Removable Prosthodontics Flashcards
1
Q
What are the 6 reasons for rendering a patient edentulous?
A
- Caries
- Periodontal disease
- Appearance
- Malocclusion
- Overload of opposing jaw (especially edentulous lower)
- Patient’s request
2
Q
What are the 4 arguments against rendering a patient edentulous?
A
- Masticatory efficiency reduced
- Alveolar resorption
- Muscular skills required to manage F/F (this can be difficult for elderly)
- Medical conditions
3
Q
What is the key alternative treatment plan to rendering a patient edentulous, where roots of teeth are caries free with good surrounding bone levels?
A
Use of an over-denture abutment (retain some roots that will support a denture)
4
Q
What are the two main advantages to maintaining an over-denture abutment compared to extracting the full tooth?
A
- Preservation of alveolar bone
- Retain proprioception
5
Q
Define, resistance of a denture to vertical movement away from the tissues.
A
Retention
6
Q
Define, the resistance of a denture to displacement by functional forces.
A
Stability
7
Q
What are four forces that could displace a denture? (The first answer is a force that only affects the upper denture)
A
- Gravity
- Muscle activity
- Sticky foods
- Function
8
Q
Define, tension that is generated when a thin layer of fluid is present between two parallel planes of rigid material.
A
Interfacial surface tension
9
Q
Define, the force holding two parallel plates together that is due to the viscosity of the interposed liquid (e.g. saliva).
A
Interfacial viscous tension
10
Q
What happens to viscous tension when thickness of saliva increases?
A
Force falls rapidly
11
Q
What type of saliva is best to allow for optimum adaptation between the denture and mucosa?
A
Thin saliva
12
Q
Define, the physical attraction of unlike molecules for each other.
A
Adhesion
13
Q
Define, the physical attraction between similar molecules (e.g. salivary film).
A
Cohesion
14
Q
Why is a greater base extension achieved in the maxilla compared to the mandible for an edentulous patient?
A
Because loss of alveolar bone height is often greater in the mandible compared to the maxilla. Therefore, remaining basal bone left to support the denture will always have a greater surface area in the maxilla.
15
Q
Where should post dam of a maxillary denture sit in relation to palatine fovea in order to generate a good border seal?
A
Just anterior to palatine fovea
16
Q
Where is it important for a lower denture to extend over in order to offer some bracing to the denture?
A
Adequate extension into the retro-mylohyoid fossa (lingual pouch)
17
Q
What is the advantages of utilising natural mucosal undercuts when placing a denture?
A
Increases retention
18
Q
How do undercuts increase retention of a denture?
A
The denture will need to be tilted and rotated to fit into position in the mouth, there isn’t a straight line of insertion. This increases retention.
19
Q
How does an atrophic ridge make denture retention and stability difficult?
A
There is less surface area that can be covered for retention of a denture and less scope to engage useful undercuts
20
Q
Where are teeth normally positioned in a lower complete denture?
A
Over the centre of the ridge
21
Q
Where are teeth normally positioned in an upper complete denture?
A
Buccal aspect of the ridge
22
Q
Define, an area on the denture where the outward forces from the tongue are balanced by the inward forces from the cheeks.
A
Neutral zone
23
Q
What are the advantages of placing teeth on a denture in the neutral zone?
A
Increase in stability, retention and comfort.
24
Q
How does addition of “valves” to a denture achieve a good base fit?
A
Valves act by sucking air out from under base of denture
25
The presence of natural teeth against an opposing edentulous ridge can lead to what? (List 3 things)
1. Trauma
2. Increased resoprtion
3. Lack of stability of dentures
26
What area of the edentulous maxilla is particularly affected when opposed by forces of natural teeth?
Pre-maxilla (anterior region)
27
What is the consequence of trauma to the edentulous maxillary denture bearing area?
1. Soft tissue damage (ulceration and discomfort)
2. Alveolar resorption (combination syndrome) and fibrous tissue replacement (flabby ridge)
28
What effect can a fibrous/flabby ridge have on a denture?
Cause tissue displacement and tipping of the denture
29
Why type of impression do you want to take of a fibrous ridge?
A mucostatic impression
30
For more severe fibrous ridge, what type of impression should be taken?
Two stage silicone impressions
31
What are two ways to reduce trauma to the maxillary edentulous denture bearing area?
1. Maximum coverage of the denture bearing area with the prosthesis
2. Ensure the prosthesis covers the primary load bearing sites
32
What is the advantage of using overdenture abutments?
Helps to support the denture and maintain alveolar bone (prevents flabby ridge formation!)
33
What are the 5 management options for an irregular occlusal plane on the natural teeth?
1. No adjustment
2. Minimal localised occlusal grinding
3. Radical occlusal adjustment (crown tooth)
4. Extraction of teeth
5. Overlay appliance
34
Why are issues much more severe in the case of a complete lower denture with upper natural teeth, compared to a full upper denture with lower natural teeth?
Because there is excessive occlusal forces and imbalance, which may lead to accelerated resorption of the lower ridge.
35
What are the 3 management options for a complete lower denture with upper natural teeth opposing?
1. Soft lining in denture
2. Retain roots and provide overdenture
3. Implants
36
What is a Reline?
Adding a more 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.
37
What is a rebase?
Replacing the entire denture base material of an existing denture (only complete dentures)
38
What are the three types of relines?
1. Temporary
2. Soft
3. Permanent
39
What would be the indications for using a temporary Reline (tissue conditioner)?
- where lower ridge is inflamed and softer lining is required
- to improve fit of ill-fitting dentures
- for immediate dentures to improve adaptation
- after implant surgery while implant abutment integrates
40
When are soft relines indicated for dentures?
- patients with parafunctional habits
- patients with atrophic ridges
- cancer/cleft patients
41
What are the downsides to soft linings?
1. Plasticiser leaches and deteriorates with time so needs regular maintenance
2. Soft linings harbour microorganisms so patient is more prone to Candida infection
42
What are the 4 types of soft lining materials?
1. Heat cured acrylics
2. Self cured acrylics
3. Heat cured silicones
4. Self cured silicones
43
What is an example of a chairside self-cured acrylic soft lining?
Coe-soft
44
What is an example of a laboratory based heat-cured soft lining?
Molloplast B
45
What are permanent relines usually made of?
Heat cured acrylic
46
When is a permanent Reline a useful addition to a denture?
1. If there are issues with the peripheral seal of denture 2.corrections need to be made following inadequate master impressions. 3. Immediate/post-immediate dentures. 4. Prolongs lifespan of some older dentures
47
What does a glossy/shiny fitting surface of a denture indicate?
That it is fairly worn
48
How do you rebase a denture? (8 steps)
1. Remove undercuts from fit surface of denture
2. Take wash impression with closed mouth technique
3. Impression is poured in stone
4. An overcast in plaster is used to ensure denture is in same location as when lining is placed
5. Post-dam carved into working model
6. The fitting surface and palate of denture has been removed to allow space for new acrylic
7. Palate added in wax
8. We flask this using injection technqiue
49
What type of fracture is commonly seen in complete dentures?
Midline fractures
50
Name 5 different ways damage to denture occurs.
1. Midline fracture
2. Tooth detached from denture base
3. Loss of flange (usually from dropping)
4. Acrylic saddle detached from Co/Cr baseplate
5. Clasp fracture/bent
51
What is most common cause of midline palatal fracture of a denture?
Acrylic in thin section
52
Name 8 common reasons as to why dentures fracture?
1. Impact
2. Acrylic in thin section
3. Work hardening of metal
4. Parafunctional habits
5. Occlusion- deep overbite
6. Soft linings
7. Denture processing problems- porosity
8. Bonding between tooth and base acrylic or acrylic and Co/Cr
53
How would you repair a midline fracture of a complete denture if the pieces can be located together?
1. Disinfect And send to lab
2. Cast poured
3. Fractured area removed
4. New acrylic processed
54
How would you manage an acrylic denture which has a lost flange?
1. Take impression with fractured denture in mouth
2. Disinfect
3. Cast poured
4. New acrylic processed into defect
55
What are the three types of additions for partial denture?
1. Immediate addition
2. Post-immediate addition
3. Retention
56
What is an immediate addition to a denture?
When a tooth is lost after denture construction and tooth added on the day of tooth extraction
57
What is a post-immediate addition?
When a tooth is lost after denture construction and at a later date a tooth is added
58
What is a retention addition?
When a denture has inadequate retention a clasp is added to try improve retention
59
What type of clasp is usually added in a retention addition case?
Stainless steel clasp
60
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 dental implants.
61
Name 10 advantages of overdentures?
1. Correction of occlusion and aesthetics
2. Support
3. Tooth wear management
4. Preservation of ridge form and bone
5. Proprioception
6. Denture retention (precision attachments)
7. Avoids extractions in MRONJ and radiotherapy patients
8. Psychological benefits
9. Useful in elderly patients
10. Eases transition to edentulism
62
Name 7 disadvantages of overdentures.
1. Need for good oral health
2. Increased caries/periodontal issues
3. Care homes (diet can be high in refined sugars)
4. Denture fracture
5. Discomfort/infection
6. Medical history (dry mouth)
7. Potentially more traumatic extractions
63
What are the two components of precision attachments and their function?
There are ‘male’ and ‘female’ components.
Male component is fixed to the natural teeth.
Female component is incorporated into the denture.
These components lock together to yield a very stable prosthesis
64
What are the 4 important messages to tell patient for overdenture care?
1. Good oral hygiene
2. Fluoride toothpaste on roots
3. Regular examinations and radiographs
4. Denture hygiene
65
What are the 4 main advantages of immediate replacement dentures?
1. Maintenance of appearance
2. Continuity of denture wearing
3. Maintenance of vertical and horizontal Jaw relationships
4. Denture covering extraction socket may protect initial blood clot
66
What are the 3 different design options of immediate replacement dentures?
1. Flanged
2. Part flanged
3. Open face
67
What immediate replacement denture design is the most retentive?
Flanged IRD
68
Where there is an undercut in the buccal sulcus or bulkiness of the buccal bone, what immediate replacement denture designs are suitable?
Part flanged and open face
69
What are the 4 key points of advice to give patients regarding aftercare of their immediate replacement dentures?
1. Dentures to be kept in for 24 hours post insertion
2. Patient to come in for review ideally the day after insertion if feasible
3. After 24 hours, patient should use warm saline mouthwash.
4. After 24 hours, patient should remove their denture after mealtimes, rinsing and cleaning with soft toothbrush, soap and water.
70
Why is it so important for the patient to keep IRD in for the first 24 hours, usually overnight?
To prevent the situation of the tissues swelling post-extraction overnight and then the patient would be unable to re-insert the dentures in the morning.
71
At what stages should a IRD be reviewed?
1. Review after 1 week
2. Review after 1 month
3. Need for regular recall every 6 months
72
Describe construction stages of a one stage immediate denture.
1. Upper and lower imps recorded
2. Wax squash bite if required to record occlusion
3. Choose shade
4. Prescription to laboratory including design
5. Extraction and insertion for denture at next visit
73
What is a one stage immediate denture used for?
To replace one or two anterior teeth in an otherwise intact arch
74
What are the clinical stages to constructing an immediate replacement denture?
1. Examination and assessment
2. Primary impressions
3. Occlusion
3. Design
4. Second impressions
5. Tryin
6. Extractions and finish
75
Define, an artificial tooth root that is surgically anchored into the jaw to hold a replacement tooth to teeth or a denture in place.
Dental implant
76
By what process does a dental implant merge and make contact with the bone?
Osseointegration
77
Name the 3 components of an implant.
1. Implant
2. Abutment
3. Abutment Screw
78
Approximately how long after placing an implant, will you then uncover and connect the abutments?
Usually 3-4 months after placement
79
Give 8 examples of medical conditions that could/would be a contraindication for placement of an implant?
1. Chemoradiotherapy
2. Poly pharmacies
3. Immunosupression
4. MRONJ risks
5. Cardiac issues
6. Mental health issues
7. Diabetes
8. Thyroxine
80
What are the minor surgical risks of placing implants?
1. Pain
2. Bruising
3. Swelling
81
What are the major surgical risks of placing implants?
1. Parasthesia
2. Perforation into nasal cavities or maxillary antrum
82
What stages are involved in implant planning?
1. History/examination
2. Radiographs
3. Other imaging - CBCT/CT
4. Surgical and radiographic templates
83
What are the 4 clinical stages of the “placement” of an implant?
1. Raise flap
2. Place implant
3. Place cover screw
4. Suture
84
What are the 6 clinical stages of the “prosthetic stages” of an implant?
1. Uncover implants
2. Place abutment
3. Take impression with coping
4. Choose colour
5. Place temporary crown
6. Cast impression with lab
85
What two ways can multiple teeth be retained by an implant-bridge?
1. Cement retained
2. Screw retained
86
What are the two main disadvantages of a cement retained implant-bridge?
1. The abutments are so retentive that it can be difficult to take off if necessary
2.if you get cement around margins this can lead to inflammation and bone loss around the implant.
87
What is the most popular way to retain a denture with implants?
Locator abutments
88
What four ways can a denture be retained by implants?
1. Locator abutments
2. Ball abutments
3. Gold bar
4. CAD-CAM titanium bar
89
What are 4 common post implant treatment complications?
1. Peri- implant mucositis
2. Peri-implantitis
3. Loose/fractured components
4. Late implant failure
90
How could you add to a denture to help withstand biting forces if the patient is a bruxist?
Addition of chrome
91
What are the 4 main roles of the GDP in implant patients?
1. Oral health advice
2. Triage and diagnosis of a complication (if possible)
3. Referral if necessary
4. Manage taking account of SDCEP guidelines
92
The BPE is appropriate for assessment of dental implants. True or false?
False, it is not appropriate.
93
Define, inflammation (where the tissues appear red and swollen and May be bleeding) of the peri-implant mucosa with no evidence of crestal bone loss.
Per-implant mucositis
94
Define, an infection with suppuration and inflammation of the soft tissues surrounding an implant, with clincially significant loss of peri-implant crestal bone after the adaptive phase.
Peri-implantitis
95
Why is die hardener applied to the cast prior to preparing to wax up an inlay?
Helps to prevent chipping or flaking of the model when carving the wax
96
Why is die relief applied to the cast prior to preparing to wax up an inlay?
Creates space for the luting cement when the inlay is fitted
97
Why is a separator applied to the cast after die relief, when preparing for inlay?
So that the inlay may be removed when the craving is complete
98
What property is distinctive of carnuba wax, used to wax up an inlay?
It contributes to brittleness of the material
99
At what temperature is the inlay mould heated at?
900 degrees Celsius
100
After the investment is set, why is the top of the investment scraped off?
To allow more porosity of the surface so that gasses can escape
101
Die stone is a gypsum product. How do its physical properties differ compared to dental plaster?
Harder
102
Inlay wax is brittle, why is this a desirable property?
The wax will break at the margin rather than distort
103
Dental inlay wax is brittle, what competent of the wax confers this property?
Carnuba wax
104
At wax up stage you applied die relief to this working model. What function does this serve?
Space for luting cement
105
Once sprued, the wax pattern is invested under both vibration and vacuum. Why are these conditions necessary ?
So that air is not beaten into the mix resulting in a denser mould
106
What dimensional effect takes place when constructing your wax?
Contraction
107
What dimensional effect takes place during die fabrication?
Expansion
108
What dimensional effect takes place when investing the inlay?
Expansion
109
What function does the lining placed in the casting ring serve?
Allows for expansion of the investment
110
At try in your inlay will not seat home. Give an example of an area that may need adjusting.
Contact point
111
Describe Kennedy class 1
Bilateral free end saddle
112
Describe Kennedy class 2
Unilateral free end saddle
113
Describe Kennedy class 3
Single bounded saddle that does not cross midline
114
Describe Kennedy class 4
Single bounded saddle that crosses midline
115
When classifying with modifications, what saddle should be used to define the main Kennedy classification?
Most posterior saddle
116
In order to prevent tooth movement of a clasped tooth, what is required?
A reciprocal component
117
Give two examples of reciprocal components for clasped dentures.
1. Extension of base plate around opposing side of tooth
2. Clasp arm around opposing side of tooth
118
What are the dimension requirements for a mid-palatal bar or anterior bar?
Between 7-12mm
119
What are the different types of gingivally approaching clasps?
- roach T or T clasp
- variations of T clasp
- I Bar clasp
120
What is the advantage of an I-bar clasp over other gingivally approaching clasps?
Puts the least amount of stress on the tooth compared to other designs
121
What clasp design is often used for clasping critical abutment teeth posteriorly?
Ring clasp (with occlusal rest)
122
What advantage does the dental bar design have over a plate design?
Frees up the gingival margins and lingual mucosa so is more hygienic
123
What is a requirement for use of a dental bar?
No spacing between anterior teeth
124
What crown height is required for use of a dental bar?
9mm
125
What is the bar width, clearance from gingival margin, and clearance from incisal tip required for placement of a dental bar?
Bar width = 5mm
Clearance from gingival margin = 2mm
Clearance from incisal tip = 2mm
126
What is the minimum space from the sulcus depth to the gingival margin required to prescribe a lingual bar?
7mm
127
How much clearance does a lingual bar allow for from the gingival margin and what is the bar width?
3.5mm clearance
3.5mm bar width
128
What mandibularconnector can be used where there is spacing between anterior teeth?
Lingual bar
129
What component can be added to lingual bar to increase indirect retention?
Cummer arms
130
What is the purpose of an undercut gauge?
Determines the amount of undercut a clasp can engage depending on the material is is made of.
131
What size of undercut can a cobalt chrome clasp utilise?
0.25mm
132
What size of undercut can a stainless steel clasp utilise?
0.5mm
133
What size of undercut can a gold clasp utilise?
0.75mm
134
Describe how to measure an undercut using the undercut gauge?
Hold the gauge barrel against the tooth and draw upwards until the ledge touches the tooth.
135
What information about clasp position can you get from use of undercut gauge?
Where the undercut gauge touches the tooth is where the terminal third of the clasp will finish
136
What part of an occlusally approaching clasp is the bracing component?
The part above the survey line
137
What part of an occlusally approaching clasp is the retentive component?
Flexible tip of clasp below the survey line
138
Why is a facebow used with semi-adjustable articulators?
To record the relationship of the maxilla in relation to the TMJ
139
What are the advantages of injection moulding over dough packing?
1. No flash minimising open bite when fitting dentures
2. No trial pack
3. Less handling of material
4. Less pressure when injecting material
140
What are the disadvantages of injection moulding over dough packing?
1. Need to add sprue
2. Extra training
3. Expense of equipment
4. Difficult to de-flask
5. Technqiue sensitive
141
What is “flash”?
This is the excess acrylic dough that comes out of mould when compressed.
142
If after dough packing, the denture is placed on articulator and pin does not touch incisal table, what would be required when fitting the denture?
Occlusal adjustment due to raised bite
143
What are the two causes of contraction porosity when finishing denture?
1. Lack of pressure on the acrylic resin when clamping flasks
2. Not enough resin filling mould
144
What is a clinical sign of contraction porosity in a newly made denture?
Small holes throughout acrylic denture
145
What is the cause of gaseous porosity when processing final denture?
Wrong curing cycle, too rapid heating when processing denture so mono or boils and porosity shows in the thickest part of the denture.
146
What can happen if alginate impressions are left in the sterilising solution for a prolonged period of time?
Imbibition (swelling by absorption of water)
147
What happens if the alginate impression is not kept in a sealed bag with wet napkins?
Syneresis (shrinkage)
148
What impression material is used for removable pros?
Alginate
149
What impression material is used for fixed pros?
Silicones (addition and condensation silicones- addition is more accurate detail)
150
What is the willis bite gauge used for?
Recording the OVD
151
What is the fox’s guide plane used for?
For determining a level of occlusal plane
152
Can an indication of when flat cusped teeth may be used?
When the patients bite is non reproducible
153
Is it better to have a thick or thin soft lining and why?
Thin soft lining, if really thick this may weaken the denture as more acrylic will have to be removed to accommodate for the soft lining.
154
What are the indications for rebasing a denture?
1. The denture is loose fitting
2. The teeth are not worn and are in good condition
155
Why is a closed bite technique used when taking a wash impression?
To avoid occlusal errors such as an open bite
156
Term used to describe the change in length of a specimen
Strain
157
What term describes, elongation of a specimen
Tensile
158
What term describes force used to flatten a cylinder
Compressive
159
Term that describes the hardness of a material
Hardness/ plastic deformation
160
Term that describes a force applied to a mid beam to fracture it
Flexural
161
Term that describes a force applied to a mid beam to fracture it
Flexural
