1. Preliminary Edentulous Impressions

2. Preliminary Edentulous Impressions
Preliminary impressions needed for diagnostic casts for making custom trays

3. Custom Tray Required to accurately register moveable mucosa
Create seal for retention

4. Stock Trays
Stock trays can result in distortion and shortening of the final denture flange

5. Alginate Syringe Technique
Irreversible hydrocolloid
Ensures capture of critical anatomy - sometimes missed with just a tray

6. Border Molding Minimizes distortion of the movable vestibular tissues
Displacement could lead to dislodgment during function

7. Irreversible Hydrocolloid Storage
Pre-weighed pouches
Easier dispensing
Minimizes contamination
Bulk material
Store in cool dry airtight containers

8. Irreversible Hydrocolloid Storage
Deteriorates if:
Stored above 54°C
Repeated openings
Deterioration results in:
Thin mixtures
Reduced strength
Permanent deformation

9. Tray Selection 5 mm of clearance with soft tissues
Hydrocolloid requires bulk for accuracy, strength and stability

10. Tray Selection
Maxillary trays should extend slightly beyond vibrating line
Mandibular trays should cover the retromolar pads

11. Tray Selection Sto-K edentulous trays
Short flanges, so don’t distort vestibule

12. Tray Modification
Trays can be modified with compound to extend the tray if desired

13. Irreversible Hydrocolloid Syringe Technique
Critical anatomy registration
Retromylohyoid area
Hamular notches
Retrozygomal area

14. Patient Preparation
Practice placing tray
Rotate into place

15. Patient Preparation Dry the mucosa Dry the maxilla with folded gauze
Pack 3 gauze in mandible
Don’t let patient close

16. Mark Vibrating Line Prior to making preliminary & final impressions
Fovea should not be used

17. 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

18. Locate & Mark the Hamular Notch
Posterior border of a complete denture
Between the bony tuberosity & hamulus

19. 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

20. Locate & Mark the Hamular Notch
Use the head of a mirror, to palpate the notch
Mark with an indelible marker

21. Locate Posterior Border of Hard Palate
Ensure the denture terminates posteriorly by palpating

22. 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

23. Syringe Preparation 12 cc disposable syringe
Cut off the tip where it begins to curve
5 mm orifice

24. Plunger Preparation Vaseline plunger Ease of extruding material Use:
Uncontaminated bowl, spatula
Regular set alginate

25. Measuring Powder
Fluff (shake) the powder, measure, tap and flatten the scoop with powder
Use three scoops for syringe impressions

26. Mixing Assistant mixes for at least 45 seconds
Smooth creamy homologous mixture that glistens
Not granular or lumpy

27. Syringe Loading
The assistant loads the syringe nearly full from the back and inserts plunger

28. Syringe Technique Syringe a broad rope into the vestibule
Begin at the posterior
Move quickly toward anterior
Fill the vestibule to labial frenum

29. Cheek Retraction Use a mirror, instead of a finger
Provides better visibility, more maneuverability

30. Maxillary Impressions
Begin opposite the tuberosity
Inject until alginate is seen in the hamular notch before moving forward

31. Mandibular Impressions
Start with the buccal vestibule adjacent retromolar pad
Move forward to the labial frenum
Repeat on the opposite side

32. 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

33. Deep Palatal Vaults Material can be syringed into the palate
Smooth with a finger, or voids may occur

34. Partially Edentulous
Syringe a small amount of hydrocolloid on the occlusal surfaces
Force into the occlusal surfaces with finger

35. Cleaning the Syringe

36. 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

37. 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

38. Finger Sweep at Posterior
If excess material at border
Use finger or cotton swab

39. Preliminary Impressions
Support the tray during setting - do not leave the patient
Movement causes distortion

40. Preliminary Impressions
Break peripheral seal
Drops of water
Pull up cheek and let air in
Wiggle tray until hear seal break

41. Preliminary Impressions
Once seal broken, remove quickly (to avoid permanent deformation)
Evaluate impression
Pour within 12 minutes

42. Preliminary Impressions
Rinse thoroughly with water
Gently shake to remove excess water

43. Preliminary Impressions
Spray with disinfectant to coat all surfaces, and seal in a bag for ten minutes

44. Sample Impressions

45. Sample Impressions

46. Syringe Technique Problems
Vestibular material may not join the tray material
Saliva contamination
Insufficient material

47. 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

48. Problems with Syringe Technique
Severe gaggers poor tolerance for intraoral motion
Use traditional technique

49. Diagnostic Casts

50. Pouring a Model Weighing powder, measure water
Vacuum mix (less time, stronger cast)
Use a two pour technique

51. Two Pour Technique In Removable Prosthodontics: Preliminary Impressions Only

52. Pouring a Model
Modulate speed of pouring by tilting back and forth or pressing the tray more firmly onto vibrator

53. Pouring a Model Model moist during trimming
Soak in slurry water, or soak with base of cast in water

54. 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

55. Trimming Casts
Trim the base on the model trimmer parallel to the residual ridges
Leave the vestibular reflection intact for making a custom tray

56. Trimming Casts
All anatomical surfaces should be included with minimum voids