Restorative Flashcards
(169 cards)
1
Q
What are the steps in immediate treatment of traumatised 12 and 11. 12 is completely missing crown and has sub alveolar fracture, 11 has pulpal exposure greater than 2mm. Both are sensitive.
A
Trauma sticker
Apply LA and dam
Clean with water
Remove 2mm of pulp with high speed (whole width)
Place saline cotton wool over exposure until
haemostasis achieved (if not proceed with full coronal pulpotomy)
Apply CaOH the vitrebond
-> restore with composite
2
Q
What makes a tooth with sub-alveolar fracture unrestorable?
A
Not enough coronal dentine to retain a crown/indirect restoration
Moisture control is impossible
Cannot take impression for indirect restoration
Difficult to clean
Cannot establish marginal integrity
3
Q
What can be done to replace an anterior tooth following extraction?
A
Bridge
Implant
Partial denture
4
Q
If a patients anterior bridge has de-bonded, what is the likely design of the bridge?
A
Adhesive fixed-fixed
5
Q
Bridge de-bonded on abutment tooth 12 but not on abutment tooth 21. The de-bonded wing on the 12 became a plaque trap leading to caries and ultimately causing pain. Name a better alternative bridge design for this patient and explain why your design would be better?
A
Adhesive cantilever
-> not affected by divergent guide paths
-> would come out and not trap plaque
6
Q
What can cause a bridge to de-bond?
A
Heavy/unfavourable occlusal forces
Lack of moisture control during bonding
Parafunction
Trauma
7
Q
What components in CoCr provide tooth support?
A
Occlusal rests
Cingulum rests
8
Q
What are the different Kennedy classifications?
A
Class 1- bilateral free end
Class 2- Unilateral free end
Class 3- unilateral bounded
Class 4- anterior bounded crossing midline
Most posterior saddle used, extra saddles are classified as modification
9
Q
What else can rest seats be used for instead of support ?
A
Indirect retention
Bracing and reciprocation
10
Q
What are the different types of clasps?
A
Gingival approaching
-> T, roach T, I bar
Occlusally approaching
-> Ring
11
Q
Why may there be areas of mucosa relieved by framework in an RPD?
A
Less mucosal covergae
Easier cleaning
12
Q
A patient attends with radiolucencies present from 32-42 which are all endodontically treated and have post and core. What are the treatment options?
A
Extraction
Periradicular surgery
Re-RCT
13
Q
What are the criteria for valid consent?
A
Informed
Voluntary
Not coerced
Not manipulated
With Capacity
14
Q
What things should you tell the patient before proceeding with treatment?
A
What the treatment is and what it involves
The risks of the treatment
The benefits of the treatment
Alternative options
Risks of no treatment
Cost of treatment
Your recommended option
15
Q
What are the restorative options for a 26 which has a fractured MOD amalgam and has been root treated?
A
MCC
Onlay with cuspal coverage
16
Q
What are the restorative options for a 26 which has a fractured MOD amalgam and has been root treated?
A
MCC
Onlay with cuspal coverage
17
Q
What do you do if GP has been exposed in the mouth for more than 6 months?
A
Re-RCT as GP has been exposed to oral environment for more than 3 months
18
Q
What is a Nayyar core?
A
Retention is obtained from undercuts in canals and pulp chamber
2-4mm of GP is removed and replaced with amalgam
19
Q
What materials can bond amalgam to tooth?
A
GIC
RMGIC
20
Q
What are the types of tooth wear?
A
Attrition
Abrasion
Abfraction
Erosion
21
Q
What are the different scores in the BEWE classification?
A
0= No erosive wear
1= Initial loss of surface texture
2= Distinct defect-hard tissue loss <50% of surface
3= Hard tissue loss >50% of the surface area
22
Q
What can be used to desensitise a tooth?
A
DBA
FV
Densitising toothpaste
Tooth mouse
23
Q
What is the Dahl technique?
A
Using restorations or appliance to create space for restorations in areas of localised tooth wear
24
Q
How does the Dahl technique work?
A
Propping occlusions open anteriorly with a bite plane/composite build up creating posterior disocclusion to allow over-eruption
*Anteriors should intrude slightly
-> can increase OVD by 2-3mm
25
What are 4 contraindications for use of Dahl technique?
Active Perio
TMD
If existing conventional bridges present
If implants present
If patient on bisphosphonates
Post orthodontics
26
What are the constituents of composite?
Glass filler particles- quartz, mircofine silica
Monomer- BIS-GMA
Photointiator- Camphorquinone
Low weight dimethacrylates- TEGDMA
Silane coupling agent
27
Why is RMGIC preferred instead of composite in cervical abrasion cavities?
Lower modulus, more flexible than composite in this situation
-> better retention
Easier moisture control
28
What factors would influence your choice of treatment for traumatic exposure of pulp?
Time since exposure- if less than 24 hours
Size of exposure- <1mm
29
How would you treat an exposed pulp in practice?
Partial or complete pulpotomy
30
When irrigating with sodium hypochlorite what are the causes of extrusion?
Using excessive pressure- >1ml/15 secs
Needle locking in canal
Loss of control of working length
Larger apical diameter
31
What are the steps of immediate management of sodium hypochlorite extrusion?
Stop treatment
Inform patient- reassure them
If pain present- LA block to affected area
Observe Haemostasis
Place odontopaste in canal (contains a steroid)
Seal coronal access cavity
32
What would your action be after that?
Cold compresses during the first few days- reduce swelling
Warm compresses for resolution of the soft tissue swelling and elimination of the hematoma
Analgesics (Ibuprofen 400-600mg QDS/Paracetamol 1000mg QDS)
Review within 24 hr
Prescription of antibiotics (case specific)- prevent secondary infection
Refer if severe
33
How would you prevent a sodium hypochlorite extrusion from occurring?
Depress plunger on syringe with index finger
Use side vented needle
Securely attach luer lok needle to 3ml syringe
Set silicone stop on needle ar 2mm less than working length
Ensure all syringes are labelled
Use dental dam with oral-seal if required
-> test with CHX
Ensure needle does not bind in canal
Pre-op radiographic assessment- ensure no open apices
34
What stage would you expect to use greenstick on posterior saddles?
Master imps
35
What are the components of compound (green stick)?
Wax
Resin
Stearic acid
36
What are the components of alginate?
Sodium alginate
Calcium sulphate
Trisodium phosphate
Filler
Modifiers, flavouring, chemical initiators
37
What are the options to replace central incisor fractured off to root completely at short notice ?
Adhesive bridge
Vacuum formed splint with tooth
Provisional over denture
Provisional post crown
38
What are the different post materials?
Stainless Steel
Fibre- glass, quartz, carbon
Gold
Titanium
Ceramic- alumina, zirconia
39
What are the indications for post size?
Minimum 1:1 post length/crown length ratio
At least half of post length into root
Post should be no more than 1/3 of root width at narrowest point with 1mm of remaining circumferential dentine
Ferrule- 1.5mm in height and width of coronal dentine
40
How are posts cemented?
41
How can posts be removed?
- Ultrasonics
- Masseran Kit
- Eggler post remover
- Moskito forceps
- Stieglitz forceps
- Sliding hammer
42
What are the signs of erosion?
Cupping on occlusal and incisal surfaces
Translucency of incisal edges
Lack of staining
Composite/amalgam restorations sit proud of tooth
Base of lesions is out of contact with opposing tooth
43
What are the causes of erosion?
- Intrinsic- GORD, bulimia, vomiting, xerostomia, hiatus hernia
- Extrinsic- carbonated drinks, alcoholic drinks, asthma inhalers, sport gels, habits- swilling drinks, vegan diet
44
How is erosion managed?
- Fluoride supplementation
- Dietary management- less acidic foods, less snacking
- Desensitising toothpastes
- Habit changes- avoid swilling drinks in mouth, drink through straw
- Control gastric acid- Gaviscon, PPIs, H2 blockers
- Referral for help with eating disorders
45
What factors does an implantologist consider before placing an implant?
Smoking status
Amount of bone- 10mm of healthy bone
Periodontal condition
Occlusion
Will graft will be required
Aesthetics
Age
Distance between
Soft and hard tissue defects
46
What are the alternatives to implants for a space?
Bridge
RPD
Do nothing
47
How can you check a bridge has debonded?
Visual inspection
Mobility
Probe
Floss
Push and check for air bubbles
48
What factors should be taken into account before placing a bridge?
Aesthetics
Occlusion
Length of span
If tooth had been prepared
Material to use
Abutment teeth condition
OH
49
What are the alternatives to bridges?
No treatment
RPDs
Implants
Overdentures
50
What are the treatment options with a patient who has congenitally missing 22 and 23?
Implants
Bridge
RPD
Orthodontics (combined with restorative)
51
What are the aesthetic and functional issues with congenitally missing teeth?
Aesthetic
- Teasing
- Self consciousness/psychological issues
- Awkward spacing- difficult to fill with prostheses
Function
- Difficulty eating
- Difficulty speaking
- Over eruption of opposite teeth
52
What would a dentist check before referring a patient for implants?
For Periodontal disease
Smoking
Diabetes
OP
Bisphosphonates
Blood clotting disorder
53
What local features would an implantologist check?
Quality of bone
Proximity to nearby anatomical structures
OH
Position of existing teeth
54
What are the signs and symptoms of reversible pulpitis?
Pain is not spontaneous- lasts for a few seconds when stimulated
Pain to cold and sweet
Responds to sensibility testing
No radiographic changes
55
How is reversible pulpitis managed?
Remove caries or deep restoration
56
What are the signs and symptoms of irreversible pulpitis?
Sharp pain on thermal stimuli
-> can linger for 30secs
Spontaneous pain
Referred pain/poor localisation
Accentuated by postural changes
OTC drugs are ineffective
Kept up at night
Non-TTP- hasn't reached periodontal tissues yet
57
How is irreversible pulpitis managed?
RCT
Extraction
58
What are 5 causes of transient sensitivity to thermal stimuli and pain on biting following replacement of amalgam filling with composite?
Deep restoration with no lining
High in occlusion
Uncured resin irritating the pulp
Polymerisation contraction stress
Tooth preparation has irritated the pulp
59
How can transient sensitivity and pain on biting after composite placement be prevented?
Reduce polymerisation contraction stress
-> Place composite in increments less than 2mm to allow for complete curing
-> Place increments touching as little amount of surfaces as possible (low configuration factor)
Place lining material- RMGIC, flowable
Check occlusion after completing restoration with articulating paper
Use FV- 22600ppm
Use desensitising toothpaste
Use water with high speed when preparing
-> consider excavator for deep caries
60
How does local anaesthetic work?
Prevents propagation of neural signals (action potentials) through blockage of voltage gated sodium channels
61
What nerve fibres are most susceptible to LA?
Ad-> C-> Ab-> Aa
62
What are the amide anaesthetics?
Lidocaine
Articaine
Prilocaine
63
What are the ester anaesthetics?
Procaine
Cocaine
Benzocaine
64
What are the components of a cartridge of anaesthetic?
Anaesthetic agent- base hydrochloride
Vasoconstrictor
Fungicide
Propyl parabéns
Sodium metasulphite/bisulphite
65
What is the max dose of lidocaine?
5mg/kg
66
What are the characteristics of an ideal post?
Non threaded (passive)
Non-tapered (parallell)- avoids wedging
Cement retained
67
What are the factors which we assess to see if a tooth would be suitable for a post?
Ratio of crown to post should be 1:1
Ratio of crown to root should be 1:1.5
4-5mm of root filling present apically
Ferrule present- 1.5mm of coronal dentine present in height and width
Post width- no more than 1/3 of root width at narrowest point and 1 mm of remaining circumferential coronal dentine
Avoid curved canals
68
What are 3 core materials?
Amalgam
Composte
GIC
69
What are the treatment options for large MOD amalgam fractures along both buccal cusps with exposed GP?
Extraction under LA
Onlay
Crown
70
If GP has been exposed for 6 months on tooth with fractured MOD amalgam what would you do?
Remove restoration and perform ReRCT
71
What has greater bond to tooth out of composite and amalgam?
Composite- amalgam does not bond to tooth
72
What are the reasons for debonding of gold post and core?
73
Why does fracture of a post occur at junction of post and core?
If post and core are made of 2 different materials
74
What are the principles of cavity preparation?
1. Identify carious enamel
-> remove to identify maximal extent of lesion at ADJ and smooth margins
2. Remove peripheral caries in dentine from ADJ first then move circumferentially deeper
3. Remove deep caries over pulp
4. Modify outline form
-> Enamel finishing- rounded and smooth (no acute angles)
-> Occlusion
-> Any requirements for restorative material
5. Modify Internal design
-> Smooth/remove internal line and point angles
-> Any requirements for restorative material
CSMA
-> remove unsupported enamel
-> aim for smooth finish
75
What is they hybrid layer?
The layer of dentine which has been conditioned to remove smear layer and into which adhesive resin flows into to produce collagen/resin phase
76
What are the types of dentine and how do they affect bonding?
Primary dentine- laid down during development
-> open tubules which are good for bonding
Secondary dentine- laid down with age
-> ok for bonding
Tertiary Dentine- laid down by odontoblasts (reactionary to mild stimuli/reparative to intense)
-> Poor for bonding due to irregular structure with fewer/sclerosed tubules
77
What is the inorganic content percentage of dentine?
Calcium hydroxyapatite- 70%
78
What is the setting reaction for Amalgam?
Ag3Sn + Hg -> Ag3sn + Ag2Hg3 + Sn7Hg9
Y + Hg= Y + Y1 + Y2
79
What changes have been made to modern amalgam to improve it?
Y2 phase has poor strength and corrosion resistance
-> modern amalgam has high copper (>12%) which has no Y2 phase meaning more corrosion resistance, better strength, less creep, better marginal durability
Use of single composition amalgam
Zinc free- prevents h2 bubbles forming
80
What are the advantages of Amalgam?
Durability
Shorter placement time than composir e
Radiopaque
Colour contrast
Self hardens at mouth temp
Resistance to surface corrosion
Good wear resistance
Good bulk strength
81
What are the disadvantages of amalgam?
Potential mercury toxicity
Poor aesthetic
Does not usually bond to tooth
High thermal diffusivity
Requires removal of sound tissue during cavity prep
Lichenoid reactions- T4 hypersentivity
Tooth discolouration
Amalgam tattoos
Creep/Marginal breakdown
82
What're the advantages of using non-Y2 amalgam?
Less corrosion
Less marginal breakdown
Higher early strength
Less creep
83
How is Y2 removed?
Using copper
84
Why was zinc added to amalgam?
Acts as scavenger which preferentially oxidises and removes slag
85
What is the drawback of adding zinc to amalgam?
It interacts with saliva/blood forming h2 bubbles which can cause pressure build up and expansion
86
What are the symptoms a patient may feel from zinc in amalgam?
Expansion causes
-> downward pressure leading to pulpal pain and upward causing restoration to sit proud
87
What criteria must be fulfilled before obdurating?
Tooth must be asymptomatic
Canal must be dried
Chemomechanical instrumentation must have been carried out
88
What are the constituents of GP?
Gutta Percha
Zinc oxide
Plasticisers
Radio-opacifiers
89
What are the functions of a sealer?
Seal space between dentine and cone
Lubricate the canal
Fill voids- in canal, lateral canals, between GP
90
What are examples of common sealers?
Epoxy resin- AH plus
Glass ionomer
ZOE based
Calcium Silicate
91
How would you assess an obturation on a radiograph?
Look at length- should be within 2mm of radiographic apex
Check for voids
Check coronal seal
Check taper
Check GP has been removed to oriface level
Check that you haven't missed canals
92
What are the reasons for obturating?
Creates apical seal/coronal seal
Creates environment suitable for healing
Prevents reinfection- entombs exiting bacteria
93
What are the different methods of obturation?
Cold lateral compaction
Warm vertical compaction
Continuous wave
Carrier based
Thermoplastic injection
94
What percentage of maxillary FPMs have MB2 canal?
93%
95
What are the 3 design objectives of Endodontics?
Create a continously tapering funnel shape
Maintain apical foramen in its original position
Keep apical foramen as small as possible
96
What are the advantages of the crown down technique?
Coronal part has most bacteria
-> remove this first to prevent inoculating bacteria into the apical region
Less impeded file path
97
What are the laws of pulp floor anatomy?
Law of symmetry (excludes maxillary molars)
1. Orifaces of canals are equidistant from line drawn in mesial-distal direction across pulp floor
2. Orifices of the canals lie on a line perpendicular to a line drawn in a mesial-distal direction across the centre of pulp floor
Law of Colour change- colour of the pulp chamber floor is always darker in comparison to the vertical surrounding dentin walls
Law of oriface location:
1. Orifices of the root canals are always located at the junction of the dentin walls and the floor of the pulp chamber.
2. Orifices of the root canals are located at the angles of the junction of dentin wall to the pulpal floor
3. Orifices of the root canals are located at the terminus of the root developmental fusion lines
98
What are the reasons for irrigating?
Remove smear layer
Detachment of biofilm
Dissolution of organic matter
Mechanical process alone does not remove all bacteria
Flushes out debris
Disinfects canal
99
Why is sodium hypochlorite a good irrigant?
Potent antimicrobial activity
Dissolves pulp remnants and collagen
Dissolves necrotic pulp and vital tissue
Helps disrupt smear layer by acting on organic component
100
What strength of NaOCl is used in Endo?
3%
101
What are the other common irrigants?
CHX- 2%
102
What is used to remove the smear layer?
EDTA- 17%
-> chelating agent that exposes collagen
103
What are examples of Intra-canal medicaments?
CaOH- antibacterial (pH 11)
Ledermix- contains steroid/tetracycline used in management of inflamed hot pulps
104
What are the features that make re-fitting of debonded MCC successful?
Quality of tooth tissue
Amount of tooth tissue remaining
Mobility
Periodontal status
Pulp Status
Crown root ratio being favourable
105
What are the differential diagnoses for throbbing pain keeping patient up all night- 37 has caries and 38 is impacted?
Symptomatic Irreversible pulpitis
Periocoronitis
106
What types of bridge could be used to replace missing upper laterals and what abutment teeth would be used?
Resin bonded mesial cantilever
Fixed-Fixed
107
What information is required by technician in order for them to produce a bridge?
Material
Tooth- FDI
Shade
Type of pontic
What teeth are being used as abutments
Bite registration
108
How does clinical presentation of caries compare to radiograph?
Caries is usually deeper clincially
109
What are the advantages of composite over amalgam?
Better aesthetics
Bonds to tooth
Minimal prep required
On demand set
Lower thermal conductivity
Supports remaining tooth structure
110
What are the different types of composite?
Bulk-fill
Hybrid
Syringable
Macro-filled
Micro-filled
Condensible
Flowable
111
What are the disadvantages of composite, how can these be minimised?
Under-polymerised base
-> Place increments smaller than 2mm
Polymerisation shrinkage
-> Place composite in small increments (keep configuration factor low)
Composite insufficiently cured
-> cure for longer than 30 secs
Moisture sensitive
-> use dental dam
Post-op sensitivity
-> use correct technique and bonding
112
What are the indications for resin retained bridge?
Young teeth- Less destructive
Good enamel quality
Large abutment tooth surface area- more space for bonding
Minimal occlusal load
Single tooth replacement
To simplify partial denture design
113
What are the contraindications?
Insufficient or poor quality enamel
Long spans
Excess soft or hard tissue loss- perio
Heavy occlusal force e.g. Bruxist
Poorly aligned, tilted or spaced teeth
Contact sports?
114
How do you cement a porcelain bridge?
Using nexus- dual cure composite resin with Silane coupling agent
-> bonds to oxide groups and makes hydrophilic porcelain surface hydrophobic so it can bond to C=C double bonds in composite cement
115
How do you cement a metal bridge?
Using GIC or RMGIC
116
What is done to surface of porcelain veneer to improve adhesion?
Etched with Hydrofluoric acid
117
When else is a silane coupling agent used for in dentistry?
118
When is use of dual cure cement indicated?
When indirect restoration is thick or opaque and light cure cannot penetrate
119
What is the Shortened dental Arch?
20 healthy units with 3-5 occluding pairs
120
Why is it considered acceptable?
Acceptable matiscatory function
Acceptable aesthetics
Easier OH- less teeth to maintain
Provides sufficient occlusal stability
121
What are the indications for SDA?
Patient does not want denture
Good prognosis of remaining teeth
Missing posteriors with 3-5 occlusal units remaining
Patient unable to afford further treatment
122
What are the contraindications for shortened dental arch?
TMD
Poor prognosis of remaining teeth
Periodontal disease
Pathological tooth wear
Malocclusion
123
How can SDA be extended?
Resin retained bridge
Implant
RPD
124
What are the requirements for occlusal stability?
125
What are the signs of occlusal trauma?
Widening PDL on radiograph
Progressive tooth mobility
Fremitus
Wear facets
Fracture
Migration
Cement tears
Root resorption
126
Describe the appearance of the 4 types of tooth wear?
Attrition- tooth to tooth contact (parafunction)
-> polished facets/flattening of incisal edges and occlusal plane
Erosion- exposure of teeth to acid
-> loss of surface detail, becomes flat and smooth
Abrasion- physical wear due to foreign object repeatedly contacting tooth
-> wear at site exposed to foreign object
Abfraction:
The loss of hard tissue from eccentric occlusal forces leading to compressive and tensile stresses at the cervical fulcrum areas of the tooth
-> Typically appears as loss of tooth substance at cervical margin
127
How can tooth wear be monitored?
Indices- BEWE
Photographs
Study models
128
What % of adults have tooth wear?
60%
129
What are the intrinsic causes of tooth discolouration?
Porphyria
Cystic fibrosis
Loss of vitality- blood products
Fluorosis
Amalgam
Root filling materials
Sickle cell
Hyperbilirubinameia
130
What are the extrinsic causes of tooth discolouration?
Tannins
Smoking
Iron supplements
CHX
Chromogenic bacteria
131
How does vital bleaching with Hydrogen peroxide work?
Hydrogen peroxide is an oxidising agent that breaks down long chain chromogenic compounds into smaller non pigmented compounds
-> also causes ionic exchange in metallic molecules giving lighter colour
132
What is the active ingredient in whitening bleach?
Carbamide peroxide
-> breaks down to form hydrogen peroxide and urea
133
What are 4 risks of vital bleaching?
Sensitivity
Relapse
Allergy
May not work
Restoration don't change in colour
Soft tissue irritation
134
What are the features of a cavity for composite?
Does not require undercuts
Smooth margins
No unsupported enamel
No sharp line angles
Beveled Cavo-surface margin angle- increase bonding area
135
What techniques are used to successfully placed composite?
Etch enamel- 10 secs
Etch Enamel and dentine- 10 secs
Apply DBA- primes surface for bonding
Put flowable at base- reduce contraction stress and achieve optimal adaption to non-load bearing margins
Place composite in increments that are touching as few surfaces as possible
-> Lowers configuration factor
Place increments <2mm so that adequate curing can occur
Warm composite- mediates contraction stresses
136
What are the features of a cavity prep for amalgam?
Undercuts required- retention and resistance form
CSMA- 90 degrees for butt joint finish
Add grooves, isthmus, dove tails for retention
Must be at least 2mm deep
No unsupported enamel
137
How would you find out the aetiology of a discoloured tooth that has been previously traumatised but is non-sensitive or symptomatic? What special investigations would you do?
Aetiology:
History- ask about trauma
Examination
Investigations:
Sensibility testing
PA radiograph
138
Treatment options for discolouration?
Accept/monitor
Veneer- composite/porcelain
Microabrasion
Bleaching- V/NV
Crown
139
What are some features of design and preparation that may lead to a bridge debonding?
Unfavourable Occlusion
Parafunction
Poor abutment teeth health
Poor crown-root ratio
Over-tapered prep (no parallelism)
140
What are the alternative options to a conventional fixed fixed bridge with 2 prepped abutments?
141
What are the reasons for debonded post and core?
Moisture contamination on cementation
Using incorrect cement
142
What are the reasons for cores fracturing from posts?
143
What are the complications that can occur when using a stainless steel file in a canal with 20 degree curve?
Perforation
Instrument seperation/fracture
Ledge creation
Zipping
144
What is the protaper sequence for shaping and cleaning a canal to 0.25mm?
Before working length calculated: 10k, 15k, S1, Sx
After working length is calculated: 10k, 15k, S1, S2, F1, F2
145
What are the landmarks for an inferior alveolar nerve block?
Coronoid notch
Posterior border of ramus
Pterygomandibular raphe
Contralateral premolars
146
What are the alternative techniques to IAN?
Akinosi
Gow-gates
147
How do you manage patient if you accidentally inject into parotid gland?
Inform patient
Reassure patient that palsy is temporary and will last a few hours
Put eye patch on affected eye to prevent any dust causing damage
Review in 24 hrs
148
What are the reasons for instrumentation of root canal?
Removal of infected tissue
Allows delivery of irrigants to apex
Shape canal
Creates shape for obturation
149
What advantages does protaper have over K files
Increased flexibility in larger sizes and tapers
Increased cutting efficiency
If used appropriately good safety in use
Can be more user friendly with less instruments and simple sequences
Shape memory
Super-elasticity
150
What are the rotary Endodontics systems?
Reciproc
Protaper Gold
151
What are the types of motion files can do?
Filing
Reaming
WW- back and forward oscillation of 30-60* with light apical pressure
Balanced force- quarter turn clockwise, half turn counter clockwise
152
What are the reasons for file separation?
Curved canal with non-flexible instrument
Lack of straight line access
Cyclic fatigue- flexural stress
Torsional fatigue
153
What are the parts of Posselt's envelope?
ICP- maximum interdigitation
E- edge to edge position of incisor
Pr- maximum protrusion
T- Maximum opening
R- retruded axis position
RCP- retruded contact position
154
What is RCP?
First tooth contact when mandible is in retruded axis position
-> reproducible
155
What is Hanau's Quint?
5 variables that affect occlusal contacts:
1. Occlusal plane
2. Condylar distance
3. Incisal Guidance
4. Cuspal angle
5. Compensating curve
156
What is the thickness of shim stock?
8 Microns
157
What is the average Biologic Width?
2mm
158
If patient says they have had GP exposed in the mouth for 6 months what does that mean for your treatment?
You must re-RCT if it has been longer than 3 months
159
How can overhangs on Amalgam be avoided?
Correct adaption of matrix band
Use of wedge
Adequate condensing of amalgam
160
What issues can occur due to overhangs?
Difficulty cleaning
Food packing
Periodontal disease
Secondary caries
161
How can you manage overhang?
Use finshing strip
Replace restoration
162
What are the functions of Facebow?
Records intercondylar distance
Records terminal hinge axis
163
What are the different types of articulator?
Simple hinge
Average value
Semi-adjustable
Fully adjustable
164
Why is anterior guidance preferred?
Less stress on musculature
Posterior teeth are not designed to take lateral forces
Less occlusal trauma and undesirable tooth movements
165
What are the principles of Crown Preparation?
1. Preserve tooth structure
2. Retention and resistance form
3. Structural durability
4. Marginal integrity
5. Preservation of periodontium
6. Aesthetics
166
What are the stages of crown preparation?
Occlusal reduction
Seperation
Buccal reduction
Palatal and lingual reduction
Finishing
167
What are the reductions for an all metal crown?
Functional cusp- 1.5mm
NF- 0.5mm
Finish line- 0.5mm chamfer
168
What are the reductions for MCC?
F- 1.8
NF- 1.3
Finish line- Buccal shoulder 1.3mm, 0.5mm palatal chamfer
169
What are the reductions for an all ceramic?
F- 2mm
NF- 1.5mm
Finish Line- 1-1.5mm chamfer
