ENDODONTICS Flashcards
Which law is this statement associated with
“ the floor of the pulp chamber is always located in the centre of the tooth at the level of the CEJ”
A. Law of Centrality B. Law of Concentricity C. Law of the CEJ D. Law of Symmetry E. Law of Orifice Location F. Law of Colour
A - correct
What is the law of concentricity
Walls of the pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ
Which of these is incorrect in relation to the law of colour;
A. the floor of the pulp chamber is always darker than surrounding dentinal walls
B. the colour difference creates a distinct junction where the walls and floor of the pulp chamber meet
C. the developmental root fusion lines are darker than the floor
D. reparative dentine/calcifications are darker than the pulp chamber floor
D - is incorrect
The reparative dentine and calcifications appear lighter than the pulp chamber floor
What are the 3 points in the laws of orifice location
- ofirices are always at the junction of walls and floor
- orifices are located at the angles of the wall-floor junction
- orifices lay at the terminus of developmental root fusion lines (if present)
Define the Anatomic and Radiographic apex
Anatomic - the tip of the root determined morphologically
Radiographic - the tip or the end of the root as determined radiographically
What file is this?
Stainless Steel
Tightly spiralled cutting edges
Tip is cutting
Cutting occurs when pushed, pulled or rotated
Cross-section is square (can also be diamond, triangular)
A. H-file
B. K-file
C. Barbed broach
D. C-file
B- correct
Which of these characteristics is incorrect for a H-file
A. aggressive relative to K file
B. Stainless steel
C. Cutting occurs in pulling and pushing motion
D. Round cross-section
C - cutting only occurs on the pulling stroke
What is the difference between a C+ and a C-pilot file
C+ files have a pyramid shaped cutting tip
C-pilot files have a non-cutting tip
Both are stainless steel and square in cross section
Which statement is most correct regarding endodontic files?
A. K files are used in the coronal and middle section of mechanical cleaning and shaping in the crown-down technique
B. Flexofiles are similar to K-files except they have a non-aggressive tip and increased flexibility
C. Barbed broaches are not effective in removing necrotic tissue debris from the root canal
D. H-files are utilised in the apical zone when hand-filing in a crown-down technique
B is correct
A - this is actually the function of H files
C - Barb broaches are very effective in this function
D - this is actually the function of K-files
What are the benefits of the crown-down technique in root canal therapy
- Reducing procedural error
- Improves access of instruments and irrigation to apical 1/3
- Reduces apical extrusion of debris
- Creates a canal escapeway for debris to flow coronally
Define; Transportation Perforation Ledge Zip
Transportation - removal of structure outside the curve of the root canal in the apical 1/2 due to the files tendency to restore a linear shape
–> can lead to a ledge OR perforation
Perforation - mechanical or pathologic communication between the canal system and periodontium/external root surface
Ledge - artificial irregularity impeding instrument access to the apex
Zip - tear drop shaped widening of apical foramen that has been formed during instrumentation of a curved canal. The file has transported through the apical foramen to the outer wall of the tooth
A tooth has one canal orifice, two root canals and one apical foramen
What is it’s Weine Classification?
Weine Type II
The other types
Type I - one orifice, one canal, one apical foramen
Type III - two orifices, two canals, two apical foramina
Type IV - one orifice, one canal, two apical foramina
Which of the statements is incorrect
A. Mandibular lateral incisors can present with Type I, II and III canal forms
B. Maxillary 1st molars have 3 roots and 4 canals 50% of the time
C. Maxillary second pre-molars typically have a Type I canal form in 48% of cases
D. Maxillary central incisors can have 3 pulp horns in a young patient
B - Maxillary 1st molars have 3 roots and 4 canals 95% of the time
When is it ideal to obturate - what are 5 key things we are looking for before we fill a root canal system
- When adeqaute biomechanical preparation hasbeen completed and confirmed (apical stop, clean/tapered walls)
- When the tooth is asymptomatic
- When the canals can be dried –> no exudate/fluid still present from periodontal tissues
- When the draining sinus and/or swelling has resolved (if it was initially present)
- When the tooth has normal mobility
What are the two most common sealer materials?
ZOE-based (zinc-oxide eugenol) and AH26/plus
What are four routes of root canal infection
Dentinal Tubules - any cause of dentine exposure where bacteria can invade tubules
Direct Pulp Exposure - the most obvious and common route
Periodontal Disease - only when the periodontal pocket reaches the apical foramen
Anachoresis - circulating blood or lymph reaching an area of damaged tissues
Which of the following is an example of a intra-radicular infection
A. acute apical abscess
B. initial infection where the bacteria invade and colonise pulp tissue –> necrosis
C. apical actinomycosis from peri-radicular surgery
B
A & C are examples of extra-radicular infections
What are the most common micro-organisms in primary endodontic infections?
Gram -ve
Dialister, Prophyromonas, Tannerella, Prevotella
What is the most common bacterial species that is found in root-canal treated teeth
E. faecalis
What patterns of colonisation do microbes have in the root canal system and what effects does this have on treatment
Planktonic (unnatached) - these are easy to access and eliminate
Aggregates/Coaggregates - adhered to the walls (biofilm)
Clogged in Lateral Canals/Isthmuses (biofilm)
- biofilm is difficult to eliminate and requires chemical, mechanical cleaning, irrigation, medicaments etc.
Which of the following is correct regarding electrical pulp testing
A. A-delta and C-fibres are stimulated
B. The numbers (1-80) of the EPT is important for severity
C. EPT should be performed on the roots of the teeth
D. EPT could give a false +ve due to poor isolation or contacting soft tissue
D is correct
A - only A-delta are stimulated
B - the numbers are just relative to this patient, the test utliamtely only give a yes/no
C - should be performed on the mid buccal of a sound crown
Briefly discuss how hot and cold cause a pain response in the tooth?
Short, sharp cold pain = vitality
Hydrodynamic mechanism:
Contraction of fluids –> outward flow –> deforming the A-delta fibre –> stimulation and pain
In the case of an acute advanced pulpitis there are no A-delta fibres, in this case the cold decreases intrapulpal pressure and relieves pain from C-delta fibres (for a short period)
Hot response:
Delayed = normal
Immediate/no response = abnormal
A normal tooth has to reach a certain temperature prior to pain from heat - response is delayed
A tooth with an inflamed pulp already has increased pressure and so the applicaiton will cause immediate pain
A necrotic pulp will have no response to hot or cold
Which of the following is correct regarding root canal treatment
A. for every mm lost in WL the chance of failure increases 14%
B. The goal is to be at the radiographic apex
C. in a 2% taper the file increases 0.2mm in size every 1mm from the tip
D. The purpose of recapitulation is to pass through and keep the apical foramen open
A
B. goal is to be 1mm from apex
C. taper increases by 0.02mm
D. this is referring to ‘apical patency’. Recapitulation is to keep the apical area clean and patent, without compromising the seal.
When would you want to be more than 1mm from the radiographic apex?
In cases where;
The apex is slightly open
There is root resorption
There is a lateral canal exit
Explain the importance of the file taper and goal of working up 3 files sizes in relation to bacterial penetration of canals
Coronal-middle zones of a root canal will be easily irrigated throughout the RCT process and therefore undergo sufficient chemical preperation to reduce microbial load
The apical zone is much harder to access and its imperative to then ensure the apical zone is cleared of bacteria, so this portion relies more heavily on the mechanical removal
Studies have show bacteria can penetrate up to 300microns (0.3mm) into the dentine - our goal is to remove around 150 microns (0.15mm)
A 15K file with a 2% taper will be 0.15mm at its tip
Each mm from the tip will increase this by 0.02 e.g. 1mm up will be 0.17
If a 15k file binds tightly 1mm from the apex this means in this zone the width is 0.15mm and there is at least 0.15mm of dentine we need to remove to clear the bacteria so we would need to widen this to at least 0.30-0.35
This is done by increasing working size to a K30-K35
What are the two positive features of NaOCl in endodontics
- dissolves organic tissue
2. antimicrobial effects
Which of the following is correct regarding irrigants
A. NaOCl is a 0.5-6% solution with a pH <11
B. EDTA is a 5% solution with a pH of 7
C. Citric acid is a 10% solution with a pH 1
D. NaOCl and EDTA are chelating agents
C is correct
A. NaOCl pH >11
B. EDTA is a 15-20% solution
D. EDTA and Citric acid are chelating agents
Define a chelating agent
A chelating agen is a solution which dissolves inorganic tissue (smear layer) through Ca+ ion chelation
The smear layer prevents penetration of irrigants, medicaments and sealers
You are doing a root canal and find you have a heavily calcified canal, which irrigant should you use to help gain access to this canal?
EDTA or Citric acid - need a chelating agent to soften the dentine
A patient returns to you with a persistent apical periodontitis of an RCT 46 that you completed 1 year ago. Which of the following would not help your treatment
A. Calcium hydroxide
B. NaOCl
C. Clorhexidine
D. EDTA
A. calcium hydroxide is ineffective against E. faecalis and C. albicans which are the most commonly associated bacterial species in a persistent/secondary RCT infection
Match the paste to its AB & steroid components
Ledermix
Grinazole
Odontopaste
Clindamycin & Triamcinalone
Metronidazole
Demeclocycline & Triamcinalone
Ledermix - Demeclocycline & Triamcinalone
Grinazole - Metronidazole
Odontopaste - Clindamycin & Triamcinalone
*Demeclocycline is a tetracycline AB and has the potential to stain teeth
Which of the following is NOT a pre-treatment emergency
A. Irreversible pulpitis
B. Hyperchorite accident
C. Acute apical abscess
D. Symptomatic apical periodontitis
B. Hyperchorite accident - this is an intraappointment emergency
A paitent attends your clinic for a relief of pain appt for Q4, they have the following symptoms;
Severe intermittent/spontaneous pain
Sensitivity to hot drinks
Trouble sleeping
They think its a premolar or molar thats causing pain
You perform some tests on the teeth
Control tooth 35: +ve to cold, +ve to ETP and delayed +ve to hot. -ve to ttp and percussion
44: +ve to cold, +ve to ETP and delayed +ve to hot. -ve to ttp and percussion
45: -ve to cold, ++ve to ETP, immediate and prolonged pain to heat. +ve to ttp and percussion
46: +ve to cold, +ve to ETP and delayed +ve to hot. -ve to ttp and percussion
A PA of Q4 shows no abnormalities
What is your pulpal diagnosis and periapical diagnosis?
45 Irreversible Pulpitis with Symptomatic Apical Periodontitis
The 35, 44 and 46 delayed +ve response to heat is normal
A patient attends your clinc for the first time for a routine examination, in the interview they mention 6 months ago a tooth which “has always been an issue” on the LLHS became a “massive toothache” for 2-3 days and then the pain seemed to stop. The mention that they generally have a bit of a bad taste in their mouth but note thats probably because they haven’t had a clean in 3 years. Otherwise they have NIL complaints
You perform some tests;
control tooth 46: +ve to cold, +ve to ETP and delayed +ve to hot. -ve to ttp and percussion
35: +ve to cold, +ve to ETP and delayed +ve to hot. -ve to ttp and percussion
36: has a large restoration, -ve to cold, ETP and heat. -ve to ttp and slight +ve to palpation. you notice clinically there is a small swelling on the B mucosa that seems to have some exudate coming from it.
37: has a large restoration, +ve to cold, +ve to ETP and delayed +ve to hot. -ve to ttp and percussion
A PA shows a radiolucency associated with the apices of the 36
What is your pulpal and periapical diagnosis?
36 Necrotic Pulp with Asymptomatic Apical Periodontitis and a Chronic Abscess
In which case would you NOT prescribe AB
A. Localised infection in an immunocompetent patient
B. Localised infection in an immunocompromised patient
C. Spreading infection in an immunocompetent patient
D. Spreading infection in an immunocompromised patient
A
When would you provide AB prophylaxis
- Immunocompromised patients
- Patients at risk of infective endocarditis: complex congenital heart defects, prosthetic cardiac valves, Hx of IE
- H&N cancer patients exposed to high dose irradiation
- IV bisphosphonates
What is the standard prescription for AB prophylaxis
Amoxicillin per os 2g 1hr pre-tx
Clindamycin per os 600mg 1hr pre-tx
Briefly describe the protocols for a hypochlorite injury
Mild: immediate copious saline irrigation, NSAID’s and cold compression. Follow up appointments, review tooth, recomend warm compression
Moderate: immediate copious saline irrigation, NSAID’s - maybe opioids, and cold compression, contact OMFS. Follow up appointments, review tooth, recomend warm compression, AB’s if necessary
Severe: immediate referral to OMFS, opioids, IV steroids & AB. Follow up appointments, review tooth, recomend warm compression, AB’s if necessary, incision and drainage if required
List the 5 roles of medicaments in endodontics
- Antibacterial
- Reduce periradicular inflammation & pain
- Eliminate Apical Exudate
- Arrest Inflammatory Resorption
- Prevent Reinfection
When would you get a false +ve from an apex locator?
Incomplete apex Resorption of a root Instrument too small Moist-wet chamber Contacting metal (ie. access through a crown)
Which of the following is correct
A. You should place a band on any tooth undergoing RCT
B. You can leave bands in place for a long period of time
C. A band is recomended for a tooth undergoing RCT once there is a large proximal restoration
D. You don’t need RD to place a band
C
A - it depends on the tooth structure remaining
B - they negatively affect the gingiva so they should not be left longer than necessary
D - IF you are undertaking a banding procedure for a tooth undergoing endo you will need RD
If you have an endo-perio lesion you should treat the perio component first
true/false
False
For optimal outcome the endodontic lesion should be treated first
Differentiate between a primary endo and a primary perio lesion
Primary endo lesion will usually have -ve response to sensibility tests (cold/EPT)
Radiolucency tends to only involve the apex
Primary perio lesion will usually have a +ve response to sensibility tests (cold/EPT)
There will be a broad clinically identifiable pocket and calculus present on the root surface
Radiolucency/bone defect will often not reach the apex
- If there is a perio lesion reaching an apical foramen this would signify severe perio and this tooth will likely not have a good prognosis with endo tx or not
What are the three bleaching materials
Hydrogen Peroxide
Sodium Perborate
Carbamide Peroxide
What is the difference between replacement resorption and external inflammatory root resorption?
Replacement resorption - where traumatic event leads to a healing process where bone predominates - overwhelms PDL healing and replaces tooth tissue with alveolar tissue
External inflammatory root resorption - trauma exposing dentine tubules + infected pulp will lead to external inflammatory root resorption - root can be significantly resorbed within months
What are 4 significant factors that could predispose a patient to an interappointment flare up?
What factor could almost ensure the patient will not have an interappointment flare up?
- preoperative pain
- pulp status - necrotic increases pain chances by 6x
- presence of periapical lesions
- retreament
The presence of a sinus tract - almost ensures there will NOT be a flare up
What are the 3 causative factors of an interappointment flare up?
Mechanical Injury
Chemical Injury
Microbial Injury
Which of the following is NOT a theory for an interappointment flare up
A. Apical extrusion of debris
B. Secondary radicular infections due to poor isolation during tx
C. Cleaning also removes the commmensal, positive bacteria
D. Increase in the oxidation-reduction potential
C. Removing all bacteria from the chamber is the goal, adequate cleaning should ensure that there will not be a microbial insult/interappointment flare up
Changing the microbiotic environment could cause one species to predominate, if preparation is not done adequately, and this predominance could throw off the hot-microbe balance
Briefly explain how you would incise a localised swelling
Using a scalpel, incise the centre of the lesion with an approx 5mm long incision and depth of incision should reach the bone.
haemostatic forceps can be used to open/break any internal capsules to ensure pus is drained
Which of the following is incorrect regarding AB and endodontics
A. PenV is given as 1000mg initial dose, with 500mg maintenance dose 4-6hrs for 3-7 days
B. Azithromycin and Clindamycin are given when a patient has an allergy to penicillin
C. Amoxicillin is given with clauvanic acid
D. Azithromycin is given as a 1000mg initial dose
D. Azithromycin is given as a 500mg initial dose
PenV, Amoxicillin w/ clauvanic acid, Cephalosporins and Metronidazole are all given as a 1000mg intitial dose
A perforation at the gingival margin has a worse prognosis than an apical perforation
True/False
True
You are placing calcium hydroxide as a liner/indirect pulp cap on a deep cavity, what are its affects on dentine?
Calcium hydroxide has a high pH (12.4) which stimulates transient necrosis –> this leads to a process of healing where there is cellular differentiation to form a dentine bridge
Briefly discuss the similarities and differences between apexification and apexogenesis
Both are only performed in a tooth with an open apical foramen
Apexogenesis - in a vital inflamed tooth.
- only a small amount of pulp tissue is removed and then calcium hydroxide is appllied directly to the pulp
- the aim is to keep the pulp vital as the root development/closure continues
Apexification - in a necrotic tooth
- removal of necrotic tissue and minimal instrumentation, calcium hydroxide (CH) placement in canal (these first steps may need repeating due to CH wash-out)
- the aim is to clear the necrotic tissue and stimulate a dentine bridge to form at the apex (apical barrier) BEFORE obturation
It is beneficial to use both ledermix and/or odontopaste with calcium hydroxide (in the same visit)
True/False
False
Calcium hydroxide rapidly destroys the triamcinalone steroid in ledermix/odontopaste so there is no reasoning to use them simultaneously.
What are the 6 aims of access cavity?
- Allows the removal of all the chamber contents.
- Allows for complete, direct vision of the floor of the pulp chamber and canal openings.
- Facilitates the introduction of canal instruments into the root canal openings.
- Provides access as direct as possible to the apical one third of the canal for both preparation instruments and filling instruments.
- Provides a favourable space for temporary fillings.
- Always have four walls (i.e. need to restore any proximal cavities) → Prevent contamination of the chambers again
Briefly explain the application process for NaOCl vs chelating agents (EDTA and Citric acid).
NaOCl: 2-5mL between instrumentation
Chelating agents: 5-10mL left for a maximum of 1 minute only after instrumenting, rinse out with NaOCl
What are the disadvantages and/or contraindications of chlorhexidine as a medicament?
- Ineffective against gram negative (primary infections)
- No regeneration of periapical tissues
- Does not dissolve necrotic tissue
- Contraindicated for patients with chlorine allergy
- Should not be used with NaOCl = Brown precipitate formation
What are the advantages and disadvantages of GP as an obturation material?
Advantages
- Adapts and seals in all preparations
- Inert
- Does not facilitate microbial growth
- Easily removed
Disadvantages
- Requires sealer
- Elasticity causes tension/pulling from the walls
- Lacks rigidity
- Shrinks when heated
What instrument is used to detect pulp horns? A) #17 Explorer B) DG16 C) Barbed broach D) DG17
A
What are the three ideal characteristics of sealer?
Adheres RC filling to root canal walls.
Sets slowly.
Insoluble in tissue fluids
Which of the following is most correct?
A) A high metallic tone generally heard upon percussion in external inflammatory root resorption
B) A high metallic tone generally heard upon percussion in replacement resorption
C) Radiographic images always detect surface root resorption as bowl-shaped cavitations
D) Radiographic images show radiolucency where the pulp cannot be traced in cervical resorption
B)
A) Should be dull tone
C) Usually no changes in radiographic imaging as resorption fairly superficial
D) Pulp chamber can be traced as external resorption
Which is most correct management of these root resorptions?
A) External inflammatory root resorption - RCT and apply CaOH review after 3 months
B) Replacement resorption - Extract tooth
C) Cervical resorption - RCT or extract
D) Internal inflammatory resorption - RCT +/- CaOH if perforation has occurred
D)
A) Ledermix or odontopaste applied first and then after 3 month review, CaOH applied (toxic to PDL cells so avoided as initial medicament)
B) Avoid extraction as bone loss occurs - should decoronate and sink root below alveolar bone until prosthetic can be placed
C) Expose resorption area and remove resorptive tissue with curettage or trichloroacetic acid
Which of the following is most correct regarding these medicaments?
A) CaOH - Minimum of 7 days for effectiveness
B) CHx - pH of 7
C) Ledermix - Medication duration of 7 - 14 days
C) Odontopaste - Contains demeclocycline
A)
B) pH of 5
C) 3-7 days
D) Clindamycin instead of demeclocycline (this is ledermix)
A patient attends your clinic with a painful tooth that has kept the patient awake all night. Clinical assessment are as follows:
- Cold test: + (Control +)
- Hot test: ++ (Control -)
- TTp: ++ (Control -)
- pA: NAD
Most likely diagnosis would be?
A) Symptomatic irreversible pulpitis and acute periapical periodontitis
B) Asymptomatic irreversible pulpitis and acute periapical periodontitis
C) Pulpal necrosis and acute periapical periodontitis
D) Symptomatic irreversible pulpitis and chronic periapical periodontitis
A)
What are the three reasons for instruments separating?
Fatigue
Improper use of file
Complex root canal anatomy
