1
Q
What are 6 reasons for rendering a patient edentulous?
A
1) caries
2) periodontal disease
3) appearance
4) malocclusion
5) overload of opposing jaw, esp edentulous lower
6) patient’s request
2
Q
What are four reasons against rendering a patient edentulous?
A
1) masticatory efficiency reduced
2) alveolar resorption
3) muscular skills required to manage F/F (special difficulty in elderly)
4) medical conditions
3
Q
What is a possible alternative to edentulousness?
A
overdentures
- retain some roots and restore to be used to support dentures
- preserve alveolar bone
- retain proprioception
4
Q
What are the advantages of immediate replacement dentures?
A
- maintain pre-extraction information - tooth mould, shade, arrangement, OVD, appearance
- maintenance of appearance
- continuity of denture wearing - ensuring maintenance of skills and familiarity
- maintenance of vertical and horizontal jaw r-ships
- denture covering socket may protect initial blood clot
5
Q
What careful case selection is required for immediate replacement dentures?
A
- leave only straightforward extractions for IR - surgicals not ideal
- may need to coordinate around sedation/GA apptmts
- always advise pt before treatment that denture will become loose and will require replacement (financial)
- require regular review
- can pt cope? financially, physically, emotionally
6
Q
What are the three design types of immediate replacement dentures?
A
1) flanged
2) part flanged
3) open face
7
Q
What is a flanged immediate replacement denture and when are they used?
A
flanged denture covers the clot completely and protect the area, also exerts equal pressure on both lingual and labial sides reducing post extraction haemorrhage maintains border seal, engages undercuts
- retention, undercuts, aesthetics
8
Q
When would a part-flanged immediate denture be used?
A
Part flanged immediate denture when there are issues with undercuts or bulkiness of buccal bone
does not extend into full buccal/labial sulcus
9
Q
When would an open face immediate denture be used?
A
due to undercut in buccal sulcus or bulky bone
less retention compared to full or partial flange
10
Q
Where do the teeth sit in an open-face immediate replacement denture?
A
directly above the ridge
11
Q
What type of immediate replacement dentures can be used following extractions?
A
- open face
- flanged
- part flanged
12
Q
What type of immediate replacement dentures can be used after extractions and bone removal (septal or radical alvelolectomy)?
A
flanged
13
Q
What are the indications for an open-face immediate replacement denture?
A
- bulky upper anterior alveolar ridge
- cannot utilise undercuts for retention as too deep, flange would give too much support to upper lip causing fat lip
14
Q
What is a disadvantage of using an open-face immediate replacement denture?
A
- less retentive
- resorption of ridge will lead to gap between denture and ridge
- transition from flangeless to flanged denture aesthetically difficult
15
Q
What are the stages involved in the manufacture and placement of an immediate replacement denture?
A
1) 1st imps
2) design
3) 2nd imps
4) occlusion
5) try-in
16
Q
What instructions are required for the lab to make an immediate replacement denture?
A
- which teeth are to be extracted
- arrangement
- shade
- flange type - part/full/flangeless
- material
- date for insertion/extractions
17
Q
What is the necessary aftercare for patients required for immediate replacement dentures?
A
- Dentures to be kept in for 24hrs
- review apptmt ideally on day after insertion
- remove denture, examine for healthy clots, identify areas of inflammation and ease denture
- after 24hrs - advise warm saline mouthwash and pt to remove denture after mealtimes to rinse mouth and clean denture - soft toothbrush, soap and water
18
Q
What aftercare is necessary following placement of immediate replacement dentures?
A
- review after 1 week
- review after 1 month - assess adaptation
- consider temporary reline
- need for regular recall - 6 months
- rebase or replace
19
Q
What is involved in a one stage immediate denture?
A
- to replace one or two anterior teeth in an otherwise intact arch
- upper and lower imps
- wax squash bite if required to confirm occlusion
- choose shade
- prescription to lab including design
- extraction and insertion of denture at next visit
20
Q
What is retention?
A
resistance of a denture to vertical movement away from the tissues
21
Q
What is stability?
A
resistance of a denture to displacement by functional forces
22
Q
What are four examples of displacive forces?
A
1) gravity
2) muscle activity
3) sticky foods
4) function
23
Q
What is interfacial surface tension?
A
the force holding two parallel plates together that is due to the viscosity of the interposed liquid (saliva)
24
Q
What effect does the viscosity of saliva have on the interfacial surface tension?
A
serous/watery saliva has a greater ability to wet the acrylic than thick/mucinous saliva
25
What is adhesion?
the physical attraction of unlike molecules for eachother
e.g. saliva and mucous membrane
saliva and denture base
26
How can you maximise adhesion in a denture?
by extending over potential load bearing area as far as possible
27
What is cohesion?
the physical attraction between similar molecules e.g. salivary film
28
In the sandwich example, what is the adhesive part and what is the cohesive part?
adhesive forces (bread) surrounding cohesive forces (filling)
29
A border seal is really only achievable in what prosthesis?
maxillary prosthesis
30
What fitting surface factors must be considered when trying to optimise retention and stability with complete dentures?
base shape
adaptation to mucosa
31
What is the primary supporting tissue in the maxilla?
basal bone
32
What is the secondary supporting structures/tissue in the maxilla?
soft tissues, rugae, tuberosities
33
What do we aim for to try and achieve a border seal in a maxillary denture?
fitting surface as close as possible to mucosa to
create negative pressure underneath to create seal
34
What is a post dam?
ridge of acrylic around 0.5mm thick which applies extra pressure at the posterior edge of the denture
35
Where should a post-dam be placed?
just anterior to the vibrating ah line, anterior to palatine fovea as it can depress soft but relatively immobile tissue which will create a good seal
36
Why should the post-dam not be placed behind the vibrating 'ah' line?
distal to the vibrating line is the area of the SP that moves, causing instability
37
What are the palatine fovea?
two small dots either side of the midline on the SP just anterior to the vibrating 'ah' line
38
What is the importance of adequate extension in to the retromylohyoid fossa (lingual pouch) in mandibular dentures?
lingual pouch sits above and anterior to where the muscles move, extension of denture around the corner of the curve of the mandible will offer bracing from lateral movement and offer greater area to extend denture over
39
What ensures a denture with a close relationship to the fitting surface?
good impressions
40
What kind of path of insertion improves retention?
a path of insertion that is not straight
41
What factors can make retention and stability difficult?
- an atrophic ridge - less SA to cover and less scope to engage useful undercuts
- damaged alveolar ridge - trauma/surgery
- damaged alveolar ridge - replacement of bone by fibrous tissue "flabby ridge"
- tori - benign bony growths
- gagging
- insufficient saliva
42
Where are maxillary teeth usually placed in relation to the ridge?
to the buccal aspect
43
Where are mandibular teeth usually placed in relation to the ridge?
over centre of ridge "neutral zone"
44
What is the neutral zone?
area where the outward forces from the tongue are balanced by the inwards forces of the cheeks (buccinator, orbicularis oris). Placing teeth here increases denture stability, retention and comfort
45
What it tongue spread?
if a patient has either not had natural teeth or not worn a prosthesis for some time, then the tongue may spread laterally into the area, creating issues when trying to find sufficient space to position teeth
46
What is an example of an aid to denture retention and stability and how can it be applied?
- denture adhesives and linings e.g. fixodent, polygrip, seabond
- ideally 3 small dots applied in triangular pattern on fit surface
47
What is an alternative method used to achieve a good seal?
valves - act by sucking out air from under denture base to create negative pressure
48
What is an alternative way to anchor a denture?
implant placed in bone with a male attachment sitting above gum level, female part is in denture. Denture can then be located and clicked into place. 2 implants required as minimum to prevent rotation of prosthesis
49
What are the risks of complete dentures opposed by natural teeth?
presence of natural teeth means that excessive forces can be applied to opposing edentulous ridge, leading to trauma, increased resorption and lack of stability
50
What are some challenges presented by complete dentures opposed by natural teeth?
- uneven occlusal plane resulting in inabillity to achieve balanced occlusion
- inadequate or excessive FWS
- difficulty recording jaw r-ship
- challenges with tooth position of denture teeth affecting aesthetics
- drifting of teeth esp those w perio can alter OJ or OB
- tooth wear of denture teeth
51
Trauma to the maxillary denture bearing area can result in what?
- soft tissue damage - ulceration and discomfort
- alveolar resorption and fibrous tissue replacment - flabby ridge, fibrous ridge, combination syndrome
52
How can you take an impression of a fibrous ridge?
- if not too severe, using a special tray with perforations anteriorly
we want a mucostatic impression (tissues at rest)
- if fibrous ridge more severe, 2 stage silicone impression using special tray with window anteriorly and take an initial first stage imp with putty, then cut away excess around fibrous ridge and inject light bodied material around fib ridge to record mucostatic imp
53
How can you reduce the trauma to the maxillary denture bearing area?
- maximum coverage with prosthesis
- ensure prosthesis covers primary load bearing areas
- impression is fully extended but not overextended
54
What particular anatomical areas should care be taken with to avoid trauma to the maxillary denture bearing area?
- labial sulcus
- labial frenum
- hamular notch
- buccal sulcus
- buccal frenum
- post dam
55
How can the stability of a maxillary denture be optimised?
- use of overdenture abutments (support denture and maintain alveolar bone)
- effect of absence of posterior lowers - lower 3-3 can occlude and with no posteriors, denture is unstable and post-dam seal can be broken
- free end saddle in mandible - more stable as even occlusal contact
- bounded saddle in mandible - replacement of missing teeth in lower arch improves occlusal contacts
- management of incisor overbite - position of denture teeth, reduction of incisal edges of natural teeth , if OB too large, leads to tipping and instability of denture
- articulation of eccentric mandible movements - if occlusion unbalanced, uneven contacts on either side
56
How can irregular occlusal plane on natural teeth be managed?
- no adjustment
- minimal localised occlusal grinding
- radical occlusal adjustment (crowning)
- extraction of teeth
- overlay appliance - usually when teeth are quite worn
57
What are the potential issues with a complete lower denture with upper natural teeth?
- potential significant trauma to lower ridge due to:
- excessive occlusal forces
- occlusal imbalance
- minimal denture base foundation area
- may lead to accelerated resorption of lower ridge
58
What are the management options to prevent damage in complete lower denture with upper natural teeth?
- soft lining (needs replaced every so often)
- retain roots and provide overdenture
- implants (expensive but gold standard)
59
What is a reline?
adding new base material to the tissue surface of an existing denture in a quantity sufficient to fill the space which exists between the original denture contour and the altered tissue contour
60
What is a rebase?
replacing the entire denture base material of an existing denture
61
What are four types of relines?
- temporary
- soft (cushioning)
- permanent (resilient)
- chairside vs laboratory based
62
What is the purpose of a temporary reline?
tissue conditioning
- when grossly ill-fitting dentures
- post immediate dentures
- after implant surgery
63
What are soft linings used for?
- useful if parafunctional habits, very atrophic ridges, and in cancer/cleft palate patients (obturators)
64
What is a disadvantage of a soft lining?
- plasticiser leaches, deteriorates over time (hardens) and can harbour micro-organisms
65
What is a permanent lining generally made of and what is its purpose?
- usually hard acrylic
- useful in peripheral seal problems, correction of errors following inadequate master imp
- immediate/post-immediate dentures
- often lab-based
- prolongs lifespan of some older dentures
66
What are the four types of soft lining materials?
- heat cured acrylic
- self cured acrylic
- heat cured silicone
- self cured silicone
67
What is heat cured acrylic composed of and used for?
- soft lining
- powder is methacrylate based (eg. polyethyl methacrylate) activated by benzoyl peroxide in liquid containing monomer and plasticiser
68
What is self cured acrylic composed of and used for?
- soft lining
- powder is methacrylate based activated by tertiary amine that acts upon benzoyl peroxide
69
How is a heat cured silicone processed, what is it used for and what is an example?
- soft lining
- processed against acrylic
- contains a siloxane material and a filler of silica
e.g. molloplast B
70
What is the rebase technique for a complete acrylic denture?
remove any undercuts
wash imp using denture
imp poured in stone
overcast in plaster made
denture removed to reveal working model
post-dam carved
fit surface removed from denture (horseshoe)
cutback denture placed on cast
overcast, model and denture back together
gap filled with wax
overcast removed
palate added in wax
dundee injection method
71
What are five common types of denture fracture?
1) midline
2) tooth detaches from denture base
3) loss of flange
4) acrylic saddle detaches from CoCr baseplate
5) clasp fracture/bent
72
Why do dentures fracture?
- impact
- acrylic in thin section
- work hardening of metal
- parafunctional habits
- occlusion - deep overbite
- soft linings
- denture processing problem - porosity
- bonding between tooth and base acrylic or acrylic and CoCr
73
How is a simple denture repair achieved and what is an example?
eg. midline fracture of complete denture
- if fractured piece can be located together, disinfect and send to lab (no impression needed), cast poured, fractured area removed and new acrylic processed
74
How is a piece of denture missing resolved?
e.g. part of acrylic flange lost
- impression taken with fractured denture in mouth, disinfected, cast poured and new acrylic processed into defect
75
How can a acrylic-CoCr repair be done?
- may need to add retentive tags, solder on tags and/or use 4-META or silicoat CoCr to retain acrylic on CoCr
76
What can be used for a temporary repair of a fractured denture?
- self-cure acrylic
- cyanoacrylate glue
usually chairside
77
What are the three types of additions?
1) immediate addition
2) post-immediate addition
3) retention
78
What are additions for?
partial dentures not complete dentures
79
What is an immediate addition?
when a tooth is lost after denture construction and tooth added on the day of tooth extraction
80
What is a post-immediate addition?
when a tooth is lost after denture construction and at a later date a tooth is added
81
What is a retention addition?
when denture retention is inadequate a clasp is added to improve retention (usually wrought stainless steel clasp)
82
What are the clinical issues with additions?
- additions usually require an impression of the arch with the denture to be added to IN THE MOUTH during the impression
- sometimes cannot add to CoCr e.g. lower incisor when lingual bar connector
83
What is an overdenture?
any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth and/or implants
84
What are the advantages of overdentures?
- correction of occlusion and aesthetics
- support
-tooth wear management
- preservation of ridge form
- proprioception
- denture retention
- can be used with precision attachments
- MRONJ and radiotherapy pts - avoids extractions
- psychological benefits
- useful in elderly pts - retaining root treated roots
- eases transition to edentulism
85
What are the disadvantages of overdentures?
- need for good OH
- increased caries/perio issues
- care homes
- denture fracture
- discomfort/infection
- MH
- potentially more traumatic extractions
86
What is an example of a precision attachment overdenture?
Zest anker female component in root treated tooth
Zest anker male component in fit surface of denture
simple to replace worn out male components and cold-cure new ones into denture
87
In the manufacture of what is an overcast used?
a rebase
88
What is the laboratory technique used for rebasing a denture?
- remove any undercuts from denture - when imp cast could cause breakage
- wash imp using denture and closed mouth technique
- imp poured in stone
- overcast in plaster to reproduce occlusal position
- overcast separated and denture removed from stone cast to reveal working model
- post dam carved
- fitting surface and palate removed to allow space for new acrylic
- cut-back denture re-placed onto overcast
- overcast, model and denture back together - sticky wax to hold in place (gap between denture and model now due to removed imp material
- gap filled with wax
- overcast removed and palate added in wax
- flask using dundee injection method
89
What are the lab steps in creating an immediate denture in the lab?
- model prepared to add teeth in place of those to be extracted
- teeth to be extracted marked X
- denture teeth matched to size of natural teeth on model
- teeth to be replaced sawn off model up to gingival margin (one at a time)
- model smoothed and given contour of alveolar ridge
- denture tooth positioned in space
- wax added and softened and tooth placed in correct position
- model placed on articulator to check tooth position and occlusion
- same repeated for other tooth
- if adjustment required, tooth width can be decreased by grinding distal aspect
- waxwork smoothed, margins cut
- flask pack and process waxwork into acrylic
- once processed, teeth extracted and denture fitted
3rd year - module 6
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