Endo Flashcards
(238 cards)
1
Q
Checklist for radiographic assessment of root filled tooth
A
Root filing - length, quality, voids
Missed root canals
Shape of canal
Patency
Bone support
Crown to root ratio
Pathology
2
Q
Clinical assessment of root filled tooth checklist
A
Coronal seal
Amount of remaining tooth structure
Is the tooth restorable?
Swelling
Sinus
TTP
Buccal sulcus
Mobility
Increased pocketing
Perio disease
Root fractures
3
Q
Potential problems after a RCT
A
Amount of remaining tooth structure
Lack of or no ferrule
Wide post holes
Endo complications - fractured instruments, perforations, short/long root fillings
4
Q
Do teeth become more brittle after RCT?
A
No
5
Q
What is coronal microleakage?
A
Ingress of oral micro-organisms into the root canal system
6
Q
When should a tooth be re-root treated?
A
Unrestored for 3 months
7
Q
How to help prevent coronal microleakage?
A
After trimming GP to ACJ, place RMGIC over pulp floor and root canal openings
8
Q
Why is a coronal seal important?
A
Prevents saliva, bacteria, and bacterial byproducts into the canal system and reaching the periradicular tissues
9
Q
Anterior restoration options for endodontically treated tooth (3)
A
Core build up with crown
Bleaching
Composite restoration
10
Q
What is a post/core?
A
Core provides retention for crown, post retains the core
Gains interradicular support for a definitive restoration
Posts do not strengthen or reinforce teeth, preparation of the root canal for a post weakens the tooth
11
Q
What are the components of a post/core and where are they placed?
A
Post - placed in the root canal
Core - What the prosthesis is cemented to
12
Q
Guidelines for post placement - root filling length
A
4-5mm root filling apically
13
Q
Guidelines for post placement - post width
A
No more than 1/3 of root width at narrowest point and 1mm of remaining circumferential coronal dentine
14
Q
The ideal post (3)
A
Parallel sided
Non threaded
Cement retained
15
Q
Classification of posts (3)
A
Manufacture - pre formed/ pre fabricated or custom
Material - cast metal, steel, zirconia, carbon/glass fibre
Shape - parallel sided or tapered
16
Q
What is a core build up?
A
Internal part of tooth is built up with restorative material to replace lost tooth tissue
Provides retention for definitive restorations
17
Q
Core materials (3)
A
Composite
Amalgam
Glass ionomer
18
Q
Composite as a core material
A
Good aesthetics
Bonds to tooth
Moisture control important
Most common
Used with fibre posts
19
Q
Amalgam as a core material
A
Tend to avoid - retention required
Poor aesthetics
Need 24 hours to set
20
Q
Glass ionomer as a core material
A
Not really used as it absorbs water and core expands
21
Q
Checklist for design of restoration over post/core
A
How long will post be?
Have you got a ferrule?
How wide
3-5mm remaining GP
Is canal straight?
How much space for the core
Type of crown to be placed
22
Q
Definition - ferrule effect
A
A band that extends the external dimension of a residual tooth structure
23
Q
How many roots in maxillary teeth
A
1 - 1
2 - 1
3 - 1
4 - 2 (95%), can be 1/3
5 - 1 (75%) or 2 (24%) can be 3
6 - 3 (93%) or 4
7 - 3 (63%) or 4
24
Q
Roots in mandibular teeth
A
1 - 1
2 - 1
3 - 1 (95%) or 1/3
4 - 1 (73%) or 2
5 - 1 (85%) or 2
6 - 3 (67%) or 4
7 - 3 (79%) or 2 (13%) or 3
25
Hydrodynamic theory
Generation of movement of tubular fluid leads to activation of the mechanoreceptors in the nerve fibres of the superficial pulp.
this in turn leads to activation of the nerve fibres
26
Which nerve fibres are responsible for sharp pain of short duration?
A - beta and A - delta
27
Which nerves are responsible for dull, throbbing pain or long duration?
C fibres
28
What makes biofilms resistant to antimicrobials?
Fail to penetrate beyond the surface layers of the biofilm
May be trapped and destroyed by enzymes
Many not be active against non-growing micro-organisms
Expression of biofilm specific resistance genes
Stress response to hostile environmental conditions (over expression of antimicrobial destroying enzymes)
29
What are the two main clinical objectives of root canal treatment?
Removing canal contents
Eliminating infection
30
What are the three main design objectives in RCT?
Create a continuously tapering funnel shape
Maintain apical foramen in original position
Keep apical opening as small as possible
31
What are the uses/advantages of dental dam in RCT?
Prevents contamination
Airway protection
Allows use of toxic disinfectants
Improve vision and acces
32
How can you describe pain?
Unpleasant feeling often caused by intense/damaging stimuli
33
What are the 3 branches of the trigeminal nerve?
Opthalmic
Maxillary
Mandibular
34
Average life of an endo treated tooth?
7-10 years
35
What could spontaneous pain be a symptom of?
Irreversible pulpitis
36
What might pain causing sleep deprivation be a sign of?
Irreversible pulpitis
37
What might a lack of response to painkillers be a sign of?
Irreversible pulpitis
38
Define referred pain
The perception of pain on one part of the body that is distant to the source of the pain
39
Where might posterior teeth refer pain to?
Opposite arch or peri-auricular area (more common in the mandible) but always on ipsilateral side
40
What should be taken note of when performing intra-oral exam of endodontically involved tooth?
Intra-oral swelling
Sinus
TTPalpation
Percussion notes
Mobility
Perio exam
41
How do hot and cold tests work?
Utilise hydrodynamic theory to check if response to hot or cold stimuli
42
Which fibres are mostly stimulated in an EPT?
A delta fibres (fast conducting)
(C fibres may or may not be stimulated)
43
Steps in carrying out an EPT
Dry and isolate teeth
Use conducting medium such as toothpaste
Place probe on incisal edge or cusp tip
Patient hold other end to complete circuit
Current slowly increased until response generated
44
What other tests may be used on endodontically involved teeth apart from sensibility testing?
Bite test - pressure to give indication if tooth is fractured or not
Test cavity
Staining and transillumination
Selective anaesthesia
45
What components are required in the diagnosis of an endodontically involved tooth?
Crown of tooth
Pulp diagnosis
Periapical diagnosis
46
Define normal pulp
Symptom free and normally responsive to pulp testing (mild or transient response to thermal cold, lasting no more than 1-2 seconds after stimulus is achieved)
47
What are the key components, signs and symptoms in reversible pulpitis?
Discomfort when stimulus applied only lasting a few seconds due to exposed dentine, caries or deep restorations
No significant radiographic findings in PA region
Pain not spontaneous
Inflammation should resolve following management of aetiology
48
Key components/signs/symptoms of irreversible pulpitis?
Vital inflamed pulp that is incapable of healing - RCT indicated
May include sharp pain on thermal stimulus, lingering pain (30 sec+ from removal of stimulus)
Spontaneous or referred pain
Pain may be worse on lying down/bending over
OTC analgesics typically ineffective
Sleep may be disturbed
Aetiology may be deep caries, extensive restorations or fractures
Inflammation may not have reached PA tissues and so may not be TTP
49
Key signs/symptoms of asymptomatic irreversible pulpitis
Vital inflamed pulp that is incapable of healing - RCT indicated
No clinical symptoms
Usually responds normally to thermal testing
May have had trauma or deep caries that would result in pulp exposure following removal
50
Key signs/symptoms of pulp necrosis?
Death of the dental pulp - RCT indicated
Non - responsive to pulp testing
Asymptomatic
Does not by itself cause apical periodontitis (TTP or radiographic evidence of bone breakdown) unless canal is infected
51
What are the key signs and symptoms of previously root treated teeth?
Tooth previously endodontically treated with root canal obturation with material other than intracanal medicament
Tooth doesn't respond to sensibility testing
52
Key findings in tooth with previously initiated therapy?
Tooth previously treated by partial endodontic therapy such as pulpotomy or pulpectomy
May or may not respond to pulp testing depending on level of therapy
53
Possible apical diagnoses
Normal apical tissues
Symptomatic apical periodontitis
Asymptomatic apical periodontitis
Chronic apical abscess
Acute apical abscess
Condensing osteitis
54
Key signs of normal apical tissues
Not sensitive to percussion or palpation
Rx - lamina dura intact and uniform PDL space
55
Key signs of symptomatic apical periodontitis
Inflammation, usually of apical PDL
Painful response to biting and/or percussion/palpation (severe pain to percussion - degenerating pulp, RCT needed)
May or may not be RX changes, normal width of PDL or PA radiolucency
56
Key signs of asymptomatic apical periodontitis
Inflammation and destruction of apical PDL of pulpal origin
No clinical symptoms - no pain and not TTP
Rx - apical radiolucency
57
Key signs of chronic apical abscess
Inflammatory reaction to pulpal infection and necrosis
Characterised by gradual onset, little or no discomfort and intermittent discharge of pus through an associated sinus tract
Rx - signs of osseous destruction - radiolucency
Sinus tracing possible
58
Key signs of acute apical abscess
Inflammatory reaction to pulpal infection and necrosis
Characterised by rapid onset, spontaneous pain, extreme tenderness to pressure, pus formation and swelling of associated tissue
RX - may be no signs of osseous destruction
May experience malaise, fever and lymphadenopathy
59
Key signs of condensing osteitis
Diffuse radiopaque lesion representing a localised bony reaction to a low grade inflammatory stimulus, usually seen at the apex of the tooth
60
What are the endodontic treatment options?
Leave and monitor
RCT
Re - RCT
Extraction
Surgical intervention/endodontics
61
How long after an MI should you wait to do endo treatment?
6 months
(emergency treatment - consult cardiologist)
62
If pt is allergic to latex, what is used for dental dam?
What must be considered in this case?
Vinyl dam - be aware some solvents may dissolve specific types of dental dam
63
If a mixed endo-perio lesion is found in a non-vital tooth, what order should treatment be completed in?
RCT
Observe response and give perio therapy as necessary
64
What degree of caries would be considered as rendering the tooth unrestorable?
Sub- osseous caries (below crestal bone level)
65
Aside from restorability and PDL condition, what other consideration prior to endo treatment?
Calcification - want to be able to see pulp chambers clearly
Dilacerations
Resorption (internal continuous with the canal but external superimposed on canal) -if end of root resorbed difficult to control irrigant and obturate
Ability to isolate tooth
Unusual anatomy
Ledges and perforations
Posts
Separated instruments
66
What is assumed when there is loss of vision of the canal before the apex of the tooth?
The canal has divided into two
67
Why may ledges occur in RCT?
RCT involves inserting straight file into curved canal and so will want to go straight down, causing a ledge
68
What options are available for assessing operator ability to carry out an RCT case?
1. Simple formula - root number of chronic/acute
2. American association of endodontics - endodontic case difficulty assessment form; minimum, moderate and high degree of difficulty
3. Restorative Dentistry index of treatment need - complexity assessment
69
Outline some risks associated with endo treatment
Perforation
Instrument separation
Pain
70
What are the two main concepts/stages in chemomechanical disinfection?
Cleaning - removal of organic pulpal debris, microorganisms and toxins
Shaping - controlled removal of dentine to give a tapering shape that can be sealed throughout its length with a RCF
71
7 stages of mechanical preparation
Prep of tooth
Access cavity prep
Creating straight line access
Initial negotiations
Coronal flaring
Working length determination
Apical preparation
72
What are the laws of symmetry of the pulp chamber floor?
Except maxillary molars, the orifices of the canal are equidistant from a line drawn in a mesio-distal direction
Except for maxillary molars, the orifices lie on a line perpendicular to the line drawn in the mesio-distal direction across
73
What is the law of colour change of the pulp chamber?
Colour of the floor is always darker than the walls
74
What are the laws of orifice location?
Orifices are always located at junction of walls and floor
Orifices are located at the angles of the floor-wall junction
Orifices are located at the terminus of the root development fusion lines
75
What instrument can be used to locate the canal orifices and negotiate the coronal portion?
DG16
76
What does coronal preparation do and allow?
Gives unrestricted access apically
Removed bulk of infected materials
Creates reservoir for irrigant
Improves tactile feedback
77
Where should the working length be?
At the narrowest part of the canal, known as the apical constriction, as close to the cemento-roto canal junction as possible
78
What is the aim of the modified double flare technique?
To create a continuously tapering, funnelled root canal without forcing intra-canal debris apically and without changing the basic shape/direction of the canal
79
How many sizes from the apical gauging file used should you go when preparing the canal?
2 sizes up
80
How does step back technique work?
For every 1mm away from the working length you step back, the ISO file should be increased by one size
81
What does mechanical preparation allow?
Irrigating solution and medicament to more effectively reach and eliminate micro-organisms from the apical portion of the root canal system
82
What are the objectives for irrigation?
Disinfect canal
Remove organic debris
Flush out debris
Lubricate RC instruments
Remove endodontic smear layer
83
What are the modes of action of sodium hypochlorite?
Antimicrobial - acid environment shifts equilibrium towards hypochlorous acid formation which kills bacteria
Dissolves pulp remnants
Dissolves necrotic and vital tissue - only irrigant which can dissolve organic material
Acts on organism component of smear layer
84
What % of sodium hypochlorite should be used?
3% (2.5-5.5% acceptable
85
Sodium hypochlorite disadvantages
Unpleasant taste
Possible toxicity
Can't remove smear layer by itself
Organic material can prevent antimicrobial action
(Possible negative effects on dentine properties)
86
What is smear layer formation and what are the problems with it?
1-5micrometer layer of organic pulpal material and dental debris formed during canal prep.
Leads to bacterial contamination
Acts as a substrate
Interferes with disinfection
Prevents sealer penetration
87
What is EDTA used for and at what concentration and duration?
Removes smear layer
17% solution
1 minute
88
What alternative irrigation may be used instead of sodium hypochlorite, how does it work and what is its disadvantage?
Chlorohexidine Digluconate
Antibacterial - may be similar action to NaOCl or may interact with bacterial cell wall, alter equilibrium and cause cell wall to rupture
Less anti-fungal activity than NAOCl, can't disrupt biofilms
CHX sensitivity is possible - risk of reaction
Antimicrobial substantivity - absorption prevents colonisation event after time of application
89
Possible uses of intra-canal medicaments
Placed in root between visits to destroy micro-organisms, prevent reinfection, reduce inflammation and exudate and control root resorption
90
What is found in anti-microbial ledermix paste and when might it be used?
Corticosteroid and tetracycline
Used in management of hot pulp as may aid in reducing pulpal inflammation
5-7 day activity
91
How does non setting CaOH work as intra-canal medicament?
High pH for antibacterial activity
Effective in removing debris
Treatment for 7 days
92
Options for temporary dressing to seal canal between visits?
Cavit, IRN, Polycarboxylate cements, GI cements
93
What are the aims of instrumentation of the canal?
Remove infected soft and hard tissue
Give irrigant access to apical canal space
Create space for medicament and subsequent obturation materials
Retain integrity of radicular structures
94
Define estimated working length
Estimated length at which instrumentation should be limited
Obtained by measuring pre-op radiograph to determine distance between coronal reference point and radiographic apex then subtracting 1mm
95
Define correct working length
Length at which instrument and subsequent obturation should be limited
Obtained by the use of an electron apex locator and/or working length radiograph
96
Define master apical file
The largest diameter file taken to the WL and therefore represents the final prepared size of the apical portion of the canal at WL
97
What is watch winding and when is it used?
Back and forth oscillation of 30-60 degrees with light apical pressure
Used for passing small K files through canals (e.g. checking patency)
98
Explain balanced force motion and when is it used?
Insert file and turn 1/4 clockwise then turn 1/2 back anticlockwise to strip dentine away
Used for working file to working length
99
What is barbed broach used for and what are the considerations of its use?
Used to extripate pulp tissue not enlarge pulp space
Can be used to remove GP in re-RCT
Must not engage canal walls (can easily break) so largest which will fit passively is used
100
What is the length and taper of ISO K files?
16mm
0.32mm taper
101
Name colour coding of the ISO files from 6 - 50
Pink
Grey
Purple
White
Yellow
Red
Blue
Green
Black
Pure Good Patter When Your Relatives Buy Gallons Bev
102
What might headstrom files be used for?
Removing GP or fractured instruments as cut on withdrawal
103
What are some complications of hand instrumentation?
Ledges
Blockage
Zipping (of foramen)
Extrusion of debris (as a result of filling motion)
Perforation
104
What causes blockage?
Dentine debris getting packed into the apical portion
105
What is a ledge and why does it occur?
A ledge is internal transportation of the canal. Occurs if curved canals are instrumented as if straight
Can result in apical few mm remaining infected
106
What is apical zipping, why does it occur and what are the effects?
Occurs as a result of the tendency of the instrument to straight inside a curved canal which cause over enlargement on outer side of curvature and under prep on inner aspect so that the main axis of the canal is transported
If the apical foramen is transported it will fail to provide resistance for the packing of GP
107
How to avoid apical zipping
Always pre-curve the initial instruments, dont ski instrument and never rotate the instruments in curved canals
108
How might you diagnose a perforation?
Persistent bleeding into canal
Multiple radiographs
Apex locator
Microscope
109
What are the features of an endodontic rotary instrument?
Taper - diameter change along length
Flute - groove to collect dentine and soft tissue
Leading/cutting edge - forms and deflects dentine chips
Land - surfaces between two flutes
Relief - reduction in surface of land
Helix angle - angle cutting axis forma with long axis of file
110
What are the difference and advantages of NiTi files compared with SS?
NiTi has upper elasticity, increased flexibility means less lateral forces when placed in curved canal, less ledging, zipping etc
Greater taper and more variable taper
Increased cutting efficiency
111
Disadvantages of NiTi files compared with SS
Expensive
Access can be difficult in posterior teeth
Not suitable for complex canal anatomy
112
Outline sequence and use of pro taper hand files
Purple S1 to prepare coronal third first, to middle third, then to WL
White S2 to prepare middle third to working length
Finishing files to WL
F1 - yellow (20)
F2 - red (25)
F3 - blue (30)
F4 - black (40)
F5 - yellow w black stopper (50)
113
Outline key features of true reciprocation
Mimics manual movement
Reduced risks associated with continuously rotating a file through canal curvatures
Decrease cutting efficiency
Required increased onward pressure
114
Outline steps involved in creating a glide path
Confirm straight line access
Explore anatomy
ISO 10-25 for resistance only
Coronal flare
ISO 10-15 WWW to establish apex
115
How might instrument fracture occur as a result of torsional stress and fatigue?
When a file is rotated it can resist a certain degree of torque in elastic phase, however at some point the torque force may exceed elastic limit leading to fracture
Torque is increased by friction of instrument on canals wall and if instrument tip is larger than canals section to be shaped it may lock into canal
116
How might instrument failure occur as a result of flexural stress and cyclic fatigue?
If a file is freely rotating in a curvature there will be generation of tension and compression cyclic which can over time lead to cyclic fatigue and failure
117
How does the status of the pulp affect the timing of obturation?
In a vital tooth or in a tooth with pulp necrosis (with or without asymptomatic periodontitis) it is acceptable to prepare/disinfect and obturate in the same visit (may reduce risk of inter-appointment contamination through leakage) However, if symptomatic then obturation should be delayed to allow use of inter-visit medicaments and reduce inflammation
118
Where should the apical limit of obturation be?
Should be same as the apical limit of preparation - at the dentinocemental junction (apical constriction) which is anywhere between 0-2.5mm from radiographic apex (varies with age, anatomy and resorption)
119
What would be described as an underfilled RCT?
More than 2mm from radiographic apex of tooth
120
What are the functions of a sealer?
Seal space between dentinal wall and core material
Fills voids and irregularities in canal, lateral and between GP points to prevent recolonization
Lubricates during obturation
121
Ideal properties in sealers
Tackiness for good adhesion
Hermetic seal
Easily mixed
No shrinkage on setting
Radiopaque
Bacteriostatic
Tissue tolerant
Slow set
Non-staining
Insoluble in tissue fluids
Soluble on retreatment
122
Name some properties of AH plus epoxy resin sealer
Slow setting
Good flow and sealing ability
Initial toxicity declines after 24 hours
123
Ideal properties of a core obturation material
Easily manipulated with long enough working time
Dimensionally stable
Non irritant
Unaffected by tissue fluids
Impervious to moisture
Inhibits bacterial growth
Radiopaque
Doesn't discolour tooth
Sterile
Easily removed if necessary
124
What are the disadvantages of silver points?
Encourages poor canal prep
Inability to fill irregularities - result in leakage
Corrode within root producing cytotoxic componenets
Difficult to remove
125
What form of GP is used as an obturation material?
Beta phase - trans isomer of polyisoprene
Alpha phase melted then cooled rapidly to make beta phase
126
Components of GP cones
20%GP
65% Zinc oxide
10% radiopacifiers
5% plasticisers
127
Give an advantage and disadvantage of cold lateral compaction
+ can be used in most clinical situations and good length control
- Does not allow good adaptation to canal abnormalities
128
Briefly describe cold lateral compaction technique
Master GP cones placed - forced to side of canal using lateral pressure with finger spreader/file, accessory points then inserted and again forced to side using lateral pressure
Repeat until canal completely filled
Excess GO removed at entrance to pulp chamber
129
What is the advantage of thermal obturation techniques?
GP is flowed into canals which is good for use in abnormally shaped canals
130
What thermal obturation techniques are there?
Warm vertical compaction
Continuous wave obturation
Warm lateral compaction
Thermoplastic injection techniques
Carrier-based techniques
131
Briefly describe warm vertical compactions
Cold GP is inserted and cut with heat
It is then plugged with a cold instrument and this is repeated to give good adaptation at the apex before warm GP is used to fill the space coronally
132
What should be considered when assessing obturation from a post op radiographs?
Length
Taper
Density
GP and sealer removed to canal orifice
133
To be deemed successful by the ESE what 3 things must not occur in the 4 years after RCT?
Development of Rx radiolucency in periapical area despite initial healing apparent
Development of Rx radiolucency in PA area where none has been present before
Increase in size of area of radiolucency after RCT
134
What signs of inadequate RCT may be visibile radiographically?
Underextended filling
Overextended filling
Poorly compacted filling
Poor coronal seal
Missed canals
Perforation
Inappropriate post preparation and placement
135
Reasons for failure before, during and after RCT
Before - misdiagnosis, poor treatment planning/case selection
During - missed canals, ineffective cleaning, shaping or filling or iatrogenic damage
After - recurrent caries, coronal leakage and post prep problems
136
3 factors which increase the chance of success of RCT
Canal filled within 2mm of radiographic apex
Good coronal restoration
Good penultimate rinse with EDTA
137
3 factors which decrease chance of success od a RCT
Presence of PA lesion
Extruded GP
Voids within filling materials
Presence of sinus
Missed canals
138
What treatment options are available in RCT failure?
Monitor
Orthograde retreatment
Periradicular surgery
Extract (in case of root fracture)
139
What should be used to remove insoluble resin from a root canal?
Ultrasonics
140
What can be used to remove GP from canals?
Headstrom hand files - C and D
Solvent
Protaper D handfiles - used with solvent if soluble pastes, not just GP
141
Outline Pro-Taper retreatment
Select slowed speed to gauge obturation material
Press D1 (ISO 30) into GP to remove material from coronal third (remove frequently to clean flute)
Repeat for middle third with D2
Repeat for apical third with D3, stopping 2-3mm from apex
Check patency and determine WL with hand files
Use C files in last 2-3mm to avoid debris extrusion
142
What can be used to bypass ledges?
Precurved C+ files (8, 10, 15)
143
What solvent may dissolve non-latex dam?
Eucalyptus oil
144
What is the difference between C and K files?
C files have a semi active tip and are stiffer to penetrate the GP mass
145
What may be used after removal of the filling material to kill bacteria?
CaOH
146
What are the different types of periapical pathology?
Granuloma (73%)
Abscess
True cyst
Pocket cyst
147
What are some indications for periradicular surgery?
Failure of previous endo where RCT not possible or won't correct the problem
Anatomical deviations which prevent complete cleaning and obturation
Procedural errors such as ledges/blocks
Exploration surgery
148
Contraindication for periradicular surgery
Anatomical factors - too close to nerves, maxillary sinus or mental foramen
Inadequate periodontal support
Non restorable tooth
MH
149
What options are available for intra-operative topical haemostasis in periradicular surgery?
Epinephrine pellets - placed in bony crypts
Ferric sulphate - causes agglutination of blood proteins but cytotoxic and can cause necrosis and adverse effects on healing
Calcium sulphate - blocks open vessels and aids in bone regeneration
150
When in periradicular surgery might you use a mucogingival flap as opposed to a sulcular full thickness flap?
On anterior crowned teeth so as to not alter crown margin (45 degree incision made on middle of attached gingiva)
151
What is the name given to the stage or peri-radicular surgery which involves removal of the cortical plate of bone to expose the root end?
Osteotomy
152
How much of the root end should be resected in periradicular surgery?
3mm (perpendicular to long axis of the tooth) as this removes the majority of lateral canals (93%) and ramifications
153
How much RCF material should be removed from apex of tooth after resection?
3mm removed with ultrasonic tip
154
What options are there for drying of the apical preparation?
Absorbent paper points
Stopko device - reduced pressure to avoid air emobolism
155
What is an isthmus?
Narrow band or passage which connects two or more root canals containing pulp tissue which acts as a storehouse for bacteria - one of the main causes for surgical failure
156
How might isthmi be detected?
Methylene blue dye
157
Which teeth are isthmi most common in?
Mesial root of mandibular first molars, (then mesiobuccal roots of maxillary first molars)
158
Once identified, how can isthmi be treated?
Ultrasonic preparation with a KiS-1 tip
159
What are the ideal properties of an ideal root end filling?
Well tolerated by apical tissue
Bacteriocidal/static
Adhere to tooth
Dimensionally stable
Easy to handle
Do not stain
Non-corrosive
Do not dissolve
Promote cementogenesis
Radiopaque
160
What properties of MTA make it a good root end filling?
Long setting time
Superior sealing ability
Moisture tolerant
Radiopaque
Excellent biocompatibility
Bioinductive - induces healing and tissue regeneration
Allows regeneration of cementum
161
What will influence the outcome of regenerative procedures?
Quantity of remaining cortical bone
162
How does guided bone regeneration work?
Facilitates healing by creating an optimum environment
Prevents in-growth of fast proliferating cells
163
What post op complications may occur after periradicular surgery?
Pain - use analgesia 48hrs
Swelling - ice pack
Bruising - may occur distant to site, worse 3-4 days after
Paraesthesia - abnormal sensation or impingement (often transient as a result of swelling, normal in 4 weeks)
Serious infection - antibiotics
Lacerations
Maxillary sinus perforation
164
What are the possible healing outcomes following periradicular surgery?
Healing
Incomplete healing (scar)
Uncertain healing
Failed
165
Prognostic factors for periradicular surgery
Age
Tooth position (worse posterior)
Root end filling material
Periodontal disease existing
Apical and coronal seal
Crypt size
166
What is the ideal crown to root ratio for an endodontically treated tooth?
Root:crown
1.5:1
167
What is a ferrule and what are its ideal dimensions?
Ferrule is a collar/band of dentine (remaining tooth tissue) that extends around the cervical margin of a restoration which aids in retention, prevents root fracture and improves prognosis of any placed restoration
1.5cm - height and width ideally
168
What is meant by coronal microleakage?
The ingress of oral microorganisims into the root canal system
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After how long would a root filled unrestored tooth (GP exposed to outside environment) require re-RCT before restoration placement?
3 months
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If a restoration cannot be placed the day of obturation what is an appropriate method for sealing the RCT and preventing microleakage?
Trim GP to ACJ and place RMGI over pulp floor root canal openings
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What occlusal set ups would be a contraindication to veneer placement?
Class 3 or edge to edge
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What is the function of a post core system?
Gain interradicular support for a definitive restoration when there is insufficient tooth tissue to retain and support it alone
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Which anterior teeth should posts be avoided in?
Any with curved or tapering/narrow canals - mandibular incisors typically have narrow tapering roots
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If necessary which canal of a maxillary premolar would you place a post in?
Widest and straightest canal - typically buccal
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How much root filling should be left apically when placing a post?
4-5mm
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What are the ideal dimensions of a post - width and length?
Width no more than third of the root width at the narrowest point (and at least 1mm of remaining circumferential coronal dentine)
Length minimum 1:1 ratio of post length:crown length
At least half of post length into the root
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What is the minimum core thickness either side of the post?
Minimum 1cm either side
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What are the properties of an ideal post?
Parallel sided - more retentive and avoids wedges
Non threaded/passive - less stress to tooth and chance of fracture
Cement retained - less retentive than threaded by acts as a buffer between masticatory forces and tooth
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What is an advantage of a prefabricated posts?
Only one visit required - no initial impression or lab required - immediate preparation of core chairside after post placement then take impression for crown all in one visit
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What is an advantage and disadvantage of custom made posts?
Unified post and core made of one material - avoid material interfaces so preferred in non vital teeth
2 visits required and risk of recontamination of RCT between visits
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Advantage and disadvantage of metal posts
+ radiopaque
- Poor aesthetics, risk of root fracture, corrosion and nickel sensitivity
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Advantage and disadvantage of ceramic posts e.g. alumina and zirconia
+ high flexural strength and fracture toughness, favourable aesthetics
- Difficult to retrieve and root fracture common
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Advantage and disadvantage of fibre post
+ flexible and similar properties to dentine, aesthetics, retrievable and bond to dentine with DBAs
- Radiolucent
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What is a core and what is its purpose?
A core involved build up of the internal aspect of a tooth with restorative material to replace the lost tooth tissue
It provides retention and resistance for the permanent restoration
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Advantage and disadvantage of composite cores
+ good aesthetics, bonds to tooth structure
- technique sensitive so good moisture control required
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Disadvantages of amalgam cores
Retention required
Poor aesthetics and core cannot be prepared straight away
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Why are GI cores no longer used?
Absorb water which causes the core to expand in size
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What is a Nayyar core?
Technique used in posterior teeth where root treatment material is removed and amalgam packed into the root canals to provide retention for the amalgam
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What are some potential problems with posts?
Perforation (internal or external repair or extraction required)
Core fracture
Root fracture of neck
Post fracture
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Methods of post removal
Ultrasonic - to remove cement around core
Moskito forceps - for screw retained posts Masseran Kit
Eggler
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5 reasons for restoring endodontically treated teeth
Coronal seal - stops reinfection and prevents bacteria from access to the canals
Cuspal protection - protects remaining tooth structure
Function
Occlusion
Aesthetics
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By what % is proprioception reduced in an endodontically treated tooth?
30%
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What is the minimum depth of core required to not necessitate use of a post in posterior teeth?
4mm depth of core
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When might you consider using a direct composite restoration on an endo treated tooth? Why not other times?
Premolar tooth where only 2 surfaced being replaced (e.g. DO)
Any more than this and the chance of fracture is directly proportional to the number of surfaces restored hence avoid if possible
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What degree of taper is required to give adequate crown retention?
Less than 11 degree taper
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What is the resistance form and what may help increase this in short molar teeth?
Design of the prep such to prevent dislodging on lateral movement
In molars this may be increased by incorporating notches
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What is the advantage of inlays and onlays compared to crowns?
Use inside of pulp chamber to give resistance form and usually require minimal preparation and so removal of tooth tissue
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If no ferrule, how might it be achieved?
Orthodonic extrusion or crown lengthening
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Advantages of prefabricated posts
Only 1 visit required
No impressions or lab work required
Chairside core build up
Large selection of designs and material
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Considerations for each post material
Metal - poor aesthetics, root fracture, radiopaque on radiographs
Ceramics - high flexural strength and fracture toughness, good aesthetics, difficult retrievability and root fracture common
Fibre - flexible, similar properties to dentine, aesthetic, bone with DBA, radiolucent on radiographs
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Reasons for post failure
60% due to restorative reasons
32% due to periodontal problems
8% due to endodontic reasons
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What type of post and core is preferred in non vital teeth?
Unified post and core - avoids material interfaces
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True or false - all cores require a post
False
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How much GP should be left at apex when adding a post?
3-5mm
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Ferrule preparation
Crown margins place on solid tooth tissue - not restorative material
1.5-2mm collar of dentine supragingivally, 360 degrees around the tooth
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Taper in crown
6 degree
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What is used to remove GP?
Heat then Gates gliddens (to minimum size 3)
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Disadvantages of rotary NiTi files
Multiple file system
Instrument separation
Expensive
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Normal pulp
Symptoms free and normally responsive to pulp testing
Pulp may not be histologically normal
Clinically normal pulp results in a mid or transient response to thermal cold testing, lasting no more than one or two seconds after the stimulus is removed
Compare tooth in question to adjacent and contralateral, test other teeth first so pt is familiar with experience of a normal response to cold
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Reversible pulpitis
Inflammation should resolve following the appropriate management of aetiology
Discomfort is experienced when a stimulus is applied only lasting a few seconds
Exposed dentine, caries or deep restorations
No significant radiographic changes in the periapical region of the suspect tooth and the pain experienced is not spontaneous
Follow up required to determine whether reversible pulpitis has returned to a normal status
Although dentinal sensitivity per se is not an inflammatory process, all of the symptoms of this entity mimic those of a reversible pulpitis
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Symptomatic irreversible pulpitis
Vital inflamed pulp is incapable of healing and root canal is indicated
Characteristics may include sharp pain upon thermal stimulus, lingering pain (often 30s or longer after removal of stimulus) and referred pain
Pain may be accentuated by postural changes - lying down/bending over
OTC analgesics typically ineffective
Common aetiologies include deep caries, extensive restorations or fractures exposing the pulp
Teeth may be difficult to diagnose because the inflammation has not yet reach PA tissues so no pain or discomfort to percussion
Dental history and thermal testing are the primary tools for assessing pulpal status
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Asymptomatic irreversible pulpitis
Vital inflamed pulp is incapable of healing and root canal is indicated
No clinical symptoms and usually respond normally to thermal testing but may have had trauma or deep caries that would likely result in exposure following removal
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Pulp necrosis
Diagnostic category indicating death of the dental pulp, necessitating RCT
Non responsive to pulp testing and symptomatic
Does not by itself cause apical periodontitis (pain to percussion or radiographic evidence of osseuous breakdown) unless canal infected
Some teeth may be non responsive to pulp testing because of calcification, recent trauma or tooth just not responding, this is why all testing must be done comparatively
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Previously treated teeth
Clinical diagnostic category indicating that the tooth has been endodontically treated
Canals are obturated with various filling materials other than intracanal medicaments
Tooth typically does not respond to thermal or electric pulp testing
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Previously initiated
Clinical diagnostic category indicating that the tooth has been previously treated by partial endodontic therapy such as pulpotomy or pulpectomy
Depending on the level of therapy, the tooth may or may not respond to pulp testing modalities
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Normal apical tissues
Not sensitive to percussion or palpation testing and radiographically the lamina dura is intact and PDL space is uniform
Comparative testing for percussion and palpation should always begin with normal teeth as a baseline for the patient
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Symptomatic apical periodontitis
Represents inflammation, usually of the apical periodontium
Painful response to biting and/or percussion or palpation
May or may not be accompanied by radiographic changes depending upon the stage of the disease
Sever pain to percussion and or palpation is highly indicative of a degenerating pulp and RCT is needed
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Asymptomatic apical periodontitis
Inflammation and destruction of the apical periodontium that is of pulpal origin
Appears as an apical radiolucency and does not present clinical symptoms (no pain on percussion or palpation)
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Chronic apical abscess
Inflammatory reaction to pulpal infection and necrosis
Characterised by gradual onset, little or no discomfort and an intermittent discharge of pus through an associated sinus tract
Radiographically, signs of osseous destruction such as a radiolucency
Sinus tract tracing possible
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Acute apical abscess
Inflammatory reaction to pulpal infection and necrosis
Characterised by rapid onset, spontaneous pain, extreme tenderness of the tooth to pressure, pus formation and swelling of associated tissues
May be no radiographic signs of destruction and the pt may experience malaise, fever and lymphadenopathy
221
Condensing Osteitis
Diffuse radiopaque lesion representing a localised bony reaction to a low grade inflammatory stimulus usually seen at the apex of the tooth
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Pulpal diagnoses
Normal pulp
Reversible pulpitis
Asymptomatic irreversible pulpitis
Symptomatic irreversible pulpitis
Pulp necrosis
Previously treated
Previously initiated therapy
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Apical diagnoses
Normal apical tissues
Symptomatic apical periodontitis
Asymptomatic apical periodontitis
Chronic apical abscess
Acute apical abscess
Condensing osteitis
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Watch winding
Back and forward oscillation 30-60 degrees, used with small diameter files
225
Recriprocation
A file working motion consisting of an anticlockwise cutting direction and a clockwise release of the instrument motion, whereby the anticlockwise direction is greater thn the angle of the reverse direction
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Filing
A dynamic movement of a hand file to optimally effect canal debridement, predominantly a push pull rasping, rotational reaming movement or a combination of the two
Engine driven filing motions can be rotary, reciprocating or oscillating
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Recapitulation
Using a small hand file to ensure patency and dislodge debris into solution prior to introducing a larger file into the root canal system
Essential to prevent blockages or iatrogenic damage to canals
228
Patency filing
Passing a small hand file through the apical constriction and apical foramen to contact the apical tissues
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Balanced force technique
60 degree clockwise rotation, maintaining apical pressure rotate anticlockwise at least 60 but not more than 120 degrees, repeat x3
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Modified double flare technique
The process involves development of an initial coronal flare, followed by an apical flare
These distinct regions of preparation, upon intersection create a continuous taper
Preparation involves the use of gates glidden drills and stainless steel K files
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Correct working length
The distance in mm from a known coronal reference point to the position in the apical region of a tooth, where the endodontic preparation terminates, in most cases at the apical constriction
232
Most reliable way to calculate correct working length when instrumenting a root canal
Electronic apex locator
233
Tertiary dentine
Classified as reactionary or reparative
234
Reactionary dentine
Type of tertiary dentine characterised by a tubular structure with greater irregularity
235
Reparative dentine
Tertiary dentine formed beneath the area of irritation characterised by dead tracts where the odontoblastic layer has been eradicated. Atubular and is formed from mesenchymal stem cells which differentiate into odontoblast like cells
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Embryonic origin of dentine-pulp complex
Neural crest derived ectomesenchyme
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Embryonic origin of enamel
Ectoderm
238
Pulpal diagnoses that may appear with periapical radiolucency
Reversible pulpitis
Irreversible pulpitis
Pulp necrosis
