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Preliminary Edentulous Impressions. Preliminary Edentulous Impressions. Preliminary impressions needed for diagnostic casts for making custom trays. Custom Tray. Required to accurately register moveable mucosa Create seal for retention. Stock Trays.

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preliminary edentulous impressions1
Preliminary Edentulous Impressions
  • Preliminary impressions needed for diagnostic casts for making custom trays
custom tray
Custom Tray
  • Required to accurately register moveable mucosa
  • Create seal for retention
stock trays
Stock Trays
  • Stock trays can result in distortion and shortening of the final denture flange
alginate syringe technique
Alginate Syringe Technique
  • Irreversible hydrocolloid
  • Ensures capture of critical anatomy - sometimes missed with just a tray
border molding
Border Molding
  • Minimizes distortion of the movable vestibular tissues
  • Displacement could lead to dislodgment during function
irreversible hydrocolloid storage
Irreversible Hydrocolloid Storage
  • Pre-weighed pouches
    • Easier dispensing
    • Minimizes contamination
  • Bulk material
    • Store in cool dry airtight containers
irreversible hydrocolloid storage1
Irreversible Hydrocolloid Storage
  • Deteriorates if:
    • Stored above 54°C
    • Repeated openings
  • Deterioration results in:
    • Thin mixtures
    • Reduced strength
    • Permanent deformation
tray selection
Tray Selection
  • 5 mm of clearance with soft tissues
  • Hydrocolloid requires bulk for accuracy, strength and stability
tray selection1
Tray Selection
  • Maxillary trays should extend slightly beyond vibrating line
  • Mandibular trays should cover the retromolar pads
tray selection2
Tray Selection
  • Sto-K edentulous trays
  • Short flanges, so don’t distort vestibule
tray modification
Tray Modification
  • Trays can be modified with compound to extend the tray if desired
irreversible hydrocolloid syringe technique
Irreversible Hydrocolloid Syringe Technique
  • Critical anatomy registration
    • Retromylohyoid area
    • Hamular notches
    • Retrozygomal area
patient preparation
Patient Preparation
  • Practice placing tray
  • Rotate into place
patient preparation1
Patient Preparation
  • Dry the mucosa
    • Dry the maxilla with folded gauze
    • Pack 3 gauze in mandible
    • Don’t let patient close
mark vibrating line
Mark Vibrating Line
  • Prior to making preliminary & final impressions
  • Fovea should not be used
vibrating line
Vibrating Line
  • If denture terminates anteriorly, poor seal
  • If terminates posteriorly, soft palate movement may cause it to dislodge
  • Denture may be unretentive and/or uncomfortable
locate mark the hamular notch
Locate & Mark the Hamular Notch
  • Posterior border of a complete denture
  • Between the bony tuberosity & hamulus
locate mark hamular notch
Locate & Mark Hamular Notch
  • Denture border must terminate on soft displaceable tissue
  • Provides comfort and retention
  • Notch may be posterior to depression in soft tissue
locate mark the hamular notch1
Locate & Mark the Hamular Notch
  • Use the head of a mirror, to palpate the notch
  • Mark with an indelible marker
locate posterior border of hard palate
Locate Posterior Border of Hard Palate
  • Ensure the denture terminates posteriorly by palpating
indelible marks prior to impression
Indelible Marks Prior to Impression
  • Transfer to the impression and cast when it is poured
  • Eliminates error
  • Tissue should be relatively dry to be most effective
syringe preparation
Syringe Preparation
  • 12 cc disposable syringe
  • Cut off the tip where it begins to curve
  • 5 mm orifice
plunger preparation
Plunger Preparation
  • Vaseline plunger
  • Ease of extruding material
  • Use:
    • Uncontaminated bowl, spatula
    • Regular set alginate
measuring powder
Measuring Powder
  • Fluff (shake) the powder, measure, tap and flatten the scoop with powder
  • Use three scoops for syringe impressions
mixing
Mixing
  • Assistant mixes for at least 45 seconds
  • Smooth creamy homologous mixture that glistens
  • Not granular or lumpy
syringe loading
Syringe Loading
  • The assistant loads the syringe nearly full from the back and inserts plunger
syringe technique
Syringe Technique
  • Syringe a broad rope into the vestibule
  • Begin at the posterior
  • Move quickly toward anterior
  • Fill the vestibule to labial frenum
cheek retraction
Cheek Retraction
  • Use a mirror, instead of a finger
  • Provides better visibility, more maneuverability
maxillary impressions
Maxillary Impressions
  • Begin opposite the tuberosity
  • Inject until alginate is seen in the hamular notch before moving forward
mandibular impressions
Mandibular Impressions
  • Start with the buccal vestibule adjacent retromolar pad
  • Move forward to the labial frenum
  • Repeat on the opposite side
lingual vestibule
Lingual Vestibule
  • Roll syringe tip under tongue
  • Inject into retromylohyoid space until alginate appears between tongue & ridge
  • Move anteriorly, filling to lingual frenum
    • Repeat on the opposite side
deep palatal vaults
Deep Palatal Vaults
  • Material can be syringed into the palate
  • Smooth with a finger, or voids may occur
partially edentulous
Partially Edentulous
  • Syringe a small amount of hydrocolloid on the occlusal surfaces
  • Force into the occlusal surfaces with finger
preliminary impressions
Preliminary Impressions
  • The assistant loads the tray while the clinician is syringing
  • Place the anterior portion of the tray first, then seat the posterior of the tray
preliminary impressions1
Preliminary Impressions
  • Less gagging if the patient is lying down
  • Tongue position avoids gagging
  • Mold the vestibular area
  • Pull on the cheeks and lips to activate muscles and frena
finger sweep at posterior
Finger Sweep at Posterior
  • If excess material at border
  • Use finger or cotton swab
preliminary impressions2
Preliminary Impressions
  • Support the tray during setting - do not leave the patient
  • Movement causes distortion
preliminary impressions3
Preliminary Impressions
  • Break peripheral seal
    • Drops of water
    • Pull up cheek and let air in
    • Wiggle tray until hear seal break
preliminary impressions4
Preliminary Impressions
  • Once seal broken, remove quickly (to avoid permanent deformation)
  • Evaluate impression
  • Pour within 12 minutes
preliminary impressions5
Preliminary Impressions
  • Rinse thoroughly with water
  • Gently shake to remove excess water
preliminary impressions6
Preliminary Impressions
  • Spray with disinfectant to coat all surfaces, and seal in a bag for ten minutes
syringe technique problems
Syringe Technique Problems
  • Vestibular material may not join the tray material
    • Saliva contamination
    • Insufficient material
syringe technique problems1
Syringe Technique Problems
  • Omitting plunger lubrication may make it difficult to express the alginate
  • Trapping tongue under the tray will result in underextension of the lingual vestibule
problems with syringe technique
Problems with Syringe Technique
  • Severe gaggers poor tolerance for intraoral motion
  • Use traditional technique
pouring a model
Pouring a Model
  • Weighing powder, measure water
  • Vacuum mix (less time, stronger cast)
  • Use a two pour technique
pouring a model1
Pouring a Model
  • Modulate speed of pouring by tilting back and forth or pressing the tray more firmly onto vibrator
pouring a model2
Pouring a Model
  • Model moist during trimming
  • Soak in slurry water, or soak with base of cast in water
pouring a model3
Pouring a Model
  • Casts should be a minimum of 12 mm (.5 inch) in thinnest part
  • Separate the alginate impression from the stone cast after 45 minutes
trimming casts
Trimming Casts
  • Trim the base on the model trimmer parallel to the residual ridges
  • Leave the vestibular reflection intact for making a custom tray
trimming casts1
Trimming Casts
  • All anatomical surfaces should be included with minimum voids