14.
- 1) Excellent dimensional stability
- 2) Hydrophilic in nature
- 3) Will lock into undercuts if not blocked out
- 4) 0.5% of individuals have shown some reaction to this material
- 5) 8:1 ratio of base-accelerator
- 6) Can be somewhat brittle
- Commonly called rubber base
- Comes as two tubes of base and catalyst
- Will begin to shrink after one hour from removal
- Should be poured immediately
- Only radiopaque impression material
- Can become locked into undercuts
- Can have pronounced shrinkage due to evaporation of alcohol during reaction [poor dimensional stability]
- Used in a similar fashion to polysulfides
- Must be poured within six hours
- Dies produced from this material are undersized
- The above occurs due to the evaporation of the biproduct of the condensation reaction.( H2O for polysulfides and ethanol for Condensation silicones)
- Also know as addition silicones
- Dimensional stability is quite high in this group
- Least affected by pouring delay of any material(due to no volatile biproduct formation, carbon double bonds, in the form of vinyl groups open up during polymerization and link the monomer groups together via an addition reaction)
- Comes in many varieties (putty-wash, wash-wash)
- Surfactants have been added to the material to decrease it hydrophobia, but dies are 14-33% softer
Our Material - Polyvinyl Siloxanes 18.
- Mixing guns are the most popular form of this material
- We utilize a monophase-wash system (one step)
- Latex gloves retard the setting of this type of material
- Must not come into contact with any surface touched by a glove
Our Material - Polyvinyl Siloxanes 19.
- Type of Impression:
- Heavy body wash (Monophasic material) in a stock tray with medium or light wash around
- Light body wash in a custom tray
Polyvinyl Siloxane Impression Technique 20.
- One step monophasic-wash technique:
- Stock tray preparation
- Tissue management
- Final wash
Polyvinyl Siloxane Impression Technique 21. Stock Tray Preparation 22. Washing Hands Is A Must! Powder from latex gloves can react with impression material.It must be removed to prevent incomplete setting of the impression material. 23.
Phase One: Stock Tray Preparation 24.
- Tray adhesive is applied to help retain material within tray [ the adhesive for aquasil and impragum are different ]
Phase One: Stock Tray Preparation 25.
- No cord - margins supragingival
- Single cord technique
- Dual cord technique
- Either single or dual cord technique with hemostaticagent
- Either single or dual cord technique with epinephrine
Phase Two: Tissue Management 26.
- Astringedent contains 20% Ferric Sulfate which stimulates blood clotting
- ViscoStat contains 20% Ferric Sulfate
Phase Two: Tissue Management 27.
- Different delivery options for hemostatic agent.
Phase Two: Tissue Management 28.
- Reaction begins immediately upon application to bleeding area
Phase Two: Tissue Management 29.
- The Ferric Sulfate [ViscoStat] is applied to the bleeding tissue using this tip attached to a syringe
Phase Two: Tissue Management 30.
- The Ferric Sulfate can be injected onto a cord that has been previously packed into the gingival sulcus
Phase Two: Tissue Management 31.
- Cord packing (placing) instrument
Cord Placement Armamenterium 32.
- Clinical presentation after completion of preparation
Phase Two: Tissue Management 33.
- Ferric sulfate being scrubbed into sulcus via tufted syringe tip
Phase Two: Tissue Management 34.
- Two types of cord are available for purchase:
- 1) Braided and 2) Knitted
Phase Two: Tissue Management Braided Knitted 35.
- Cord can be purchased in a variety of sizes to be used in varying sulcus widths and depths
Phase Two: Tissue Management 36.
- Different cord thickness
Phase Two: Tissue Management 37.
- Cord is positioned above the sulcus and using a length cut to surround the tooth without overlap
Phase Two: Tissue Management 38.
- Cord is packed into the sulcus to retract tissue and aid in moisture control
Phase Two: Tissue Management 39.
- Tissue is rinsed after scrubbing with ferric sulfate, hemostasis is confirmed, more ferric sulfate is placed into sulcus prior to introducing th