11. Altered Cast Impression Flashcards
Distal Extension PRDP • Not completely \_\_\_\_ supported – One or more bases cover the ridge \_\_\_\_ to the last abutment • Depends on \_\_\_\_ for: – Support – Stability – Retention • Patient must be advised about movement
tooth
distal
residual ridge
Factors Influencing Support of Distal Extension Base
• Contour and quality of the ____
• ____ of residual ridge coverage by the
denture base
• Type and accuracy of the ____ registration
• Accuracy of the fit of the denture base
• Design of the PRDP framework
• Total occlusal ____ applied
residual ridge
extent
impression
load
Anatomic Form Impression
• One-stage impression method using an ____ impression material
– Produces a cast that does ____ represent a functional relationship between supporting structures of the partially edentulous mouth
• Represents hard and soft tissue at ____
elastic
not
rest
Anatomic Form Impression
• When masticatory load is applied
– Rest(s) will act as a ____
• Limits ____ near abutment tooth from transmitting load to underlying anatomic structures
– Distal end of base(s) moves more ____ and will transmit more ____ to underlying tissue
– More ____ will be transmitted to the abutment teeth through the framework
stop base freely load torque
• PRDP fabricated from a ____-stage, ____-form impression, places more of the masticatory load on the ____ teeth and that part of the bone that underlies the distal end of the extension base.
– can result in ____ loss and loosening of the abutment tooth.
one
anatomic
abutment
bone
No single material can record both the ____ form of the teeth and tissue in the dental arch and the ____ form of the residual ridge at the same time…
anatomic
functional
Definition
Altered Cast Removable Partial Denture Impression
• A negative likeness of a portion or portions of the edentulous denture bearing area made ____ of and after the initial impression of the natural teeth
• This technique employs an ____ tray(s) attached to the ____ of the removable partial
denture or its likeness
independent
impression
framework
Definition
Altered Cast Removable Partial Denture Impression
• Impression and tray attached to ____ framework
removable partial denture
Definition Altered Cast • A \_\_\_\_ cast that is revised in part before processing a denture base • Also called – \_\_\_\_ cast – Modified cast
master
corrected
Objectives
• Provide maximum support for PRDP bases to minimize tissue-ward movement
– Some movement unpreventable
– Maintain occlusal contact between natural and artificial dentition with ____ movement of base
• Creates less ____ on abutment teeth
minimum
leverage
Objectives • Reduce number of \_\_\_\_ visits • Preserve \_\_\_\_ ridges • Improve \_\_\_\_ distribution • Decrease \_\_\_\_ impaction • Decrease \_\_\_\_ of abutment teeth
ALL LEAD TO INCREASED PATIENT SATISFACTION
postoperative residual stress food torquing
Objectives • Poor support can result in: – \_\_\_\_ of abutment teeth – \_\_\_\_ of mucosa – Accelerated \_\_\_\_ of the remaining residual ridge
MAY RESULT IN PREMATURE FAILURE OF THE PROSTHESIS
mobility
ulceration
resorption
It has been demonstrated that the single most important factor in minimizing abutment tooth movement is the ____ of the base
fit
The prosthesis can be stabilized in response to ____ stresses by means of favorable ____ distribution between supporting ____ and abutment ____
vertical
load
bone
teeth
Objectives
• Clinical studies have demonstrated that the altered cast impression technique demonstrated
– (1) the ____ amount of movement of the base
– (2)the most ____ ridge-to-denture- base relationship
least
favorable
Requirements for Providing Adequate Support
• (1) it records and relates the supporting ____ under some loading
• (2) it distributes the load over as ____ an area as possible
soft tissue
large
Selective Tissue Placement Impression Method
• Soft tissue that covers basal seat areas may be:
Minimally displaced (placed) displaced >> Differs in: (1)\_\_\_\_ of alteration from resting form (2)physiological reaction to the amount of \_\_\_\_
Recorded in resting or anatomical form
degree
displacement
Selective Tissue Placement Impression Method
Overly displaced tissues > Attempt to gain \_\_\_\_ form > tissues become \_\_\_\_ and physiological functions impaired > \_\_\_\_ resorption
Minimally displaced tissues
>
respond ____ to additional pressures placed on them (if pressures are intermittent)
anatomic
inflamed
bone
favorably
Selective Tissue Placement Impression Method
• Properly prepared, individualized impression tray
– Can record ____ stress-bearing areas in a ____ form
– Non stress-bearing areas in ____ form
primary
functional
anatomic
Selective Tissue Placement Impression Method
• ____ is the most important part of the impression
tray
Altered Cast
• Mandibular arch
– Most commonly used for ____ distal extension partially edentulous arches
– Kennedy Class I and II
• Greater variation in tissue ____ and tissue distortion or displaceability
– Need ____ tissue placement
– May be due to ____ of mandibular ridge resorption
mandibular
distortion
selective
pattern
Mandibular Ridge Anatomy
Should not be ____ in impression (record in anatomic form)
____ support
area (additional
pressure placed
displaced
primary
Altered Cast
• Maxillary arch
– Not used as much due to amount of firm ____ tissue for soft tissue support
– If excessive tissue mobility, recommend ____
palatal
surgery
Maxillary ridge anatomy
Take a look!
yay
Goal
Selective Tissue Placement
Maximize soft tissue ____
+
Use ____ to their supportive advantage
> >
____ fitted to teeth while registering soft tissue support
support
teeth
framework
Technique
\_\_\_\_ fitted > \_\_\_\_ tray attached > selective \_\_\_\_ placement impression > altered \_\_\_\_ formation
framework
custom
tissue
cast
Technique • Fit framework • Use disclosing media • Identify \_\_\_\_ to enable complete seating • Identify appropriate contact(s) of components – During \_\_\_\_ – When seated • Do NOT \_\_\_\_!!
interferences
seating
force
Technique
• Remove ____ and see where binds
– Will prevent complete ____
framework
seating
Technique
• Framework is carefully adjusted
– Over-adjustment can result in a poorly ____ framework
adapted
Technique
• Following adjustment, check
for complete ____ of framework
• If not completely seated, may be problem with accuracy of ____
seat
framework
Technique
• Occlusion checked and adjusted
– until natural tooth contacts that exist without framework ____ are achieved with framework in place
• Polish with ____ points
seated
rubber
Technique
• If there are opposing frameworks
– Each is adjusted ____ to the natural dentition
– Then, tried in ____ and adjusted until natural tooth contact**
**Need to maintain the same ____ with the frameworks in and out of the mouth!
separately
together
contact relationship
Custom Tray Fabrication • Mark tray \_\_\_\_ on cast • \_\_\_\_ seated on cast • Place a \_\_\_\_ layer baseplate wax – \_\_\_\_ tissue stop – \_\_\_\_ tissue stop
extension framework single anterior posterior
Custom Tray Fabrication
• Warm framework and press into position on cast
• Place ____ on cast
• A sheet of tray material is adapted to cast and over framework
• Material is trimmed back to borders
• Tray is ____ cured
MRA
light
Custom Tray Fabrication
• Cured acrylic resin trays with
framework are removed from cast
– Trays are trimmed to ____ of wax spacer
outline
Custom Tray Fabrication • Borders adjusted to extend \_\_\_\_mm short of tissue reflections • Holes placed in trays – Crest of \_\_\_\_ and \_\_\_\_ pads – Escape excess impression material – Retention of impression material
2
ridge
retromolar
Selective Tissue Placement Impression
• Try framework and trays in mouth
• Adjust ____mm from reflections
• Cover ____ pads
2-3
retromolar
Selective Tissue Placement Impression
• ____ compound or
triad is added to tray
impression
Selective Tissue Placement Impression • Impression compound – \_\_\_\_ – Tempered – \_\_\_\_ – Placed in patient’s mouth
softened
seated
Selective Tissue Placement Impression
• Borders are heated in individual areas
– ____ cheeks
– ____ movements
manipulate
tongue
Selective Tissue Placement Impression
• Alternatively, triad is added to tray to ____
border mold
Selective Tissue Placement Impression
• Following intraoral manipulation, ____ is cured
triad
Selective Tissue Placement Impression • Slight relief provided on border molding – Borders \_\_\_\_mm – Undersurface approximately \_\_\_\_mm • With exception of \_\_\_\_
1-1.5
1
buccal shelf
Selective Tissue Placement Impression
• Impression compound
removed from ____ in tray
holes
Selective Tissue Placement Impression
• Final impression is completed with ____ impression wash
• Framework must be perfectly ____ and maintained in ____ during setting
elastic
seated
position
Altered Cast Fabrication
• Edentulous regions of cast are ____
• Cut surfaces are ____ for additional retention of stone for altered cast
eliminated
grooved
Altered Cast Fabrication
• Framework and impression are returned to cast and luted with ____
sticky wax
Altered Cast Fabrication
• Impression is ____ and boxed and poured
beaded
Altered Cast Fabrication
• Altered master cast with framework in position
* Buccal shelf regions have been recorded in \_\_\_\_ form * Other regions of basal seats have been recorded in \_\_\_\_ form
functional
anatomic
Mechanism of Action
Minimize amount of ____ during custom tray fabrication
>
restricts flow of material in ____ stress-bearing areas
>
enables placement or displacement of the ____ over the primary support areas
>
causes ____ pressure to be exerted on the tissue in this area
>
provides support to denture base when PRDP is functionally ____
relief primary soft tissues greater loaded
Clinical Considerations
•____ are placed on altered cast for interocclusal records and tooth arrangement
wax rims
Clinical considerations
Underextension results in less ____ which may result in instability
Adequately extended ____ base extension
support
distal
Clinical Considerations
• ____-edge residual ridge with ____-to- severe resorption
knife
moderate
Summary
Altered Cast Impression Technique
Attempts to make accomodations between differences in:
> resiliency of ____ of edentulous ridges
> ____ tissue of remaining teeth
May result in:
> improved ____ of PRDP
> ____ of remaining supporting structures
> increased patient ____
soft tissue
hard
fit
preservation
satisfaction
Guidelines at Penn (January 2019)
• Making altered cast impressions is left to the clinical judgement of the supervising faculty
• Final impression must accurately capture all ____ structures (soft and hard tissue) which support the PRDP
– Includes functional impression of all vestibular denture borders, retromolar pads, the retromylohyoid space, hamular notches and retrozygomatic spaces
anatomical
Guidelines at Penn (January 2019)
• If adequate ____ tissue detail and accurate ____ extensions have been captured in the master impression for the PRDP framework, the altered cast impression will no longer be required.
• Policy will be reassessed after 1 year
hard and soft
peripheral
