Endodontics Flashcards
1
Q
medical considerations prior to RCT (6)
A
- pregnancy; should be done in 1st trimester as emergency only, liaise with pt GMP
- cardiovascular disease; contraindicated if pt has had MI in past 6mths
- cancer; mode of tx is required, liaise with oncologist, consider XLA if tooth has poor long term prognosis
- diabetes; appt should not mess with insulin schedule, minimise stress
- MRONJ; liaise with pt physician
- allergies; GP us safe, possible NiTi or latex allergy
2
Q
clinical considerations for RCT (5)
A
- pulpal; sinus, abscess, TTP
- caries status; consider XLA if caries extension renders insufficient tooth to remain post XLA
- periodontal status; deep pockets >4mm, pus, mobility, furcation involvement
- restorative status; remaining coronal tooth structure, pre-existing crown status
- adjacent teeth status; sound periodontal & apical status
3
Q
radiographic considerations prior to RCT (6)
A
- endo status; if tooth is previously RCT consider apical & coronal seal quality, obturation not within 2mm of apex, poorly condensed
- periapical status; PDL widening, apical radiolucency, immature root apex
- root anatomy; no of canals, large curvatures, calcifications, dilacerations, resorption
- restorative; crown : root ratio, preexisting crown status
- bone levels; periodontally compromised teeth with significant bone loss may not be suitable for endo
- caries status; subcrestal caries is unrestorable, significant caries may prevent adequate isolation
3
Q
risks to discuss with pt (9)
A
- perforation
- instrument separation
- continued symptoms i.e. failed tx and need for re tx from specialist or XLA
- hypochlorite accident
- missed canals
- trismus
- post op pain, swelling, bruising
- need for multiple visits
- file #
4
Q
RCT overview
A
- pre op radiograph, LA, rubber dam
- remove any caries / restorations & assess restorability prior to initiating tx as isolation must be possible at later appts
- cut appropriate access cavity & locate canals
- carry out coronal prep to gain straight line access using ISO files & gates glidden
- determine WL - use electronic apex locator & WL radiograph
- benign canal prep
- throughout prep carry out recapitulation, patency & irrigation
- types of irrigant = EDTA / NAOCL
- obturate canals
- heat & cut down GP
- seal GP with RMGIC - remove 1mm of GP within entrance of canals & produce good coronal seal
- place appropriate core
- assess need for cuspal coverage
- follow up - annual radiographic assessment indicated for up to 4yrs
5
Q
types of irrigant (2)
A
- 2.5% NaOCl; dissolves necrotic & vital organic tissue, antimicrobial, lubricant
- 17% EDTA; dissolves smear layer, inorganic tissue, lubricant, chelator, decalcifying agent (useful in sclerosed canals)
6
Q
access cavity design principles (6)
A
- allow removal of entire contents of pulp chamber
- allow visualisation of pulp floor & canal orifices
- allow direct access to apical 1/3 of canal for instrumentation
- allow retention & support of a temporary filling material & good seal
- provide reservoir for canal irrigant
- be as conservative as possible
7
Q
canal access
A
- before starting analyse radiograph looking at: distance between occlusal surface & pulp chamber & root canal anatomy i.e. no of canals, length, curvature, calcification
- access cavity design - flat fissure bur often good
- place dam then penetrate pulp chamber at a single point above a recognisable canal orifice
- use safe ended access bur or ultrasonic to remove entire roof of pulp chamber
- flush out chamber & coronal aspect of canals with NaOCl (inject slowly using forefinger never thumb & be careful of droplets when removing from pt head)
- use a DG16 endo probe to locate canal orifices
- 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
8
Q
canal prep - modified step back technique
A
- 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
- prepare coronal 2/3s
- 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
- 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
- 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
- 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)
- 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
- 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
9
Q
what is the reason for 3 file sizes larger in the step back technique (3)
A
- to remove dead pulp, bacteria & their substrates
- to increase capacity of canals to retain a larger amount of irrigation agent
- to prepare canal for adequate operation
10
Q
options for apical to coronal prep (3)
A
- standardised
- step back
- modified step back
11
Q
options for coronal to apical canal prep (6)
A
- step down
- crown down
- hybrid
- double flared
- modified double flared
- balanced force
12
Q
canal prep - crown down technique
A
- 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
- 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
- establish WL; 0.5-1mm short of apex locator 0 reading or radiographic apex
- 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
- canal prep; prepare canal to 3 sizes larger than the first file that binds at the apex
- 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
- 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
13
Q
advantages of coronal prep first (3)
A
- improves tactile sensation
- prevents pushing bacteria from the infected coronal aspect further into canal, reducing the incidence of flare ups
- allows more accurate WL determination
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
