RPD CLINICAL - CLINICAL STAGES Flashcards
what are the clinical stages of RPD
visit 1 - assessment and primary impressions visit 2 - master impressions visit 3 - framework trial visit 4 - tooth trial visit 5 - delivery (fit) visit 6 - review
what happens in visit 1
assessment
primary impressions
what does assessment consist of
history and examination
what does the history consist of
denture history
dental history
medical
social/personal history
why do we take a denture history
it is important to get the patients opinion of any current denture as if an RPD has been worn with reasonable satisfaction it is advisable to reproduce the denture design.
why do we take a dental history
recent extractions may indicate the presence of active caries or periodontal disease that needs to be addressed by preventative aspects of the treatment plan
when taking dental history why is it important to find out when extractions took place
the most rapid phase of bone resorption occurs during the few months following the tooth loss – dentures constructed around the time of extractions therefore soon lose their fit
why do we take a medical history
to accomodate any conditions e.g diabetes
lso, the practice of oral and denture hygiene may be compromised by a reduced ability
why do we take a social/personal history
determines patient motivation
smoking habit should be noted
what does the examination consist of
extra oral
intra oral
what happens in an extra oral assessment
assess the facial form and symmetry. Study the jaw’s opening and closing movements alongside palpation of the TMJ and muscles of mastication. This information derived from these observations is helpful in the assessment of the health of the masticatory system.
what happens in an intra oral assessment
look for the standard of oral hygiene, begin detailed examination of soft tissues (mucosa of the lips, cheeks, tongue, palate and floor of the mouth). Note edentulous spaces and distribution and alignment of remaining teeth. The form of the residual ridges and the compressibility of the investing soft tissues in the edentulous areas should be assessed visually and by palpation (incompressible areas may have to be avoided by denture margins). Assess current restorations and health of periodontal tissues.
what are the two types of impression trays
edentate and dentate
what is the difference between dentate and edentate trays
dentate trays have a greater depth than edentate
how should the size of tray be selected
so that the teeth sit centrally within the trough of the tray and if possible there should be a space of about 4mm between the flange of the tray and the buccal and labial surfaces of the teeth
what impression material should be selected when there is no free end saddle
alginate
what impression material should be selected when there is a free end saddle
alginate and impression compound
describe how the impressions tray is modified for a free end saddle
dead space is filled with impression compound
why should any impression compound contacting the teeth be cut away
it prevents accurate reinsertion of the impressions ray and will eliminate space around the teeth necessary for a sufficient thickness of alginate used to complete the preliminary impressions
how do you border mould for the lingual border
it is achieved by the patient first pushing the tongue to contact the upper lip and then thrusting the tongue into each corner of the mouth in turn.
how is buccal and labial moulding achieved
moulding for both the maxillary and mandibular impressions, it is achieved by supporting the tray with one hand while manipulating the cheeks and lips with the other
when you have taken the impression how is it assessed
Those sulcus areas which will be related to the denture borders
The edentulous area
The teeth
how should impressions be treated
they should be rinsed and disinfected
how is the impression prevented from drying
by covering it with a damp napkin and placing it in a plastic bag
what should the lab instructions be sent with the primary impressions
- Details of the patient and the dental practice
- Confirmation that the clinical items have been disinfected
- Date of the next appointment
- A request for the study cast to be surveyed if required
- Request for wax occlusal rims where necessary, if mounting of the study casts on an articulator required to assist in the RPD design stage
- Specification of material and design of the individual impression trays
- Size and location of ay stops to be performed on the tray
what is the normal bite
the intercuspal position
when can casts be hand articulated
when it is obvious where the teeth meet
what is not needed when the casts can be hand articulated
you do not need a primary record block and do not need to record the occlusion
you can get the casts mounted on the articulator with a wax wafer or nothing at all
how can the interocclusal record be done in visit 1
using a wax wafer
The wax is warmed and the patient bites on it.
why should you see the teeth meeting in a wax wafer
you will create a space.
when can a cast not be hand articulated
when there is a free end saddle
what is required if the cast cannot be hand articulated
record the occlusion using a primary record block and ask the technician to mount the primary cast using you registration
how is the master impression material decided
undercuts - requires more elastic material
what is the lab instruction for a hand articulated
pour primary cast
special tray with spacer (1-2 sheets of wax depending on master impression material with handles/fingers rest)
what is the lab instruction for non-hand articulated
pour primary cast
special tray with spacer (1-2 sheets of wax depending on master impression material with handles/fingers rest)
construct primary record block for preliminary jaw registration - base can be wax, shellac or light cure acrylic
how does the accuracy of the material effect the spacing of the special tray
more accurate, less space
what do you want done in terms fo the design of the denture before visit 2
Survey to decide the path of insertion
Survey to decide undercuts ect so you know where to put clasps
Do you need to modify the teeth to produce rest seats, guide planes and undercuts
Draw the design on the lab work card and get it signed of by a clinician
what happens in visit 2
master impressions are obtained
why do we take a master impression
The production of a cast sufficiently accurate for the construction of an RPD frequently necessitates the use of an individual tray. Such a tray enables an accurate impression to be made of the functional depth and width of the sulci in those areas that will be related to the denture border and to components such as gingivally approaching clasps, connecting bars and plates.
what can you do when trying in special trays
you can trim the peripheries if overextended and modify the peripheries with greenstick and fit surface for free end edentulous saddles
what are the impression materials at the GDH
poly vinyl siloxane
polyether
alginate
impression compound
what is poly vinyl siloxane
o Brand name = extrude
o Medium body
o Be careful how much material you put in as it could be swallowed, and it is not biodegradable
o Dimensionally stable
what is polyether
o Brand name = impregum
o It is very rigid – do not use with undercuts
o Also be careful with patients who have periodontal disease as you do not want it to get stuck
o Dimensionally stable
what is alginate
o Well mixed
o Poured up as soon as possible
o Good if undercuts are present
o Be careful for air blows – it can compromise the accuracy
what are the instructions for the technician after visit 2 if you want cobalt chrome
pour model in improved stone
construct chrome framework per design
clear design signed by clinical
REMEMBER TO PREPARE OCCLUSAL RESTS/GUIDE PLANES BEFORE TAKING IMPRESSION
what are the instructions for the technician after visit 2 if you want acrylic
pour model in stone
construct record block with shellac base
what does visit 3 consist of
framework trial
recording occlusion
why should the framework trail be done without the addition of wax rims or artificial teeth
if the casting does not fit into place at once, the presence of wax hinders the search for interferences and additionally if the cast needs adjustment with stones, the heat generated may melt the wax and if the casting needs adjustment with stones the heat generated may melt the wax
what questions do we need to ask when doing a trial fit on the cast
Does it fit the cast?
Does it seat correctly in the mouth?
Is the cast damaged?
Is the framework interfering with the occlusion
how can we adjust the framework at chair side
(wearing appropriate mask for chrome adjustments) and using adam’s pliers for clasps
why do we need to record occlusion
To help design the denture
To help the technician set up the teeth
To ensure the denture is stable and is not dislodged in function
Patient comfort
Ensuring loading forces applied correctly to teeth
what are the two approaches when it comes to occlusion
conformist
reorganized
what is the conformist approach
this is when we keep the occlusion the same as it currently is. We need to know the position of the teeth in relation to each other.
what is the reorganized approach
this is when we alter the occlusion either because of tooth wear or there is not enough teeth to meet
what is the aim of visit 3
establish the inter-occlusal relationship to articulate the casts, occlusal vertical dimension and the tooth shade and mould.
what extended edentulous spaces do we want to establish
Buccal/labial contours of wax record block
Lip support
Incisal plane
Posterior plane
what are you aiming to inform the technician in visit 3
You are aiming to inform the technician where you want the artificial teeth to be positioned, their shade and mould, together with information on how the teeth occlude.
what do we use for definitive occlusal registration
wax occlusal rims
they are made on casts from the master impression
what do we need to do if there are no index teeth
we need to measure the occlusal vertical dimension (OVD) and the freeway space (FWS).
how do we measure OVD and FWS
Willis bite gauge measure the vertical dimension – the first is when the patient is biting together and the second is when the patient is at rest. Sitting at rest the patient should have at least 2/3mm between their teeth at rest. The difference is called the freeway space. It is more important in complete dentures as in RPD the patient has teeth and we try to conform to that.
what can be used to find the initial starting point for the oVD
old dentures
why do we need to trim the wax blocks
Trim the blocks – when you try the blocks in they will be bulky. It has to stay in place. Any overextension of the peripheries will drop/displace. Too much lip support and it will drop. You use a wax knife and hot plate/spatula to make adjustments. Adjust the upper rim first. You may need to adjust the rim labially/buccally.
why do we need to check the wax occlusal rims
The wax occlusal rims may be placed on temporary bases of shellac or acrylic resin or on the definitive cast metal frameworks. These must be tried in the mouth and their stability checked. If the stability is poor, yet the baseplate fits the cast accurately, consideration must be given to the possibility that the problem is due to an inaccurate impression. If this is confirmed the working impression must be retaken. The retention of the occlusal rim must be sufficient to maintain then rim in position during subsequent recording procedures.
when prescribing the position of anterior teeth what do we need to do
- Make sure index teeth (teeth that already bite together) in occlusion
- Mark centerline
- Correct incisal plane
- Correct antero-posterior position
what are the reference points for positioning of anterior teeth
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
how should you select shade
think about existing teeth, previous denture and patient preference
how should you select mould
you need to compare to existing teeth, previous denture and also measure
what should you say to the technician after visit 3 for the record block on the framework
construct wax record blocks on framework (additional visit required)
what should you say to the technician after visit 3 for the tooth trial
articulate casts for registration
set teeth for wax trial (shade and mould provided)
what is visit 4
tooth trial
what do we check in visit 4
We need to check: Framework fit Occlusion Aesthetics Extension
what is the lab instruction after visit 4
please take to finish in acrylic (if happy)
what is visit 5
delivery
what happens when the denture is made in acrylic
You do get small dimensional changes when you make the denture in acrylic – sometimes the fit will improve
what is the first thing you do in visit 5
First look at the dentures on the articulator
what do you look at in the denture on the articulator
Check design again is as requested
Examine denture for roughness/blebs – run fingers over acrylic to check for roughness
Check it seats properly
Look at the undercuts and if there are clasps there – are they engaging it? Are they staying in or are they easy to remove? Are any teeth on the cast broken?
Is the pin on the table?
Does the occlusion look correct
what do you check when the denture is in the patients mouth (visit 5)
Stability – does it rock?
Support – are rests/flanges seating accurately
Retention – adjust clasps with adams pliers
Aesthetics – carry out above checks first, last thing you do is show the patient
what do you look at when checking the occlusion in the patients mouth
Do the teeth meet in the prescribed occlusal scheme per the wax up? Check with articulating paper for heavy/early deflective contacts
Is something propping open the bite? Small change adjust with acrylic bur chairside. Large change may require removal of teeth and reset in wax.
what are the instruction given to patient based on
Insertion/removal Coping with new dentures Pain Denture cleansing Speech Eating Refer to clinic patient information leaflet
what is visit 6
The review
Here we take a history, do an examination and make any adjustments
