5.preliminary impressions

1. 5. Preliminary Impressions5. Preliminary Impressions
John Beumer III, DDS, MSJohn Beumer III, DDS, MS
Division of Advanced Prosthodontics, Division of Advanced Prosthodontics,
Biomaterials and Hospital DentistryBiomaterials and Hospital Dentistry
UCLA School of DentistryUCLA School of Dentistry
andand
Frank Lauciello DDSFrank Lauciello DDS
Ivoclar VivadentIvoclar Vivadent
This program of instruction is protected by copyright ©. No portion of This program of instruction is protected by copyright ©. No portion of
this program of instruction may be reproduced, recorded or transferred this program of instruction may be reproduced, recorded or transferred
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2. Preliminary ImpressionsPreliminary Impressions

3. Preliminary ImpressionsPreliminary Impressions
Purpose:Purpose:
-for -for diagnosis and construction of custom impression traysdiagnosis and construction of custom impression trays..
Requirements:Requirements:
-must capture all intraoral landmarks, retromolar pads, -must capture all intraoral landmarks, retromolar pads,
retromylohyoid space, hamular notches, etc.retromylohyoid space, hamular notches, etc.
-will be slightly overextended but must essentially capture -will be slightly overextended but must essentially capture
the 3-D contours of the vestibular borders of the limiting the 3-D contours of the vestibular borders of the limiting
structures.structures.
****An accurate preliminary cast that records all anatomic landmarks An accurate preliminary cast that records all anatomic landmarks
that should be covered by a denture permits fabrication of properly that should be covered by a denture permits fabrication of properly
extended custom trays that will expedite border molding and extended custom trays that will expedite border molding and
facilitate a quality final impression.facilitate a quality final impression.

4. Preliminary ImpressionsPreliminary Impressions

5. Preliminary Impressions - Armamentarium
-Alginate
(reversable hydrocolloid)
-Tray Adhesive
-Edentulous metal stock
trays
-Plastic mixing bowl
-Round edge spatula
-Periphery wax
-Water bath
-Mouth mirror
-2x2 gauge

6. Preliminary ImpressionsPreliminary Impressions
Select a stock tray
Extend tray only where necessary with soft
periphery wax
Warm the periphery wax in a warm water
bath, insert in patients mouth and mold the
periphery wax to the intraoral contours
Spray with tray adhesive
Irreversible hydrocolloid impression
The preliminary impression should have no
major pressure spots or voids and it should
capture all peripheral extensions
Pour impressions in plaster with adequate
bases including the central “tongue” area of
the mandibular impression

7. Warm the periphery wax in a warm water bath, insert in patientsWarm the periphery wax in a warm water bath, insert in patients
mouth and mold the periphery wax to the intraoral contours.mouth and mold the periphery wax to the intraoral contours.
**Note: the pts existing denture can be used**Note: the pts existing denture can be used
to help select an appropriate size tray.to help select an appropriate size tray.
Preliminary ImpressionsPreliminary Impressions

8. Preliminary Impressions Preliminary Impressions
Spray alginate adhesive onto traySpray alginate adhesive onto tray

9. Practice tray insertionPractice tray insertionMix the alginate with the Mix the alginate with the round edge spatularound edge spatula..
Mix in a vigorous manner using Mix in a vigorous manner using sweeping sweeping
strokesstrokes against the walls of the mixing bowl. against the walls of the mixing bowl.
Mix to a Mix to a creamy consistencycreamy consistency..
It is often recommended to It is often recommended to use slightly less use slightly less
waterwater than the directions specify to achieve a than the directions specify to achieve a
thicker mix. This is especially true for the thicker mix. This is especially true for the
maxillary impression to reduce the likelihood of maxillary impression to reduce the likelihood of
gagging.gagging.
Use the mirror handle to retract the lipsUse the mirror handle to retract the lips as as
you you rotate the tray into positionrotate the tray into position..
Message the lips and cheeks to border mold Message the lips and cheeks to border mold
the peripheriesthe peripheries..
Tray ready to insertTray ready to insert
Alginate Mixing Tips:Alginate Mixing Tips:

10. Preliminary ImpressionsPreliminary Impressions
Mix alginate and load tray

11. Mandibular Alginate ImpressionMandibular Alginate Impression
Seat the tray and hold it firmly in position. Seat the tray and hold it firmly in position.
Have the patient lift their tongue and displace it anteriorlyHave the patient lift their tongue and displace it anteriorly..

12. Mandibular Alginate ImpressionMandibular Alginate Impression
Ideal impression should:Ideal impression should:
Show no pressure spotsShow no pressure spots
Record the ridge, peripheries, retromolar pad, and Record the ridge, peripheries, retromolar pad, and
the retromylohyoid fossa.the retromylohyoid fossa.

13. Insert trayInsert tray
Seat posterior portionSeat posterior portion
Rotate the anterior portion into positionRotate the anterior portion into position
Border mold the impressionBorder mold the impression
Completed impressionCompleted impression
Maxillary Alginate ImpressionMaxillary Alginate Impression

14. Dense mix of plaster
Avoid entrapment of air
bubbles
Pour the impression with
adequate plaster to create a
base
Note: The plaster Note: The plaster
should capture the should capture the
contours of the labial-contours of the labial-
buccal borderbuccal border..
Pouring the Preliminary Casts

15. The preliminary impression should have no major pressure The preliminary impression should have no major pressure
spots or voids and it should capture all peripheral extensions.spots or voids and it should capture all peripheral extensions.
Pour impressions in plaster with adequate bases including the Pour impressions in plaster with adequate bases including the
central “tongue” area of the mandibular impression.central “tongue” area of the mandibular impression.
Completed ImpressionsCompleted Impressions

16. Alternate Technique- Accu-dentAlternate Technique- Accu-dent

17. Accu-Dent System 1Accu-Dent System 1
Irreversible hydrocolloid (hydrophilic)Irreversible hydrocolloid (hydrophilic)
Two viscositiesTwo viscosities
Non-slumpingNon-slumping
Premeasured sealed packagingPremeasured sealed packaging
Syringe delivery Syringe delivery
Temperature controlledTemperature controlled
Unique tray designUnique tray design
Single entry impression systemSingle entry impression system

18. Tray SelectionTray Selection

19. Post DamPost Dam
Locate the physiologic Locate the physiologic
posterior palatal seal area posterior palatal seal area
by having patient say “ah”by having patient say “ah”
Using an indelible stick, Using an indelible stick,
mark the palate just distal mark the palate just distal
to where the palate to where the palate
vibrates.vibrates.
Palpate where the palatal Palpate where the palatal
tissues are displaceable tissues are displaceable
(glandular area) and mark. (glandular area) and mark.

20. Mix the Syringe Gel using Mix the Syringe Gel using
7070°F water measured to the °F water measured to the
designated line on the vial. designated line on the vial.
Back load the syringeBack load the syringe
Replace the plunger and Replace the plunger and
express out anyexpress out any air. Set air. Set
asideaside
Syringe GelSyringe Gel

21. Mix the Tray Gel using 70Mix the Tray Gel using 70°F °F
water measured to the water measured to the
designated line on the vial. designated line on the vial.
The mix will appear dry at The mix will appear dry at
first but first but do notdo not add additional add additional
water.water.
Tray GelTray Gel

22. Accu-Dent Maxillary ImpressionAccu-Dent Maxillary Impression
Make sure a small amount of Tray Gel Make sure a small amount of Tray Gel
is pushed through the large holes in the is pushed through the large holes in the
tray for retention.tray for retention.
Hold the tray under cold running water Hold the tray under cold running water
and smooth the surface with your and smooth the surface with your
fingers.fingers.
The proper shape of the Tray Gel The proper shape of the Tray Gel
material is very important: most of the material is very important: most of the
material should be in the front sloping material should be in the front sloping
to very little in the back.to very little in the back.
Loading the trayLoading the tray

23. Wipe dry the vestibules and palate Wipe dry the vestibules and palate
with a 2x2 gauge.with a 2x2 gauge.
Express a line of the Syringe Gel into Express a line of the Syringe Gel into
the vestibule from the hamular notch the vestibule from the hamular notch
to the midline.to the midline.
Continue from opposite posterior to Continue from opposite posterior to
midline. Do not go all the way around midline. Do not go all the way around
in a single pass.in a single pass.
Taking the ImpressionTaking the Impression
Accu-Dent Maxillary ImpressionAccu-Dent Maxillary Impression

24. Taking the ImpressionTaking the Impression
Place a small amount of Syringe Gel Place a small amount of Syringe Gel
in the anterior vault of the palate.in the anterior vault of the palate.
Seat the tray from front to back.Seat the tray from front to back.
Stop seating the tray when a small Stop seating the tray when a small
amount of Syringe Gel appears in the amount of Syringe Gel appears in the
distal edge of the tray.distal edge of the tray.
Accu-Dent Maxillary ImpressionAccu-Dent Maxillary Impression

25. Pull straight down once on the filtrum Pull straight down once on the filtrum
at the vermilion border.at the vermilion border.
Massage the cheeks very lightly Massage the cheeks very lightly
downward with the fingers.downward with the fingers.
Have the patient open wideHave the patient open wide
Border MoldingBorder Molding
Accu-Dent Maxillary ImpressionAccu-Dent Maxillary Impression

26. Tray RemovalTray Removal
When set, break the seal at the When set, break the seal at the
distal buccal periphery and distal buccal periphery and
carefully remove the carefully remove the
impression. Using the handle impression. Using the handle
alone to remove the impression alone to remove the impression
might dislodge the material.might dislodge the material.
Disinfect according to OSHA Disinfect according to OSHA
guidelines and immediately pour guidelines and immediately pour
the model the model
Accu-Dent Maxillary ImpressionAccu-Dent Maxillary Impression

27. Impression tray acts Impression tray acts
only as a method of only as a method of
delivering the delivering the
impression materialimpression material
Accu-Dent Maxillary ImpressionAccu-Dent Maxillary Impression

28. Accu-Dent Mandibular ImpressionAccu-Dent Mandibular Impression

29. The lower Accu-Tray selection is
accomplished in two steps, 1) tray type
and 2) tray size
Chose the tray that best suits either a
normal ridge, or a highly resorbed
ridge. Trays # 26-30 are designed with
a moderate distal rise to accommodate
the moderately resorbed ridge.
Trays #20-24 are designed with a high
distal rise to help accommodate the
severely resorbed ridge .
Accu-Dent Mandibular ImpressionAccu-Dent Mandibular Impression
Tray TypeTray Type
Tray SelectionTray Selection

30. Use the supplied calipers to measure
the width of the residual ridge in the
first molar region. This can be done on
the existing denture, as shown, or in
the patients mouth.
Use this measurement to select the
correct size lower tray. The caliper
measurement should line up with the
large holes in the first molar region of
the lower tray. When in doubt use a
smaller tray.
Accu-Dent Mandibular ImpressionAccu-Dent Mandibular Impression
Tray SizeTray Size Tray SelectionTray Selection

31. Mix the Syringe Gel using 70Mix the Syringe Gel using 70°F °F
water measured to the water measured to the
designated line on the vial. designated line on the vial.
Back load the syringeBack load the syringe
Replace the plunger and Replace the plunger and
express out any air. Set asideexpress out any air. Set aside
Syringe GelSyringe Gel

32. Mix the Tray Gel using 70Mix the Tray Gel using 70°F °F
water measured to the water measured to the
designated line on the vial. designated line on the vial.
The mix will appear dry at first The mix will appear dry at first
but but do notdo not add additional water. add additional water.
Tray GelTray Gel

33. Mix the Tray Gel and place half on each side Mix the Tray Gel and place half on each side
of the tray. Make sure that some of the tray of the tray. Make sure that some of the tray
material is pushed through the holes.material is pushed through the holes.
This is the correct shape of the loaded tray. This is the correct shape of the loaded tray.
More material should be in the posterior of the More material should be in the posterior of the
tray.tray.
Give the Tray Gel a surface wash and rub Give the Tray Gel a surface wash and rub
smooth under cold running water with your smooth under cold running water with your
fingers.fingers.
Accu-Dent Mandibular ImpressionAccu-Dent Mandibular Impression
Loading the TrayLoading the Tray

34. Express Syringe Gel from the retromolar
pad forward to the midline.
Repeat on the other side of the arch. It is
not necessary to place Syringe Gel into the
lingual vestibules.
Place tray front to back until Syringe Gel
appears in the posterior of the tray. Have the
patient bring their tongue forward as you
rotate the tray backward into position. When
the Tray Gel rises up in the distal, Stop.
Accu-Dent Mandibular ImpressionAccu-Dent Mandibular Impression
Taking the ImpressionTaking the Impression

35. Completed lower impressionCompleted lower impression
Accu-Dent Mandibular ImpressionAccu-Dent Mandibular Impression