Tissue Management & Impression Technique

Tissue Management and Impression Techniques

and Material

Parag R. Kachalia DDS

Jessie V. Vallee, DDS

Preclinical Fixed ProsthodonticsClass of 2011

• 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!

• 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

Impressions

• 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

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

Final Impressions:

1) Polysulfides

2) Reversible Hydrocolloids

3) Condensation Silicone

4) Polyvinyl Siloxane*

5) Polyether*

* - used at UOP

Choice of Materials

• Can be described as ease of pouring with gypsum products

• Classified as readily wettable (hydrophilic), resistant to wetting (hydrophobic)

Wettability

•Hydrophilic Materials:

•Irreversible Hydrocolloid (alginate)

•Reversible Hydrocolloid

•Polyether

•Hydrophobic Materials:

•Polysulfide

•Polyvinyl Siloxane

•Condensation-Reaction Silicones

•Hydrophobic Materials:

•Polysulfide

•Polyvinyl Siloxane

•Condensation-Reaction Silicones

Love it or leave it

• 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

Viscosity

• Materials on today’s 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)

Viscosity

• 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)

• Today’s average cost of a final impression is approximately $15.00

Cost

• 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!

Reversible Hydrocolloids

• 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

• 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

Polyether

• 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

Polysulfide

• 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)

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

• 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

• 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

• One step monophasic-wash technique:

• Stock tray preparation

• Tissue management

• Final wash

• Evaluation



Stock Tray Preparation

Powder from latex gloves can react with impression material. It must be removed to prevent incomplete setting of the impression material.

Washing Hands Is A Must!

• Armamenterium

Phase One: Stock Tray Preparation


• Tray adhesive is applied to help retain material within tray [the adhesive for aquasil and impragum are different]



• Techniques:

• No cord - margins supragingival

• Single cord technique

• Dual cord technique

• Either single or dual cord technique with hemostatic agent

• Either single or dual cord technique with epinephrine

• Electrosurgery/laser

Phase Two: Tissue Management

• Astringedent contains 20% Ferric Sulfate which stimulates blood clotting

• ViscoStat contains 20% Ferric Sulfate


• Different delivery options for hemostatic agent.



• Reaction begins immediately upon application to bleeding area



• The Ferric Sulfate [ViscoStat] is applied to the bleeding tissue using this tip attached to a syringe



• The Ferric Sulfate can be injected onto a cord that has been previously packed into the gingival sulcus



• Cord packing (placing) instrument

Cord Placement Armamenterium

• Clinical presentation after completion of preparation



• Ferric sulfate being scrubbed into sulcus via tufted syringe tip


• Two types of cord are available for purchase:

• 1) Braided and 2) Knitted

Braided

Knitted



• Cord can be purchased in a variety of sizes to be used in varying sulcus widths and depths



• Different cord thickness



• Cord is positioned above the sulcus and using a length cut to surround the tooth without overlap



• Cord is packed into the sulcus to retract tissue and aid in moisture control


• Tissue is rinsed after scrubbing with ferric sulfate, hemostasis is confirmed, more ferric sulfate is placed into sulcus prior to introducing the first dry cord.



•Tooth with first cord in place. Ferric sulfate is scrubbed into sulcus again and rinsed



• Second cord (larger) Placed into sulcus for lateral retraction of soft tissue


• Second cord is in place circumferentially


• Coronal cord is removed to expose margin and apical cord

Phase III: Introduction of wash

• View margin and check for any heme. If heme is present rescrub with ferric sulfate

Note retraction could be better at ML line angle


• Wash is introduced into the sulcus making sure tip stays in contact with material at all times


• Once the prepared tooth has had wash placed around it insert stock tray with monophase material into the patients mouth.

• Seat the tray completely and do not allow the tray to move once setting has begun.

Phase III: Introduction of wash and tray

material

The impression material cervical to the margin is termed “flash”.

The more flash cervical to the impression, the easier it is to trim the dies during the laboratory phase of any project.

Flash

Lingual View

Of Our Impression

• All of the margin has been captured on the facial surface

• Far less flash is present on the facial making that portion of the die far more difficult to trim

Lingual View Of Our

Impression

Lingual View Of Our

Impression

• Note marginal clarity around each of the four anterior teeth . This was accomplished with Aquasil and good tissue management.

Ideal Impression

Apply Tray Adhesive

Load cartridges

Bleed Cartridge Attach Mixing tip

Load Tray - Monophase Inject Around Prep

• Working time 2 min. 30 sec. (seat tray)

• Setting time 5 min.

• Remove and inspect for accuracy.

• Need to measure sulcus with periodontal probe

• And assess need for hemostatic agent



• Cord is placed into the sulcus. This will allow for the tissues to be position laterally from the margin.

Cord Placement

• Make sure tip is not made too large. This will prevent adequate force on the impression material

Preparing the Syringe Tip

Wash Materials used an Pacific

•Aquasil light body

•Impragum light body

Phase Three: Final Wash

Phase Three: Final Wash

http://images.google.com/imgres?imgurl=http://www.dentaltroef.nl/image/dents_aquasil.jpg&imgrefurl=http://www.dentaltroef.nl/nieuw_dents_aquasil.htm&h=258&w=400&sz=29&tbnid=e06jHmCYbfYJ:&tbnh=77&tbnw=120&hl=en&start=31&prev=/images%253Fq%253Daquasil%252B%2526start%253D20%2526svnum%253D10%2526hl%253Den%2526lr%253D%2526sa%253DN

Tip must be kept in contact with the impression tray and impression

material to prevent bubble formation

Loading The Tray and Syringe

• Final wash is applied with force so that impression material is expressed into the sulcus.

Final Wash of Preparation

Alternative Soft Tissue Management

Techniques

• State of the art high frequency electrical device used for easy and effective soft tissue contouring and coagulation

• State of the art high frequency electrical device used for easy and effective soft tissue contouring and coagulation

Electrosurgery

• Gingivectomy –removing excess tissue

• must not violate biologic width

• adequate attached gingiva

• caution in cosmetic areas (adequare sulcus depth, and attatched gingiva), although it can be used for aesthetic contouring of gingival tissue

Electrosurgery

• Advantages over blade surgery

• Less bleeding

• Less need for sutures

• Less scarring

• Better access

Electrosurgery

• Gingivectomy –removing excess tissue Straight tip

(scalpel)

Electrosurgery

•Uses of the electrosurge•Inflamed tissue•Hyperplastic tissue•Frenum removal•Sulcus expansion

Electrosurgery

• Pacific’s laser:

• diode laserLaser unit

Fiber optic

Protective eyewear

Handpiece

Foot pedal

Dental Lasers

Gallium Alluminum Arsenide Solid State laser diode provides the optical energy

Fiber optic handpiece delivers up to 10 watts of laser energy

Pulse and power output can be adjusted

Gallium Alluminum Arsenide Solid State laser diode provides the optical energy

Fiber optic handpiece delivers up to 10 watts of laser energy

Pulse and power output can be adjusted

DioDent Laser

Cosmetic Dentistry Endodontics Periodontal

proceedures Oral soft tissue

surgery including gingivectomy, gingivoplasty, biopsy,etc.

Tissue retraction for impressions

I and D’s Implant recovery

Cosmetic Dentistry Endodontics Periodontal

proceedures Oral soft tissue

surgery including gingivectomy, gingivoplasty, biopsy,etc.

Tissue retraction for impressions

I and D’s Implant recovery

DioDent Laser

Today’s project

• Refine patient preparation as needed

• Place retraction cord

• Take final impressions utilizing Aquasil

Health & Medicine

Tissue Management & Impression Technique