Chemomechanical Disinfection Flashcards
why is chemomechanical disinfection required
remove bacteria present
stop development into biofilm which adheres to dentinal surface and embed in extracellular matrix
what are the 2 clinical objectives of endodontic therapy
- remove canal contents
- eliminate infection
what is chemomechanical disinfection
mechanical means to debride and shape canal
supplemented with chemicals to enhance biofilm destruction
design objectives of chemomechanical disinfection
create a continuously tapering funnel shape, maintian apical foramen in original postion, keep apical opening as small as possible
what is the point in mechanical preparation
creates a sapce to allow irrigating solutions and medicaments to eliminate microorganisms more effectively from RC system
what are the 7 stages in mechanical preparation
- apical preparation
- working length determination
- coronal flaring
- initial negotiation
- creating a straight-line access
- access cavity preparation
- preparation of tooth
how to achieve apical preparation
removal of pulp/nerve
filing to create a bigger space
sodium hypochlorite NaOCl use
antibacterial activity, dissolves pulp remnants and collagen, dissolves necrotic and vital tissue, helps to disrupt smear layer
why and how would you use mechanical agitation with NaOCl
better exchange of irrigatn, improved irrigation, penetration and disruption of biofilm/smear layer
done via endoactivator sinic vibration or manual dynamic irrigation MDI [GP point]
problems with NaOCl
effect on dentine properties, cannot remove smear layer alone, effect on organic material
NaOCl and dentine effects
a higher concentration reduces elasticity and flexural strength
NaOCl and smear layer
inability to remove itself
need sufficient canal preparation before obturation, where smear layer is formed and interferes with disinfection and prevents sealer penetration
how to remove smear layer
17% EDTA, 10% citric acid, MTAD and ultrasonic irrgation
ethylenediaminetetraacetic acid = 1 min contact time
NaOCl complications
disscolouration of fabrics, ophthalmic injuries due to eye contact, apical extrusion leading to tissue necrosis, allergic reactions
chlorohexidine vs NaOCl
less antifungal, active against biofilms but cannot disrupt
interactions forms cytotoxic and carconogenic
proposed protocol cleaning and shaping
once canal preparation is complete, should be irrigated with
1. 3% NaOCl throughout instrumentation and at least 30ml after instrumentation complete with MDI - at least 10 mins prior to obturation
2. 17% EDTA 1 min penultimate rinse
3. 3 NaOCl final rinse
dry canal w paper points between irrigants
sodium hypochlorite extrusion definition
extruded beyond root canal into periradicular tissues, causing effect of chemical burns leading to localised or extensive tissue necrosis
NaOCl extrusion symptoms
pain, swelling, ecchymosis (bruising), haemorrhage, neurological complications, airway obstruction
ecchymosis can manifest along course of superifical venous vasculature = rare
risk factors of NaOCl extrusion
- excessive pressure during irrigation
- needle locked within canal
- loss of control of WL
- larger apical diameters/constriction [root resorption, immature teeth, developmental abnormalities]
- anatomical factors
- proximity to sinus
- higher NaOCl concentration?
excessive pressure + NaOCl extrusion
leads to needle being locked in canal
patent apical forman facilitated by anatomy of facial venous drainage means pressure at periapex has to exceed venous pressure in superifical veins of neck
flow rate important = 1ml/15secs
management of NaOCl extrusion into tissues
- stop tx
- stay calm, dont alarm pt but advise of what has happened
- consider LA if pain
- allow bleeding until haemostasis
- steroid containing intra-canal medicament (odontopaste) shouldbe placed in RC, ensuring no pressure
- dont obturate tooth at this visit
- seal coronal access cavity
- priotity to pain relief, reduction of swelling and prevention of secondary infection
cold compress 1-2 days, warm compress for resolution of soft tissue swelling, elimination of haemotoma, analgesics, review in 24hrs, prescription of antibiotics case specific
refer if severe
pre-op assessment of pt before NaOCl
be vigilant of open apices and perforations
restorative state of tooth assesed, pre-build up may be needed
what to give pt before NaOCl use
disposable bib to cover clothing
eyewear
use and test of dental dam and NaOCl
used to isolate tooth, ensure seal with oraseal
oral seal should be moulded to tooth conoturs with damp cotton wool
place clamp first for visualisation
ensure floss to secure clamp then remove
test by irrigating with chlorohexidine to ensure no leakage
what syringe to use with NaOCl
side-vented for irrigation
must all be labelled
Luer-Lok 27G needle, securely attached to 3ml syringe and test before
only fill 3/4 to aid control
silicone stop set to 2mm short of working length
use of irrigating needle with NaOCl
should not bind canal
depress plunger with index finger not thumb to reduce pressure
pass behing pt head
when are inta-canal medicaments used
when RCT cannot be completed within a single visit
why are intracanal medicaments used
placed inside RC between appts to destroy microorganisms and prevent reinfection
[proper preparation will minimise bacteria]
prevents multiplication of bacteria
reduces inflammation and controls root resorption
anti-microbial paste as intranal medicament
corticosteroid and tetracylcine
management of hot pulps, reudction of pulpal inflammation
effective for 5-7 days
non-setting calcium hydroxide as an intracanal medicament
pH 12.5 contributes to prolonged antibacterial activity
effective removing tissue debris
7 day treatment
combine with NaOCl for improved cleaning ability
hydrolysis of lipopolysaccharide reduces inflammatory potential
inter-appt disinfection
completely fill canal with CaOH paste, come into direct contact with bacterial cell well to be effective, placed via injection
inter-appt temporary dressing
must effectively seal root canal from contamination between visits
- Cavit, IRM, GI cements
