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Flashcards in Preparation for Master Impressions Deck (36)
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What are the four phases of any treatment plan

Immediate treatment
Initial (hygiene or preparatory) phase
Reconstructive (corrective) phase


What are the clinical stages of RPD construction (9)

Primary impressions
Primary jaw registration (if required)
Mounted, surveyed study casts
Design denture
Tooth preparation and definitive impressions
Jaw registration


What are the aspects of mouth preparation for master impressions (6)

Initial prosthetic treatment
Pre-prosthetic treatment
Periodontal treatment
Orthodontic treatment
Fixed prosthodontics treatment and endodontics
Tooth preparation


Give examples of initial prosthetic treatment

Repairs and additions
Temporary relines
Occlusal adjustment
Treatment of denture stomatitis


How long do materials used for temporary relines last

2-4 weeks


When should inflammation caused by denture stomatitis be treated

Before impressions are taken


What advice should be given to patients with denture stomatitis

How to keep their denture clean
Remove it at night
Gently brush the roof of their mouth to get rid of any candidal hyphae
Sometimes antifungal medication is necessary


Give examples of pre-prosthetic surgery

Remove retained roots or unerupted teeth
Remove pathology - cysts
Improve contours of edentulous areas by reducing bony prominences and hyper plastic soft tissue
Eliminate prominent fraenal attachments - may interfere with flanges


Give examples of periodontal treatment prior to taking master impressions

Establish periodontal health
Assess patient motivation
Give detailed instruction in oral hygiene procedures
Scaling and root planing
Periodontal surgery


What is the purpose of orthodontic treatment prior to taking master impressions

To optimise space
To optimise abutment alignment


What patients are most likely to need orthodontic treatment

Cleft patients
Hypodontia patients
Periodontal patients who have lost teeth


When should fixed prosthodontic treatment occur

Should follow denture design and precede denture construction


What is the purpose of fixed prosthodontic treatment

Establishes clinical integrity of teeth before master impressions are recorded
So that you can request rests, guide planes and buccal shells for clasp retention etc


When is tooth preparation carried out

Before master impressions


Why is tooth preparation necessary

To provide rest seats
To establish guide surfaces
To modify unfavourable survey lines
To create retentive areas


What instruments should be used for tooth preparation

Slow speed instruments
Initially rotary diamond being careful not to take too much away
Can use different rubber wheels or impregnated stones to help smooth and polish any preparation


Why are rest seats necessary

To divert the forces down the long axis of the tooth
Produce favourable tooth surface for support
Prevent interference with occlusion
Reduce prominence of the rest


Describe a maxillary anterior rest seat and how they are made

Well-developed cingulum allows prep to stay within enamel
Use a cylindrical diamond stone with a rounded tip


Describe a mandibular anterior rest seat

Lingual surface too vertical and cingulum too poorly developed to avoid penetrating enamel
Incisal rest seats used instead


When is it possible to use an incisal rest seat on mandibular anterior teeth, that is good aesthetically

If teeth have worn down, you can use an incisal rest on the worn tip which isn’t visible from the labial aspect


What are alternatives from using an incisal rest on mandibular anterior teeth

Produce a rest seat in composite applied to the cingulum area
Bond a cast metal cingulum to the tooth - not likely nowadays


Describe a rest seat on a posterior tooth

Reduced marginal ridge
Saucer-shaped to allow horizontal movement and dissipation of occlusal forces
Deep enough to allow a rest of at least 1mm thick


How is a posterior rest seat prepared if there is no space occlusally for a clasp to extend buccal from the occlusal rest

The preparation must be extended as a channel onto the buccal surface


What are guide planes

Two or more parallel axial surfaces on abutment teeth which limit the path of insertion of a denture
They may occur naturally but more often need to be prepared


What is an axial surface

Surfaces parallel to the long axis of a tooth


What do guide planes provide

Increased stability
Prevention of clasp deformation
Improved appearance


How should a guide plane be prepared

Guide surface should extend vertically 3mm but be kept as far from the gingival margin as possible
Not more than 0.5mm of enamel should be removed


What is the outcome of an unfavourable survey line

Clasp would be positioned too close to occlusal surface which would cause deformation of the clasp


How can an unfavourable survey line be fixed

Can add composite in a curve following the natural anatomy of the tooth to lower the survey line


Describe the clinical part of the master impression stage

Obtain an accurate impression of the denture-bearing area using an individual tray for the patient and an appropriate impression material


Describe the laboratory part of the master impression stage

Produce casts
Produce casting (if cobalt chrome base)
Produce record blocks
Produce trial denture
Produce finished denture


What are individual trays made of

Made from primary casts from heat cured or light cured acrylic


What should be done to the individual trays before taking the impression

Disinfect them, then place them in cold water and make sure they are rinsed and there isn’t any disinfectant left


What is the purpose of green stick

Will help to support the impression material to flow and give a nice sulcus form lingually
In upper it will compress the junction between the hard and soft palate and give a posterior seal


Describe green stick

Thermoplastic material
Part of the stick is cold and hard but part is heated in a Bunsen burner so the material starts to flow and it can be added to the flanges of the trays


What are common impression materials used in master impressions

Polyvinylsiloxane eg - extrude
Polyether eg - Pentamix