Pros textbook Flashcards
How do missing teeth affect a patient’s facial appearance?
The loss of teeth causes jawbone resorption.This causes patient’s maxilla to move backwards and the patients mandible to move forwards.
Why does alveolar resorption occur?
There is a lack of downwards pressure on the alveolar bone due to tooth loss which causes bone loss.
What is the saddle?
The area in the mouth which has no teeth.
What type of saddle is this?
A Free end saddle
There are no teeth at the end.
What type of saddle is this?
A bounded saddle-
Where the gap has teeth on either side.
Discuss tooth borne support?
Tooth borne is when everything rests on the teeth rather than the soft tissue.
This is the most desirable as it prevents tissue damage.
Discuss mucosa borne support?
Mucosa borne support is where everything rests on the mucosa.
These dentures are replacing lots of teeth
Describe a denture patient assessment.
- Full denture history- Why do they have dentures/how long for/ how many/ denture preferences.
- Medical history
- Social history
- Examination (of patient and denture seperately then together)
Why is knowing how the patient lost their teeth beneficical for producing dentures?
If the patient lost their teeth due to periodontal disease this will cause the ridges to change quicker. You want to know this.
Describe these missing teeth using kennedy class:
Kennedy class I
This is a bilateral free end saddle
(free end on both sides= bilateral)
Describe these missing teeth using kennedy class:
This is kennedy class II.
This is a unilateral free end saddle.
Describe these missing teeth using kennedy class:
This is kennedy class III.
This shows a unilateral bounded saddle.
Describe these missing teeth using kennedy class:
This is kennedy class IV.
This is a anterior bounded saddle.
(The saddle crosses the midline and is surrounded by teeth)
Describe these missing teeth using the craddock class:
This is Craddock class I.
This is tooth borne support.
Describe these missing teeth using craddock class:
This is craddock class II.
This is mucosa borne support
This is where the vertical biting force is against the soft tissue saddle.
Describe these missing teeth using craddock class:
This is craddock class III
This is mixed tooth and mucosa borne support.
1 saddle is supported by teeth, the other is a free-end.
What are the three main things we consider when looking at dentures?
- Support- does the denture resist movement vertically towards the tissue? (Does the denture push up towards the tissue)
- retention- is the denture easily displaced away from the tissue? (Can the denture be moved away from the tissue easily)
- Stability- Does the denture resist horizontal movement. (Can the denture be moved from side to side?)
What is this picture showing? and discuss it
This is denture stomatitis.
This is a mixed infection of bacteria and yeast caused by wearing a denture all the time. The exact shape of the denture is showing the gum at A.
What is partial edentiulism?
This describes a patient with some but not all teeth missing in the arch
What are the visits required for a denture patient?
Assessment and primary impressions
Master impression
May need jaw reg if using record blocks
Framework trial (RPD only)
Tooth trial
Delivery & fit
review
What are you looking for in an examination of the patient’s mouth?
Ridge form (can tissue be displaced)
free end saddles
bounded saddles
Undercuts
Compare edentate trays to dentate trays.
Edentate trays are shallower than dentate trays for patients without teeth
What material(s) are used for an impression with free end saddles?
Alginate and compound
What material(s) are used for an impression without free end saddles?
alginate
How do we take a compound impression?
The compound takes an impression of the saddle areas.
Any compound impressions containing teeth should be cut away.
What is the alginate wash?
This is a thin layer of alginate that is applied over the compound to take the full impression.
We use an adhesive to attach the compound to the alginate.
How do we prepare an impression for the lab?
The impression is disinfected in perform for 10 minutes.
It is then placed in a bag with wet cotton wool to prevent the alginate from drying out.
Summarise what happens in visit 1?
We examine the patients mouth
Take the primary impression
Measure the occlusion.
What do you do once the lab produces the primary cast?
You check if you can hand articulate the primary cast or not.
If you can hand articulate the cast, then you can begin the denture design & request the special tray design.
If you cannot hand articulate the cast then we need primary record blocks to record the patient’s jaw registration .
What do you need to do before the second visit?
Survey the cast- find undercuts and alter path of insertion
Decide if any modifications are needed (rest seats/ guideplanes/ undercuts)
Draw the design.
Compare the different choices for impression materials:
Medium bodied silicone (do not want the patient swallowing this)
Polyether (very rigid so you don’t want to use it with undercuts)
Alginate (good with undercuts)
Impression compound (used for saddle areas)
How do we take the master impression?
- Try in the special tray and trim it if the tray is over extended
- Modify the tray with compound for the free end saddles/ any underextended areas
- Apply adhesive to the special tray and use chosen material to create the impressions.
- Disinfect the impression material.
What instructions should you give the technician if you are producing a cobalt chrome denture?
The model should be poured in improved stone.
Chrome framework should be constructed as per the design.
If self articulating -
Use registration provided to mount casts
Set upper teeth to lowers with minimal overjet and overbite
Use___ (shade) and ____ mould.
Any special instructions e.g. diastema.
If not self articulating (construct occlusal wire strengthened wax rims on light cured bases for the jaw registration)
What instructions should you give the technician if you are producing an acrylic denture?
The model should be poured in 100% dental stone
A record block with an arylic base should be produced.
If self articulating -
Use registration provided to mount casts
Set upper teeth to lowers with minimal overjet and overbite
Use___ (shade) and ____ mould.
Any special instructions e.g. diastema.
If not self articulating (construct occlusal wire strengthened wax rims on light cured bases for the jaw registration)
What do you check with the framework?
Does the framework fit the cast?
Does it seat correctly?
Is the cast damaged at all?
Does the framework interfere with occlusion?
Why do we record the occlusion?
To help design the denture
To help the technician set up the teeth
To ensure stability of the denture and patient comfort
Ensure loading forces are correctly applied to the teeth.
What instructions and information do you give the technician after the framework trial
Instructions: To articulate your casts to registration so you can complete a tooth trial
Information:
- The type of articulator you want your cast aligned on.
- To articulate your casts to registration so you can complete a tooth trial.
- where you want the artifical teeth to be positioned.
- The shade of artificial teeth needed.
- How the teeth occlude.
What are you checking for in the tooth trial?
Check dentrue outside the mouth
* Does the articulating pin touch the plate- if not what’s stopping it?
* Does the framework fit the cast?
* The occlusion- are there any contacts (articulating paper)
* Are there any sharp edges?
* How does the denture look aesthetically?
Try denture in :
* Occlusion
* Retention
* Extension
* Satbility
* Speech
* Aesthetics
* Comfort
What are you looking for in the denture on the articulator?
Is the design as requested?
Is there any roughness or bubbles on the denture?
Does the denture seat properly?
Are there any broken teeth on the cast (this would provide undercuts )
Is the pin on the table of the articulator?
Does the occlusion look correct?
What are you looking for in the denture on the patient?
Extension- is denture impinging on frenal area?
Does it drop when Pulling away tissues (underextended)
Does. itdrop when manipulating tissues (overextended)
Stability (does it rock from side to side)
support-Are the rests and flanges sitting accurately?
Retention- do the clasps need adjusted?
Aesthetic- what does the patient think?
Occlusion- do the teeth meet in the prescribed occlusion and are there any heavy contacts?
Speech- Is this affected? We can reduce the denture thickness.
Does the denture sit properly?
What instructions do you give a denture patient?
- That the denture will need to be worn in
- That it will affect speech and eating
- How to clean the denture
- Refer the patient to the clinic patient leaflet.
What is the difference between impression compound and greenstick?
Impression compound is used for modification of the trays during the first impressions- if there are free end saddles.
Greenstick compound is used to modify the special trays.
What is the part of the denture that the arrow is pointing to?
This is the denture flange and it is the replacement tissue which extends into the vestibular sulcus
Why can kennedy class IV not have a modification?
As the most posterior saddle defines the classification. Therefore, if the patient had another saddle it would be used for classification & the kennedy class IV would be reffered to as the modification.
Compare denture support?
Using teeth for support directs the load through the PDL of the abutment teeth.
Using mucosa for support distributes the load over a wide area. This uses the hard palate and saddles.
Which tooth should we pick to provide support
Those teeth with the largest root area.
What is a denture rest?
This is the metal bit attached to the tooth that allows distribution of the load down the abutment teeth.
What are the functions of the rest?
- Preventing movement of the RPD towards the mucosa
- Distributing the occlusal load
- Supporting the placement of clasps
- Preventing the over-erruption of unopposed teeth
- Providing bracing on the anterior teeth
- Determining the axis of rotation for free end saddle RPDs.
What is important when designing an occlusal rest?
The rest should come down to the midline of the tooth. So it is large enough for the force goes down the long axis of the tooth .
It should not be placed on an occlusal contact point (as this would be very uncomfortable for the patient)
What is important for incisal rest design?
An incisal rest should only be used on the lower arch (it is unaesthetic on the upper)
What is an advantage of a cingulum rest?
The cingulum rest applies the stress at a lower level.
This means there is less rotational force, meaning the tooth is less likely to break.
Why is it rare to have a metal rest in an acrylic denture?
The metal rest is encorporated mechanically to the acrylic base which produces a pottential weak point in the denture (leading to denture failure)
Where do we place rests on a bounded saddle?
On either side of the saddle area
Where do we place rests on a free end saddle?
The opposite side of the tooth to the saddle.
This is to prevent torquing
Why is having a small surface area of mucosal support inadvisable?
As it will place pressure at the gingival margin and acclerate bone resorption causing denture failure.
Why are mucosa only dentures not recommended on the lower arch?
As the mucosal support on the lower arch is limited.
You can only use the buccal shelf.
What is an ‘every’ RPD design?
This is an open designed denture which spreads the load and keeps the gingival margins healthy.
The denture is kept in the mouth by the frictional contacts between the artificial teeth and the abutment teeth.
What is the arrow pointing to in this denture and what is the function?
The arrow is pointing to wire stops.
These prevent distal drift of the posterior teeth.
We want to prevent this drift as it would cause the loss of the frictional contacts resulting in the denture falling out.
What is Axial Torque?
When movement of the tooth one way causes the root to move the other. This causes breakdown of the Periodontal ligament.
What can we do if the chosen rest position is an occlusal contact point?
- We can move the rest onto the opposite side of the tooth
- Complete a preparation for the rest (requires drilling into a healthy tooth)
What is retention?
What prevents the denture from being dislodged.
Compare the two types of retention?
Direct retention- prevents vertical displacement of the denture.
Indirect retention- prevents rotational displacement of the denture.
How can we achieve retention?
- Mechanically- using clasps
- Muscular forces (over time lingual and buccal muscles will hold the denture in place)
- Physically- using
Adhesion- saliva on the denture
Cohesion- substances within saliva
- Through frictional contacts.
What are guideplanes
Guideplanes are paralell surfaces that provide frictional contacts.
What are clasps?
A metal arm that contacts the tooth in an undercut in order to prevent the removal of a denture base.
Compare guideplanes to clasps
Guideplanes don’t deform over time giving you long term retention.
Clasps deform.
How does the clasp move into place?
The clasp deforms over the bulbosity of the tooth.
How does a rest help clasp function?
The rest prevents the clasp slipping down and damaging the tooth or gingival margin.
Where do you find the undercut on upper posterior teeth?
On the buccal.
Where do you find the undercut on lower posterior teeth?
The lingual.
L-lower L-lingual
Describe an occlusally approaching clasp.
This clasp comes to the undercut across the occlusal surface of the tooth.
It is used for molars.
What is a gingivally approaching clasp
This comes to the tooth crossing the gingival margin. (It comes from the sulcus)
It is used for anterior teeth, canines and premolars.
(It is also known as an I-bar clasp.
Why do we use a gingivally approaching clasp for the anterior teeth, canines and premolars?
It is the only way we can guarentee the 15mm of length that is needed in order to achieve retention.
What is a self reciprocating clasp?
This is a clasp where the clasp metal extends to where the reciprocal arm would be.
Describe the function of the reciprocal arm.
The clasp arm applies a horizontal force to the tooth when it comes in contact.
The reciprocal arm is also in contact on the opposite side.
The reciprocal arm counteracts the force to prevent tooth movement when the clasp is flexing over the bulbosity.
Why do we aim for a triangular patten of retention?
So that you will always have one retainer preventing the dislodging of the plane of the other 2 retainers.
What is the RPI?
A stress relieving clasp system used to prevent stress on the last abutment tooth of a lower free-end saddle.
What are the components of the RPI?
A- Rest (an occlusal rest on the mesial)
B- Proximal plate (placed adjacent to the saddle)
C- I bar clasp
How does the RPI clasp prevent pressure?
The I bar and the proximal plate rotate downward and mesially to come out of contact with the tooth when the patient chews.
This reduces the pressure being applied to the tooth and avoids torque.
How do we achieve indirect retention for free end saddles?
By moving the supporting element away from the saddle area at 90º from the clasp axis
What provides indirect retention?
- Major connectors
- minor connectors
- saddle
- rest
- denture base
What is the connector?
The rigid part of the partial denture that unites the other components.
What is a minor connector?
Thes join components such as rests to other components and the major components.
What is the function of the minor connector?
They transfer functional stresses to and from the abutment teeth.
What should you expect in a minor connector?
It should finish above the survey line on teeth
It should cross the gingvial margin at right angles.
It should cover as little gingival margin as possible.
What are the major connectors?
These connect components on one side of the arch to components on the other side of the arch:
What should you expect in a major connector?
- They should not cover the gingival margins
- They should have as few edges as possible
- Cover as little tissue as they can.
What are the two types of major connector?
- A plate connector
- Bar connector
Discuss plate connectors
These are used for mucosa support dentures. (therefore not recomended in mandibular as there is not much to provide support)
They cover the gingival margins
Discuss bar connectors
These connectors require less mucosal coverage.
They are much thicker to maintain rigidity.
they are used in the mandibular arch as there is less space.
Compare a lingual and sublingual bar.
A lingual bar is behind the teeth
A sublingual bar is below the tounge- this is more difficult to place as the floor of your mouth moves when you move the tounge.
Discuss the advantages and disadvantages of the anterior/ posterior bar.
Advantages:
little gingival coverage
rigid connector
relief of the gingival margins (prevents food impaction)
Disadvantages:
The many edges may be uncomfortable
As diameter is thinner, there will be thicker cross sectional metal.
Posterior bar provides less support to the free end saddle.
Discuss the advantages and disadvantages of a full palatal coverage.
Advantages:
rigid connector
Wide relief of the gingival margins
Support across the hard palate for the free end saddle
Less edges
Thinner cross section
Disadvantages:
Mucosa is covered so there is no natural sensation.
Name this denture design:
Mid palatal strap
Name this denture design:
Full coverage plate.
Name this denture design
Anterior bar
Name this denture design
Horseshoe
Name this denture
Posterior bar
Name this denture type
Anterior posterior bar.
What type of denture is this?
A lingual bar
What type of denture is this?
A lingual plate
what type of denture is this?
a dental bar
What type of denture is this?
A sublingual bar.
What is an undercut?
The area under the maximum bulbosity of the tooth
Compare the different types of undercuts.
Soft tissue undercuts- The contour of the alveolar ridge that would prevent the vertical placement of a denture. These can also cause the base to get caught-making removal more difficult.
Hard tissue undercuts- The portion of a tooth surface between the gingival margin and maximum bulbosity where you can place a clasp.
How do we identify undercuts?
By surveying the teeth- where you use a graphite marker to draw lines on the teeth.
You try and get the point of the graphite marker into the gingival crevice. If there is an undercut this is not possible.
The undercut is measured as the space between the two lines.
What is the function of Pin and Post dams?
Compare them
These are ridges which improve the adhesion of the denture.
Pin dam- A shallower groove on the anterior 5mm away from the gingival margin to prevent food slipping under the denture.
Post dam- A ledge on the posterior of the upper denture in the palatal surface.
How do you prepare rest seats?
Compare Anterior rest seats to posterior rest seats.
Using a slow speed handpeice and cutting into enamel.
Anterior rest seats are cut into the cingulum. Upper rest seats are easier to complete than lowers as uppers have a well defined cingulum.
Posterior rest seats are cut into the marginal ridge.
They should be saucer shape
They have to be deep enough to take a 1mm rest plate.
How do you prepare guide planes?
You can only cut 0.5mm of enamel.
But a guide plane should extend 3mm vertically.
How do we prepare the tooth to improve unfavourable surveylines?
We add composite to shape the tooth and produce a lower survey line.
Label A
Labial frenum
Label A
The buccal suclus
Label A
The Rugae area
Label A
Hamular notch
Label A
Palatine fovea
Label A
The vibrating line
Label A
Maxillary tuberosity
Label A
The Palatine raphe
Label A
The labial sulcus
Label A
The incisive papilla.
Label A
The retromolar pad
Label A
The Mylohyoid ridge.
Label A
The lingual sulcus.
Label A
The lingual frenulum.
Label A
This is the buccal shelf.
How does resorption affect the alveolar ridge.
Upper width decreases.
Lower width widens.
Anterio-posterio - upper resorbs backwards .
Anterior-posterior lower resorbs more vertically.
Where are stops located in the upper tray ?
In the canine and post dam regions.
Where are stops located in the lower tray?
Retromolar pad and the canine area of the ridge.
What is the incisal plane and what should it be?
This is the level of the incisal edge.
This should be parallel with the interpupillary line.
Where does the buccal corridor start?
At the mid-canine line
To find the mid-canine line- Take floss from the inner corner of the eye and drop it down to the nose and then the canine.
How do we measure the occlusal plane?
Using fox’s biteplane and a wooden spatula.
How do we measure the vertical dimension?
We can use:
Dividers- and select two points in the midline of the face (sites of minimal influence from the muscles of facial expression)
Willis bite gauge- Fixed metal arm should be placed under the nose. The flexible arm should rest below the chin.
What is the freeway space?
The RVD-OVD.
What is this and what do we use it for?
The alma gauge.
Used to determine the vertical and horizontal position of the anterior teeth relative to a point in the denture base (incisive papilla)
What is the data transfer line A-A on the cast?
The centre line.
What is the data transfer line B-B on the cast?
The central incisor plane.
What is the data transfer line C-C on the cast ?
This is the residual alveolar ridge contour.
What is the data transfer line D on the cast?
This is the canine line.
Label A, B and C.
A-Fit or impression surface.
B- Polishing surface
C-occlusal surface.
Descibe the clinical presentation in this picture
Flabby ridges- the soft tissue on the ridge interferes with denture retention.
Can happen with combination syndrome.
Describe the clinical presentation in this picture
Denture induced hyperplasia-
Check if the ulcer goes away if denture is removed.
Commonly happens if patient wears a temporary denture long term.
what is this?
Torus (a bony promienence)
