endodontology part 2 Flashcards
what are the steps of root canal treatment
access
chemo mechanical preparation
medication- temporisation with ca(oH2) and pledget
obturation with GP
restore- on post teeth with cusp coverage restoration
on anterior- composite restoration usually
why do we use ca(oh2) during temporisation
as it is very alkaline- has a pH of 12 and therefore kills any bacteria that was left in the canal
prevents bacteria getting back in
give examples of steroid based dressings
odontopaste
ledermix
why are steroid based dressings not used
as steroids require a blood supply to work and you have removed the pulp
when is the only time we will used ledermix
on lower molar teeth- hard to anaesthetise and the steroid dressing will make it easier to anaesthetise next time
what are the options after we have located and accessed the tooth
hand preparation and using the rotary instruments to shape the canals
what are we trying to achieve when we shape the canals
a continuous smooth tapered to the apex
why is a tapered shape ideal for the canals
facilitates both irrigation and the obturation of the canal
what is chemo-mechanical preparation of the canals
it is when we use chemicals such as sodium hypochlorite/chlorhexidine to clean out the canals as well as rotary instruments and hand files to remove the necrotic pulp
where is most bacteria found in the tooth
the coronal part of the tooth therefore we have to remove the pulp roof adequately
what is coronal flare
the flaring of the coronal third of the tooth using gates gligdens and widening the part of the tooth
what technique do we use for hand instrumentation
step down technique
stem winding- doesn’t change the shape of the canal
what is the step down technique
using the smallest
what is the balance force technique
engage the file into the dentine and dentine whilst applying apical peressure which breaks a bit of dentine off
creates stress in the files and therefore breaks so it is NOT AS IDEAL TECHNIQUE
what is stem winding
you place the file into the canal and rotate the file slowly to remove debris
takes more time but less procedural errors
what is the anti curvature filing technique
file away from the curvature of the root canal- as the curvature is usually the thinner part and therefore you will just file out of the root (strip perforation)
what are the types of files
stainless steel/nickel titanium(newer) K type( K file, K flex, K flexo) H type (hedström)
how are k flexo files made
they have a rhombiodal cross section shape and they are made by twisting them
what is the issue with hedstrom files
as the flutes are mechanically cut into the file it does suffer from micro cracks which leads to the file usually cracking in the tooth
what re components of the file
handle- will stamp the size
file length
silicone stop- helps with the reference point
if a file size is 35 what size is the tip
0.35
what are usual file lengths
21
25
31mm
what is the cutting length of the file
19mm- MIGHT GET ASKED IN EXAM ***
which file should we use
the shortest file that can do the job as there is more tactile sensation
what can differ in the tips
they can be cutting or non cutting
which k files are non cutting
k flexo
which files have cutting tips
hedström files
what do the files have
2% taper- meaning for every 1mm back from the tip the diameter increases by 0.02mm
MIGHT ASK IN EXAM***
who first described the step-down preparation
goerig in 1982
what is the double flare
coronal flare and then the apical flare and blending back to create a taper
what prep shall we do first
the coronal flare- do not force files into the canal
how can we tell the size of the gates glidden
by the number of bands on the non working end
what is the working end of a GG2 the same size as
a size 70 file- 0.7mm
what is the working end of a GG3 the same size as
a size 90 file
what is the working end of a GG4 the same size as
110 file
how do gates gliddens work
use with a brushing motion and cut on the out stroke
how do we finish apical preparation
determine the working length
using an apex locator and a radiograph using a size 10/15 length
what is the working length
the length from the coronal aspect of the tooth to the apical constriction
what is the apical constriction
where the apex of the tooth narrows it is a few mm away from the apical foramen
what is the step down technique
use the smallest file eg 10 and using the stem winding technique rotate until loose
then use eg the size 15 file and work till loose
and then the size 20 file until loose
if a file does not fit DO NOT FORCE it just go back to the size smaller file and continue to rotate
what is cold lateral compaction
GP into the root canal and the finger spreader along the side and push the GP to the side of the canal
keep going till you cannot fit anymore GP in the canal
how do we cut the GP
using a heater instrument and cut the GP to the CEJ
what is the master apical file
the largest file that is used to the full working length
what is the master apical file dependant on
the size of the curvature and the original size of the canal
how do we obturate
use a master apical file to see the full size of the working length and then get GP of the same size
dry the canal with paper points and ensure it goes to working length till you can feel a tug back
how does the cold lateral compression technique work
using a finger spreader and GP to fill the canal and use accessory cones to fill the canals
what do we do once we have all the GP in the canals
take a radiograph called the mid fill radiograph- to check if you’ve got GP in the right place
what is thermoplasticised techniques
using a hot instrument to melt the GP so it flows into lateral canals as well as vertical canal
where do we cut back the GP to in a posterior tooth
the oriface
