cleaning and shaping II Flashcards
biomechanical
1) use of instruments with irrigants
chemomechanical
1) chemicals with instruments
purpose of instrumentation
1) remove debris
2) shape canal
3) permits irrigant penetration
4) prepare for obturation
tapering funnel
1) tapering funnel from apex to access cavity
2) cross-section should be narrow at every point apically
3) foramen in original spot, small as practical
4) looks like a tornado
working length
1) defined as length between coronal reference
recapitulation
1) small K file or master apical file to remove debris
patency
1) a size #8 k fil to go slightly through the foramen without binding or enlarging
2) removes the vapor lock so irrigant reaches apex
working length and patency
1) working length is 0.5mm shorter
anticurvature filing
1) danger zone near the furcation area
2) straighten as we use them, which can cause strip perforation
balances force technique
1) K files with rounded batt tips
2) counterclockwise and clockwise
what is taper
1) diameter increase per millimeter
step back technique
1) you can create taper by backing off each 1 mm and increase 0.5mm diameter in size file
pre-flaring crown doqn
1) less risk of extrusion
2) less risk of flare up
3) earlier penetration of irrigant
4) less change in working length
5) greater tactile sensation
6) apex locators are more accurate
7) less risk of breaking a file
where to find apical constriction
1) 0.5 mm from the major diameter (apical foramen)
2) portal of exit is frequently not at the apex
determine working length
1) apex locator and tells you where you are touching PDL
2) file in the root and take radiograph
3) paper point to check for tissue fluid after all the tissue has been removed
apical preparation size
1) root canal systems were enlarged 2,3,4,5,6 sizes bigger than initial instrument
2) at least 3 sizes bigger promotes healing
3) minimum of 25.06 or 30.04
(diameter at apex and taper)
- for irrigant to reach the apex
why use irrigants
1)35% of the canal is untouched by the instruments
2) impossible to remove bacteria from apex and ramifications
3) tissue and bacteria exist in isthmus between canals
effect of taper
1) bigger taper increases the irrigation
effect of size
1) bigger size increases irrigant
ideal irrigant
1) antibacterials
2) remove smear layer and inactivate LPS
3) dissolve tissues
no irrigant
1) possess all good qualities
2) sodium hypochlorite is irritating, cannot remove all smear later, not induce cell mediated response
how does NaOCl work
1) saponification
- break down fatty acid
2) acid base reaction
3) chlorination
- break down AA, inhibit enzymes. damage cell membranes, denatures proteins, damage DNA
maximize efficacy
1) multisonics that allow irrgant to work its way down to canals
danger of sodium hypochlorite
1) if it goes outside the tooth into periodontal tissues
2) pain, swelling, major bleeding through the canal
3) bend the needle short, and side vented, measure the needle, keep syringe moving
EDTA
1) chelator
2) removes the smear layer right before obturation
3) aids in canal instrumentation (negotiating blocked canals)
4) used in regenerative procedures to release GF from dentin
chlorohexidine
1) DO NOT USE
2) doesn’t dissolve tissue
3) causes precipitation
do not use compressed air or water
1) if it is not sterile or do not contain disinfecting properties
calcium hydroxide
1) basic between 11-12 pH
2) dissolves tissues
3) inactivates LPS and cytokines
4) bacterial free in 7 days
necessary radiographs
1) pre-op
2) working length
3) cone fit
4) mid obturation
5) post op
proper sequence
1) subjective
2) we use brassler, NiTi rotary instruments = faster and preps are more centered
3) coronal flaring should be accomplished with the brassler to 1/3 WL
3) use apex locator and advance file to red area, then retract until bery last green
4) take WL radiograph
cleansing and shaping
1) glide path must be established
- accomplished with hand files to a loose size #15
2) #25 then to #30 blue
3) canals should be flooded with sodium hypochlorite but glyde should not be used with rotary instruments because it increases torque
mishaps
1)inspect files
2) do not reuse files
3) torsional failure or cyclic fatigue
common complications
1) not enough irrigation
2) not maintaining patency
3) using instruments that are too big
4) using instruments out of sequence
5) packing dentin debris
6) never use a rotary instrument without creating a guide path to size #15 first
pitfalls
1) transportation
2) ledge
3) apical zip
4) perforation
golden rules
1) always have NaOCl in canal when shaping
2) use files in order
3) maintain patency
rotary instrumentation
1) determine working length
2) coronal flaring
3) glide path to 15
4) irrigate and confirm patency with #8
5) 30.04 to working length
6) apical gauging
