Endodontics Flashcards

1
Q

medical considerations prior to RCT (6)

A
  1. pregnancy; should be done in 1st trimester as emergency only, liaise with pt GMP
  2. cardiovascular disease; contraindicated if pt has had MI in past 6mths
  3. cancer; mode of tx is required, liaise with oncologist, consider XLA if tooth has poor long term prognosis
  4. diabetes; appt should not mess with insulin schedule, minimise stress
  5. MRONJ; liaise with pt physician
  6. allergies; GP us safe, possible NiTi or latex allergy
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2
Q

clinical considerations for RCT (5)

A
  1. pulpal; sinus, abscess, TTP
  2. caries status; consider XLA if caries extension renders insufficient tooth to remain post XLA
  3. periodontal status; deep pockets >4mm, pus, mobility, furcation involvement
  4. restorative status; remaining coronal tooth structure, pre-existing crown status
  5. adjacent teeth status; sound periodontal & apical status
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3
Q

radiographic considerations prior to RCT (6)

A
  1. endo status; if tooth is previously RCT consider apical & coronal seal quality, obturation not within 2mm of apex, poorly condensed
  2. periapical status; PDL widening, apical radiolucency, immature root apex
  3. root anatomy; no of canals, large curvatures, calcifications, dilacerations, resorption
  4. restorative; crown : root ratio, preexisting crown status
  5. bone levels; periodontally compromised teeth with significant bone loss may not be suitable for endo
  6. caries status; subcrestal caries is unrestorable, significant caries may prevent adequate isolation
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3
Q

risks to discuss with pt (9)

A
  1. perforation
  2. instrument separation
  3. continued symptoms i.e. failed tx and need for re tx from specialist or XLA
  4. hypochlorite accident
  5. missed canals
  6. trismus
  7. post op pain, swelling, bruising
  8. need for multiple visits
  9. file #
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4
Q

RCT overview

A
  1. pre op radiograph, LA, rubber dam
  2. remove any caries / restorations & assess restorability prior to initiating tx as isolation must be possible at later appts
  3. cut appropriate access cavity & locate canals
  4. carry out coronal prep to gain straight line access using ISO files & gates glidden
  5. determine WL - use electronic apex locator & WL radiograph
  6. benign canal prep
  7. throughout prep carry out recapitulation, patency & irrigation
  8. types of irrigant = EDTA / NAOCL
  9. obturate canals
  10. heat & cut down GP
  11. seal GP with RMGIC - remove 1mm of GP within entrance of canals & produce good coronal seal
  12. place appropriate core
  13. assess need for cuspal coverage
  14. follow up - annual radiographic assessment indicated for up to 4yrs
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5
Q

types of irrigant (2)

A
  1. 2.5% NaOCl; dissolves necrotic & vital organic tissue, antimicrobial, lubricant
  2. 17% EDTA; dissolves smear layer, inorganic tissue, lubricant, chelator, decalcifying agent (useful in sclerosed canals)
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6
Q

access cavity design principles (6)

A
  1. allow removal of entire contents of pulp chamber
  2. allow visualisation of pulp floor & canal orifices
  3. allow direct access to apical 1/3 of canal for instrumentation
  4. allow retention & support of a temporary filling material & good seal
  5. provide reservoir for canal irrigant
  6. be as conservative as possible
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7
Q

canal access

A
  1. before starting analyse radiograph looking at: distance between occlusal surface & pulp chamber & root canal anatomy i.e. no of canals, length, curvature, calcification
  2. access cavity design - flat fissure bur often good
  3. place dam then penetrate pulp chamber at a single point above a recognisable canal orifice
  4. use safe ended access bur or ultrasonic to remove entire roof of pulp chamber
  5. flush out chamber & coronal aspect of canals with NaOCl (inject slowly using forefinger never thumb & be careful of droplets when removing from pt head)
  6. use a DG16 endo probe to locate canal orifices
  7. at this point consider modifying your access cavity design to allow straight line access to canals; the goal is to allow thorough cleaning & shaping
    * RCT system is complex & inaccessible so the activation of NaOCl helps to maximise its effect; this is done via use of ultrasoincs
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8
Q

canal prep - modified step back technique

A
  1. scout canals & carry out coronal pre-flaring; this is flooding the coronal aspect 1st to eradicate most of the bacteria then introduce a pre curved size 10 K file to gently negotiate canals & flare upwards and outwards using size 2 and 3 GG burs in coronal few mm only
  2. prepare coronal 2/3s
  3. establish WL; this is 0.5-1mm short of apex locator zero reading or radiographic apex. for apex locator only a 0 reading is accurate
  4. establish a ‘glide path’ using a size 10 K file; using hand instruments explore & negotiate the coronal 2/3s & flush with NaOCl then using hand or rotary NiTi files prepare & enlarge coronal 2/3s
  5. canal prep - prep canal to 3 sizes larger than the first file which binds at the apex; this can be done with hand files or rotary filing
  6. step back using the next file size up 0.5-1mm from that length. copious irrigation, recapitulation & patency reestablished. consecutively keep working the hand file size up 0.5-1mm short of previous length to join your apical presentation to coronal prep (usually 3 file sizes)
  7. using a watch winding technique with no pressure. wipe flutes throughout tx on a sponge/gauze to stop clogging. file sizes larger than ISO 45 can be too stiff for use in molars
  8. if there is abscess or uncontrolled bleeding or weeping canals dress the canals with non setting CaOH for 2-wks 7 review for cleaning & obturation; there is no significant different in outcome between single & multiple visit RCT
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9
Q

what is the reason for 3 file sizes larger in the step back technique (3)

A
  1. to remove dead pulp, bacteria & their substrates
  2. to increase capacity of canals to retain a larger amount of irrigation agent
  3. to prepare canal for adequate operation
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10
Q

options for apical to coronal prep (3)

A
  1. standardised
  2. step back
  3. modified step back
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11
Q

options for coronal to apical canal prep (6)

A
  1. step down
  2. crown down
  3. hybrid
  4. double flared
  5. modified double flared
  6. balanced force
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12
Q

canal prep - crown down technique

A
  1. scout canals & carry out coronal pre flaring; this is flooding the coronal aspect 1st to eradicate most of the bacteria then introduce a pre curved size 10 K file to gently negotiate canals & flare upwards and outwards using size 2 and 3 GG burs in coronal few mm only
  2. prepare coronal 2/3s; using hand instruments explore & negotiate coronal 2/3s, flush with NaOCl then using hand or rotary NiTi prepare & enlarge coronal 2/3s
  3. establish WL; 0.5-1mm short of apex locator 0 reading or radiographic apex
  4. establish a ‘glide path’ by hand or rotary filing. this is the rotary technique but a size 10K file must be loose in canal prior to introducing rotary instruments
  5. canal prep; prepare canal to 3 sizes larger than the first file that binds at the apex
  6. based on rotary system selected select file size to match canal & prepare in brushing motion (away from furcation) to WL, use files in sequence. do not place pressure on file. canals should be irrigated copiously throughout filing with recapitulation & patency. check file after apical prep; if feeling ‘loose’ then go one size larger and if this is loose go larger again
  7. if there is abscess or uncontrolled bleeding or weeping canals dress the canals with non setting CaOH for 2-wks 7 review for cleaning & obturation; there is no significant different in outcome between single & multiple visit RCT
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13
Q

advantages of coronal prep first (3)

A
  1. improves tactile sensation
  2. prevents pushing bacteria from the infected coronal aspect further into canal, reducing the incidence of flare ups
  3. allows more accurate WL determination
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14
Q

hypochlorite accident management

A
  • stop procedure immediately, inform & reassure pt
  • irrigate with copious saline & leave tooth open for drainage
  • for pain administer LA & prescribe NSAIDs
  • to reduce risk of 2ndary infection prescribe amoxicillin / metronidazole
  • advise pt to use cold compress for analgesia in first few days & warm compresses for circulation in the latter
  • review after a few days & place temporary seal
  • good record keeping with clinical photographs is a must
  • referral to 2ndary care based on clinical judgement but if swelling of affected site is >30% compared to contralateral side then consider referral
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15
Q

canal obturation

A
  1. cold lateral condensation
  2. thorough irrigation; penultimate rinse with 17% EDTA for 1 min followed by rinse with NaOCl
  3. select appropriate master GP cone according to master apical file & mark at WL. consider taking mid fill radiograph to confirm WL. disinfect GP with NaOCl & master GP should exhibit tug back at the WL
  4. lightly coat master cone in sealer; types of sealer inc: resin, GIC, ZOE, CaOH
  5. seat cone in canal ensuring it goes to WL
  6. select finger spreader set to 1mm short of WL and place alongside master GP - this allows GP to deform against canal walls. ensure not too much pressure is placed on finger spreader as this can cause root #. if heated finger spreader is used then this is warm lateral condensation
  7. dip accessory points in sealer & insert into canal simultaneously removing the finger spreader using rotational movement
  8. reinsert spreader & repeat with more accessory points until filled
  9. remove excess GP with heated excavator at level of canal orifice
  10. clean access cavity using ultrasonic & cotton pellet dipped in alcohol (allows better bonding of restoration)
  11. post prep at this stage if required
  12. seal RCT with a core
    * this is the most common method for obturation
16
Q

management of ledges

A
  1. be patient & slow down
  2. identify location of ledge with small hand file & tactile sensation
  3. enlarge canal space t 1mm short of ledge i.e. if ledge is 16mm down the canal enlarge up to 15mm of canal using hand files / rotary
  4. place a small sharp kink in the end of an ISO 8 K file which should easily go down enlarged canal
  5. scout the walls and fee for a drop into the canal
  6. once in canal do not exit
  7. file & smooth ledge away with gentle up & down movements
  8. once the ISO 8 can glide & feels loose move successfully up to an ISO 10, 15, 20 K file
  9. continue with canal prep via hand or rotary files
  10. if further tx is beyond your limit then refer
    important that complications are explained to pt BEFORE commencing tx
    ledges can be avoided by ensuring a good access cavity design with straight line access to the canals. use pre curved hand files with lubricant & a gentle watch winding motion, never force the files
17
Q

management of perforations

A
  1. all RCT should be properly consented & risks explained to pt
  2. inform pt of perforation & decide with pt how best to proceed
  3. consider referral if procedure is not within scope of your practice
  4. prior to referral place cotton wool over perforation with CaOH & dress with ZOE/GI & inc info regarding cause & location in referral letter
  5. if managing inhouse first achieve haemostasis using pressure - 5mins with sterile cotton pellet / heat - heated instrument or system B tip to gently cauterize bleeding
  6. plug perforation - gold standard is to use calcium silicate based cements i.e. MDTA or biodentine but ZOE/GIC can also be used
  7. allow appropriate setting time i.e. biodentine takes 9-12mins & MTA takes >12hrs. dress MTA with damp cotton pellet, close up to allow setting & return NV to complete RCT
  8. seal over with GIC
  9. complete RCT, review at 6mths then annually up to 4yrs
18
Q

why do perforations occur

A

due to over instrumentation or poor understanding of anatomy of tooth

19
Q

what is the success of perforation management dependent on

A

success dependent on location size & time. coronal perforations have a lower prognosis than apical perforations as they can develop perio-endo lesions around them. smaller perforations & those treated quickly have a better success rate