Clinical stages of RPD's Flashcards
What are the 6 clinical stages of RPD’s?
Visit 1: Assessment and primary impressions
- Visit 2: Master impressions
- Visit 3: Framework trial (+/- record occlusion)
- Visit 4: Tooth trial
- Visit 5: Delivery (fit)
- Visit 6: review
What would you examine on visit 1? (2 points)
The patient
- The previous denture
In the first visit you would look in the mouth of the patient. What would you be looking for? (4 points)
Ridge form (feel for displacement tissue)
- Free end saddles
- Bounded saddles
- Undercuts (particularly when selecting impression material)
What is the difference between an dentate and edentate impression tray?
Edentate tray is shallower than dentate
Which type of impression material would you typically use when there are no free end saddles?
Alginate
Which type of impression material do you typically use for primary impressions?
Alginate
Which type of impression material would you typically use for people with free end saddles? (2 points)
Compound (stock trays don’t always fit everyone so can use compound to modify this)
- Alginate
Is alginate an elastic compound?
yes
What are 2 examples of elastomers?
Silicone
- Polyether
Is impression compound an elastic material?
No
What is the process of taking primary impressions? (4 points)
Select stock tray and modify peripheries/fit surface with wax or compound
- Apple adhesive and use alginate or alginate/compound for impression. Border mould +++
- Disinfect and place in sealed bag with wet cotton wool/paper towel
- Label bag and write instructions to technician
How do you decontaminate and disinfect primary impressions?
Put in perform for 10 mins
- Then rinse and put in a bag
What happens during visit 1?
Assessment and primary impressions
During the first visit, you need to record the occlusion. What does this mean?
Measure how the teeth meet
- What is the comfortable bite?
When can study casts be hand articulated?
IF it is obvious where the teeth fit together - good occlusion
Do you need to record the occlusion if you can hand articulate the cast?
No, you can move on without a primary record block
When you are unable to hand articulate the casts, what needs to be done?
Need to take a primary registration using a wax bite
What can you use to take an inter occlusal record of a patient?
A wax wafer
- Warm wax the patient bites on - not the most accurate if you make the wax really thick or really soft
What clue on the articulator can indicate that the wax wafer for an inter-occlusal record is too thick?
The pin of the articulator is not on the table
- Shows teeth are not meeting
You are not able to hand articulate a cast with a free end saddle present. What would you use to record the occlusion?
A primary record block
Why may you take primary record blocks? (4 points)
You can’t obviously see how the teeth meet
- Use to mount casts accurately
- Look for space to place rest seets and base plate
- Plan for preparation of rests seats if no space is available
Why is there an extra clinical stage (visit) when there are not enough teeth to hand articulate?
As need to record the occlusion before the primary models can be mounted on an articulator
When giving instructions to the technician you need to think about what material you are going to use for the master impression. What do you need to consider? (2 points)
How much spacing is required (The space required for the impression material)
- Are there many undercuts (If got a lot of undercuts then would not use anything rigid - needs to be able to flex so needs to be elastic)
What instructions would you give to the technician if the casts are going to be hand articulated? (2 points)
Pour primary casts
- Special tray with spacer (1-2 sheets of wax depends on master impression material with handles/finger rests etc)
What instructions would you give to the technician if the casts are not going to be hand articulated? (3 points)
Pour primary casts
- Special tray with spacer (1-2 sheets of wax depends on master impression material with handles/finger rests etc)
- Construct primary record block for a preliminary jaw registration (base can be wax, shellac or light cure acrylic)
Before visit 2 you need to design the denture. What do you need to do to be able to do this? (4 points)
Survey to decide the path of insertion
- Survey to decide undercuts etc (so you know where to put clasps)
- Do you need to modify teeth to produce rest seats, guide planes and undercuts
- Draw the design on the laboratory work card
Must the denture you are producing conform to the patients occlusion?
Yes, unless you are planning to change it for a valid reason
If there is no inter-occlusal clearance for a rest on the denture what must you do?
Must either make space by cutting a rest seat or do not place the rest in that position
- If you don’t make space the occlusion will not be correct
- IF there is no space the rest will simply open the bite
What is the system for design of a RPD? (6 points)
Outline saddles
- Support
- Retention
- Bracing
- Connectors (minor and major)
- Review design
What happens during visit 2?
Master impressions are taken
When trying in a special tray for master impressions what may you need to do?
Trim peripheries if overextended
- Modify peripheries with greenstick and fit surface for free end edentulous saddles
Why are handles on special trays orientated in a specific way?
To avoid disturbing the lip
What are the options for impression materials at the dental hospital? (4 points)
Poly vinyl Siloxane (medium bodied silicone)
- Polyether (sets more rigid than PVS)
- Alginate
- Impression compound (to modify the tray)
- Use specific tray adhesive for the material you are going to use
What is an example of a medium bodies silicone (poly vinyl siloxane) used as an impression material?
Brand name: Extrude
- Comes in 3 different bits
- Don’t need a lot as you have a custom tray that has a very narrow spacing - only need enough to cover the surface you are trying to record
- Does not biodegrade so do not want the patient swallowing a big lump of it
What is an example of a polyether used as an impression material?
Brand name: Impregum
- Very accurate, will give nice impression
- Very rigid, do not use with undercuts
- Be careful with people with periodontal disease
What are a few positives and negatives of alginate? (4 points)
WEll mixed (smooth mix)
- Poured up as soon as possible
- Good if undercuts present
- Careful for air blows
What is the process of taking master impressions? (4 points)
Try in special tray and trim peripheries if over extended
- Modify peripheries with greenstick and fit surface for free end saddles
- Apply adhesive and use alginate/polyether/PVS for impression. Border mould+++
- Disinfect, place in sealed bag and write instructions to technician
Do you need to decontaminate and disinfect a master impression?
Yes
What instructions would you give the technician with master impressions for a cobalt chrome denture? (3 points)
Pour model in improved stone
- Construct a chrome framework per design (clear design signed by the clinician)
- (remember to prepare occlusal rests/guide planes before taking impression)
What instructions would you give the technician with master impressions for an acrylic denture? (2 points)
Pour model in stone
- Construct record block with shellac base
What do you do during visit 3?
Framework trial (+/- recording the occlusion)
For the framework trial what do you need to consider? (4 points)
Does it fit the cast (if it looks like it does not fit the cast then it will probably not fit the patient)
- Does it seat correctly in the mouth?
- Is the cast damaged (might mean undercut is too big)
- Is the framework interfering with occlusion?
- If happy with the above checks then register the occlusion
Why do we need to record the occlusion? (5 points)
To help design the denture
- To help the technici an set up the teeth
- (to ensure the denture is stable and not dislodged in function)
- Patient comfort
- Ensuring loading forces are applied correctly to teeth
What is meant by a ‘conformist approach’ when recording the occlusion?
Want to keep the occlusion the same as it currently is
- Need to know the position of teeth in relation to each other
What is a ‘reorganised approach’ when recording occlusion?
Can reorganise the bite
- Do this by altering the occlusion
- May need to be done because of tooth wear or if there are not enough teeth to meet
What is the aim of visit 3 in regards to recording the occlusion? (4 points)
Want to establish:
- Inter-occlusal relationships to articulate casts
- Occlusal vertical dimension
- Tooth shade and mould
Extended edentulous spaces:
- Buccal/labial contours of wax record block
- Lip support
- Incisal plane
- Posterior plane
IF there are no index teeth, you need to measure the OVD And FWS. What do these terms mean and what do you use to do this?
OVD = occlusal vertical dimension
- FWS = Freeway space
- Do this using a Willis bite guage
- Measure the OVD and the resting occlusal dimension - 2-3mm called the freeway space
If adjusting the framework on chairside what would you use to adjust the clasps?
Adam’s pliers
What is the process of trimming blocks for recording the occlusion? (7 points)
Try it in, it will be bulky
- It has to stay in place
- Any overextension of the peripheries as it will drop/displace
- Too much lip support and it will drop
- Use the wax knife and hot plate/spatula to make adjustments
- Adjust the upper rim first
- You may need to adjust the rim labially/buccally
How do you prescribe the position of anterior teeth? (4 points)
- Make sure index teeth are in occlusion
- Mark Centreline
- Correct incisal plane
- Correct antero-posterior position
What are reference points for placing anterior teeth in RPD’s? (8 points)
- Teeth present
- Dento-facial midline
- Inter-pupillary line
- Ala-tragus line
- Curvature of lower lip
- Smile line
- Gingival margins of existing anterior teeth
- Previous dentures
What factors would influence the shade in tooth selection? (3 points)
Existing teeth
- Previous denture
- Patient preference
What factors would influence the mould in tooth selection for RPD’s? (3 points)
Existing teeth
- Previous denture
- Measure
After visit 3 what instructions should you give the technician in relation to articulators?
Need to tell them which articulator you want them on
- Usually want an average value articulator
After visit 3 if you need a wax record block what would your instructions to the technician be?
Construct wax record blocks on chrome framework
- (Additional visit required)
After visit 3 if a wax record block is not needed what would your instructions to the technician be? (2 points)
Articulate casts to registration
- Set teeth for wax trial (shade and mould provided)
What happens during visit 4?
Tooth trial
Visit 4 is usually the framework tooth trial. What is included in this? (4 points)
Framework fit
- Occlusion
- Aesthetics
- Extension
If there are problems with the framework tooth trial what do you need to do?
Need to agree with the patient what you want and then have a re-trial
What instructions would you give to the technician after visit 4: the tooth trial
Please take to finish in acrylic
- (all the wax will be burned out and acrylic will be put in)
What happens during visit 5?
Delivery
- Dentures will be on articulator
- Need to check everything is okay e.g. pin is on the table
After visit 5, What should you look for when examining the denture on the articulator? (6 points)
Check design again as requested
- Examine dentures for roughness/blebs
- Check it seats properly
- Undercuts - are any teeth in the cast broken?
- Is the pin on the table?
- Does the occlusion look correct?
After visit 5, what should you look for when looking at the denture in the patients mouth? (6 points)
Does it seat properly?
- Don’t force it in (check undercuts)
- Check:
- Stability (does it rock?)
- Support (are the rests/flanges seating correctly?)
- Retention (adjust clasps with adams pliers)
- Aesthetics (carry out the above checks first, last thing you do is show the patient
At visit 5 you need to check the occlusion. What are you looking for?
Do the teeth meet in the prescribed occlusal scheme per the wax up? (check with articulating paper for heavy/early defective contacts)
- Is something propping over the bite?:
- (small change adjust with acrylic bur chairside)
- (large change may require removal of teeth and re-set in wax)
What instructions would you give the patient when they re cieve the complete denture? (7 points)
Insertion/removal (make sure patient is able to get it in and remove it themselves)
- Coping with new dentures (going to be uncomfortable at first but will adjust)
- Pain
- Denture cleansing
- Speech
- Eating
- Refer to clinic patient info booklet
What happens during visit 6?
Review (can be most difficult appointment of the whole process)
What must be included in the review visit? (3 points)
History
- Examination
- Adjustments
What are index teeth?
Teeth that you can reproduce if the patient bites together
