cleaning and shaping the root canal Flashcards
RCT
prevent and intercept pulpal and pariradicular pathosis
2) preserve natural dentition when affect by pathosis
3) 95% for irreversible pulpitis
- 85% success for necrotic
aim of RCT
1) clean, shape, disinfect
2) obturate
3) healing
4) primary goals are remove soft and hard tissue, create space for delivery irrigants, obturation material
5) preserve integrity of radicular structures
mechanical objectives of cleaning and shaping
1) continuously tapering cone
2) prep in multiple plane creating a flow concept
3) prep should be wide coronally and narrow apically
4) apical foramen should remain in its original position
5) apical opening should be kept as small as is practical
ideally
1) root canal should include complete and centered incorporation of the original canals into the prepared shape
- with current techniques, this goal is unlikely to be met
2) to retain as much cervical and radicular dentin as possible so not to weaken the root
prep shape
1) removal of infected pulp and dentin
2) create prep shape and antimicrobial efficacy through the removal of pulp and dentin and creation of space for delivery of irrigants
continuous taper that encompasses the original shape and curvature of a given root canal
1) final prep size and taper is debatable
alloys in RCT
1) stainless steel
- stiff and inexpensive
1) nickel titanium
isolation
1) single tooth isolation
tip design
1) guide the file through the canal
2) cutting, non cutting, partially cutting
3) mishaps
- transport the canal if the tip is capable of enlarging the canal (cutting) and it remains too long in one position
4) break the file if a non cutting tip is forced into a canal smaller than the tip
blade
1) the cutting edges of the file that deflects and chips from the wall of the canal
2) effectiveness depends on its angle of incidence
flute
1) groove inbetween the blads
helical angle
1) angle that the cutting edge males with the long axis of the file
pitch length
1) distance between a point on the leading edge and the corresponding point on the adjacent leading edge
taper
1) amount the file diameter increases each mm along its working surface from the tip towards the file handle
2) can have constant or variable taper
ISO norms
1) taper .02 the increment in diameter is 0.02mm x each mm of length
2) all the colors except pink, gray, purple repeat every 6
K type
1) k- files
- made by twisting a stainless steel wire with a square cross section
- increase the resistance to torsion and make the file useful in the negotiation of the canals
5) f-flexofiles
- triangular cross section, rounded end
hedstrom
1) conical steel or niti wire with round section
2) it is ground into this shape
barbed broach
1) machined from a conival blank filament of SS creating numerous hooks
2) have an elevated capacity of breaking
filing
1) push pull movement 2-3 mm distance
2) can use circumferential filing
3) watch winding
ni-ti rotary file features
1) ability to alter their type of atomic bonding which causes a significant changes in the mechanical properties of the properties and crystallographic arrangement of the allow
- temperature and stress
2) super elasticity and memory shape
ESR CM vs WAVEONE
1) ESR CM is size #30 and less invasive, can be autoclaved
2) safety tip
where to end the apical prep
1) apical limit
- distance from the major diameter (apical foramen to the CDJ 0.72m)
2) optimal end point is the apical constriction
- this in theory, would create the smallest wound
3) make a stable flat reference point
- in close proximity to straight line path of instrument
how to determine working length
1) radiograph
2) apex locator
3) paper point
- used to confirm at the end of the appt
radiograph
1) parallelling technique
inaccuracy of radiographic WL
1) some clinicians have advocated the use of the electronic WL in lieu of the placement of a file in the canal and a radiograph
2) should be in the green, and you can decide if you want to be 0.5 mm shorter
- repeat the measurement 3 times
apical patency
1) refers to passage of a small hand file to the apical foramen to prevent the blockage of the foramen due to debris
glide path
1) smooth radicular tunnel from canal orifice to phsyiologic terminus
2) mechanical or manual