BDS5 past paper Qs Flashcards
Multi-rooted endo:
List the factors you need to take into account prior to deciding if a tooth should be root treated
Establish diagnoses:
* pulpal diagnosis is enough +/- apical
Tooth factors:
* Tooth is restorable (after removal of all the caries, assess if 360 2mm ferrule that does not interfere w biologic width)
* Tooth has sufficient periodontal support
* Absence of fractures
* consider re-building walls w temporary restoration (composite / ortho-band) needed to place rubber dam clamp
* Favourable root and coronal anatomy
Pt factors:
* Co-operative pt (can tolerate rubber dam & can keep mouth open 3 fingers)
* Satisfactory oral hygiene
* Pt aware of no of apts & cost (incl crown post RCT)
Prior to RCT, what do you need to investigate & how?
- Pulp status: sensibility testing to figure out if reversible pulpitis, irreversible pulpitis or necrosis
[through HPC, cold test & EPT] - PPD
[williams probe] - Tooth mobility
[blunt end mirror & finger] - Caries
[BW radiograph & clinically] - Root length and shape
[PA radiograph] - Root sclerosis
[look at density of root in radiograph / attempt to insert size 10 file to full WL] - Fractures
[radiograph, tooth sleuth] - Apical pathology
[PA radiograph]
What would you do before carrying out endo on a very badly broken down molar
- Clinically assess restorability of tooth
* Remove any & all caries first
* Ensure sufficient crown height for ferrule which doesn’t invade biologic width
* Sensibility test
* Check for mobility
* Check for periodontal disease (PPD @ 6 sites)
* Check for parafunctional habits
* Check for cracks & vertical fractures
* Radiograph (PA - rule out internal/external reportion, assess curvature/root morphology)
Diagnose - May build up molar with composite prior to carrying out the endo in order to achieve single tooth isolation. Note: this is not the definitive restoration
- Place ortho band around the tooth to prevent it from fracturing
- Assess patient compliance and ensure patient aware of costs implicated & no of apts i.e. nayyar core and crown post?
- Confirm tx plan (type of coronal restoration / function of tooth e.g. overdenture abutment)
- obtain valid consent (voluntary, informed & have capasity)
What are the signs and symptoms of periapical pathology “
Acute periapical periodontitis: pain accurately localised to specific space. Tooth feels elevated. Widening of periodontal ligament space due to oedema.
* Tooth is TTP
Chronic periapical periodontitis: May be asymptomatic but may also be pain due to acute exacerbations
TTP and may be tender to palpation.
* Radiolucency at apex due to osteoclast resorption of bone
Alveolar Abscess: Rapid onset of pain. Redness, swelling. TTP and palpation. Mobility.
* May suppurate w/ sinus tract. Infection can spread to other locations causing cellulitis, suppuration and gangrene in some locations.
A patient presents with a badly broken down carious UL4. You decide to endodontically treat this tooth.
List TWO factors that would influence whether or not to carry out endodontic treatment? (2 marks)
- Tooth restorability - break down of tooth and caries may so severe such that tooth cannot be saved using RCT, may require extraction
- Extent of pulpal damage - only treat it irreversible damaged/necrotic pulp with or without clinical and or radiological finding of apical periodontitis
- Patient preference
List FOUR contraindications to root canal treatment of a tooth
- Teeth that cannot be made functional or restored
- Teeth with poor prognosis such as extensive external/internal resorption, extensive vertical fractures
- Tooth with insufficient periodontal support
- Uncooperative patients or patients where dental procedure cannot be undertaken (limited opening)
What is the criteria for determining the success of endodontic treatment (RCT)
absence of pain & other symptoms
absence of swelling
no sinus tract
no loss of function
radiological evidence of normal periodontal ligament
space around root
In terms of assessing quality of RCT:
* Length (same as WL)
* Quality of condensation (no voids)
* Taper - ideally 5%”
You clean the canals, temporise - what conditions are needed on the next visit prior to obturation? (4 marks)
- Tooth must be asymptomatic
- Temporary dressing must be intact
- No sinus present
- Root canal must be dry”
A file breaks in the canal during final shaping, what should you do during this appointment? (5 marks)
- Inform the patient
- Attempt to remove the file
- If not possible, attempt to bypass the file
- If not possible, may want to refer to endodontist and temporise in the meantime
- May accept the RCT prep as it is and seal the canals and restore “
What are FOUR aims of the access cavity? (4 marks)”
- Remove the entire roof/contents of the pulp chamber
- Allow visualisation of all root canal orifices/pulp chamber
- Straight line access
- Convergent walls (in an apical direction) to support the temporary dressing material
- Minimal - conserve as much tooth tissue as possible to prevent weakening
Which irrigants would you use based on the clinical scenario presented with? (6 marks)
- NaOCl 2.5% - gold standard and can be combined with other irrigants apart from chlorhexidine. Dissolves proteolytic (organic) debris and material.
- EDTA 10-18% - removes smear layer, best used in conjunction with NaOCl, useful in sclerosed canals and alternative to NaOCl as deeper penetration of antibacterial effects into infected tubules
- Chlorhexidine - not proteolytic and adheres to dentine. More forgiving to soft tissues than NaOCl as does not dissolve organic tissue
- Saline - can be used in patients allergic to other irrigants
- Aqueous iodine based compounds - therapy resistant cases, effective against broad spectrum bacteria
b. Explain the limitation of radiography with two examples
- Provide 2D image of 3D tooth - difficult when multi-rooted teeth and trying to work out WLs and know the different canals
- Bitewings - underestimate depth of carious lesions, appears confined to enamel on image but actually into dentine leading to insufficient or improper treatment
- Accessory canals (depending on resolution) usually cannot be found using radiography due to their small size
- Additional canals such as lingual canal for lower incisors may not always appear in radiograph - therefore look for this canal on patient”
Discuss FOUR ways in which the working length of root canals can be determined (10 marks)
- Electronic apex locator
* Use only zero reading, at the actual apex
* Work backwards 0.5 - 1 mm from zero-reading for WL
* Using minimum file size of 15
* Contraindicated in patients with cardiac pacemakers
* Care to ensure no short circuiting occurs, for instance, because of canal being too moist - Working length radiograph - periapical radiograph
* Identify length in mm from coronal reference point to radiographic apex
* Substract 1 mm from this value to obtain the estimated working length, which is where the apical constriction is estimated to be
* Use size 15 file after coronal preparation to carry out another radiograph in order to obtain the definitive working length - ideally after EAL measurement, place size 15 file to WL determined from EAL
* If the tip of the instrument and the desired WL is > 3 mm the WL is adjusted and another radiograph taken - Paper point
* Placed at specific lengths to identify working length of canal - Tactile
* Based on tactile sensation can determine length of canal
Curved canals provide special problems for successful endodontic treatment. List the potential problems and describe possible strategies to overcome these problems (10 marks)”
- Ledges: iatrogenically created irregularity in root canal that impedes access of instruments to apex and canal blockage caused by packing of dentine debris. Consider precurving size 10 file at the tip to negotiate ledge and ensure good coronal flare.
- Zipping: apical transportation, which occurs in curved canals that become straightened. Zips make canals difficult to dry and clean
- Perforations: communications between root canal space and surrounding tissue or oral cavity. May be enclosed in bone or in contact with oral cavity. Repair with MTA (however cannot use if in contact with oral cavity). If coronal perforation then use GIC.
- Blockages: root canal system may become blocked due to debris. Can be overcome by copious irrigation, and small file with light picking motion to feel for a sticky bit.
- Instrument separation: e.g. fracture files, coronally can be removed, as progress further apically through canal system becomes more difficult, with apical 1/3 almost being impossible.
How to overcome these problems
* Precurve files prior to use
* Effective irrigation and patency filing
* Good coronal flare
* Use watch-winding technique when filing
How would you place a temporary dressing material after you have prepared a canal? (5 marks)
- Dry with paper point
- Line canal w/ medicament e.g. non-setting calcium hydroxide which can be injected into canal or placed onto size 15/20 file and applied into canal
- Apply cotton pledget (just enough to cover the canals) - allows identification of canals when you regain access
- Temporarise w/ IRM or GIC (Fuji IX) as interim dressing
- Alleviates pain and allows for tooth to be returned to at a later stage to complete full RCT once pt stabilised
- Easily removed by irrigating w/ sterile water/NaOCl and agitate w/ files
What do you look for following RCT for signs of good obturation?
- Length (same as WL)
- Quality of condensation (no voids)
- Taper - ideally 5%
List FOUR reasons why we use temporary dressing materials?
- To maintain pulp vitality
- Antibacterial effect
- Good seal
- Release growth factors which induce pulpal repair
- Low grade irritation from coagulation necrosis producing hard tissue barrier
THREE reasons why analgesia may fail pre-RCT?
- Operator error - poor technique, wrong injection site, not enough LA
- Active infection - alteration in pH (more acidic reduces efficacy of LA)
- Hypersensitive pulp tissue
What reasons would result in inadequate preparation and filling of root canal to the working length
- Canal has incorrect taper, not 5% due to poor step back technique
- Poor quality obturation - GPs not compressed enough –> voids AND master GP not placed to correct working length
- Working length radiograph not accurate or apex locator giving defective readings
- Ledges/zips/perforations in canal when preparation
- Pushed GP past apex - did not measure length of canal correctly
What is zipping? And what problems does it cause? (2 marks)
- Apical transportation
- Difficult to dry and clean canal
- Occurs when curved canals become straightened
What are perforations and how does it happen.
What can you do to treat a perforation? (4 marks)
Iatrogenic communication between root canal system and surrounding tissue or oral cavity. May be enclosed in bone or in contact with oral cavity
- Occurs as a result of operator error during canal preparation e.g. due to too much force, wrong motion, using files at furcation
Treatment - use MTA (mineral trioxide aggregate) to repair (if apical). For coronal perforations GIC material of choice for repair.
What factors increase the chance of an unsuccessful RCT (6 marks)
- Sclerosed canals and complex root anatomy e.g. curved
- Mobile teeth
- Poor coronal seal
- Re-RCT
- Periodontal disease
- Tooth fracture
- Obturation - inadequate length, taper and quality of condensation
Describe the classical symptoms of pulpitis noting how they change as the disease progresses for the following:
a. Reversible pulpitis
b. Irreversible pulpitis
c. Acute periapical periodontitis
d. Abscess “
“REVERSIBLE PULPITIS: Sharp transient pain in response to a stimulus, which subsides when stimulus removed e.g. cold/hot
* Pain difficult to localise * Tooth not TTP
* Radiographically - caries and normal peri-radicular tissue
* Due to either caries, erosion, attrition
Tx = densentising agent e.g. sensitive toothpaste, temporary dressing of CaOH2 or IRM
IRREVERSIBLE PULPITIS: dull ache throbbing severe pain
* Spontenous, lingering pain even without stimulus * Lasts minutes to hours
* Made worse by hot, relieved by cold
* Radiographically caries, normal peri-radicular tissue and widening of PDL in late stages
Tx = RCT or extraction
ACUTE PERIAPICAL PERIODONTITIS
* *Pain localised to single tooth (due to PDL involvement)
Similar symptoms to irreversible pulpititis but pain not as severe and can be localised more easily *
* Tooth may feel elevated
* Periapical radiolucency
Tx = RCT or extraction
ABSCESS
* Very painful
* Buccal sulcus tender
* Tooth mobility
* Periapical radiolucency
Tx = RCT/extraction +/- antibiotic (use if systemic infection) and drainage of abscess “
If a tooth is tender to percussion, which structure is inflammed?
PDL
Give TWO reasons why a tooth might be TTP
- Infected pulp and/or inflammation at apex e.g. acute periapical periodontitis
- Cracked cusp syndrome
- Periodontal disease
- Irreversible pulpitis (if severe and later stages)”
Describe the steps of cold lateral condensation “
- Try in finger speader - should be loose in canal to working length
- Fit master GP to full working length with tug back (wet canal) - may need to cut GP tip or change size to fit the master GP point as not as accurately sized as file sizes
- Dry canal with paper points
- Coat master GP at tip with sealer and place to working length
- Place spreader length 1 mm from working length
- Measure accessory cones to same length as spreader
- Place 2-3 accessory cones and obtain mid-fill radiograph
- Continue adding accessory points till canal is filled
- Seal GP off ~ 1mm below canal orifice
- Either using heated instrument (heat carrier then plugger or system B) to sear GP off
Write down TWO main aims of obturation (2 marks)
- Prevent micro-organisms and their toxins percolating into the peri-radicular tissues
- Seal the remaining bacteria in the root canal system in an environment they cannot thrive
- Prevent reinfection of root canal system from the coronal aspect
- Prevent percolation of peri-radicular exudate (nutrient supply for the bacteria) into the root canal space
List FOUR ways to reduce the chances of sodium hypochlorite accident? (5 marks)”
- Never bind the irrigation needle
- Use side venting needle
- Never inject the solution with thumb, gentle pressure w index finger
- Always irrigate very slowly
- 27g = 0.4 mm needle (an external diameter of 0.4 mm (27 gauge)
What is the role of radiology in endodontology?
Used to ensure root canals are adequately filled, to assess status of root canal system and monitor success of RCT. In endodontology the gold standard radiograph is periapicals.
Using periapical radiographs:
1. Preoperative radiograph to establish the estimated working length
2. Definitive working length (DWL) radiograph - determine DWL
3. Mid-fill radiograph - determine apical fill
4. Post-operative radiograph - overall quality of obturation, voids and taper
Could consider radiograph after weeks - months to assess if apical radiolucency has resolved”
Write the steps followed to clean and prepare a canal for obturation, assume that gaining access (11 marks, including 1 mark for correct order)”
- Explore canal coronal 1/3 - 2/3 with size 10 file
- Prepare coronal 1-3 - 2/3 with SX shaping rotary file
- Explore apical 1/3 with size 10 file
- Establish patency using size 10 file - passed through apical foramen
- Electronic apex locator used to assess patency & whole length
- Definitive working length radiograph - use size 15 file 1mm from EAL reading
Hand filing:
* Prepare apical 1/3rd and apical gauge using serial step back - size 10, 15, 20 and 25 files inserted at same length in order to help MAF fit e.g. size 25
* Step back - achieve 5% taper of preparation by increasing file size by 0.05 mm in diameter for every 1 mm after MAF established
* Smooth canal circumferentially - using size 20/25 file 1 mm from WL
Rotary filing - ProTaper Gold system:
* S1 & S2 shaping files at DWL
* F1 (7% taper) & F2 (8% taper) finishing files at DWL
Circumfrential filing w master apical file to smooth the canal length at DWL
IRRIGATION AND PATENCY BETWEEN EACH INSTRUMENT
Outline the steps of endo tx (10 marks)
1) pre-op rad
2) access cavity
3) removal of pulp contents
4) prep 2/3rds of coronal canal (SX rotary file)
5) check patency (with EAL)
6) DWL rad (with size 15 file)
7) biomechanical prep of canals to DWL
8) assess tug back & master cone GP / mid-fill rad
9) post op rad
10) definitive restoration
Contraindications of EAL
pts w cardiac pace makers
Radiography is an integral part of successful endodontic treatment
What information can be obtained by a careful examination of a pre-op radiograph prior to commencing root canal treatment?(10marks)
- Presence of caries, restorations, posts, GPs, infection (peri-radicular radiolucency), fracture (J-shape radiolucency)
- Length from reference point e.g. incisal edge to radiographic apex - can be used to determine EWL
- Anatomy/shape of roots (narrow/curved), canals and no. of canals AND sclerosed root canals
*Bonelevels
List potential problems of endodontically treating curved canals and describe possible strategies to overcome these problems (10)
