1
Q
What are some challenges may occur when natural teeth are lost
A
- Alveolar bone loss in extraction sites (no loading…)
- Remaining teeth can change position
- Tooth overeruption
- Changes to dynamic occlusal schemes
- Extra occlusal load on remaining natural teeth
- Changes to speech
- Changes to facial appearance
- Patients self-conscious with low self esteem
2
Q
What does changes to dynamic occlusion mean
A
- Changes in contact: lateral excursion
- Sometimes associated with cause temporomandibular disorders
3
Q
What can extra load on teeth do
A
- Wear them down quicker
- Push them into different position
4
Q
What can occur in terms of changes in facial appearance in loss of teeth
A
- Reduced OVD
- Upper lip not supported
- Angular cheilitis
5
Q
What is the purpose of a dental prosthesis
A
- Replace lost tissue
- Restore normal function
- Restores normal appearance
- Prevents undesirable effects: drifting, overeruption, tooth wear
- Fixed or removable
6
Q
Why provide a denture and advantages
A
- Good for extensive tooth loss
- Sort of replaces alveolar bone
- Easily removed: sports/cleaning
- Reversible (flexibility in tx planning)
- Minimal alteration to natural teeth
- Less expensive
- Good temp option/ people who will loose more teeth
7
Q
What are the components of a partial denture
A
- Saddles (hold artificial teeth)
- Rests
- Clasps
- Connectors (major, minor)
8
Q
What are the disadvantages of dentures
A
- Removable
- Often less well tolerated by patients (bulky, uncomfortable, loose)
- Metal clasps visible
- Plaque traps (caries, perio)
- Ulcers/ pain underneath sometimes
- Needs maintaining (or replacing)
9
Q
What is the concept of shortened dental arch
A
- Adequate function can be maintained with reduced dentition
- 9-10 occluding pairs of teeth
- Anterior and premolar should be in good health
- Upper and lower tooth contact should be favourable (avoid severe ortho malocclusion)
- Is significant tooth wear likely: bruxism, patient still young
10
Q
Other than standard dentures what other types and why
A
- Onlay or overlay denture: replace part of teeth
- Transitional denture: more poor prognosis teeth
- Immediate denture: after an extraction
- Test (diagnostic) denture: restore function while teeth restored, check new jaw relationship)
- Obturators: hide holes in palate
11
Q
Why is it important to do dentures in stable dentition
A
- More comfortable in healthy tissue
- Dentures last longer: extractions need denture change
- Denture can worsen caries and perio
12
Q
What to do in denture related stomatitis (basic)
A
- Candida albicans
- Leave out at night, milton’s solution
- Keep denture clean
- Medication (nystatin, micanzole)
- Underlying cause investigation
13
Q
What is and what to do in traumatic ulcer
A
- Denture border too long into sulcus
- Identify area with pressure paste: problem areas change colour
- Trim area back
- Temporary soft lining may help: visco-gel
14
Q
What is denture granuloma
A
- Chronic inflammation
- Remove cause (denture related) or allow for inflammation to reduce
- Review
- Surgery if necessary
then take impression
15
Q
Treatment or modification to improve denture function
A
- Tooth preparation for Cobalt chrome
- Tooth support for overdenture
- Tooth wear cases
- Placement of implant to help retain/support dentures
16
Q
What are the tooth modifications for RDPs
A
- Guide planes
- Rest seats
- Unfavourable tooth surface recontouring (eg, altering survey line position)
- Occlusal adjustment (adjusting the occlusal plane)
- Creation of retentive undercuts
17
Q
What is the definition of guide planes
A
- Two or more parallel (axial) tooth surfaces on abutment teeth which are used to restrict the path of insertion of a denture
18
Q
What is the definition of path of insertion
A
- Path followed by the denture from its initial contact with the teeth until its fully seated
19
Q
What are the advantages of guide planes
A
1) Control path of insertion of a denture
2) Facilitate easy insertion and removal of denture
3) Contribute to overall retention of the denture
4) Minimise wedging stresses on abutment teeth (lateral forces)
5) Reduce amount of ‘blockout’ (space between denture and teeth)
6) Aid denture stability (prevents movement during function)
20
Q
What are the types of rest seats and what is it
A
- Provides vertical support for the denture
- Occlusal
- Cingulum
- Incisal
21
Q
What are the functions of rests
A
- Transmit occlusal forces to the teeth along longitudinal axes
- Maintain correct occlusal relationship of denture base to abutment teeth
- Prevent trauma to gingival margins
- Provide some horizontal stability
- Prevent ingress of food between abutment teeth and denture base
- Act as indirect retainers as required (resist rotation and displacement)
22
Q
When is occlusal adjustment of natural teeth necessary
A
- When rest seat preparation alone will not provide adequate space for rest or clasp
- To crease space for denture base/teeth
- To correct a natural tooth occlusal interference
- To improve the level of the occlusal plane
23
Q
How can tooth undercuts be created for clasps
A
- Dimpling (remove a bit of tooth structure)
- Addition of composite
- Cast restoration (ideal contours can be created)
24
Q
How are dentures held in place and prevents looseness(6)
A
- Saliva layer between the denture and underlying soft tissues can act as a ‘weak glue’ or help make a seal around a denture to give a suction effect (peripheral seal)
- Muscle of the oral cavity can press against denture surfaces keeping them in place (neutral zone)
- Upper and lower teeth can help keep dentures in place when patient bites together or chews food with no interferences
- Gravity with lower dentures
- clasps grip onto natural teeth (direct retention)
- rests can rest against natural teeth helping to prevent denture from rotation(indirect)
25
What if the denture flange is too thin
- Does not work as well to fill the width of sulcus
- No peripheral seal
26
What is posterior ‘post dam’ seal
- Junction between hard and soft palate
- Compressible tissue
- Near vibrating line, Fovea palatine
- Acrylic ridge extending there to create suction
27
What is the definition of support
- Resistance of a denture to displacement towards the supporting tissues (especially when subjected to occlusal loads on teeth)
28
What does complete denture support depend on (**3**)
- Amount of cover of underlying tissues or denture bearing area
- Condition/firmness of underlying tissues or denture bearing area
- denture fits supporting tissue properly
partial: rests allow force distribution
29
What is the problem with flabby ridge
- Fibrous underlying tissue: not very good
- Extremely mobile
- Implant, surgery, soft liners, denture design
30
How do you check the support of a complete denture
- Press down on occlusal surface and see if it moves or wobbles
- Look to see how much area is covered (extensions ideal?)
- Look for signs of trauma to tissues (imprint, inflammation)
31
What Is the definition of retention
- Is the ability of a denture to resist displacement away from the denture bearing area in a direction perpendicular to the surface of the tissues (whilst at rest)
32
What is the definition of stability
- Is the ability of the denture to resist movement in relation to the underlying bone during function (eating and speaking) (in any direction)
33
What does retention of a denture depend on (7)
- denture fitting supporting tissue properly (mucosa and teeth)
- Area covered by denture (denture bearing area)
- Adaptation of the denture to underlying tissues: correct flange extensions
- Border seal around edge of denture (suction)(peripheral seal)
- Muscular control by tongue and cheeks and polished surface suitable and only in neutral zone
- Gravity (lower)
- direct retainers (clasps) and guide planes
34
How to check denture has good retention
- See if moves when patient at rest (lip apart)
- Pull dentures away from supporting tissues (check tongue holding denture)
- Push anterior teeth and see if back drops
35
Clinically how can you assess where the posterior border is
- Look at colour change
- Foveae palati
- Palpate junction with blunt instrument
- Ask patient to say ‘aah’ and see where the vibration is
36
What affects stability of complete dentures
- **Degree of support available **
- **Degree of retention available**
- Area covered by denture base
- Degree of alveolar bone resorption
- Consistency of the supporting tissues
- **Position of the teeth and design of ‘polished surfaces’ and only occupies neutral zone**
- **Correct vertical and horizontal occlusal relationship**
- **Freedom to make excursive movements**
- Level of the occlusal plane
37
What 4 things maximise denture stability
- Good support
- Good retention
- Denture occupies ‘neutral zone’
- An occlusal scheme that avoids knocking dentures of place
38
How do you check the stability of a complete denture
- Patient history (denture movement during function)
- Press on occlusal surface (see if other part moves)
- Observe denture movement during speech or eating
39
What is an undercut
- Desirable undercuts: clasps can engage
- Undesirable undercut: mesial or distal of tooth or relative tissue undercuts
40
What is a surveyor
- Instrument used to determine the relative parallelism of two or more surfaces of teeth or other parts of the dental arch
- Analysing rod, graphite marker, chisel (remove plaster), undercut gauge
41
What is Kennedy classification
- Class 1, class 1 mod 1: bilateral free ended partially edentulous
- Class 2, class 2 mod 1: unilateral free ended partially edentulous
- Class 3, class mod 2: unilateral bounded partially edentulous
- Class 4: bilateral bounded anterior partially edentulous
42
What is reciprocation
- Counteract the forces applied by the retentive clasps
- When denture is inserted and removed the retentive clasps can cause abutment tooth to move
- Stabilizing force
43
What are the different types of occlusal clasps
- Terminal third below the survey line
- Occlusally approaching clasp
- Reverse c clasp
- Ring clasp
- Double arm clasp
44
Gingivally approaching clasp
- Y clasp or T clasp
- Half T
- Ball ended
45
What types of upper major connectors (Cb-Cr)
- Palatal strap
- Palatal plate
- Palatal horseshoe
- Combination of chrome and acrylic
46
What are the lower connectors
- Lingual bar
- Sublingual bar
- Dental bar
- Lingual plate
- Buccal/labial bar
47
What happens if patient has larger ridge height
- Better support and retention (larger DBA)
- Better stability (sideways due to flanges)
- Easier to judge where denture teeth should go
48
What happens in short ridge height
- Smaller DBA: retention and support compromised
- Likely to move sideways during function
- More difficult to position teeth
49
What are indications of mucosa thickness and consistency
- Thick fibrous (movable) tissue is not good for support
- Very thin mucosa: easily damaged and not good at cushioning occlusal forces
50
What is the problem with xerostomia in denture patients and what can you do
- Saliva doesn’t do its job of adhesion
- Saliva replacements , stimulants
- Denture adhesive or soft liner
51
What to do during denture design
- S: saddle
- S: tooth support (rests on each end of saddle)
- R: retention (direct and indirect)
- R: reciprocation
- C: connectors
52
Can you trim a cobalt chrome framework
- Metal framework is thin (carful when adjusting)
- Overheating (cool with water after using bur on)
- Sharp edges (careful of causing this)
53
What should happen before
making the framework
- Articulate casts properly
- Block out tooth undercuts properly
- Survey casts properly: check natural undercuts are present
- Take accurate master impressions
- Cast impression accurately
54
What is an overdenture
- Covers at least one tooth or root
- Useful for teeth cannot be fully resotred
- Dome shape (can be metal)
- Preserves bone and provides support
- Severe tooth wear cases?
55
What are the advantages of overdentures
- Support
- Preservation of alveolar bone
- Stability: better than complete dentures
- Retention: if correct attachment used
- Proprioception: preserved via PDL
- Appearance: improved
- Psychological: patient is not rendered edentulous
56
What are the disadvantages of overdentures
- Treatment complexity: RCT may be needed
- Increased risk of caries and periodontal deterioration
- Soft tissue support?
- Time and cost
57
What are the advantages of acrylic denture over cobalt chrome
- Easy to modify
- Quicker to make than cobalt
- No metal components needed: aesthetics, allergy
- Cheaper
- Ideal as temporary denture: costs, time
58
What are the advantages of cobalt chrome dentures
- Tooth support possible: stability and comfort
- Better retention: more efficient clasps, path of insertion control
- Less bulky/ more lightweight
- Hygienic design possible: avoid gingival margins of teeth
- Better thermal conductivity: patient more aware of food/drink temp
- Less likely to break: this applies to the major connector only
- Less likely denture induced stomatitis: palate isn’t covered
59
What do you need to do before taking impression for denture
- Manage soft tissue inflammation: traumatic ulcer, denture granuloma
- Manage oral infection: candida, angular cheilitis
- Remove unwanted structures: fibrous tissue, poor prognosis teeth, abutment prep, ridge contour (bony torus)
- Manage tooth related problems (allow socket to heal
60
Tell me about zinc oxide/ eugenol impression paste
- Dimensionally stable
- Excellent surface detail
- Unaffected by saliva
- Problems: not elastic (needs suitable path of withdrawal), contraindicated in dry mouth or eugenol allergy
61
What can you tell me about silicone impression
- Dimensionally stable
- Good surface detail
- Elastic
- Easy to mix
- Hydrophobic
62
What to check in a stock tray fit
- Space for teeth
- Check sulcus depth
- Can extend with wax (not too much inside wax)
- Edentulous (can use putty)
63
What is the functional impression
- Viscogel ‘impression inside fit surface of complete denture’
- Let patient wear for a day
- They give it back and can send to lab for cast of master impression
64
What is the basics of jaw relation
- 3D spatial relationship between the upper and lower jaws
- Both vertical and horizontal component
65
What is ICP
- intercuspal position can be defined as the position of the jaws when the maxillary and mandibular teeth are in maximum intercuspation. This has also been referred to as centric occlusion.
66
What is RCP and terminal hinge axis
The terminal hinge axis position is where the condyles of the mandible are in their most superior and posterior position in the glenoid fossa. If an imaginary axis is drawn through the centre of each condyle (Fig 7-4a–c), pure rotation of the mandible occurs for the first 20 mm on opening (Fig 7-4b). The first tooth contact, when the mandible is in the terminal hinge axis position, is called the retruded contact position (RCP) or centric relation. In over 90% of dentate patients RCP and ICP (centric occlusion) do not coincide. There is usually an anterior and superior slide of approximately 2 mm between the two positions (Fig 7-4b and Fig 7-5a–c). When adopting a conformative approach, it is important that restorations do not interfere with this slide.
a bilateral, unstrained position of the mandible in which the condylar disc assembly is in the most anterior superior position within the glenoid fossa. In this position, the initial 20 mm of incisal opening is a pure ‘hinge’ movement around the hinge axis.
67
What is the ideal occlusion for partial dentures
- natural teeth as guide
- reproducible ICP
- if not enough contact use RCP or in tooth wear use reproducible RCP
68
what is freeway space
- Resting vertical dimension: bottom of chin to base of nose, patient at rest (take out a denture)
- OVD: patient biting, occlusal vertical dimension (with dentures in place)
- Freeway space: ideal 2-4mm difference between the two
- Willis gauge
69
Explain the choice of base material for occlusal rims
- An occlusal rim base made in wax with wire strengthener: can distort
- Heat cured bases is only possible in endentulous arches and more stable cos it doesn't distort
70
Recording jaw reg in RCP
- Guided into RCP by clinician
- Tell patient to relax
- Can use beauty wax to record (there will be gaps inbetween the teeth so use this)
- Tongue spatula to help them be manipulated into RCP or Hard occlusal splint
71
What does a facebow do
- Transfers the 3D spatial relationship between a patients hinge axis and the their upper arch of teeth onto an articulator
- Angle of patients occlusal plane is also transferred
72
What are the considerations about lost denture tooth
- Wax sometimes gets left behind during flasking causing a weak bond
- Lab can add tooth back on
- May need opposing arch or interocclusal record
- Check occlusion and adjust at the end
73
How bad is a major connector fracture
- Simple: two pieces, send to lab
- Complex: multiple pieces, more difficult to repair
74
What are the causes and solutions for a midline fracture
- Flexing of denture due to **occlusion problem**: repair and resolve occlusal issue
- Flexing of denture due to **uneven support**: repair and reline/rebase
- **Weak structure**: repair and add thickness
- **Denture dropped**: repair and advise how to clean
- **Deep frenal notch**: repair and strengthen if possible
- **Palatal torus** present: repair and provide relief in area of torus
75
What happens when major metal connector fractures
- Rare and mainly lingual bars
- Not repairbale
- Casting error
- Distortion more common; related to poor fit and flexing
76
What is reline
- New acrylic resurfaces the fit surface of a denture
- No old acrylic removed
77
What is rebase
- New acrylic resurfaces the fit surface of a denture
- Some old acrylic removed to reduce thickness
78
What are the indications for reline/ rebase
- Where the fit surface **‘doesn’t fit’** : painful and loose
- **Bone resorption**: recent extraction or jaw surgery
- **Quick fix**: alternative to new dentures
- As part of a **fracture repair**
- May help when adding flanges: continuous fit surface
- May also add **soft linings** in lab: permanent
79
What are the consideration of choice of material for reline and rebase
1. Permanent or temporary
2. Heat cured or self-curing
3. Chairside reline or laboratory reline (need impression)
4. Hard materials or soft
5. Only some materials suitable for rebase
80
What is temporary, soft reline
- Chairside
- Viscogel
- Similar to taking impressions
- Cushions mucosa
- Quick and easy to use
- Lasts few weeks (can replace)
81
What is temporary hard reline material
- Chairside
- Colacryl
- Poor colour match
- Fairly durable
- Quick and easy to sue
- Similar to taking impressions
- Remove excess whilst soft and can get trapped in undercuts
82
Tell me about permanent soft reline chairside
- Eversoft
- Reasonable colour match
- Lasts months or years
- Cushions mucosa
- Quick and easy, like taking impressions
83
Tell me about permanent hard reline laboratory
- Heat cured acrylic used so denture goes in flask
- Need chairside conventional impression of fit surface (silicone)
- Excellent colour match
- Permanent and durable
- Remove acrylic fit surface undercuts before taking impressions
- Suitable material for rebase
84
Tell me about permanent soft reline laboratory
- Heat cured flexible
- 3mm thickness needed
- Lower denture: upper denture too thick
- Reasonable colour and permanent
- Cushions mucosa
- Remove acrylic fit surface undercuts before taking impressions
- Far more successful if this is incorporated into denture when first made
85
Questions to ask when denture fractures
- **What is the cause**
- Did it break in the mouth
- Was it dropped on hard surface
- Was it whilst cleaning over a sink
- Weak or thin denture structure
- Mid line palatal torus
- **Has it been repaired before**
- **Can patient manage without dentures**
- **Will repairing solve the issue or time for new denture**
86
What are strengtheners or inclusions
- **Non bonding** – stainless steal mesh, don’t strengthen but hold parts together after fracture
- **Bonding** – bonds to acrylic
- Replacement of denture in high impact acrylic interrupts fracture propagation
87
What are the problems with relines or rebasing
- Increases OVD: use a thin layer of material
- Occlusal errors
- Damage during the process which is irreversible: warn the patient
88
Upper arch anatomy
- Front: orbicularis oris
- Sides: buccinator
- Frenum: labial and buccal
- Flat areas for support: alveolar ridge, palatal aspect
89
Lower arch anatomy
- Front: orbicularis oris
- Side: buccinator
- Frenum: lingual frenum also
- Flat areas good for support: buccal shelf, alveolar ridge
90
What if not enough freeway space
- Soreness denture: basically applying pressure at rest
- Aching jaw (ovd to excessive, no relaxing)
- Patient will find dentures to uncomfortable
- Patients lips may become incompetent, too much teeth showing
91
What happens if too much free way space
- Might see deep creeses at corners of the patient mouth
- Might see infection/redness/soreness at corners of the mouth (angular cheilitis)(may also have denture stomatitis)
- Patient may complain of poor appearance (poor lip support or reduced tooth height)
- Patients have jaw/muscle ache because they are over closed
- Denture become too worn as they eat leading to this
92
Balanced occlusion and balanced articulation
- Simultaneous contact of the occluding surfaces in various jaw positions (and articulation refers to during function)
93
Piezograph
- Lower usually
- Material: viscogel
- Minimum pressure zone in edentulous areas, (where problem with stability )
94
Impressions errors
- Thick labial borders
- Not having rolled border (sulcus missed)
95
denture advice
insert and remove
3-6 months to adapt fully
remove at night and clean over sink
call if any concerns
BDS5
flashcards
Decks in class (10)
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