Removable Pros Morning Tuts Flashcards
Why do we do primary impressions
- To construct special trays
- To make stone models to design partial dentures - metal, acrylic, clasps (BUT you can also design after prelim jaw reg)
what equipment do you need before taking primary impressions
- Examination kit
- Selection of dentate stock trays (because you dont know size of patients mouth yet)
- Equal quantities of silicone putty base and catalyst
- Silicone and alginate adhesives in disposable dappens pots
- Alginate plus mixing bowl, spatula and water measurer
- Disposable scalpel
- Gauze, bag for impressions and laboratory prescription form
- Mirror, probe tweezers etc - sounds obvious but you need to write all this in exam
How can you modify a stock tray if overextended?
Trim it back using clippers + reduce the extentions
What landmarks do you need to record in primary impressions
- Teeth that are present
- Buccal and labial sulci
- Saddles - edentulous spaces
- Maxillary tuberosities if free end saddle
- Maxillary hard palate
- Mandibular buccal shelves + retromolar pad/ retromylohyoid fossa if FES
Why do we use putty in primary impressions
- it fills in big voids, e.g. hard palate + saddles
- it can only record soft tissues, not teeth (can’t pick up fissures/ cusps)
- so we use alginate as well
What will determine if a primary impression is acceptable?
- Quality of alginate (no tears/ air bubbles/ mixed properly)
- Landmarks (recorded everything needed? Can you see all surfaces of teeth/ sulcus/ retromolar pads/ tuberosities)
- if unacceptable, peel out alginate and do again
How will you manage a pt who is gagging/ has a gag reflex due to impressions
- Can use warmer water = faster setting time
- Don’t overload tray with material
- Use putty = reduces risk of pt gagging w alginate
- NB putty can be taken out straight away alginate cant, impression has to stay in mouth
- If gag w alginate, use distraction techniques, e.g. big breaths, wiggle toes
What do you ask lab to make from primary impressions?
Made into dental stone casts
Depending on your next stage, would ask lab to either make:
1. WIRE-REINFORCED WAX BASES + OCCLUSAL RIMS for prelim jaw reg
or
2. SPECIAL TRAYS for secondary impressions
We don’t always do prelim jaw reg stage. Why/ When do we do it? What are we looking for
Allows you to articulate primary casts on articulator.
So you can study the occlusion.
To make sure that your denture design doesn’t interfere with occlusion
We look for:
- overerupted teeth (is there room to fit an opposing tooth)
- interdigitation of teeth (tooth to tooth contact), is there room to place denture components - rests/ clasps need room
When do you not need a preliminary jaw reg?
- For most acrylic dentures (as no occlusal rests which would interfere w occlusion)
- if no opposing teeth
- If you can accurately articulate casts without a reg, e.g. pt is only missing a couple of teeth = can hand articulate casts as you know the occlusion.
What are the steps of a preliminary jaw reg?
- Familiarise self with occlusal contacts before putting in bases.
(Sometimes natural teeth may not come together - identify before you start trimming wax) - Ensure bases are comfortable (can trim)
- Place occlusal rim (1 at a time) in mouth and trim until max intercuspation is re-established.
(tooth-tooth contact) - Then put both wax rims into mouth simultaneously + trim so that max intercuspation is established.
- Remove a further mm from height of wax block - to allow space for registration material
- Cut grooves in the rims w a wax knife (to hold reg material onto wax block)
- Can use zinc-oxide eugenol paste/ softened wax/ light-bodied silicone to record position of max intercuspation.
(ZOE paste - thin layer on one wax rims, pt bites down, remove when material has set) - Put back onto stone casts, disinfect, send to lab.
THEN SURVEY CASTS + DESIGN DENTURE
Before using ZOE paste, what do you need to check?
- Ensure pt isn’t allergic to eugenol
- Smear petroleum jelly on pt lips
- Ensure pt clothes are well covered, staining doesn’t come off sometimes
- Explain about strong taste
(it can be very messy)
What are the properties of ZOE
(used in recording position of maximum intercuspation in a preliminary jaw registration)
ZOE
- accurate, dimensionally stable
- long time to set
- cheap
- usually only apply to 1 rim even if you have 2
- strong taste (like cloves, stinging feeling)
What are the properties of softened wax
(used in recording position of maximum intercuspation in a preliminary jaw registration)
SOFTENED WAX
- hardens rapidly
- not as accurate or dimensionally stable as ZOE
- must ensure wax is well softened + uniformly softened
- hot air bur can be used to soften wax
What are the properties of light bodied silicone material
(used in recording position of maximum intercuspation in a preliminary jaw registration)
- very accurate, dimensionally stable
- very expensive
- e.g. hydrobide is easy to use
What do you do in the visit after preliminary jaw reg
- Confirm design w patient
- do any necessary tooth preparations (rest seat/ guide plane preps)
- take secondary impressions
What do you tell the lab after the preliminary jaw reg?
- Please use jaw reg record to articulate the primary casts
–> THEN you survey the casts and create your denture design.
What are the possible designs for special trays?
Space perforated OR space non perforated
> Always spaced if pt has some teeth
Alginate = perforated
Silicone = non-perforated
What are the clinical stages of making an RPD
- Pt examination + primary impression
- Primary jaw reg - articulated + surveyed casts used to design denture
- Tooth prep + secondary impressions
- Trial insertion of metal framework (only if metal)
- Secondary jaw reg
- Trial insertion of teeth in wax (on metal framework)
- Insertion (‘fit’)
- Review
Why record secondary impressions
- To create a very accurate impression and an accurate secondary cast on which your partial denture is made.
- After we survey models + design denture, we may do tooth preps to accommodate the denture design, SO we need an impression after doing the modifications
What tooth preparations may be required
- Rest seat prep (so that there isn’t occlusal interferences when metal is on teeth. It should be at least 1mm deep on posterior teeth to allow for metal thickness.)
- Guide plane prep (Abutment teeth proximal surfaces need to be parallel to path of insertion, the more that are parallel = more retention (due to friction) = more stability).
- Modification of survey lines
(e.g too high/ too close to occlusal surface -> shape enamel w diamond bur to lower survey line - Improve undercuts if there aren’t any retentive undercuts - by adding composite on cervical 1/3 of buccal aspect of tooth.
Which materials could you use when taking a secondary impression
- Alginate (spaced, perforated)
- Medium body silicone (spaced, non-perforated tray)
- Polyether (impregrum) – be careful, if mouth has deep undercuts = difficult to remove once set! (Spaced, non-perforated tray)
All materials are equally good.
If special trays are overextended/ underextended, what do you do?
Extensions should be approx 2mm short from the buccal/ lingual sulcus
overextended: trim using an acrylic bur on a straight handpiece
underextended: add green stick to extend
What are the steps of taking secondary impressions
- Apply right tray adhesive (blue- silicone, red- alginate )
- put pt in correct position, upright, support head
- Mix impression material
- Load tray, can use metal spatula to distribute silicone evenly & avoid bubble formation.
- Don’t overload, less needed than primary as this is a special tray
- Behind pt (upper impression) In front of pt (lower impression)
- Border mould ( so that we record lingual/ buccal sulcus functional depth as well as anatomical depth. Gently massage cheeks)
- Hold impression in place using light pressure, so that you don’t distort impression during setting
- Disinfect, send to lab
After secondary impressions are taken, what do you say to lab?
CoCr denture:
Please construct a CoCr framework to denture design drawn
Acrylic denture:
Please construct a wax base and occlusal rims to denture design drawn.
What will you do in the visit after secondary impressions have been taken
CoCr denture
- metal framework try in
Acrylic denture
- secondary jaw reg
What do we need rest seats for?
SUPPORT
Why do we ask pt to raise tongue when taking lower impression
- We need to record impression where floor of mouth is raised as we need to know how DEEP to make the LINGUAL FLANGE.
- If there is above 7mm sulcus depth between floor of mouth in RAISED position and gingival margin – can have a lingual bar.
What is a Willis bite gauge, when it is used
- Used to measure vertical dimension (OVD) between maxilla and mandible.
- Used during definitive jaw reg
when used?
- when pt has lost facial height, e.g. bruxist
- had complete dentures for many years
- when nose is too near t chin
- measures vertical height - how far you want chin from nose etc.
What to check before trying metal framework in pt’s mouth?
- check lab has followed your prescribed design
- before trying in the pt’s mouth, study the fit of the casting on the master cast/ duplicate model
What clues can you obtain from these models that you may have problems fitting your framework?
- If tooth has broken + been incorrectly glued back into position - framework made on this model will not fit the pt
- scrape marks on model/ scratches on abutment teeth –> shows framework has been forced down, will be too tight to fit.
- If framework doesn’t seat down correctly on the cast – won’t fit pt
- over-trimmed model
- air blows/ blobs of stone/ drags on the cast
Why do we make a duplicate model as well as the master cast?
For things like fitting the framework = so that we don’t damage the master cast as it can be reused
How do you check the fit of the metal framework on the pt
- gently seat into mouth
- use stone model to identify the correct path of insertion
- do not force into mouth
- make sure patient doesn’t bit down to ‘click’ it into place
- make sure denture is comfortable + doesn’t hurt pt
Why would a metal framework fit in the cast but not mouth?
- Impression on model was taken out too soon + distorted = causes drag marks around teeth
or - original impression was distorted in general
How can you tell if the framework is seated down completely?
- Are the rests fully engaging the rest seats
- Is the major connector flush with the underlying tissues (no gap should be seen)
NB: There will be a space between the saddle area and meshwork as this is for the acrylic to flow into that gap so that it can lock. onto the metal.
Why do we not check if the clasp is sitting properly during the metal framework try in?
- clasps are flexible, so it is more likely that a rigid part of the framework is preventing it from sitting properly
> e.g. where the connector / bracing arms fit around the teeth. - Rather than adjusting a loose clasp at this stage, we may wait until final fit, to create an undercut w sufficient depth with shade matched composite resin.
- Composite should have a smooth domed contour w no ridge to trap the clasp
If the framework does not seat down fully, how will you correct this?
- Identify part of framework that seems a bit tight around the teeth
- Use occlude spray (green or pink dye), spray on fitting surface.
- Reseat framework + take it out again
- Where framework is tight, dye rubbed off
- Use a (metal tungsten carbide bur) to adjust framework in that area. Reapply spray and check again until fixed.
{When you adjust metal, gets very hot, make sure to cool it down before placing in pt’s mouth!}
If the metal framework fit is acceptable, what do you do next?
- Check occlusion (articulating paper)
- Ensure natural teeth are coming down correctly in the same way they do without the metal framework
- Ensure no premature contact w metal framework, if there is: adjust w bur
- Rests, clasps, minor connectors can prevent teeth coming together.
If metal framework fit + occlusion is acceptable, what is next clinical stage?
definitive jaw registration
What do you ask lab to do after metal framework try in?
Please add wax occlusal rims to framework.
(Sometimes rims are already added to framework, so can carry out metal framework try in + definitive jaw reg in one visit. In this case, next visit = wax try in.)
What do you use to measure definitive jaw reg (CoCr vs acrylic)
CoCr denture: metal framework with wax occlusal rims attached
Acrylic: wax baseplate + occlusal rims
Why do we need to do a definitive jaw reg?
- To allow secondary casts to be articulated prior to setting up denture teeth, so that teeth can be placed in correct jaw relationship
- For adjustment of wax rims on the secondary casts from a secondary impression
What is additional info needed by lab in definitive jaw reg vs preliminary?
Record shade + mould of tooth (esp for anteriors) which you want to be set into wax.
- existing denture can be used as a guide
If anterior teeth are missing, what do you need to record on the occlusal rim?
- Centre line
- Smile line
- Canine line
If replacing a class 4 (3-3, upper teeth), what do you need to tell the lab
- How buccally positioned the teeth are
- Anterior-posterior position of teeth
- Incisive papilla can be a good guide as to where natural teeth used to be
- Midline, smile line, canine line
- Shade of tooth
- Mould of tooth - for anteriors
What materials would you use to measure the definitive jaw reg?
Hydrobite - light bodied silicone
ZOE
Softened wax
After definitive jaw reg has been taken, what do you ask the lab?
Please articulate casts using the jaw registration record provided.
Then set up teeth in wax, shade __, mould __, for a try in.
[Denture teeth should be placed on wax rim, covering the edentulous ridges]
Remember to put name of shade guide used.
What is some information about mould of teeth which can help choose?
Usually square/ oval/ slightly tapered
- Can use photo if pt has of their natural teeth showing/ previous study models can be used.
Male: tend to be square
Female: tend to be more oval/ slightly tapered.
At trial insertion, what do you check before putting denture in pt’s mouth
- Check teeth in wax rims are SECURED - in case they follow out, pt may swallow a tooth
- Check articulation is correct + rests are engaged correctly on the cast
What do you check when trying the denture wax up in the pt’s mouth?
- Try dentures one at a time if replacing both
Check:
1. check rests engage rest seats properly/ check clasps. (CHECK STABILITY, SUPPORT, RETENTION)
2. Check alignment of dentition and occlusion
3. Check appearance - does it look natural?
4. Check mould & shade compared to natural dentition
5. Check jaw relationship
6. Check comfort of pt - hurting anywhere?
Remember teeth are set in wax so don’t leave denture in mouth for too long, as it is warm and will distort.
What do you check at the trial insertion denture visit when a free end saddle is present?
UPPER: use Fox’s occlusal guide to check occlusal plane is parallel with Alar Tragal line
- posterior occlusal plane = parallel to alar-tragal line
- incisal plane = parallel to inter-pupillary line
LOWER: check occlusal plane in relation to tongue + retromolar pad
What do you check when checking the jaw relation at the denture trial insertion ?
- Check contacts in max intercuspation
- Check you have natural tooth contacts
> You may find a vertical/ horizontal error in jaw reg
What is freeway space?
The space between mx and md teeth when muscles of mastication are relaxed.
- Estimated between 2-4mm in the incisal edge
What instrument can we use to measure and estimate freeway space/ RVD and OVD
Willis bite gauge
What is RVD
Resting vertical dimension
- when MoM are relaxed, usually is a space between Mx and Md teeth.
What is OVD
Occlusal vertical dimension
-When upper and lower teeth are in position of maximum intercuspation of posterior teeth
What is the equation we can use to measure vertical dimension
RVD-OVD = Freeway space
If we have excessive OVD, what is there a reduction of
Freeway space
What can lack of freeway space cause?
- Risk of trauma to tissue underlying denture
- Painful mucosa over denture bearing area + muscle soreness
- Can affect speech
- Cause clicking of teeth
- Difficulty in bringing lips together for certain words
- Poor aesthetics
- Discomfort and pain w the TMJ over some time
If we underestimate OVD, what happens
- Lack of support of angle of mouth
- Cause dribbling and may reduce masticatory efficiency
- Poor aesthetics - inadequate support of lips and cheeks (as increase in freeway space = results in cheek protrusion)
- Risk of angular chelitis in vulnerable pts
What does vertical error mean
= If vertical dimension of lower third of face is increased when trying in the denture.
Can be due to
- Biting too high
- Gap between natural teeth
- Not biting all the way down
What does horizontal error mean
= Happens due to the error in measurement of occlusal plane / in error in cuspal and fossal relationship between buccal, palatal or buccal, lingual articulation of teeth
- Horizontal occlusion now has deviation – pt may bite a little more forward/ a little more to the side when working in ICP
What do you need to make sure before measuring RVD?
That pt’s jaw is fully relaxed - can ask pt to swallow/ lick lips/ close eyes to help relax.
If you find there is a vertical/ horizontal error in the jaw relationship during the trial insertion, what do you do?
- Retake jaw relationship again
- Remove denture teeth + place on sticky ribbon wax to return to lab for them to reset the teeth
- Record jaw reg + ask lab to rearticulate Mx/ Md casts and set teeth in new registration recorded for another try in.
Or can try to sort it yourself:
- Adjust level of occlusal rim - take away/ add to get correct occlusal level
Imagine you are replacing all the upper incisors for your patient.
What do you need to check, with regards to appearance?
- Shade, shape of teeth, lip support, flange shade
- lip support = has pt got competent/ incompetent lips? How much teeth are showing. Dependent on how buccally/ palatally u position the teeth.
- bulky flange = can look like pt has something stuck under their lip - Teeth position - overjet, etc. Make sure teeth are in neutral zone - no interference w tongue/ muscles
What do you do if denture is an immediate denture?
- Take study casts, shade, mould + record occlusion prior to extractions (for construction of denture)
What do you check when checking appearance at denture trial insertion
- Shade, Mould
- Centre line, smile line – can you see edge of flange/ clasps visible?
- Labial support (90 degrees)
- Position of incisal edges
- Do teeth look natural, part of dentition?
- Are clasps visible? How much of teeth are showing?
What do we ask pt to do at trial insertion stage to check?
- Count to 60 + observe mouth opening
- Listen to speech and make sure p-t has enough freeway space + can pronounce words correctly
- Make sure pt is happy w appearance
If your patient is not completely happy with the appearance at trial insertion, what do you do?
- Discuss with pt and teacher
- DON”T persuade pt that they look good if they don’t. If pt isn’t happy, they won’t wear denture.
Find out what the pt doesn’t like:
- shade/ mould/ alignment?
- try to alter alignment clinically, if you can’t, return denture to lab
- If mould/ shade isn’t satisfactory, send to lab to reset teeth
If your patient complains that their upper teeth “look like false teeth” what could you do to make them appear more natural?
clinically:
- alter alignment of anterior teeth/ angulation of it
lab:
- may have to send back to lab to alter appearance w GOOD instructions
- sometimes lab can put staining on teeth = more natural look
- make sure to give lab exact instructions
If denture is accepted at trial insertion stage, what do you tell lab for next appt?
Check flange shade guide, pick shade
And
Ask lab to “process the denture to finish in heat-cured acrylic”
If pt has pain on top of the ridge, what does this mean?
Problem with occlusion
If pt has pain in the sulcus, what does this mean?
There is an overextended flange
If pain in back corner of denture
There is an overextension of flange.
What stage comes after the wax try in/ trial insertion?
Final insertion of denture
Before inseeting final dentures into mouth, look at them + master casts. What problems may you identify?
- Sharp edges on acrylic work (can cause trauma on pt)
- Acrylic pearls (blobs) on fit surface – smooth using a tungsten carbide bur/ aerator + bur before trying in pt’s mouth
- Damage to cast - such as scratching + glued on teeth
- Acrylic resin covering metal guide planes – can cause problems in fitting denture.
How do you try the final denture in pt’s mouth?
- Gently insert denture, if it doesn’t seat down fully, do not force it in (may get stuck if forced)
- Make sure pt doesn’t bit denture intp place
Why may the denture not be seating down at the final insertion?
- Hopefully not a problem w metal work as we already checked. But, maybe clasps got a bit bent since last time.
MORE LIKELY:
- Where wax was processed into acrylic, it could be a bit tighter in those regions.
- Esp where acrylic is u against natural teeth
(Wax can compress, acrylic can’t)
[Can be same reason for acrylic denture, rigid acrylic can be a bit tighter.]
How will you adjust denture to enable it to seat down at final insertion?
(If it’s a bit tight in certain areas)
Pressure Indicator paste ‘PIP’
- White paste which you paint onto denture using a microbrush + seat denture into place
- Take denture out again, where paste has rubbed away = indicates a heavy spot/ area + can use tungsten carbide metal bur to trim back acrylic in tight area.
How will you adjust denture to enable it to seat down at final insertion?
(If clasps have been distorted)
Adams pliers for clasps
- but don’t adjust too much, not more than 1/2 times as clasps can snap
What problem may you see with a flange?
Flange may be digging into the region, may see blanching of tissues = indicates denture is too tight.
How will you know whether the denture is fully seated at the final insertion
- Look at rests - are rests fully engaging the rest seats?
- Look at major connector - is it flush w underlying tissues?
Ensure denture is fully seated!
Once denture is fully seated at final insertion, what else do you need to check?
- Comfort - any discomfort/ pressure/ digging in anywhere? (Any issues: apply PIP and adjust)
- Occlusion - use articulating paper. Check for even contacts around the arch, any high spots?
Check lateral excursion (pt moves teeth side to side, slide over each other, can use different coloured articulating paper) - Retention
- Appearance
What are the possible causes of an unretentive partial denture?
(Denture comes away from underlying tissues quite easily)
- Clasps may NOT be engaging an undercut (may need to adjust w Adam’s pliers)
- Flange may be overextended - could be too far down into sulcus + causing denture to pop up (can be trimmed back/ adjusted)
- Original design may have been inappropriate and you maye not have enough guide planes/ clasps or claps may be in wrong place.
- Maybe due to nature of case - abutment teeth/ pattern of tooth loss (e.g. Ken class 1 = bilateral FES, bound to have less retention no matter what)
If your patient complains that they do not like the appearance of their new denture at final insertion, what will you do ?
- What is the complaint, investigate and see what you can adjust
- e.g. if pt doesn’t like shade – we can’t adjust
- e.g. if pt feels 1 tooth is a bit long, can be fixed and adjusted bur
- e.g. pt feels teeth doesn’t look natural, can put wear facets
After fitting the denture, what else do you need to do before discharging your pt?
- Make sure pt can insert and remove their denture
– spend time showing pt how to put them in and out, show them path of insertion + removal - Give the Patient Statement document + record this in clinical notes
– legal requirement to offer to pt (if they decline, scan into notes + record in notes that pt declined it)
What are denture care instructions that you need to give to pt?
- Ideally avoid sleeping with dentures in
- When not wearing, dentures should be kept wet
- Brushing/ cleaning dentures: Use soft bristled toothbrush and soap 2x a day + after meals.
Ask pt to do this over a basin full of water as common cause of frctured denture = due to pt dropping them while cleaning. - Brushing of natural teeth- very important as there are higher plaque retentive factors with a denture in, more plaque control needed!
What instructions do you give to pt about soaking dentures?
- Avoid soaking in hot/ boiling water
- Can use proprietary cleaners to remove staining
- Follow manufacturer’s instructions carefully
- Remember to rinse/ brush dentures following soaking before putting back in mouth
- Denture cleaning tablets can be used (extraorally!)
- IMPORTANT: avoid bleac/ hypochlorite containing cleaners if using CoCr dentures (may stain/ corrode metal-based dentures)
How would you manage expectations of a patient after giving denture
- Tell pt that if dentures are painful over time, take out and make a note of where they were hurting.
- Start with soft foods
- Make pt aware that it takes time to adapt to wearing
- Arrange a review appt (usually 1 week later)
What if a patient doesn’t agree to taking out dentures overnight?
- Ask pt to at least take it out for a few hours during the day
- Mae pt aware of the implications of not taking it out - more likely to get candida infections etc.
Difference between PIP and occlude spray?
PIP: for acrylic flanges
- for hard surface against soft surface
Occlude spray: for denture against teeth
- for hard surface against hard surface
