removable pros Flashcards
Which of the following materials is most suitable for modifying a stock tray for a primary impression?
a. green stick
b. pink stick
c. silicone putty
d. ribbon wax
c - silicone putty
What can be defined as the resistance to vertical movement of a denture away from the underlying mucosa
a. stability
b. retention
c. support
d. rigidity
B - retention
According to Cawood and Howell’s descriptive classification, a class IV ridge is:
a. negative
b. atrophic
c. recent extraction
d. knife-edged
D - knife edged
Provil putty is a type of what:
a. polysulphide
b. condensation cured-silicone
c. polyether
d. addition cured silicone
D - addition cured silicone
Which of the following can be defined as:
the difference between the resting face height and the occlusal vertical dimension?
a. interproximal space
b. vertical overlap
c. stability
d. freeway space
D - freeway space
Which impression material has a double decomposition reaction involving calcium sulphate and is popular because it is cheap and can be used in a stock tray?
a. condensation cured silicone
b. polyether
c. polysulphide
d. zinc oxide eugenol impression paste
e. irreversible hydrocolloid (alginate)
E - irreversible hydrocolloid
Which impression material is available in sheet or disc form and is softened in a water bath set to 55-60º to be used in stock trays for edentulous ridges?
a. irreversible hydrocolloid (alginate)
b. reversible hydrocolloid (agar)
c. zinc oxide eugenol impression paste
d. impression compound
e. silicone putty
D - impression compound
Overjet is defined as:
a. a horizontal measure
b. a vertical measure
A - horizontal measure b
How many times greater does ridge resorption occur in the mandible compared to the maxilla?
4 x
Define retention -
Resistance to displacive forces directed away from the tissues.
Define support -
resistance to forces directed towards the hard / soft tissues.
Define reciprocation -
the compensating element to counteract horizontal force from active clasps.
Define bracing -
resistance to horizontal forces when fully seated.
Define what a connector is -
links all the components of the denture together in a place that won’t damage the soft tissues.
Define indirect retention -
resistance to displacive forces along the retentive axis.
Define syneresis -
evaporation from the colloid compound, causing the alginate to shrink due to loss of water.
(prevented by wrapping the imp in damp gauze)
Define inbibition -
when a hydrocolloid compound absorbs too much water, leading to swelling.
(happens when imp is stored for too long in moist environment)
Define vibrating line -
The junction between the hard and soft palate.
What is the purpose of having tissue stops on special trays?
Ensures uniform thickness of impression material - can’t press the tray any further.
What should be written in the lab prescription when requesting an upper special tray for alginate?
please cast impressions in dental stone and construct:
upper special tray for alginate (2-3mm spacing) with tissue stops and stepped handle.
What should be written in the lab prescription when requesting a lower special tray for PVS?
please cast impressions in dental stone and construct:
lower special tray for PVS (1.5-2mm spacing) with tissue stops, sub-handle and finger rests (x2 in the premolar region).
What is the recommended spacing for alginate?
2-3mm
What is the recommended spacing for PVS?
1.5-2mm
Which is the only reproducible position in edentulous patients?
Retruded Contact Position (RCP)
Describe Retruded Contact Position
Tooth contact maintained with with jaw moved back around 1mm until the condyles can’t go any further.
Which positioning is not present in edentulous patients?
Intercuspal Position (ICP)
Describe Intercuspal Position
The vertical and horizontal position of the mandible when the upper and lower teeth are in maximum intercuspation (biting).
Describe Occlusal Vertical Dimension
The distance between 2 points (tip of nose and bottom of chin) when teeth are in occlusion.
How is OVD measured?
With a Willis Bite Gauge
How is freeway space calculated?
RFH - OVD = FWS
What does Foxes Occlusal Plane Guide measure?
The occlusal plane parallel to the alar tragal line.
What does the Alma gauge measure?
The incisal edge relationship to the incisive papilla in a horizontal and vertical measure (8-10mm)
Curve of Spee
anterior-posterior curve from the cusp tip of the mandibular canine along the cusps of rest of posterior teeth.
Curve of Monson
bilateral curve through the buccal and lingual cusps of mandibular molars going through the tongue.
Are radiographs justified in the treatment planning stage of complete denture provision?
No - unless there is a clear indication (e.g: suspected retained roots).
Which pathogen is associated with denture stomatitis?
candida albicans
Which condition may occur concurrently with denture stomatitis? (also fungal)
angular chelitis
What is the minimum inter-occlusal clearance in the premolar region? (FWS)
2-4 mm
Example of a chairside soft reline material:
Coe-soft
Example of a tissue conditioner:
visco-gel
Example of a definitive soft-lining material:
molloplast-B
(silicone based)
Example of a definitive soft reline material:
self or heat cured acrylic resin
When is a primary jaw reg indicated?
For cobalt-chrome - design is influenced by occlusal relationships.
When is a primary jaw reg not indicated?
- when a complete denture is going to oppose the partial
- acrylic dentures only
How deep should rests be prepared into enamel?
0.5-1mm
Which stage follows second impressions when creating a cobalt chrome denture?
framework try-in
Outline the clinical stages when making complete dentures.
- Treatment planning, diagnosis and 1st imps
- 2nd imps
- Jaw Reg
- Try In
- Fit
Problems arising from insufficient FWS:
(teeth too big)
- pain beneath dentures
- MoM and TMJ pain
- difficulty chewing and speaking
- difficulty making an oral seal with lips
Problems caused by excessive FWS:
- poor appearance (over-closed)
- difficulty chewing
- TMJ discomfort
- cheek biting
Which 3/4 components provide support?
- rests
- saddles
- connectors and collets
Which components provide retention?
- clasp length
- guide planes
- ridge undercut in saddle areas
Which components provide reciprocation?
- collets
- passive arms opposing clasps
- rests
Which components provide bracing?
- collets
- passive arms opposing clasps
- rests
- clasps
- flange extension in saddle areas
- connectors on vertical surfaces
- guide planes
How many mm of depth does a lingual bar need?
8mm
How much of a clasp needs to be in undercut?
the final 1/3
Sizes of Undercut:
0.25mm - Co/Cr
0.5mm - stainless steel
0.75mm - gold
Preston’s Golden Nugget
You can have a rest without a clasp but you can’t have a clasp without a rest.
What do you need for stable occlusion?
tripodisation of 3 index teeth
What is the path of insertion for when an anterior saddle is present?
anterior to posterior
Path of insertion for when no anterior saddle is present.
posterior to anterior
What type of acrylic is used for over denture bases and why?
polyethereytherketone (PEEK) -
used due to excellent chemical resistance.
Which type of lower CoCr connector provides maximum indirect retention?
lingual plate
When picking a mould of denture teeth, the theory of the shape of a tooth resembling the face shape can be used.
What is the name of this theory?
Leon-Williams face form -
(think of it as mr bassi - mrs williams collab)
Which piece of equipment is used to measure lip support and what should the ideal reading be?
alma gauge - 9-12mm
(measures incisal edge position in both a horizontal and vertical plane relative to the incisal papilla)
What material is applied to the upper and lower reg rims to record centric occlusion?
aquasil
When would a reg be required for immediate dentures?
no stable occlusion
What is the one surface that cannot be changed for a copy denture?
the polished surface
In what situation would a jaw reg be appropriate when constructing a copy denture?
when a change in OVD is planned
Classes of ridge assessment:
1 - dentate
2 - immediately post XLA
3 - well formed ridge
4 - knife edged ridge
5 - flat ridge
6 - negative ridge
What is the name for the distance between upper and lower incisors in the horizontal plane and what is its average value?
overjet (forward), 2-4mm
The distance between upper and lower incisors when viewed anteriorly.
overbite
Saddle -
The part of the denture which covers the edentulous area containing toothwork etc.
Connector -
Joins together the components of a denture.
(e.g: plate, ring, lingual bar / sub-lingual bar)
Retention -
Resistance to displacive forces AWAY from the tissues.
(clasps, guide planes, ridge undercut in saddles)
Support -
Resistance to displacive forces directed TOWARDS the tissues.
(rests, saddles, connectors and collets)
Reciprocation -
The compensating element to counteract the horizontal forces from an active clasp.
(collets, passive arms, rests)
Bracing -
Resistance to horizontal forces when fully seated.
(collets, passive arms, rests, clasps, flange, connector, guide planes)
Indirect Retention -
Resistance to displacive forces along the retentive axis — this is through the tips of clasps.
(rests, connectors, collets, guide plates)
Guide Planes -
two or more parallel surfaces on abutment teeth used to limit the path of insertion and provide retention/stability.
Free End Saddle -
An edentulous area posterior to the natural teeth.
Kennedy Class I -
bilateral free end saddle.
Kennedy Class II -
Unilateral free-end saddle.
Kennedy Class III -
Unilateral bounded saddle.
Kennedy Class IV -
anterior bounded saddle only - no modifications!
When can a lingual bar be used?
When there is around 8mm between the floor of the mouth and the gingival margin to give 3mm clearance from the gingivae.
What are the 2 purposes of rests?
To provide support and prevent overeruption.
How do clasps provide retention?
By engaging the undercut of the tooth.
Which type of clasp can be used when there is a high survey line present?
ring clasp
Which clasp can be used when a diagonal survey line is present sloping downwards?
gingivally approaching clasp
What should be done when a low survey line is present?
Modify the tooth with composite.
Which type of clasp can be used when a medium survey line is present?
C clasp
