composition of zoe, mixing time and setting time, advantages and disadvantages, manipulation of zoe, materials required, steps from primary impression making to master cast fabrication, primary impression of maxillary cast, anatomic landmarks of maxillary cast, anatomic landmarks classification, spacer, tissue stops, chair positioning for maxillary impression making
7. MIXING TIME AND SETTING
TIME
ā¢ MIXING TIME = 45-60s
ā¢ SETTING TIME = 3-5mins
8. ADVANTAGES AND DISADVANTAGES
ADVANTAGES DISADVANTAGES
ā¢ CAN BE CHECKED REPEATEDLY
WITHOUT DEFORMING
ā¢ REGISTERS ACCURATE SURFACE
DETAILS
ā¢ DIMENSIONALLY STABLE
ā¢ DOESNT REQUIRE A SEPARATING
MEDIUM
ā¢ MINOR DEFECTS CAN BE CORRECTED
WITHOUT DISCARDING THE ENTIRE
IMPRESSION
ā¢ REQUIRES A SPECIAL TRAY
ā¢ STICKY IN NATURE
ā¢ EUGENOL CAN CAUSE A BURNING
SENSATION AND TISSUE IRRITATION
ā¢ CANT BE USED FOR DENTULOUS
PATIENTS
ā¢ CANT BE USED IN THE AREAS WHERE
THERE ARE SEVERE UNDERCUTS
10. MATERIALS REQUIRED FOR PREPARING THE
IMPRESSION PASTE
1. GLASS PLATE
2. OIL SHEETS
3. REACTOR AND BASE PASTES
4. CEMENT SPATULA
5. CUSTOMIZED TRAYS OF THE PATIENT
11. EQUAL LENGTHS OF BOTH
REACTOR AND BASE PASTE
ON THE GLASS PLATE OR
OIL IMPERVIOUS PAPER
CEMENT SPATULA IS USED TO
MIX BOTH THE PASTES IN A
CIRCULAR MOTION
HOMOGENOUS MIX
WITH UNIFORM
COLOR THROUGHOUT
12. STEPS FROM PRIMARY IMPRESSION TAKING TILL
SECONDARY IMPRESSION TAKING{ZOE}
PRIMARY IMPRESSION USING
IMPRESSION COMPOUND
BEADING OF PRIMARY IMPRESSION
BOXING OF PRIMARY IMPRESSION
PLASTER POURING
PRIMARY CAST
SPACER MARKING
13. SPACER ON WAX
FABRICATION OF CUSTOM TRAY
WITH HANDLE
BORDER MOULDING
ZOE IMPRESSION ON CUSTOM TRAY
FABRICATION OF MASTER CAST
17. RELIEF AREAS LIMITING
STRUCTURES
SUPPORTING
STRUCTURES-
PRIMARY STRESS
BEARING AREAS
SUPPORTING
STRUCTURES-
SECONDARY
STRESS BEARING
AREAS
The portion of the
denture-bearing area
over which the
denture base is
altered to reduce
functional pressure.
Limiting structures
are sites that will
guide us in having an
optimum extension
of denture so as to
engage maximum
surface area without
encroaching upon
the muscle action.
The trabecular pattern in
the bone is perpendicular
to the direction of force,
making it capable of
withstanding any amount
of force without marked
resorption. The primary
stress-bearing areas
generally have thicker
mucosa and /or
underlying bone that is
less subject to resorption
because it is cortical
bone.
The residual ridge is
generally a secondary
stress-bearing area
as it is made up of
cancellous bone.
18. SPACER MADE ON MAXILLARY CAST
ā¢ UNIFORM SPACER OF 2MM IS MADE USING BASEPLATE WAX
ā¢ THE PERIPHERAL EXTENSION OF SPACER= 2MM SHORT OF THE CUSTOM TRAY
ā¢ FUNCTION= ALLOWS THE TRAY TO BE PROPERLY POSTIONED BEFORE BORDER MOULDING + ALLOW THE
IMPRESSION TO HAVE EVEN THICKNESS OF IMPRESSION MATERIAL
TISSUE STOPS
ā¢ TISSUE STOPS ARE RECTANGULAR OR SQUARE AREAS WHERE THE SPACER IS REMOVED. CUSTOM TRAY IS
DIRECTLY IN CONTACT WITH THE RIDGE IN THESE AREAS. THEY FUNCTION TO CORRECTLY ORIENT AND STABILIZE
THE TRAY DURING IMPRESSION MAKING AND ENSURE UNIFORM THICKNESS OF THE IMPRESSION MATERIAL.
ā¢ THEY ARE 2MM IN DIMENSION
ā¢ TWO IN CANINE REGION AND TWO IN MOLAR REGION, ON THE CREST OF THE RIDGE.
19. CHAIR POSITIONING FOR MAXILLARY ARCH
IMPRESSION
1. PATIENT IS MADE TO SIT IN AN UPRIGHT POSITION
2. OCCLUSAL PLANE OF THE PATIENT IS PARALLEL TO THE FLOOR
3. THE DENTAL SURGEON IS AT 11 OāCLOCK POSITION FOR MAXILLARY IMPRESSION
4. ADJUST THE LIGHT
20. ā¢ Boucher`s Prosthodontic treatment for edentulous patients -
9th edition
ā¢ Textbook of Prosthodontics - V. Rangarajan
ā¢ Lyman S, Boucher LJ.-Radiographic examination of
edentulous mouths. J Prosthet Dent. 1990 Aug;64(2):180-
182.
ā¢ House M.M.-The relationship of oral examination to dental
diagnosis. J Prosthet Dent. 1958 Mar;8(2):208-219.
REFERENCES
