11. Altered Cast Impression Flashcards by J L

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

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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

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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

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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

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• 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

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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

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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

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Definition
Altered Cast Removable Partial Denture Impression

• Impression and tray attached to ____ framework

removable partial denture

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Definition
Altered Cast
• A \_\_\_\_ cast that is revised in part before processing a denture base
• Also called
– \_\_\_\_ cast 
– Modified cast

master

corrected

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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

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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

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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

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It has been demonstrated that the single most important factor in minimizing abutment tooth movement is the ____ of the base

fit

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The prosthesis can be stabilized in response to ____ stresses by means of favorable ____ distribution between supporting ____ and abutment ____

vertical
load
bone
teeth

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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

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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

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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

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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

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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

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Selective Tissue Placement Impression Method

• ____ is the most important part of the impression

tray

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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

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Mandibular Ridge Anatomy

Should not be ____ in impression (record in anatomic form)

____ support
area (additional
pressure placed

displaced

primary

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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