Endodontics Flashcards
(103 cards)
1
Q
List three reasons for carrying out obturation of the prepared root canal.
A
- Inhibits bacterial growth - It can be easily removed - It seals the canals apically and laterally
2
Q
Briefly describe the steps involved in obturating the root canal of an upper central incisor
A
- apply dental dam and disinfect access area - remove provisional restoration seal using a sterile round bur, remove cotton pledgets from from pulp chamber - irrigate using sodium hypochlorite to remove all traces of calcium hydroxide medicament - Starting with size 10 or 15, introduce files sequentially to confirm access to the working length and to prepare the apical stop - dry the canal using a narrow bore aspirator and size matched paper points in locking tweezers - select master GP which will fit the canal at working length and give tug back. - mix the root canal sealer (AH plus/setting CaOH) - coat the tip of the GP with sealer before reinserting into the canal carefully and gently to length - carry out cold lateral compaction
3
Q
Describe the steps of cold lateral compaction
A
- Take a size A finger spreader with a silicone stop set at 1-2 mm short of the CWL and gently place into the canal alongside the master GP point - gently remove the finger spreader, and in the space left, insert a small size A accessory point which has been coated in sealer - repeat this until 3 or 4 points have been used - heat the end of an excavator or plugger in a bunsen flame to cut/melt the GP. - remove excess GP from the pulp chamber
4
Q
Which part of the root canal filling is most important in ensuring long term success?
A
a good coronal seal ensures a higher success rate and reduces the risk of reinfection
5
Q
What is the hydrodynamic theory?
A
this is the theory used to explain the mechanism by which a tooth perceives pain due to the abrupt movement of fluid within the dentinal tubules due to stimuli. Thermal; hot and cold Osmotic; sugary foods Mechanical; chewing Evaporative; air blasts
6
Q
what fibres are responsible for sharp pain of short duration?
A
A-beta and A-delta fibres
7
Q
what fibres are responsible for dull throbbing pain of longer duration?
A
C fibres
8
Q
How many canals are found in the first maxillary premolar?
A
1 (6%) 2 (95%) 3 (1%)
9
Q
How many canals are found in the second maxillary premolar?
A
1 (75%) 2 (24%) 3 (1%)
10
Q
how many canals are found in the first maxillary molar?
A
3 (7%) 4 (93%)
11
Q
how many canals are found in the second maxillary molar?
A
3 (63%) 4 (37%)
12
Q
How many canals are found in the first mandibular premolar?
A
1 (73%) 2 (27%)
13
Q
How many canals are found in the second mandibular premolar?
A
1 (85%) 2 (15%)
14
Q
How many canals are found in the first mandibular molar?
A
3 (67%) 4 (33%)
15
Q
How many canals are found in the second mandibular molar?
A
2 (13%) 3 (79) 4 (8%)
16
Q
What bacteria is suggested as the prominent isolate in non-healing endodontic cases?
A
Enterococcus faecalis
17
Q
What type of bacteria are found in necrotic untreated endodontic cases?
A
gram negative anaerobic
18
Q
What type of bacteria are found in failed cases of RCT with persisting infection?
A
Predominantly gram positive anaerobic
19
Q
What fibres are responsible for sharp pain of short duration?
A
A-beta and A-delta
20
Q
What fibres are responsible for dull throbbing pain of longer duration?
A
C fibres
21
Q
Give three reasons for Biofilm resistance to antimicrobials…
A
* antimicrobials may fail to penetrate beyond the surface layers of the biofilm * antimicrobials may be trapped and destroyed by enzymes * antimicrobials may not be active against non-growing micro-organisms * Expression of biofilm specific resistant genes * stress response to hostile environmental conditions (eg leading to an overexpression of antimicrobial agent destroying enzymes)
22
Q
What are the four features of apical periodontitis?
A
- chronic polymicrobial infection of the oral cavity - Predominance of gram negative anaerobic bacteria - stimulation of host response - connective tissue destruction
23
Q
What are the clinical objectives or RCT?
A
- removing canal contents - eliminating infection
24
Q
Give four reasons for the use of dental dam in endodontics…
A
- prevents contamination - airway protection - allows use of appropriate disinfectants - Improves access and vision - improves patient comfort - improves efficiency
25
What are the design objectives of RCT?
- create a continuously tapering funnel shape - maintain apical foramen in original position - keep apical opening as small as possible
26
What is achieved by cleaning and shaping the root canal?
- removing infected soft and hard tissue - give disinfecting irrigants access to apical space - create space for the delivery of medicaments and subsequent obturation - retain the integrity of radicular structures
27
What is the process of reaching a diagnosis in endodontics?
- why is the patient seeking advice? - history and symptoms prompting visit - objective clinical tests - correlation of objective findings and subjective details to create differential diagnosis - formulation of definitive diagnosis
28
When a patient attends your surgery with pain, what questions should be asked?
- where is the pain - what does it feel like - how bad is it - how long is it there for? - does anything take the pain away? - what makes it worse - does it keep you awake at night - does the pain come on spontaneously - have you had this before - have you had any dental work recently? - have you suffered any trauma
29
When taking a pain history, what does SOCRATES stand for?
-Site - Onset -Character -Radiation -Association -Time course -Exacerbating/relieving factors -Severity
30
If a patient presents with swollen lymph nodes and the origin doesn't appear to be dental, what could be the cause?
TB lymphoma
31
If a patient presents with paraesthesia and the origin doesn't appear to be dental, what could be the cause?
leukaemia anaemia
32
If a patient presents complaining of bone pain and the origin doesn't appear to be dental, what could be the cause?
sickle cell anaemia
33
If a patients presents with tooth mobility and the origin doesn't appear to be dental, what could be the cause?
multiple myeloma
34
If a patient presents complaining of pain and it doesn't appear to be of dental origin, and is otherwise unexplained. What could be the potential causes?
multiple sclerosis acute maxillary sinusitis trigeminal neuralgia
35
How would you carry out a systematic endodontic exam?
- extra oral - intra oral - STE - intra oral swelling -sinus tract -palpitation -percussion -mobility -perio exam
36
List what can be used and how cold and heat sensibility testing is carried out
Frozen carbon dioxide (-78degrees), ethyl chloride or refrigerant spray can be used Cold sensibility testing tests the hydrodynamic forces. -dry and isolate the tooth - test close to the pulp horn Heat tests can be carried out using hot GP and vaseline or hot water and dental dam
37
Describe how an electric pulp test is carried out and how it works
- electric current used to stimulate sensory nerves -primarily A-delta fast conducting fibres -unmyelinated C-fibres may or may not respond -teeth are dried and isolated -probe is placed near the pulp horn -a conducting medium is used such as tooth paste -the circut is complete, current slowly increased until there is a response A negative response is a reliable indicator unreliable in teeth with an open apex
38
List four special tests that could be carried out to check pulp sensibility
- bite test - test cavity - staining and trans illumination - selective anaesthesia
39
What radiographs should be taken before carrying out endodontics?
Two pre-op radiographs taken from different angulations
40
Endodontics Describe a normal pulp
-symptom free and normally responsive to pulp testing -pulp may not be histologically normal -clinically normal pulp results in a mild or transient response to thermal cold testing lasting no more than a few seconds
41
Describe reversible pulpitis
(pulpal diagnosis)
-inflammation should resolve following appropriate management of the aetiology -discomfort is experiences when a stimulus applied lasting only a few seconds -occurs with exposed dentine, caries or deep restorations -no significant radiographic changes in the periapical region of the suspect tooth -pain is not spontaneous
42
Describe symptomatic irreversible pulpitis
(pulpal diagnosis)
-vital inflammed pulp incapable of healing and RCT indicated -characteristics may include sharp pain upon thermal stimulus, lingering pain, spontaneity and referred pain -pain may be accentuated by postural changes such as lying down or bending over -over the counter analgesics typically ineffective -common aetiologies may include deep caries, extensive restorations or fractures exposing pulpal tissue -may be difficult to diagnose as inflammation has not yet reached periapical tissues, thus not TTP -dental history and thermal tests are the primary tool for assessing pulpal status
43
Describe asymptomatic irreversible pulpitis
(pulpal diagnosis)
-vital inflammed pulp is incapable of healing, RCT indicated -no clinical symptoms and usually responds normally to thermal testing. May have had trauma or deep caries that would result in exposure
44
Describe pulpal necrosis
(pulpal diagnosis)
-diagnostic category indicating death of the pulp, necessitating RCT -non responsive to pulp testing and is asymptomatic -could be non responsive due to calcification, recent trauma or an unknown reason -does not by itself cause apical periodontitis -TTP or radiographic evidence of osseous breakdown
45
Describe previously initiated RCT
-tooth has been previously treated by partial endodontic therapy such as pulpotomy/pulpectomy -depending on the level of therapy, the tooth may or may not respond to pulp testing modalities
46
Describe normal apical tissues
-not TTP -radiographically, the lamina dura surrounding the root is intact and the PDL space is uniform -comparitive testing for percussion should always begin with normal teeth as a baseline
47
Describe symptomatic apical periodontitis
(apical diagnosis)
-represents inflammation, usually of the apical periodontium -painful response to biting and or percussion -may or may not be accompanied by radiographic changes depending on the stage of disease -severe TTP is highly indicative of a degenerating pulp, RCT needed
48
Describe asymptomatic apical periodontitis
(apical diagnosis)
-inlammation and destruction of the apical periodontium that is of pulpal origin -appears as an apical radiolucency and does not present clinical symptoms
No TTP or palpation
49
Describe a chonic apical abscess
-inflammatory reaction to pulpal infection and necrosis -characterised by gradual onset, little or no discomfort and an intermittent discharge of pus through and associated sinus tract -radiographically, signs of osseous distruction (apical radiolucency) -sinus tract tracing possible
50
Describe an acute apical abscess
(apical diagnosis)
-inflammatory reaction to pulpal infection and necrosis -characterised by rapid onset, spontaneous pain, extreme TTP, pus formation and swelling of associated tissues -may be no radiographic signs of destruction and the patient often experiences malaise, fever and lymphadenopathy
51
Describe condensing osteitis
(apical diagnosis)
diffuse radiopaque lesion representing a localised bony reaction to a low grade inflammatory stimulus usually seen at the apex of the tooth
This causes more bone production rather than bone destruction
52
when is EDTA used?
as the penultimate rinse when carrying out RCT
53
what concentration of sodium hypochlorite (parcan) is used for irrigation?
3%
54
Name the ideal features of CaOH as to why it's a good medicament
- It has bacteriostatic and bacteriocidal properties
- it has a high pH making it alkaline which;
\*stimulates odontoblasts for reparative dentine formation
\*stimulates recalcification of demineralised dentine by stimulating pulpal cells
\*neutralises low pH from acidic restorative materials
- it adheres directly to dentine rather than the restorative material
- It is thin which means it won't reduce the strength of the restorative material
- It won't dissolve in biological fluids
55
Give three reasons why you should obturate?
- inhibits bacterial growth
- it can easily be removed
- it seals the canals laterally and apically
56
What are the ideal properties of a sealer?
- exhibits tackiness to give good adhesion
- establishes hermetic seal
- radiopacity
- no shrinkage on setting
- non staining
- bacteriostatic
- slow setting
- insoluble in oral fluids
- tissue tolerant
- soluble on re-treatment
- easy to mix
57
What are the consituents of GP?
- 20% gutta percha
- 65% zinc oxide
- 10% radiopacifiers
- 5% plasticisers
58
Why is the working length 1-2mm short of the radiographic apex?
The apical foramina is located 0.5-0.7mm away from the anatomical and radiographic apex. The apical constriction is 0.5-0.7mm short of the foramina.
59
What are the average working lengths of the maxillary teeth?
1 -21 2-20 3-25 4/5-19 6-19 7-18
60
What are the average working lengths of the mandibular teeth?
1-19 2-19 3-24 4/5-20 6-19 7-18
61
What are indications for initiating RCT?
Pulp irreversibly damaged, necroting +/or evidence of apical periodontitis elective devitalisation prior to restorative Tx such as overdenture
62
What are contra indications of initiating RCT?
non functional/non restorable teeth insufficient periodonatl support
63
How does RCT work?
It is the chemical and mechanical debridement of the root canals, removal of the pulp tissue, shaping of the canal, and sealing the disinfected canal by root obturation and a coronal seal
64
What are the objectives of shaping the canal?
1. there should be a continuously tapering shape (effective for irrigation, disinfection and obturation) 2. maintain the apex location 3. maintain the apex shape
65
What is the aim of obturation?
to provide a hermetic 3D seal to prevent the ingress of bacteria and tissue fluids which could act as a culture media incarcerate any microbes remaining the the canal system prevent reinfection of the root canal system
66
How do you use k-files?
These are stainless steel files. Used in watch winding action or balanced force clockwise binds the flutes into the dentine anticlockwise removes the dentine
67
What is the difference between NiTi and StSt files?
NiTi is significantly more flexible, exspecially at thicker files. They can have a range of tapers can still # from torsional fatigue and torsional stress
68
What are irrigants used for in RCT and what are the choices?
Flushing, lubricating, bacteriocidal, dissolving organic debris NaOCl at 5% EDTA can help with blocked or scleronsed canals
69
What intercanal medicaments can you use and what is their mechanism of action
nsCaOh paste (hypocal/ultracal) high pH, bacteriocidal iodine containing paste (vitapex) if organisms are resistant to CaOh
70
What do you use to obturate and what are the constituents?
gutta percha has rubber, dyes, plasticisers and radiopaque materials such as barium - used with resin based sealers (AH plus)
71
How would you restore a tooth after RCT?
seal the canals with flowable composite. fill pulp with GI restore with: crown onlay inlay composite post/core/crown
72
how would you carry out an RCT?
Have a post operative radiograph to show the full length of the root provide LA place non-latex dam with single tooth isolation - seal the dam with oraseal access the pulp chamber - remove all caries before you enter it access pulp chamber, remove any pulp with slow speed bur. use safe ended bur to get straight line access gates-glidden burs can be used to open the coronal aspect of the canal Identify canals using dg16 probe - remember the rules
73
How do you prepare a canal for RCT?
initial negotiation - iso 10 - watch winding. NaOCl. glide path - increase iso unil size 20 coronal flare - NiTi or gates glidden. recapitulate with iso10 and lots of irrigation apical negotiation - rest of canal to size 20 working length determination - radiographically and apex locator apical preparation to working length - minimum iso25
74
What are some common errors in canal prep
incomplete debridement lateral perforation apical perforation ledge formation apical zipping elbow formation strip perforation
75
What are some different obturation techniques?
cold lateral compaction warm lateral compaction thermoplasticised injectable GP coated carriers
76
If a patient came to you with an acute periapical abscess, how would you proceed?
radiographs, history and sensibility testing. Establish drainage - under dam and through the pulp. Use a diamond bur to access the pulp irrigate thoroughly with sodium hypochlorite seal with GI/ZOE see patient again in 24 hours to start RCT If the abscess is fluctuant, anaesthetise around the abscess, incise the abscess at the heaviest point if the infection is not systemic, no cellulitis then no ABs are required
77
How do you remove old GP for re-rct?
eucalyptus oil dissolves the GP, but this can leave smear layer which is hard to remove hedstrom files
78
Why do you need a definitive restoration after RCT?
coronal seal to prevent ingress of bacteria into canal protect the remaining tooth structure - weakened by cavity prep, dehydration, loss of elasticity of dentine aesthetics function
79
What are the prognositc factors influencing the outcome of RCT?
pre-treatment status of the periapical tissues - no pathology = 95%, smaller lesion better outcome that larger quality and length of RCF - well compacted, within 2mm of radiographic apex quality of coronal restorationn
80
If a patient presents with an acute periapical abscess, how would you treat it?
Drain the abscess - if possible through the tooth under a rubber dam and using a diamond tip but to open the pulp irrigate the canal with hypochlorite and reseal. see the patient again in 24 hours. if abscess is fluctuant, anaesthetise the surrounding tissue and incise at the most fluctuant point. if the infection is not systemic/cellulitis then no ABs are required
81
What are some differences between endo on a primary and secondary tooth?
primary - larger pulp chambers, closer to surface. bulbous crowns. ribbon-like canals, splayed roots, resorption of roots, check root formation
82
Give the aims of peri-radicular surgery
Achieving an apical seal remove any exisitng infection (excision of apex and curettage)
83
Why can endodontics fail?
calcification of canals, # instrument, dilaceration or fracture of root, under/over filled, open apex, lateral canals
84
What are the indications for peri-radicular surgery?
Apical pathology - cyst or infected apex in communication with developing follicle significant restorative work completed which has intact seal lateral perforations RCF extruded beyond apex
85
When irrigating a canal with NaOCl, patient feels severe pain. What is the likely cause?
extrusion of NaOCl through the apex can be from too much force pushing needle too far through open apex can lead to tissue necrosis
86
How would you act if you extruded NaOCl through the apex of a patient?
- stop - reassure pt, tell them what the likely cause is - dry canal and temporise - remove dam - call Maxfacs for referral - cold pack in 15 min intervals for 24 hours - pain relief - document all information, including measures taken to avoid this happening - recall next day
87
How do you avoid NaOCl contacting tissues?
- bib - eye protection - dam - dam sealer - EWL from Rx - bend in needle 2mm short of EWL - finger pressure on plunger - blunt ended needle with side venting - aspiration with yanker - needle doesnt engage canal walls - pass needle behind pt head
88
What are symptoms of NaOCl extrusion through apex?
severe pain bleeding from canal progressive swelling in area immediate ecchymosis and haematoma of skin trismus ana/para or hyperaesthesia
89
What is the technique for cold lateral compaction?
- choose GP point which is the size of the apical constriction - check fits with tug back and no concertinaing -cover in AH plus resin adhesive -place in canal to WL using locking tweezers -use finger spreader (A) in lateral direction - use accessory cones until no more fit - remove exccess with hot firing instrument and condense with cold plugger - seal with RMGI
90
What are different problems that can occur when preparing a canal with StSt instruments
zipping apical transportation perforation ledge formation blockage fracture of instrument
91
What criteria must be fulfilled before the root canal system of a tooth can be obturated?
symptomless canal must be dried full biomechanical cleaning
92
give 3 types of sealers used in root canal obturation
ZOE resin based CaOH calcium silicate
93
When taking a pre operative radiograph, what 6 things should you look out for?
\* Is there peri-radicular pathology and how far does it extend?
\* The anatomy of the root canal system
\* Canal calcifications
\* Check the angulation of the root in relation to adjacent teeth
\* Number, length and morphology of roots
\* Proximity of vital structures
94
What are the advantages of using dental dam for RCT?
\* To eliminate bacterial contamination
\* To prevent inhalation of instruments
\*Retracts and protects soft tissues and tongue
\* Prevents patient from rinsing, chatting
\* Reduces chairside time and operator stress
95
What are the objectives of access cavity preparation?
\*Remove entire roof allowing complete removal of pulpal tissue
\* Allow visualisation of root canal enterance
\* Produce smooth walled preparation with no overhangs
\* Allow unimpeded straight line access of instruments
96
Sodium hypochlorite. Strength and uses
3% NaOH
Dissolve organic material. Bactericidal. Used for disinfection.
30ml continual irrigation tame for at least 10 minutes following completion of prep
97
EDTA liquid. Strength and uses
17%
Smear layer removal
Penultimate rinse for one minute. 3ml per canal
98
Chorhexidine digluconate (corsodyl). Strength and uses
0.2% used to check dam integrity/disinfect tooth surface
99
Chlorhexidine digluconate (gluco-chex). Strenght and uses
2%. Antimicrobial. Only used if NaOH contra-indicated
100
Name the four motions in which hand files are used
\*Filing
\*Reaming
\*Watch winding
\*Balanced forced motion
101
Describe watch winding
Back and Forward Oscillation of 30-60 • Light apical pressure • Effective with K files • Useful for passing small files through canals
102
Describe the balanced force technique
Insert file and engage clockwise 1/4 turn. With continued pressure, turn anticlockwise 1/2 turn to strip dentine away. Do this 1-3 times before removing the file to check the file and remove debris. Remove, clean, reintroduce to WL
103
What are the objectives of using irrigants in the root canal?
\*To disinfect the root canal
\* Dissolve organic debris
\*Flush out debris
\*Lubricate root canal instruments
\* Remove endodontic smear layer
