Year 4 Flashcards
(166 cards)
1
Q
Describe the physiologic rest position
A
The mandibular position assumed when the head is in an upright unsupported position and the involved muscles are in equilibrium in tonic contraction, and the condyles are in a neutral, unstrained position
2
Q
Describe the rest vertical dimension (RVD)
A
The vertical dimension of the lower face with the mandible in the rest position
3
Q
Describe the occlusal vertical dimension (OVD)
A
The vertical dimension of the lower face with the teeth in centric occlusion
4
Q
Describe the freeway space
A
Difference between RVD and OVD, usually 2-4mm at the incisors
5
Q
Describe the retruded contact position (RCP)
A
The relation of the mandible to the maxilla with the mandible in its most retruded position at a prescribed occlusal vertical dimension
6
Q
Describe intercuspal position (ICP)
A
The mandibular position that gives maximum tooth contact
7
Q
5 factors required for balanced articulation (Hanau’s Quintet)
A
Condylar guidance
Incisal guidance
Cuspal angles
Plane of occlusion
Compensating curves
8
Q
2 physical effects of tooth loss
A
Impacts appearance
Impacts function of speech and mastication
9
Q
1 emotional effect of tooth loss
A
Decreased self confidence
10
Q
4 things to assess when assessing the edentulous patient
A
Soft tissues
Alveolar ridges
Salvia
Hard tissues
11
Q
6 stages in the provision of complete denture
A
Patient history and assessment
Preliminary impressions
Master impressions
Wax registration
Wax try-in
Insertion
Review
12
Q
3 features of alveolar ridges to assess
A
Shape
Firm or flabby
Sensitive or comfortable
13
Q
What modification does sensitive or mobile ridges require
A
Modified impression technique
14
Q
What modification do sharp ridges/ prominent mylohyoid ridges require
A
Provision of relief
15
Q
Define denture stability
A
Quality of a denture to be firm, steady, constant and resist displacement by functional forces
16
Q
Define denture retention
A
Resistance of a denture to removal from the denture bearing tissues in a vertical direction
17
Q
Define denture support
A
Resistance of a denture to occlusally-directed forces, determined by the form and consistency of the denture-bearing tissues
18
Q
3 factors that contribute to loose dentures
A
Lack of stability
Lack of retention
Lack of support
19
Q
2 features likely to give good denture stability
A
Adequate firm, bony support
Well-formed ridges
20
Q
Describe the ideal relationship between retentive and displacing forces for denture stability
A
Retentive forces should be greater than displacing forces
21
Q
2 factors retention depends on
A
Acquired muscular control
Physical forces of retention
22
Q
Describe acquired muscular control
A
Control with lips, cheeks and tongue (via polished surfaces) and by the muscles of mastication (via occlusal surfaces of teeth)
23
Q
5 features of dentures that improve acquired muscular control
A
Correct extension
Correctly contoured polished surfaces
Lower teeth placed on top of alveolar ridge in the neutral zone
Level of lower occlusal plane below level of resting tongue
Correct occlusal relationships
24
Q
Describe the physical forces of retention
A
Adhesion and cohesion of saliva between mucosa and acrylic producing a negative pressure to cause retention
25
3 features of denture impressions that improve physical forces of retention
Accurate impression
Border-moulded impression with effective post-dam
Correctly extended impressions
26
4 displacing forces for dentures
Lip and cheek muscles
Tongue
Occlusal interferences
Viscous and sticky foods
27
Define the neutral zone
That area where the forces between the tongue and cheeks or lips are equal
28
Define the land area
Space behind last tooth on the retromolar pad for tongue to spread over
29
Describe how muscular balance is achieved
Setting the lower teeth on top of the lower ridge
30
Size of the average upper denture bearing area
24cm2
31
Size of the average lower denture bearing area
14cm2
32
2 features of good complete denture impressions
Cover the maximum possible denture-supporting area
Close contact with the underlying mucosa
33
Describe the 3 features a correctly extended complete upper denture impression should include
Tuberosities into hamular notch
Full functional depth and width of buccal and labial sulci
Non-moving junction of hard and soft palate
34
Describe the 2 features a correctly extended complete lower denture impression should include
At least 2/3 of the retromolar pad
Full functional depth and width of buccal, labial and lingual sulci
35
Ideal impression material for complete preliminary impressions
Impression compound
36
4 impression compound properties
Mucocompressive
Supports itself beyond the tray
Poor surface detail
Rigid
37
3 complete preliminary impression materials
Impression compound
Silicone putty
Alginate
38
Describe special impression trays
Custom made impression trays by the lab in acrylic used for taking master impressions
39
Describe why special trays are extending 2mm short of maximum denture bearing area
Allow space for impression material and border moulding
40
3 features of special impression trays
Rigid and dimensionally stable
Incorporated handle to avoid interference with lip
Incorporated finger rests for lowers to avoid displacing cheeks
41
Correct wax spacer for ZnO/Eugenol master impressions
0.5 mm
42
Correct wax spacer for PVS master impressions
1.5 mm
43
Correct wax spacer for alginate master impressions
3 mm
44
2 reasons why is greenstick used
Obtain correct functionally border moulded extension
Correct any area of under extension
45
4 areas greenstick should be added
Post dam
Hamular notches
Lingual pouches of lower
Posterior buccal sulci
46
3 complete master impression materials
Zinc-oxide eugenol
Polyvinylsiloxane if undercuts
Plaster of Paris
47
4 properties of zinc-oxide eugenol
Gradual set, to allow border moulding
Good surface detail
Dimensionally stable
Potentially causes burning sensation
48
Describe the master impression technique for grossly resorbed lower alveolar ridges
Take impression with red compound / green compound mixture (50:50 ratio) in special tray and carefully border mould then a ‘wash’ impression using paste or PVS
49
Describe the gag reflex
Muscular contraction of the back of the throat, evoked by either touching the roof of the mouth or psychogenic stimuli, mediated by the autonomic nervous system
50
3 management strategies for the gag reflex
Good communication
Minimise presence of physical stimulus
Divert patient’s attention
51
3 denture faults causing gagging
Loose upper denture
Overextension at post dam
Excess occlusal vertical dimension
52
2 functional differences between artificial and natural dentition
Natural dentition greater biting force x5
Artificial dentition less efficient chewing x6 number of chewing strokes
53
Why is RCP used when designing complete denture occlusion
ICP is non-existent
54
Occlusal scheme of choice for complete dentures
Bilateral balanced articulation occlusal set up
55
Define bilateral balanced articulation occlusal set up
Bilateral simultaneous contact of teeth in RCP and during excursions
56
4 reasons why balanced articulation is important
Increases denture stability
Distributes the occlusal load over the whole denture bearing area
Enhances masticatory function
Enhances aesthetics
57
3 advantages of using RCP
It is reproducible
Patients easily accommodate to it
Allows a set up in balanced articulation
58
Define compensating curve
Introduction of a curve to the occlusal plane antero-posteriorly
59
Function of introducing compensating curves
Maintains cuspal contact during excursions
60
2 aims of wax registration
Provide a template for tooth position and occlusal planes
Record the desired jaw relationship
61
How is the correct lip support of a denture achieved
Correct anterior placement of incisors
62
Describe the correct anterior placement of incisors
Positioned up to 1cm ahead of incisal papilla and inclined to give 90° columella-philtrum angle
63
How much of incisor height should be shown at rest and when smiling
1 or 2 mms below lip at rest
Nearly all the crown when smiling
64
Describe where the lower occlusal plane should be positioned
Below the resting level of the tongue, runs into the retromolar pad about half way up
65
Why is it important to have correct lower occlusal plane
Allows the occlusal forces applied to the dentures to be perpendicular to the alveolar ridges which improves stability
66
Equipment used to help guide the anterior and posterior occlusal plane
Fox’s occlusal plane indicator
67
What should the anterior occlusal plane be parallel to
Interpupillary plane
68
What should the posterior occlusal plane be parallel to
Ala-tragal line through tragus of the ear to lower border of ala of nose
69
2 pieces of equipment used to measure RCP
Willis bite gauge
Callipers
70
4 methods to used to help record retruded position
Tongue retrusion and gentle guiding
Swallowing
Fatigue muscles that protrude mandible
Gothic arch tracing
71
Describe 2 problems associated with a decreased OVD
Poor appearance as patient is overclosed
Increased predisposition to angular chellitus
72
Describe 4 problems associated with an increased OVD
Patient is overopen, poor aesthetics
Discomfort in facial musculature as no rest from tooth contact
Trauma and pain in denture bearing tissue
Clicking of teeth during speech
73
2 materials for recording RVD
Zinc oxide eugenol paste
Silicone paste
74
5 things to be checked when examining trial dentures on an articulator
Waxed up to full extension and well adapted
Polished surfaces correctly shaped
Tooth position satisfactory
Centric occlusion
Balanced articulation
75
2 things to be checked when examining trial dentures in the mouth
Upper anterior tooth position
Jaw relationship
76
3 things to assess jaw relationship of trial dentures
Check even contact into ICP at RCP
Antero-posterior component
Vertical component
77
Describe how to correct errors in upper anterior tooth position
Move 1-2 teeth as guide chair-side
Mark new centre line
78
3 causes of antero-posterior jaw relationship errors
Registration rims not in correct RCP at recording time
Error in mounting rims on articulator
Distortion of base plates of rims
79
Describe how to correct errors in jaw relationship
Minor error can be accepted and modify occlusion at insertion
Obvious errors require re-registeration to re-articulate casts on articulator and reset teeth for re-try
80
Describe how major errors in A-P are corrected
Corrected at the re-registration by trimming the wax on the lower
81
Describe how errors in OVD are corrected in lab
Over-open: articulator pin raised by appropriate amount and teeth reset
Over-closed: articulator pin dropped by appropriate amount and teeth reset
82
Define the posterior palatal seal
Raised portion of the denture base at the posterior of the upper fitting surface
83
What is the importance of the posterior palatal seal
Maximises the peripheral seal and retention of the upper denture
84
Describe the process of indicating placement of posterior palatal seal
Palpated with round ended burnisher after accepting trial denture
Marked by scoring study model with round-ended instrument
85
2 ideal design features of posterior palatal seal
Broad
Rounded
86
Describe the method of creating a functional post-dam when posterior seal inadequate at insertion
Use chemically activated acrylic (BMA + PEMA) chairside
Wash impression taken
Request post-dam replaced in laboratory
87
Define an articulator
A mechanical device that represents the temporomandibular joint and jaw members
88
4 advantages of using articulated dental casts
Better visibility
Allows lingual view
Time saving at chairside
Allows refinement of occlusion
89
4 classifications of articulators
Class I: simple hinge
Class II: average value
Class III: semi-adjustable
Class IV: fully adjustable
90
2 features of a plane line articulator
Not capable of eccentric movement
Can only relate casts in one static position
91
4 features of average value articulators
Based on average facial measurements
Allows a balanced articulation set up
Do not usually accept a facebow
Limited for replicating mandibular movement
92
2 features of semi-adjustable articulators
Face bow record required
Allows customisation of condylar and incisal guidance
93
Describe the 2 types of semi-adjustable articulator
Arcon: condylar element on lower member
Non-arcon: condyle on upper member
94
4 disadvantages of using articulated dental casts
Potential inaccuracy in casts
Potential for error in mounting of casts
Potential for error in record of occlusal / jaw relationships
Limited ability of rigid articulator tracks to reproduce patients mandibular movements
95
Describe a single complete denture
Complete denture that occludes against some or all of the natural teeth
96
2 complications when providing a single complete denture
High occlusal forces on the underlying edentulous tissues from the opposing natural teeth
Unharmonious occlusal plane due to position of natural teeth
97
Why is a single denture more likely to fracture at the midline
Combination of occlusal stress and position of opposing teeth
98
Describe the cause of an anterior flabby ridge
Repeated occlusal trauma causing rapid, gross bone resorption due to a complete denture opposed by natural anterior teeth
99
Problem with maxillary complete denture opposing natural anterior teeth
Require lower posterior teeth to contact upper complete denture to help keep it in place
100
Problem with mandibular complete denture opposing natural teeth
Relatively small denture supporting tissue and thin mucosa and submucosa overlying the bone of the lower residual ridge means that underlying bone is extremely prone to resorption
101
3 methods of overcoming problems associated with the single complete denture
Replace opposing missing posterior teeth
Ensure all steps in denture construction are completed correctly
Improve the occlusal plane of the natural teeth in the opposing arch by extracting teeth, reducing the height of enamel or crowning teeth
102
3 stages in the insertion of complete dentures
Adjustment of fit surface
Occlusal adjustment
Instructions and aftercare
103
2 potential adjustments of fit surface at insertion
Smoothing of processing defects
Reduction of areas of pressure
104
Reasons for occlusal errors at insertion
Changes in tooth position during processing of acrylic
Errors not detected at trial
105
3 methods of correcting of occlusal errors
Split cast remount technique to correct processing / flasking errors
Occlusal adjustment at chairside
Occlusal adjustment in laboratory following completion of a new pre-centric check record of RCP
106
Define a pre-centric check record and why it is completed
Record of RCP on the terminal hinge axis
Reduces post-insertion discomfort and patient visits
107
Describe the method of conducting a pre-centric check record
Place two thicknesses of wax onto lower posteriors, soften wax evenly
Have mandible close in RCP until teeth indent the wax
108
Describe occlusal correction of complete dentures by selective grinding
Use articulating paper
Reduce cuspal inclines and deepen fossae rather than shorten cusps where possible
109
Describe upper and lower reductions necessary to prevent premature contact in RCP
Reduce palatal upper
Reduce buccal lower
110
Describe upper and lower reductions necessary to prevent premature contact in lateral excursions
Reduce buccal upper
Reduce lingual lower
111
Describe upper and lower reductions necessary to prevent premature contact on anterior teeth in protrusive excursion
Reduce palatal incisal edge upper
Reduce labial incisal edge lower
112
Describe upper and lower reductions necessary to prevent premature contact on posterior teeth
Grind distal facing slopes of maxillary buccal cusps
Grind mesial facing slopes of mandibular lingual cusps
113
4 requirements of denture cleansers
Non-toxic, easy to remove, leave no trace of irritant material
Ability to attack or dissolve organic and inorganic portions of denture deposits
Harmless to all materials used in denture construction
Bactericidal and fungicidal
114
Describe 4 methods of rehabilitating of soft tissues when providing new dentures
Correct fit surface faults
Ease pressure spots
Reduce overextension
Instruct patient on denture hygiene
115
Describe 1 method of rehabilitating patients with overclosure and protrusion associated with worn dentures when providing new dentures
Use occlusal pivots to allow smooth adaptation to changes in OVD
116
Describe when duplication of dentures is indicated
For patients requiring replacement complete dentures which have been well designed and previously successful to allow for good neuromuscular continuity
117
4 requirements to facilitate duplicate dentures to be constructed
Satisfactory aesthetics or easily modified
Satisfactory occlusion or easily modified
Adequate extension or easily modified
Adequate OVD or easily modified
118
4 pathologies associated with complete dentures
Direct mechanical trauma
Denture-induced hyperplasia
Denture-induced stomatitis
Angular cheilitis
119
2 denture related causes of traumatic ulcers
Overextended borders
Unbalanced occlusion
120
Management of denture related traumatic ulcers
Denture reduction and correction of pressure areas
121
Denture related causes of hyperplasia
Trauma caused by over-extension or occlusal errors of poorly fitting denture
122
Define denture-induced hyperplasia
Raised areas composed of dense fibrous tissue and related to the periphery or fitting surface
123
Describe the locations where denture-induced hyperplasia lesions are usually found
Anterior labial or buccal sulci
124
Management of denture-induced hyperplasia
Grind periphery to relieve
Improve fit, use tissue conditioner
Leave denture out as much as possible whilst healing occurs
Surgical excision inadequate resolution
125
Define denture-induced stomatitis
Chronic inflammatory response of the denture-bearing mucosa to harmful stimuli
126
Describe the location where denture-induced stomatitis lesions are usually found
Beneath an upper complete denture
127
Describe Newtons classification of denture-induced stomatitis
Type I: pinpoint hyperaemia
Type II: diffuse erythema of denture bearing area
Type III: papillary hyperplasia, can be drug induced
128
6 causes of denture induced stomatitis
Continuous denture wear
Poor denture hygiene
Direct trauma from fit surface
Candida albicans infection
Poor salivary secretions
Allergy
129
3 problems untreated denture induced stomatitis can cause
Poor fit of dentures
Tissue hyperplasia
Systemic candidal involvement
130
Management of denture induced stomatitis
Leave denture out at night
Tissue conditioners
Reduce denture areas causing trauma
Antifungals
131
Define angular cheilitis
Infection of commissures of mouth, broken skin and erythema by Candida albicans and Staphylococcus aureus
132
3 predispositions to angular cheilitis
Iron / vitamin B12 / folate deficiency
Adjunctive antibiotic therapy
Immunological deficiency
133
Management of angular cheilitis
Antifungals
Hydrocortisone
134
4 conditions complicating complete denture prosthodontics
Enlarged tuberosities
Prominent mylohyoid ridges
Tori
Prominent frenal attachments
135
Describe improvements that can be made by denture reline and rebase
Improve the fit of the dentures and a moderate amount of extension
136
Define denture rebase
Laboratory replacement of the majority of the denture base following clinical impressions of the fit surface
137
3 indications for denture rebase
Residual ridge resorption
Gross alveolar resorption 3-6 months after insertion
Construction of new dentures may cause physical or mental stress
138
5 requirements for denture rebase
Denture base extension adequate
Aesthetics satisfactory
Occlusion correct
OVD satisfactory
Speech satisfactory
139
Method for rebasing dentures
Correct areas of over/under extension
Remove undercut areas from dentures
Make relief holes in anterior palate of upper
Take closed mouth impression with zinc-oxide eugenol or polyvinylsiloxane
140
Define denture reline
Reshaping the underside of a denture as a temporary solution to improve denture fit using hard or soft materials
141
3 indications for denture reline
Improves denture fit
Treat pathology: denture-induced trauma, denture-induced stomatitis / denture-induced hyperplasia
Aid to diagnosis
142
Describe the material and indication for a resilent liner soft reline
Soft elastic material which absorbs occlusal load and reduces pressure on the tissues to help relieve persistent pain
143
Describe the material and indication for a hard reline
PBMA monomer to improve looseness before a rebase is performed
144
Describe the material and indication for a tissue conditioner soft reline
Soft seudo-elastic material that flows under pressure, applied to a denture to allow a more even distribution of forces and improved fit
145
5 causes of denture base fractures
Trauma: dropped, high occlusal forces
Alveolar resorption due to poor fit
Inaccurate impression due to poor fit
Inadequate relief that rocks on bony palatal torus
Warping due to recurring during repairs, rebase
146
Describe the process for repairing a denture
Denture temporarily fixed in position with wax
Technician pours a temporary model and cut key to add repair acrylic
Technician mixes PMMA and applies it into the key to repair denture
147
Process for adding of teeth to existing denture
Take impression with denture in mouth for model fabrication
New acrylic tooth placed and held in position with plaster index
Laboratory uses chemically- cured acrylic to fix tooth in place to existing denture
148
Define immediate dentures
Denture constructed before the extraction of the teeth which it replaces and inserted immediately after the teeth are extracted
149
4 advantages of immediate dentures
No edentulous period
Duplicate tooth position closely for good aesthetic and functional result
Tongue change prevented
Sockets protected
150
2 disadvantages of immediate dentures
Additional time and expense as lose fit quickly, rebase/remake required sooner
Not possible for multiple extractions
151
Define overdentures
Removable prosthesis that completely encloses one or more teeth (or roots) or implants beneath its fitting surface
152
6 benefits of retaining teeth for overdentures
Preservation of alveolar bone
Greater surface area to transmit forces to bone
Improved retention directly from remaining tooth substance or use of precision attachments
Improved stability
Improved masticatory function
Increased patient acceptance
153
4 disadvantages of overdentures
Periodontal risk factor
Caries risk factor
Greater bulk, patient tolerance compromised
Risk of denture fracture where space lacking or heavy occlusal load
154
3 features to examine when providing overdentures
Periodontal disease status
Inter-ridge space on articulated study casts
Potential abutment teeth
155
3 potential abutment preparations when providing overdentures
Coronal reduction to dome shape
Coronal reduction and restoration with endodontics and direct or indirect coverage
Coronal reduction and restoration with endodontics and copings with precision attachment
156
Advantage of precision attachments for overdentures
Aid retention from the root
157
4 disadvantages of precision attachments for overdentures
Expensive
Difficult maintenance
Higher loading of teeth
Caries around attachment
158
3 methods of preventing of problems with overdentures
OHI
Dietary advice
Topical fluorides
159
Define dental implants
A titanium screw surgically placed into alveolar bone which acts as a root to support crowns, bridges or dentures to replace one or more missing teeth
160
3 indications for dental implants
Hypodontia
Severe trauma
Post-oral malignancy
161
5 contraindications to dental implants
Smoker
Diabetic
Osteoporosis
Radiotherapy
Immunodeficiency diseases
162
4 advantages of dental implants
Avoids dentures
Maintains alveolar bone
Avoids conventional bridgework and conserves adjacent tooth tissue
Improves chewing ability
163
4 disadvantages of dental implants
Requires surgery
Lengthy treatment
Requires some level of bone quality and quantity
Expensive
164
Define osseo-intergration
Direct mechanical and functional contact between living bone and implant
165
Describe 4 types of errors caused by registration rims not in correct RCP
Protrusive registration: did not get jaw into its most posterior position
Retrusive registration: pushed lower rim backwards off ridge
Lateral registration: protrusive error usually to the side of the operator
Premature contact: uneven contact in RCP
166
2 soft reline materials
Resilent liner
Tissue conditioner
