Tissue Management & Impression Techniques

Tissue Management & Impression Techniques for Fixed Prosthodontics

Khaled Q Al Hamad BDS MSc MRD RCSEd Assistant Professor, Faculty of Dentistry 1 Jordan University Of Science & Technology

 Tissue management Impression techniques

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Tissue Management and Impression Techniques for Fixed Prosthodontics

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Part I: tissue management  Tissue management  Aims and principles  Techniques    

Mechanical Chemo mechanical Surgical Combination

 Haemostatic agents  New cordless techniques

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Tissue Management and Impression Techniques for Fixed Prosthodontics

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The impression should provide a precise and clear model of the prepared tooth and the surrounding tissues for the technician to fabricate an accurate dies and to produce a biologically, functionally and esthetically satisfactory fit restoration

Donovan & Chee 2004 8 April 09

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Impressions not accurately recording the gingival finish lines Not reproducible finish line Inadequate restorations Overhangs

Open margins

Inflamed gingival inflammation and/or recession Increased PD 8 April 09

Loss of CAL

Bone resorption 5

Tissue Management and Impression Techniques for Fixed Prosthodontics

Tissue Displacement

“The deflection of the marginal gingiva away from the tooth”

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Academy of Prosthodontics. Glossary Glossary of of Prosthodontic Terms 2005 6 Tissue Management and Impression Techniques for Fixed Prosthodontics

Tissue Displacement Purposes Create sufficient lateral and vertical space between the gingival finish line and the gingival tissue Provide absolute control of gingival fluid seepage and hemorrhage Nemetz Nemetz et al 1984

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Ideal Retraction Material Characteristics

Effective for its intended use Should not cause significant and irreversible tissue damage Should not produce potentially harmful systemic effects

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Donovan et al 1985 8 Tissue Management and Impression Techniques for Fixed Prosthodontics

Part I: tissue management  Tissue management  Aims, purposes and principles  Techniques    

Mechanical Chemo mechanical Surgical Combination

 Haemostatic agents  New cordless techniques

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Tissue Management and Impression Techniques for Fixed Prosthodontics

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Techniques Mechanical Methods Chemomechanical Methods Retraction cords Retraction cord+ Haemostatic agents Surgical Methods Electro surgery Rotary gingival curettage Combination of these 8 April 09

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Retraction cords Traditionally been the most popular method

Safe 98% of respondents Easy used gingival retraction Quick cords, with 44% of them using a Effective plain cord Inexpensiv Hansen Poss et Hansen Poss 2007 2007 et 1999 1999 8 April 09

e

Ferencz 1991 1991

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“Gingival retraction cord may damage the periodontal tissues”

Liu et al al 2004 2004

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“Tissue damage may occur, with friable thin gingival tissue particularly susceptible and subject to Poss 2007 tearing”

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Factors Affecting Damage

Force used in packing the cord Size or Number of retraction cords Length of time the cord is left in place within the sulcus

Chemical agent with which the cord has been impregnated

Ferencz Ferencz 1991 1991 Goodacre 1990

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If the gingiva is healthy initially, healing will occur rapidly Yap Yap & & Ong Ong 1994

Took about 8 days to heal, but with average postoperative gingival recession of about 0.2 - 0.1 mm Ruel et al.. 1980 1980

Healing occurred histologically in 7 to 10 days Goodacre Goodacre 1990 1990

The damage healed clinically within two weeks as was indicated by the GI Feng Feng et et al al.. 2006 2006

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Part I: tissue management  Tissue management  Aims and principles  Techniques    

Mechanical Chemo mechanical Surgical Combination

 Haemostatic agents  New cordless techniques

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Tissue Management and Impression Techniques for Fixed Prosthodontics

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Haemostatic Agent -epinephrine -potassium aluminum sulfate (ALUM) -aluminum chloride (Hemodent) -ferric sulfate -zinc chloride -tetrahydrozoline

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                           

epi (0.1%-0.8%): -creates local vasoconstriction -a 1 inch of cord with 1.0mg of epi contains 2.5x the max dose for healthy patients and 12x the dose recommended for cardiac patients -contraindications for epi use in cord: hx of cardiovascular disease, hyperthyroidism, allergy to epi -signs of epi syndrome: tachycardia, increase in respirations, nervousness, increase in B.P., post op. depression---these symptoms will appear after the cord has been in place for a few minutes or shortly after it is removed. -ALUM (potassium aluminum sulfate): -only slightly less effective than epi at shrinking tissues -Hemodent (aluminum chloride):5-10%: -conc in excess of 10% will cause local tissue destruction -there are no major contraindications and minimal systemic effects -Ferric sulfate (13.3%): -astringent -very good for hemostasis -does not noticeably traumatize tissues and heal more rapidly than hemodent -temporarily discolors tissues for 1-2 days -provides tissue displacement for at least 30min -Zinc chloride (Bitartrate):8% & 40%: -tissue displacement equal to epi -* tissue necrosis is high -NOT RECOMMENDED FOR USE -Tetrahydrozoline (visine, afrin, murine plus, neosynephrine) -a sympathomimetic amine that produces vasoconstriction with minimal side effects 8 April 09

Tissue Management and Impression Techniques for Fixed Prosthodontics

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Part I: tissue management  Tissue management  Aims and principles  Techniques    

Mechanical Chemo mechanical Surgical Combination

 Haemostatic agents  New cordless techniques

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Tissue Management and Impression Techniques for Fixed Prosthodontics

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Cordless Techniques  Expasyl®

 Magic Foam Cord®

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Expasyl

(Kerr Kerr cooperation, cooperation, Orange, CA))

Viscous paste acts as a chemomechanical haemostatic and retraction agent Component

Organic,Easy clay and material quick(kaolin) tissue displacement Aluminum chloride Hemostatic (15%) agent Additional ingredients include colorants, Soll 2001 20 Tissue essential Management and Impression Techniques 8 April 09 water, and oil of lemon for Fixed Prosthodontics

Expasyl Cartridge Form Stainless Steel Dispenser Disposable Tips

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Technique Principle The strength of the epithelial attachment is 1 N/ mm2 Injured by the application of a pressure of 2.5 N/ mm2 Pressure of 0.1 N/mm2 enable sulcus opening of 1.5 mm & a delayed recovery up to 2 minutes per 0.5 mm opening Too low to damage

Sufficient to obtain sulcus opening Lesage 2002 2002

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Tissue Management and Impression Techniques for Fixed Prosthodontics

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Efficacy has yet to be established

Donovan Donovan & Chee 2004

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Magic Foam Cord Coltène/Whaledent Coltène/Whaledent

The first expanding PVS material designed for easy and fast retraction of the sulcus

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Magic Foam Cord Coltène/Whaledent Coltène/Whaledent

Cartridge similar to the regular impression materials  Disposable tips Cotton cap (Comprecap) Used with the same gun of the regular addition silicone impression material 8 April 09

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Principle of Work Silicone foam expands in the sulcus and its mass becomes larger precisely to achieve the retraction we require

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Effect on gingival health Efficiency in gingival retraction

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A clinical study on the effects of cordless and conventional retraction techniques on the gingival and periodontal health.  Al Hamad et al., J Clin Periodontol 2008; 35: 

1053–1058.

Principal findings: all retraction techniques caused a temporary inflammation, measured through the gingival index.The recovery at 7 days was slower for Expasyl. Bleeding during or after retraction was only encountered with the use of conventional retraction cords. Practical implications: This study showed that none of the techniques tested seems to harm the tissues in the long term; however, clinicians should be aware that Expasyl use is less friendly to the gingival tissues. Cordless techniques do not require haemostatic agents to control bleeding 8 April 09

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Part I: tissue management  Tissue management  Aims and principles  Techniques    

Mechanical Chemo mechanical Surgical Combination

 Haemostatic agents  New cordless techniques

8 April 09

Tissue Management and Impression Techniques for Fixed Prosthodontics

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Lecture Outline

 Tissue management Impression techniques

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disinfection

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Classification: Elasticity

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Viscosity

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disinfection

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Polysulphide         

Base:  Short chain Thiokol polymer. Used extensively in building industry where it is supplied as a one pack and setting takes place under atmospheric oxygen (weeks). In dentistry, setting is brought about by oxidizing agent (lead dioxide) Molecule of water is produced for every link that is made. (condensation) Objectionable odor Long setting time High shrinkage High tear resistance High permanent deformation

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disnfection

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Polyether  Base  Polyether polymer with imine group  Plasticizer & Inert filler  Activator  Aromatic Sulphonate  Plasticizer & Inert filler  Short working time  Less permanent deformation than polysulfide but not as low as silicones.  Stiff  The least dimensional change except the addition type silicone.  Absorb water.

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disinfection

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Silicone Rubber 

Condensation Type 

Base: 

  

Hydroxyl terminated Dimethyl siloxane (reactive OH).

Catalyst:

 Alkyl silicate.

Different viscosities produced by different MW of Dimethyl siloxane and the concentration of the filler. Condensation reaction producing alcohol. Resulting in dimensional change occuring mainly during the first 24 h.

 Addition Type     

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Prepolymer of polydimethyl siloxane in which some of the methyl groups are replaced by vinyl groups in one paste and with hydrogen in the other paste. Catalyst: Platinum containing compound (chloroplatinic acid). Addition reaction producing no by products. Increase in Temperature and Moisture increases the reaction. Early when they first introduced(1950’s) gaseous hydrogen was produced as a result of the cross linking reaction. Mechanism is unclear !(side reaction of the hydroxil group ? Or a reaction of the catalyst with moisture??)

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disinfection

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Comparison of elastomers  Setting time - Polysulfides > Silicones > Polyethers  Tear strength - Polysulfides > Silicones > Polyethers  Stiffness - Polyethers > Silicones > Polysulfides  Dimensional Change - Cond Silicone > Polysulfides > Polyethers > Addition Silicone

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disinfection

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Materials Polyvinylsiloxane impression material

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Trays Stainless steel perforated trays(metal) Polytrays (Polycarbonate/Yellow) Orthodontic impression trays(red)

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Part II: Impression Techniques  Classifications  Available materials  Polysulphide  Polyether  Silicones  Condensation-type  Addition-type

 Comparisons

 Packaging & Techniques  Disinfection

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Disinfection  DISINFECTANTS FOR IMPRESSION MATERIALS:  Glutaraldehyde:  - Indicated for all impression materials except hydrocolloids  Phenols:  - Indicated for polysulfide rubber base only  Iodophors and NaOCl:  - Indicated for all impression materials 8 April 09

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 Clinical Case

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