Elastic Impression Materials and Denture Adhesives - PowerPoint PPT Presentation

View by Category
About This Presentation
Title:

Elastic Impression Materials and Denture Adhesives

Description:

Elastic Impression Materials and Denture Adhesives – PowerPoint PPT presentation

Number of Views:383
Updated: 27 March 2015
Slides: 45
Provided by: Shujah

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Elastic Impression Materials and Denture Adhesives


1
Elastomeric Impression Materials
  • Dr Shujah A Khan
  • MDS Resident, Dept. of Prosthodontics
  • DIKIOHS, DUHS

2
Elastic Impression Materials
  • Hydrocolloids
  • Reversible Hydrocolloids
  • Irreversible Hydrocolloids
  • Elastomers
  • Polysulfides
  • Polyethers
  • Condensation Silicones
  • Addition Silicones - Polyvinylsiloxanes

3
Elastic Impression Materials
  • HYDROCOLLOIDS
  • water-based impression materials
  • Colloid liquid suspension of particles
  • Particles derived from seaweed kelp
  • Liquid water
  • GEL the rubber-like form of the material
  • SOL the material in liquid solution
  • Not dimensionally stable must be poured
    immediately

4
Hydrocolloids
  • Reversible Hydrocolloid
  • Agar a gelatinous material water
  • Thermoplastic NO chemical reaction
  • Reversible
  • Goes from gel, to sol, and back to gel,
  • by raising and lowering temperature
  • Dispensed in tubes syringes
  • Very accurate final impression material

5
Hydrocolloids
  • Handling Reversible Hydrocolloid
  • Special water baths with 3 chambers are used
  • 1) Material is immersed in boiling tank (212F)
  • for 10-20 minutes turns from gel to sol
  • 2) Place in storage bath (150F)
  • 10 minutes to few days remains sol
  • 3) Load tray immerse in the tempering bath
    (110F) 5-10 minutes lowers temp for pt comfort

6
Hydrocolloids
  • Handling Reversible Hydrocolloid
  • 4) Load syringe extrude onto prep site
  • 5) Seat tray in mouth
  • 6) Attach cooling hoses to tray
  • 7) Hold firmly in pts mouth until cooled and
    transformed to gel state
  • 8) Remove from pts mouth and pour immediately

7
Reversible Hydrocolloid
  • Advantages
  • Very accurate
  • Excellent compatibility with gypsum
  • Disadvantages
  • Labor-intensive
  • Poor tear resistance
  • Poor stability
  • Need equipment space and very organized staff

8
Hydrocolloids
  • Irreversible Hydrocolloid
  • ALGINATE impression material
  • Formed by chemical reaction
  • Powder water mixed
  • NOT reversible SOL to GEL only
  • Protect from inhalation
  • Dispensed in cans or bulk packages
  • Used when less detail is required

9
Hydrocolloids
  • What are indications for alginate impressions?
  • Study models
  • Opposing models of final casts
  • Casts for mouthguards, whitening trays, custom
    trays, orthodontic appliances, provisional
    crowns, etc.
  • To fabricate a direct provisional crown

10
Hydrocolloids
  • Handling Alginate
  • Fluff powder and measure accurately
  • Measure water temp!
  • Mix in a flexible,
  • rubber bowl
  • Stir to wet powder
  • Strop mixture against side of bowl to eliminate
    air bubbles
  • Mix until creamy homogeneous 60 sec.

11
Hydrocolloids
  • Handling Alginate
  • Load alginate into tray from posterior
  • Press material into tray to eliminate voids
  • Smooth indent alginate with wet finger
  • Use extra alginate to wipe onto occlusal surfaces
    of teeth

12
Taking an Alginate Impression
  • Bead the tray as necessary
  • Stand behind patient for maxillary (1100)
  • Center tray above teeth and seat posterior
  • Press tray down toward anterior and allow lip
    to cover tray material should fill vestibule
  • Hold tray in patients mouth until set (2 - 3
    min)
  • Loosen cheeks and lips with finger
  • Remove occlusally with a firm snap

13
Evaluating an Alginate Impression
  • Full coverage, including retromolar area
  • Tray centered
  • Clear sharp impression
  • No voids, air bubbles, or tears
  • Has a peripheral roll (vestibular area)
  • If all is OK, rinse disinfect impression,
  • pour-up in stone/plaster, or store in humid bag.

14
Irreversible Hydrocolloid
  • Advantages
  • Easy economical
  • Many applications
  • Patient comfort
  • Excellent wetting by gypsum
  • Disposable tray
  • Disadvantages
  • Not enough detail for final impression
  • Must be poured immediately

15
Hydrocolloids
  • SYNERESIS shrinkage in impression due to loss
    of water from heat or exposure to air.
  • IMBIBITION swelling of impression due to taking
    up moisture
  • To avoid these conditions (dimensional
    distortion), pour-up immediately!

16
Elastomers
  • Two-paste systems
  • Two tubes pastes mixed by hand
  • Two putties mixed/kneaded by hand
  • Cartridge Extruder Gun automix tips used
  • Cartridge Motor-driven Mixer automix tips
    used
  • Set by chemical reaction
  • Warmth and moisture may slow setting
  • Must use a tray adhesive (if tray not perforated)
  • Latex may inhibit set of polyvinylsiloxanes

17
Elastomers
  • Elastomers are used in a two-step process
  • Preliminary Impression - the material used to
    form the base or the tray material used in an
    impression usually more viscous or heavy-body
  • Secondary or Wash Impression the material
    applied through a syringe around the prep site
    for detail usually less viscous
  • light or medium -body.

18
Elastomers
  • POLYSULFIDE
  • Oldest elastomeric used in dentistry
  • Two pastes mix base with catalyst
  • Liquid polymer with sulfhydryl group contains
    sulfur
  • rubber-base impression material
  • Used best with custom trays
  • Other materials have replaced this one

19
Elastomers
  • Handling Polysulfides
  • Equal lengths of pastes on pad
  • Pastes are swirled together, then stropped
  • Material placed in custom tray
  • Take impression hold in place for up to 15 min.
  • Remove from pts mouth slow steady force
  • Rinse disinfect
  • Pour-up impression within several hours

20
Polysulfides
  • Advantages
  • Economical
  • Good tear resistance
  • Good compatibility with gypsum
  • Disadvantages
  • Malodor
  • Stains clothing
  • Long setting time
  • Fair stability
  • Less accurate

21
Elastomers
  • Condensation Silicones
  • Similar to silicone rubber products (but
    non-toxic)
  • Setting by-product of alcohol
  • Hydrophobic results in voids in stone
  • Shrinkage occurs as it sets
  • Must be poured immediately
  • Accurate, but slow setting time
  • Replaced by improved products

22
Elastomers
  • POLYETHERS
  • Developed in 1960s
  • No reaction by-product produced
  • Shorter working and setting time
  • Only come in a single viscosity
  • Stiff material can use a triple tray
  • Very popular Impregum
  • No need to pour-up immediately

23
Elastomers
  • Handling Polyether
  • Mix equal lengths of paste or extrude through
    the automix cartridge tip
  • Load syringe and apply to tooth thru tip
  • Load tray and invert over area for impression
  • Allow to set 4 5 minutes
  • Remove from mouth
  • Rinse disinfect

24
Polyether Impregum
25
Polyether
  • Advantages
  • Short setting time
  • Single viscosity
  • Good stability
  • Good tear strength
  • Clean easy to use
  • Disadvantages
  • Bad taste
  • Most difficult to remove from mouth

26
Elastomers
  • ADDITION SILICONES
  • Polyvinylsiloxanes silicone polymer
  • Two pastes or two putties
  • Hydrophobic by nature manufacturers adding
    components to increase wettability
  • Very accurate fast setting
  • Avoid contact with latex (gloves, rubber dams)
  • Low setting shrinkage very stable

27
Elastomers
  • Handling Addition Silicone
  • Mix equal lengths of pastes, or automix
  • Apply light-body material to tooth thru syringe
  • Load tray with heavy-body
  • Set tray over prep site
  • Set in 4 5 minutes
  • Rinse disinfect

28
Addition Silicone Polyvinylsiloxane
  • Advantages
  • Very stable
  • Short setting time
  • Good tear resistance
  • Great accuracy
  • No bad taste
  • Disadvantages
  • May have poor wettability
  • Two pastes to mix

29
DENTURE ADHESIVES
30
  • DENTURE ADHESIVES are materials used
  • to adhere a denture to the oral mucosa.

31
  • MECHANISM OF ACTION
  • Denture adhesives enhance retention through
    optimizing interfacial forces by
  • Increasing the viscosity of the medium lying
    between the denture base and basal seal and
  • Eliminating voids between the denture base and
    its basal seal.

32
  • Purpose of using denture adhesive
  • Improved fit
  • Comfort
  • Improved chewing ability.

33
REQUIREMENTS
  • Neutral or slightly basic pH.
  • Minimal toxicity to oral mucosa.
  • Bond strength for 12 to 16 hours.
  • Better taste and fit.
  • Less expensive.

34
MATERIALS USED IN DENTURE ADHESIVES
  • VEGETABLE GUMS
  • For example KARAYA, TRAGACANTH, XANTHAN
    and ACACIA.
  • Highly water soluble in hot liquids.
  • Short lived.
  • Allergic reactions to reactions to karaya have
    been reported
  • MODE OF ACTION
  • Nonionic adhesion to both denture and mucosa.
  • Very little cohesive strength.

35
  • SYNTHETIC MATERIALS
  • For example SHORT- ACTING CARBOXY METHYL
  • CELLULOSE, LONG ACTING POLY VINYL METHYL
    ETHER MALEATE and POLY VINYLPYROLIDONE.
  • Washed out by saliva.
  • MODE OF ACTION
  • SHORT-ACTING CMC Ionic adhesion.( inc.
    viscosity) by eliminating voids.
  • LONG ACTING Cohesion.

36
  • OTHER MATERIALS
  • PETROLIUM, MINERAL OIL and POLYETHYLENE
    OXIDE are included in creams.
  • SILICONE DIOXIDE and CALCIUM-STEARATE are
    included in powder to minimize clumping.
  • MENTHOL and PEPERMINT OIL are used for
    flavoring, RED DYE for color.
  • SODIUM BORATE and METHYLPARABEN or
    POLYPARABEN as preservatives.

37
INDICATIONS
  • Well made complete dentures do not satisfy
    patients perceived retention and stability
  • expectations.
  • Salivary dysfunction or neurological disorders.
  • Xerostomia due to medication side effects.
  • Head and neck resective surgery.
  • Cerebrovascular accident (stroke).
  • Orofacial dyskinesia.

38
CONTRAINDICATION
  • For the retention of improperly fabricated
    denture or poorly fitting prosthesis

39
PATIENT EDUCATION
  • Choice between cream and powder is highly
    subjective for individual.
  • Least amount of material that is used should be
    0.5g to 1.5g/ denture unit (more for larger
    alveolar ridges, less for smaller ones).

40
  • POWDER FORM
  • The prosthesis should be clean then moistened.
  • Then a thin even coating of adhesive sprayed.
  • If patient has inadequate or absence of saliva,
    sprayed denture should be moistened before being
    inserted.

41
  • PASTE FORM
  • For pastes two approaches are possible
  • THIN BEAD TECHNIQUE
  • The prosthesis should be clean and dried.
  • For maxilla thin beads of adhesive should be
    placed in the incisor, molar and mid-palate
    regions.
  • For mandible a series of thin beads at the crest
    of ridge is recommended.

42
  • SPOT TECHNIQUE
  • Small spots of cream are placed at 5-mm intervals
    throughout the fitting surface of the dried
    denture,

43
DENTURE MAINTENANCE
  • Daily removal of adhesive product from tissue
    surface.
  • Prosthesis soaked in water over night, so
    readily rinsed off.
  • Running hot water over tissue surface of denture
    while scrubbing with a hard toothbrush.
  • Adhesive on ridge is removed by rinsing with
    warm water then firmly wiping the area with
    gauze.

44
(No Transcript)
About PowerShow.com