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BDS3 - CDS > Prosthodontics > Flashcards

Prosthodontics Flashcards

1
Q

equiptment and materials for primary impressions with compound

A
  • edentulous or dentate stock trays and handle
  • vaseline
  • impression compound
  • hot water in bowl with paper towel at bottom
  • red ribbon wax?
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2
Q

impression compound uses

A
  • primary impressions for complete dentures
  • for free end saddle areas of primary impressions for RPD
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3
Q

impression compound melting temp

A

55-56 degrees celcius

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4
Q

handling impression compound

A
  • vaseline ongloves
  • shape it to tray
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5
Q

handle types for special tray

A
  • standard handle
  • large handle
  • handle with finger stops
  • intra-oral
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6
Q

special tray modification equiptment needed

A
  • hot air burner
  • impression compound (greenstick)
  • straight handpiece and carbide acrylic bur
  • special tray
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7
Q

carbide acrylic bur use

A

adjust the periphery of special tray which is over extended

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8
Q

greenstick compound key points

A
  • melts at 50-51 degrees celcius
  • muco-compressive
  • very rigid when set
  • must be tempered in warm water before putting into patients mouth
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9
Q

kit used to check OVD, RVD and occlusal plane

A
  • willis bite gauge
  • dividers
  • foxes occlusal plane guide
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10
Q

what to write on lab card for primary impression stage

A
  • please pour the casts
  • construct upper and lower special trays with standard handles
  • date: two weeks from day of impression
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11
Q

what to write on lab card for master impression stage

A
  • pour master casts
  • construct upper and lower record blocks
  • shellac base/wire strengthener
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12
Q

what to write on lab card for jaw reg stage

A
  • mount casts to registration
  • set upper and lower teeth for trial (if tooth trial next)
  • shade of tooth anterior and post
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13
Q

complete denture also called

A
  • full denture
  • CU
  • CL
  • F/F
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14
Q

material for complete dentures

A
  • PMMA (acrylic)
  • rarely cobalt/chromium
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15
Q

effects of edentulism

A
  • loss of masticatory function - decreased nutrition/enjoyment of food can result in other medical conditions
  • appearance and self esteem issues
  • QoL
  • speech
  • ridge resorption
  • soft tissue changes to lip and chin
  • decreased facial height
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16
Q

describe post extraction resorption

A
  • occurs rapidly after Xs - particularly in first 6 months
  • individually variable
  • maybe dependant on pre-extraction status of teeth - advanced perio can result in already low ridge
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17
Q

what is the classification used to measure ridge resorption

A

cawood and howell classification

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18
Q

compromises of F/F

A
  • inefficient at mastication
  • requires good neuromuscular control
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19
Q

reasons for edentulous

A
  • rampant caries
  • advanced periodontal disease
  • toothwear that is severe and debilitating
  • failing dentitions - overly ambitious tx
  • head and neck cancer chemo-radiotherapy
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20
Q

construction methods for complete dentures

A
  • conventional dentures
  • replica dentures
  • digital dentures - new technique not used in GDH
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21
Q

conventional denture technique for F/F
considerations

A
  • if no prev denture or prev one poor/unsuccessful
  • takes longer and jaw reg more complex
  • can make major modifications and correct faults more easily
  • good if significant ridge resorption since original dentures made
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22
Q

replica denture technique for F/F
considerations

A
  • keeps existing design easier to adapt
  • maintains existing aesthetics
  • 1 less clinical stage and jaw reg simpler
  • major modifications difficult
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23
Q

causes of failing dentitions

A
  • overambitious tx
  • cycles of replacement
  • human, medical and social factors
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24
Q

causes of occlusal collapse

A
  • caries
  • perio
  • tooth wear
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25
Q
A
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26
Q

F/F stages summary
stage 1clinic

A
  • primary impressions using stock trays
  • disinfect
  • take to lab with prescription for special trays
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27
Q

F/F stages summary
stage 1 lab

A
  • primary casts and special trays
  • lab pour casts
  • make special tray - specify tray handle required
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28
Q

F/F stages summary
stage 2 clinic

A
  • master impressions
  • disinfect special trays
  • master impression on special tray
  • mark postdam
  • disinfect imp
  • take to lab with prescription - record blocks
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29
Q

F/F stages summary
stage 2 lab

A
  • pour master casts
  • make record blocks
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30
Q

F/F stages summary
stage 3 clinical

A
  • jaw registration
  • disinfect record blocks
  • register occlusion
  • choose shade, setting and mould
  • disinfect registered blocks
  • take to lab with prescription - wax trial
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31
Q

F/F stages summary
stage 3 lab

A
  • mount cast and set up teeth
  • put registered blocks on holding casts
  • mount on articulator
  • set up teeth
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32
Q

F/F stages summary
stage 4 clinic

A
  • wax trial
  • disinfect try in
  • try in checks
  • re-register/make other changes as required
  • disinfect try-in
  • take to lab with prescription for retry or finish
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33
Q

F/F stages summary
stage 4 lab

A
  • finish dentures
  • wax up - flasking - deflasking - trim and polish denture
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34
Q

F/F stages summary
stage 5 clinic

A
  • try in finished denture
  • disinfect denture
  • insert and check
  • denture wear and cleaning instructions
  • arrange review visit
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35
Q

F/F review checks

A
  • pain/redness/ulceration
  • function
  • aesthetics
  • speech
  • recheck occlusion/vertical dimension
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36
Q

poor denture hygiene causes

A
  • poor manual dexterity
  • inability to self-care
  • xerostomia
  • poor diet
  • lack of oral health knowledge
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37
Q

constituents of debris

A
  • salivary proteins and bacterial products = pellicle layer
  • oral debris adhere - mucin, food, microorganisms
  • plaque turns to calculus as on natural teeth
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38
Q

bacteria and fungi in debris on dentures

A
  • staph. aureus
  • E. coli
  • alpha streptococci
  • candida have an affinity for adherence to PMMA
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39
Q

debris accumulation

A
  • acrylic is porous and rough - soft linings worst
  • fit surface of denture not exposed to cleansing effects of saliva
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40
Q

effects of poor denture hygiene

A
  • caries
  • periodontal disease
  • denture stomatitis
  • halitosis
  • pain
  • dentures can act as reservoir for potential respiratory pathogens - increased theoretical risk of aspiration pneumonia
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41
Q

types of mechanical denture cleaning

A
  • soap and soft-brush
  • microwave (no-metal) 20 seconds
  • ultrasonics
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42
Q

chemical cleaning most effective when

A
  • ineffective unless first mechanically cleaned
  • depending on product type
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43
Q

types of chemical denture cleaning products

A
  • alkaline peroxides
  • alkaline hypochlorites
  • acids
  • enzymes
  • abraisive cleaners
  • other
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44
Q

chemical denture cleaning ideal properties

A
  • cheap
  • easy to use
  • effective removal of biofilm mass
  • bactericidal and fungicidal
  • harmless to denture materials
  • non-toxic
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45
Q

alkaline peroxide denture cleaner summary

A
  • light-duty cleaner
  • active ingredient usually sodium perborate
  • tablet or powder when combined with water creates bubbles
  • does not effectively deal with calculus or darker stain
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46
Q

alkaline hypochlorites denture cleaner summary

A
  • very effective
  • antibacterial/antifungal cleaning
  • may corrode metal
  • short soak (10 mins) if metal component
  • do not use for soft linings
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47
Q

acid denture cleaner summary

A
  • good at dissolving calculus/stain
  • citric acid
  • vinegar
  • do not use for soft linings or metal based dentures
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48
Q

enzymes denture cleaner summary

A
  • expensive
  • proteolytic enzymes
  • protease, dextranase, mutanase
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49
Q

abraisive denture cleaner summary

A
  • stain removal
  • damage to dentyure
  • less effective anti-microbial activity that other chemical cleaners
  • adjunctive chemical soak needed
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50
Q

negatives of chemical denture cleaning

A
  • damage
  • bleaching
  • allergies
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51
Q

cleaning metal-based dentures

A
  • can be damaged by acid cleansers
  • soak in alkaline cleansers for maximum 15 minutes (alkaline peroxide) or 10 mins (alkaline hypochlorite)
  • soak in water overnight
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52
Q

cleaning soft linings

A
  • prone to damage - avoid hard toothbrushes
  • safe to soak in steradent (alkaline peroxide) for max 15 minutes
  • soak in cold water overnight
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53
Q

advice to pt on denture care

A
  • GDH info leaflet - discuss verbally and individualise for specific patient circumstances
  1. brush your dentures daily - non abraisive cleaner
  2. soak your dentures daily - denture cleaner
  3. leave your dentures out at night
  4. visit your dentist regularly
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54
Q

advice on brushing dentures daily

A
  • rinse dentures after every meal
  • remove debris by brushing with a soft toothbrush, soap and cold water
  • not toothpaste and hard brush - will scratch/abrade denture acrylic
  • ensure done over a basin full of water to avoid breakage if denture should fall
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55
Q

advice on soaking dentures daily

A
  • soak dentures in cold water for max 20mins with alkaline based denture cleaner (less if metal denture/soft lining)
  • rinse thoroughly with cold water, then soak overnight in water
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56
Q

denture try in and insertion
before patient arrives

A
  • do you have the lab work for the correct patient
  • has it been damaged in transit
  • does the lab work match the design
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57
Q

denture try in and insertion
before you insert try in

A
  • look at dentures on articulator - check occlusion, OB, OJ
  • correct shade and mould and number of teeth
  • are teeth set over ridge
  • look at casts - has postdam been cut - if not draw on casts with pencil and prescribe for technician to cut post dam
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58
Q

denture try in and insertion
try in checklist

A
  • retention and stability
  • base extensions
  • LIMBP
  • occlusion
  • speech
  • aesthetics
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59
Q

denture try in and insertion
LIMBO

A
  • lip support
  • incisal level
  • midline
  • buccal corridor
  • occlusal planes - anterior/posterior
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60
Q

denture try in and insertion
speech

A
  • fricatives - f, v, s ,x ,g, h
  • test fricatives with try-in in place
  • listen to f and v sounds to assess the contact between incisors and lower lip
  • not too much whilsting on s sounds
  • look - teeth should be slightly apart during speech
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61
Q

denture try in and insertion
aesthetics

A
  • allow patient to view in mirror
  • hold mirror at distance
  • give patient time and freedom to comment
  • if patient consents to finish - record consent
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62
Q

wax denture try in and insertion
speech problem

A
  • if teeth make contact during speech often insufficient FWS so OVD needs to be reduced
  • re-register at new OVD - ask lab for remount and reset for re-try
  • significant whilstling sounds during s then OVD may need to be increased or anterior tooth position changed
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63
Q

wax denture try in and insertion
aesthetic problem

A
  • shade/mould incorrect - choose again lab reset
  • midline incorrect - mark new midline
  • if minor changes to tooth pos. - alter at chairside until pt approves
  • major changes to tooth pos. - re-register and lab reset
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64
Q

wax denture try in and insertion
vertical dimension error

A
  • if OVD increased - remove teeth from one or both dentures and replace with wax rim
  • in OVD decreased - max rim can be added to the teeth
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65
Q

complete denture insertion
before you insert dentures

A
  • check all 3 surfaces of the denture for blebs, sharp edges, quality of polish
  • ensure no porosity in acrylic
  • look for large undercut areas that may prevent seating or cause pain
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66
Q

complete denture adjustment causes

A
  • roughness can cause pain
  • extension into undercuts can be painful
  • overextension may cause pain
  • occlusion may require adjustment
  • smooth and polish if necessary eg pumice
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67
Q

LIMBO changes at completed denture insertion

A
  • lip support - minor labial flange reduction only
  • IMBO - cannot alter at this stage
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68
Q

denture insertion
discomfort causes

A
  • commonly undercut areas - tuberosity, anterior labial flange, tori
  • areas of poor support - mylohyoid ridge, very resorbed knife edge ridge, flabby ridges
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69
Q

denture insertion
discomfort identification

A
  • discomfort history - site etc
  • ask patient to be specific
  • can use pressure indicating paste
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70
Q

denture insertion
wear instructions

A
  • manage expectations - may take some time to adjust to changes
  • some discomfort is normal
  • speech may lisp
  • eating may be difficult - food under denture, bite lips and cheeks, slow etc
  • wear as much as possible and take out at night
71
Q

what to do with denture prescription if pt accepts/declines denture

A
  • write outcome on precription
  • if accepted give 3rd copy to pt
  • 2nd copy in notes
  • 1st copy to lab with finished on it
  • if declined bin it securely
72
Q

complete denture review checklist

A
  • 1 - 2 weeks after insertion
  • get patients story
  • aesthetics and speech
  • function - mastication
  • recheck occlusion/FWS
  • any other problems
  • examination - redness/ulceration/hyperplasia
73
Q

what is an immediate denture

A
  • any removable dental prosthesis
  • fabricated for placement immediately following the removal of a natural tooth/teeth
74
Q

advantages of an immediate denture

A
  • speech
  • function
  • avoid drifting/over eruption or remaining teeth
  • post extraction healing - promotes healing
  • ridge form preservastion
75
Q

disadvantages of an immediate denture

A
  • poor adaptation to ridge very quickly
  • plans can change due to pain/swelling meaning XLA is during denture making process
  • increased complexity of prosthetic stages
  • design limited to acrylic plate and simple wrought clasps in partials
  • traumatic extractions can make insertion difficult
76
Q

potential contraindications to immediate denture

A
  • some ORN/MRONJ areas as denture will traumatise area
  • if pt pre-cancer tx as pt can get mucositis - dont place denture on top
  • if denture not required - no aesthetic/major functrional issues
  • if pathological issues eg large cycts which needs to heal
  • major fractures of maxilla/mandible
  • lack of pt consent
  • dementia
77
Q

clinical stages of immediate denture

A
  • sane sequence as for other dentures
  • occasional skip/modify stages
  • primary impression, design, master impressions, jaw reg, (try in), delivery
78
Q

examination and assessment considerations for pt getting immediate denture

A
  • teeth to be removed assessed clinically and radiographically if required
  • medical history important - MRONJ/ORN risks/anticoagulants
  • assess degree of difficulty of XLA
79
Q

immediate denture
lab instructions

A
  • which teeth are to be extracted - mark teeth to be extracted on cast
  • shade/mould
  • material
  • date required for insertion
80
Q

immediate denture
in the lab

A
  • saw off teeth to be extracted
  • set up new teeth to new incisal level
81
Q

immediate denture insertion post XLA

A
  • might require some modifications
  • pt still numb so might not be able to assess fit/sore areas
  • do modifications later appt if possible
82
Q

initial aftercare for immediate dentures

A
  • dentures to be kept in for 24 hours
  • ideally review day after insertion
  • after 24hours advise warm saline mouthwash and pt to remove after mealtimes to rinse mouth and clean denture
  • soft toothbrush soap and water to clean
83
Q

reviews for immediate denture

A
  • 1st review ideally day after - examine mouth for healthy clots and identify any areas of inflammation - ease denture
  • review after 1-2 weeks - further adjustment as required
  • may need denture fixative
  • review after 1 month - assess adaptation - consider temporary reline
  • may need repeat reviews, more temp relines etc
84
Q

when is immediate denture replaced

A
  • 6 months to 1 year
  • depending on rate of resorption
85
Q

chairside relines for immediate denture

A
  • temporary or soft difinitve materials available
  • reline material placed in fitting surface and moulded in the mouth
  • can be used in localised areas
86
Q

summarise one stage immediate denture

A
  • to replace one or two anterior teeth - trauma, abscess, root frascture
  • upper and lower impressions recorded
  • high quality interocclusal record required
  • choose shade
  • prescription to lab including design and teeth to be XLA
87
Q

purpose of primary impression

A
  • used to construct primary casts
  • for treatment planning
  • construction of special trays
88
Q

stock tray types

A
  • dentate impression trays
  • edentate impression trays - designed to fit ridge
  • perforated/non-perforated
89
Q

modification of stock trays
materials

A
  • putty - expensive, limited setting time
  • soft red wax - cheap, easily manipulated, poor dimensional stability
  • red composition - requires boiling water, very short working time, sticks to gloves to use vaseline
  • greenstick - requires heat, tricky to manipulate, bettersuited for special trays
90
Q

reducing the extension of stock trays

A
  • acrylic bur
  • straight handpiece
  • eye protection needed
91
Q

limitations of stock trays

A
  • not made to measure
  • peripheral extensions - often over or under extended
  • limited size available
  • require master impressions to record denture bearing area with accuracy
92
Q

common errors with stock trays

A
  • tray handle upside down
  • excessive loading of material on tray
93
Q

impressions for complete dentures
indication for red composition instead of alginate

A
  • retching patients
  • rapid working time
  • seconds rather than minutes
94
Q

assessing impressions for complete dentures

A
  • are all edentulous areas included
  • are the sulci areas to be included in the denture recorded fully
  • are deficiencies present due to an air inclusion
  • is the impression fit for purpose or not
95
Q

how can impressions for complete dentures be improved

A
  • tray modification
  • amount of material - not too much/too little
  • tray placement correct
  • was border moulding sufficient
96
Q

ideal measurement between tray flange and denture bearing area

97
Q

steps for impressions for complete dentures
primary impressions

A
  • apply thin layer of adhesive over tray (and any putty/wax/composition)
  • mix alginate and load tray with alginate
  • seat loaded tray in mouth
  • border mould muscles whilst constantly supporting tray
  • once alginate set remove it with shard suddent movement
98
Q

special tray materials

A
  • VLC resin PMMA - pre-rolled sheets which are easy to mould
  • self-cure PMMA - problems rolling an even layer
  • shellac - individual tray for replica technique
99
Q

special tray spacing

A
  • modelling wax used so tray is over a uniform thickness of spacing
  • depends on material used for impressions
  • alginate 3mm
  • silicone elastomers no spacer
  • zinc oxide/eugenol impression paste no spacer
  • silicone polysulphides 3 mm
100
Q

advantages of special trays

A
  • accurate peripheral extension
  • uniform thickness of material
  • reduced amount of material - less discomfort as tray fits individual mouth
  • records denture bearing area more accurately
101
Q

clinical prodecure impressions for complete dentures
master impression

A
  • check special tray 2mm short of sulcus depth to allow border moulding
  • greenstick used for mould stops - centre of palate and postdam area
  • insert tray in mouth to mould stops
  • check extension and modify if necessary
  • apply thin layer of adhesive - dry
  • fill tray with alginate
  • support tray throughout procedure and bourder mould
102
Q

handling of impressions

A
  • alginate - must be kept moist and cast asap - especially important for master impression
  • elastomers - more dimensionally stable and dont require moist environment
103
Q

disinfection of impressions for complete dentures

A
  • rinse in running water to remove saliva, blood or debris
  • disinfect for 10 minutes in disinfectant solution
  • note time impression is to be removed from solution
  • rinse thoroughly
  • cover alginate impression with damp paper towel
  • label and place in lab bag - take to lab asap
106
Q

patient / operator positioning for impressions

A
  • upper - stand behind
  • lower - stand in front
  • patient sitting up not flat
107
Q

keeping pt calm during impression

A
  • talk to patient throughout
  • if retches ask to take deep breaths through nose, tilt head forward and calm patient
  • effective communication
108
Q

lab prescription
stage/safety/specifics

A
  • stage - what you want done not what you have done
  • safety - record disinfected
  • specifics - upper/lower/both ; materials ; tray handels ; special instructions etc
109
Q

finger rest on special tray summary/function

A
  • used with lower special trays
  • placed in region of 2nd premolar/1st molar
  • allows finger to be placed on either side of tray and thumb under for mandible support
  • ensures fully seated posteriorly and even distribution of pressure
  • helps stabilise tray in mouth
110
Q

tissue stop on special tray function/summary

A
  • to ensure uniform thickness of impression material
  • help localise tray during impression taking
  • lower tray - place in canine region and along post dam area
  • upper tray - place in canine region and post dam area
  • can use greenstick compound
111
Q

clinical indications for close fitting special trays

A
  • use with materials requiring less space
  • resorbed ridges
  • replicas
112
Q

mucocompression and mucostasis

A
  • most impressions are mucocompressive
  • mucocompression - pressure is applied to mucosa so that shape of tissue under load is recorded
  • mucostasis - minimum pressure is applied to tissue to record their shape at rest
113
Q

special impression technique for a fibrous ridge

A
  • fibrous ridge = flabby ridge
  • avoid compression of fibrous tissue during impression recording
  • use an impression with perforated special tray with both high and low viscosity material
  • special tray perforated over flabby ridge
  • alginate impression taken first (mucocompressive) and then light bodied silicone over and take again
114
Q

define retention and types of displacing forces

A
  • resistence of a denture to vertical movement away from the tissues
  • displacing forces:
  • gravity
  • muscle activity
  • sticky foods
  • function
115
Q

define stability

A
  • resistence of a denture to displacement in a horizontal direction
  • by functional forces
116
Q

define adhesion and cohesion

A
  • adhesion is physical attraction of unlike molecules for each other
    1. saliva and mucous membrane
    2. saliva and denture base
    cohesion is the physical attractiopn between similar molecules eg salivary film
117
Q

what is atmospheric pressure in terms of denture

A
  • pressure within the atmosphere
  • if dentures have an effective seal around their borders atmospheric pressure can resist dislodging forces
  • called suction - resistence of removal in a direction opposite to that of insertion
118
Q

which area of denture important for seal

A
  • post dam seal important for ahesion, cohesion and atmospheric pressure
  • ridge of acrylic in post dam region can help provide the seal
119
Q

factors that increase difficulty of retention/stability of complete denture

A
  • atrophic ridges
  • pts with an incomplete palate eg cleft palate
  • pt with fibrous ridge - soft tissue is mobile
  • damaged alveolar ridge
  • pts who cannot tolerate base extension
  • CoCr base decreases adaptation
  • insufficient saliva
120
Q

achieving optimum retention using fitting surfaces of denture

A
  • adequate post dam seal in maxillary denture
  • adequate extension in ligual retromylohyoid fossa (lingual pouch)
  • use of undercuts - labial undercuts and bilateral soft tissue undercuts
  • should have well extended cast with good surface detail
121
Q

aids to retention/stability of dentures

A
  • denture adhesives
  • linings
  • implant-retained - high success rates
122
Q

stages in replica construction

A
  1. assessment of patient and dentures
  2. replica impressions
  3. 2nd impressions and occlusion
  4. trial insertion visits (tooth trial)
  5. insertion (delivery)
  6. review
  7. aftercare

1 visit less than conventional - no jaw reg

123
Q

copy or replica denture

A
  • copy - try to make identical denture
  • replica - modify what we think is wrong
  • if lots of changes consider conventional denture
124
Q

describe replica technique

A
  • 5 scoops putty and 5 strokes activator
  • mix until homogenous and load into tray - press impression into tray until set
  • make notches in IM once set and put vaselin over
  • mix more putty and push into exposed side of denture and ensure extends over notches - lay another tray on top
  • when set remove with knife under heel of impression
125
Q

replica denture master impression/occlusion
aims of the visit

A
  • determine tooth position
  • take master impresssion
  • record the occlusion
  • select teeth shade
126
Q

describe steps of replica denture master/occlusion visit

A
  1. check replica blocks - shellac base wax replica of dentition
  2. modify replica block
  3. take impression using light-bodied silicone using a closed mouth technique so ask pt to bite together
  4. record occlusion using bite paste
127
Q

replica master impression assessment

A
  • ensure impression covers whole of denture bearing area
  • sulci rounded and free from defects
  • correctly shaped and extended
  • have you recorded good surface detail
  • suitable to produce master cast
128
Q

occlusion for conventional dentures
jaw registration function

A
  • use record blocks to recreate vertical height when teeth are in occlusion
  • so the master casts can be mounted in occlusion
129
Q

occlusion for conventional dentures
record block types

A
  • wax block only - cheap, less retentive, lots of space for setting teeth
  • shellac base - more stable, more expensive, limited space fore setting teeth
  • heat cured base - very stable, expensive, least space for setting teeth
130
Q

what can be used to measure OVD

A
  • willis bite guage
  • dividers
131
Q

equiptment for jaw registration

A
  • to heat wax for trimming etc - hot plate, bunsen burner, hot air blower
  • wax knife
  • fox’s occlusal bite plane
  • dividers
  • willis bite gauge
132
Q

jaw registration steps

A
  1. adjust upper record block for retention
  2. adjust upper record block for tooth position
  3. adjust upper record block for occlusal planes
  4. lower tooth position and horizontal jaw relationship
  5. measure verticle dimension and establish facial height
  6. record registration
  7. select shade, mould and setting
133
Q

jaw registration steps
1. adjust upper record block for retention

A
  • often too bulky as made to standard size
  • overextension of peripheries = loss of retention
  • use wax knife and hot plate/heated pallet knife to make adjustments
  • may need to adjust rim labially/buccally
134
Q

jaw registration steps
2. adjust upper record block for tooth position

A
  • consider LIMBO - lip support, incisal level, midline, buccal coridor, occlusal plane
  • visual judgement required
  • reccomended nasiolabial angle 90degrees
  • mark midline
135
Q

neutral zone definition

A
  • potential space between lips an cheels on one side and tongue on the other
  • area or position where forces between tongue and cheeks/lips are equal
  • prosthetic teeth generally must conform to the horizontal position determined by the neutral zone.
  • Prostheses which set teeth outside this zone risk problems such as discomfort, cheek or tongue biting, and instability of the denture.
136
Q

common mistakes at jaw registration

A
  • teeth and buccal flange too close to cheek - dislodges with cheek movement
  • teeth too lingual - poor tongue space so tongue lifts denture when moves
  • lingual flange incorrect shape - so tongue lifts denture when moves
137
Q

jaw registration steps
step 4. mandibular tooth position and horizontal jaw relationship

A
  • adjust lower block with skeletal relationship in mind
  • ensure pt in retruded contact position
  • if cant get into RCP - raise mandible from rest to initial contact (muscular position)
138
Q

jaw registration steps
step 5. measure verticle dimension and establish facial height

A
  • use willis bite gauge or dividers
  • aim for 2-4mm FWS
  • dividers - 2 measuring point in midline of face with minimal influence from muscles of facial expression
  • OVD and RVD measured
  • RVD-OVD = FWS
139
Q

what is OVD

A
  • occlusal vertical dimension
  • distance between a set point on the maxilla and a set point on the mandible
  • when the denture or natural teeth are in maximum intercuspation
140
Q

what is RVD

A
  • resting vertical dimension
  • when the mandible is at rest with patient upright
  • position mandible takes up without ant conscious control
141
Q

what can affect RVD measurement

A
  • stress
  • pain
  • anxiety
  • tense up facial muscles can affect
142
Q

excessive or reduced FWS consequences

A
  • FWS usually 2-4mm
  • excessive - reduced masticatory efficiency, overclosed facial appearance and cheek biting, TMJ symptoms
  • reduced FWS - excessive load on denture bearing area, continuous muscular activity results in pain, aesthetic complaints “teeth too big”
  • noisy dentures
143
Q

jaw registration steps
step 6. record registration

A
  • final checks that blocks in correct position so teeth in neutral zone/neutral contact/OVD correct
  • cut notches on blocks and use wax or jaw registration paste
  • if using paste apply adhesive to upper and lower blocks and paste to lower block
  • ensure casts will seat back on models and check for heel interferences
144
Q

types of tooth moul

A
  • square moulds
  • ovoid moulds
  • tapering moulds
145
Q

what is manchester rim

A
  • bite block type which allows simplified registration
  • has two pillars of wax situated bilaterally in the region of the mandibular second premolar-first molar tooth positions.
146
Q

jaw registration data

A
  • OVD
  • central line
  • high lip line
  • occlusal plane
  • arch form - width-lip support
  • canine line
147
Q

setting upper teeth
occlusal plane guide

A
  • clear perspex sheet is fixed to lower base with hot wax
  • corresponds to the occlusal plane on the upper rim
  • will provide arch form for setting teeth
  • centre of lower ridge tranferred onto occlusal plane guide as well as profile of the upper rim
148
Q

setting upper incisor

A
  • incisor edge parallel to occlusal plane
  • long axis is not parallel to centre line
  • incisors placed either side of centre line
  • long axis also not paralle to vertical line - slightly proclined
149
Q

important considerations when selcting teeth for dentures

A
  • anterior tooth selection - function, appearance and speech
  • posterior tooth selection - critical for acceptable oral function
150
Q

factors influencing tooth selection choice

A
  1. dentist factors
    * previous dentures
    * ageing
    * skeletal class and size of skeleton
  2. patient factors
    * infleunces of others
    * self-esteem
    * smileorexia - pt wants perfect smike
151
Q

materials used for artificial teeth

A
  • traditionally made of acrylic
  • porcelain based - doesnt adhere to acrylic
  • composite resin based
  • combinations
  • brands - senator and vivodent
  • senator relatively mono-coloured
  • vivodent much better wear resistence and aesthetics - wont usually get on NHS
152
Q

tooth shade selection

A
  • vita shade guides are standard - understood by technicians and manufacturors
  • have natural light
  • light source + object + observer + interpreter = perception
153
Q

challenged with tooth shade selection

A
  • colour washout - when stare @ colour too long
  • illuminant metameric failure - light source causes shade to look different
  • observer metameric failure - get others for 2nd opinion
  • patient photographs
  • family member influence
  • patient preference might not be best suited
154
Q

mould guide 3 numbers what they measure

A
  • top number measures width of 6 teeth on flat (anterior) and 4 teeth on flat (posterior)
  • middle number is width of left central incisor or left first molar
  • bottom number is length of left central incisor
  • all measurements in mm
155
Q

shape of artificial teeth myths

A
  • leon williams classification - face shape corresponds to shape of max central incisor - no evidence to support
  • frush and fisher - men should have square angular teeth and women curved and rounded teeth - no evidence to support
156
Q

ways to set teeth to look more natural

A
  • characterisation of teeth/gum on denture
  • imbrication - slight rotation
  • diastema - gap between central incisors
157
Q

biometric guide to tooth positioning

A
  • tip of incisor 5.5mm forward from incisive papilla
  • not used regularly as most people differ from average
158
Q

selection and position of posterior teeth for setting

A
  • ensure sufficient space for tongue
  • lowers placed on crest of ridge
  • in some cases drop 2nd molar if more room needed
  • uppers placed slightly buccal to ridge
  • posterior teeth should be parallel to ala-tragus line
  • consider size, width, positio
159
Q

types of posterior teeth for tooth selection

A
  • anatomical cusped teeth 33 degrees
  • hybrid 12 degrees
  • non anatomicl flat cuspless teeth - used when difficult to get a reproducible jaw relationship
160
Q

treatment planning for F/F
patient complaints (CO)

A
  • appearance
  • eating
  • pain/discomfort
  • looseness
  • retching
  • speech
161
Q

treatment planning for F/F
dental history

A
  • when teeth lost
  • why teeth lost
  • any retained roots
  • any pain or swelling
  • anxiety, mobility and dental attendance
  • anything been tried to fix problem
162
Q

treatment planning for F/F
denture history

A
  • denture experience - no prev dentures?
  • age of dentures
  • are dentures a matching set
  • most recent set worn
  • when 1st set
  • how many sets of dentures - lots over few years could = dissatisfied
  • material/soft lining and any modifications
163
Q

treatment planning for F/F
social history

A
  • mobility
  • barriers to tx
  • alcohol/smoking
  • capacity to consent
  • support needed
164
Q

treatment planning for F/F
medical history which could be relevant

A
  • neuromuscular problems - stroke, parkinsons - denture pops up and down due to constant tongue and lip movement
  • xerostomia
  • bisphosphonates at risk of MRONJ
  • cardiac disease
  • diabetes - increased risk of candida
165
Q

treatment planning for F/F
extra oral signs to look for

A
  • signs of TMJ destruction - click or tenderness
  • facial pathology - angular chelitis
  • facial contours
  • overall appearance of dentures
  • look out for suspicious lesions
166
Q

treatment planning for F/F
intraoral things to look for

A
  • mucosal health - need to take impression of healthy mucosa
  • ridge height - is it flabby
  • if retained roots look at periodontal/periapical status, caries etc
167
Q

angular chelitis often happens when

A
  • worn denture decreases facial height
  • saliva in corners of mouth
  • stroke pts
168
Q

denture hyperplasia

A
  • reactive lesion due to excessive mechanical pressure
  • on vestibular oral mucosa
169
Q

treatment planning for F/F
denture examination in mouth things to assess

A
  • anterior and posterior occlusal planes - is denture at slant etc
  • RVD - OVD = FWS
  • LIMBO
  • overextension or underextension
  • retention, stability, adaptation
170
Q

describe ICP

A
  • intercuspal position
  • complete intercuspation of opposing teeth
  • independant of condylar position
171
Q

describe RCP

A
  • guided occlusal relationship
  • occuring at most retruded position of the condyles in joint cavities
  • RCP is most reproducable position
  • in complete dentures we do not use ICP as there are no opposing natural teeth
172
Q

describe stability and adaptation of dentures

A
  • stability - ability of denture to resist displacement by functional stressess
  • adaptation - degree of fit between a prosthesis and supporting structures
173
Q

treatment planning for F/F
denture examination out mouth

A
  • base extension - over/underextension?
  • tooth position
  • wear of denture - excessive wear?
174
Q

treatment planning for F/F
pre-treatment phase

A
  • usually done if need to get tissues healthy prior to constructing replacement denture
  • use of tissue conditioners
  • referral for investigation or further opinion if concerns about mucosa

BDS3 - CDS (13 decks)

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