lecture 1: policies, access and working length Flashcards
access procedure outline
- draw on the tooth
- create outline form through enamel
- bur is somewhat perpendicular to lingual surface of tooth
- stay shallow at this point just want <1mm
access procedure penetration
- penetrate pulp chamber roof with bur angled approaching parallel to long axis of root in center of outline form
- reach pulp by 7mm
- confirm pulp canal entry with endodontic explorer
do you look for a canal with a bur
NO only with an explorer
endodontic explorer = DG16: PUSH
access procedure refining
- refine access prep with safe ended diamond bur or endo-Z
- want a straight-line access to mid root (mostly in molars)
endo-Z bur
a side cutting instrument only
working length determination
**
correct WL is 1mm SHORT of the CANAL EXIT
**
what will happen if you don’t get the WL right
you get a poor outcome
how to find the canal exit
- @hand: measure before you mount tooth
- @mouth: start with average length
- chart, apex locator and xrays
can you take xrays with a #10 file
no.. it is too thin and will not be seen in xrays
use a #15.
average root length of maxillary incisors
CI: 22.5
LI: 22
average root length of mand incisors
CI: 20.7
LI: 21.1
average root length of max and mand canine
max: 26.5 and mand: 25.6
average root length of max pm
1pm: 20.6
2pm: 21.5
average root length of mand pm
1pm: 21.6
2pm: 22.3
average root length of max molars
1M and 2M 20
1M = 20.8
average root length of mand molars
1m: 21
2m: 19.8
what hand file do you use when using the apex locator
15 hand file. used to estimate the canal length
between patency and WL.
1mm between the two
WL is critical
patency
where canal exits the root. 1mm short is the constriction and what your WL is.
what is a “blow out” and how does it happen
- when it is too long and a blow out guarantees incomplete compaction at the apex and an explosion of sealer in the PA tissue.
you must have a reliable reference point… where are good locations to have a solid, reproducible location on the tooth
- tip of incisal edge (ant)
- tip of cusp for which the canal is name (molar)
usual # of roots and root canals for max incisors
roots: 1
root canals: 1
usual # of roots and root canals for max C
roots: 1
root canals: 1
usual # of roots and root canals for max pm
1pm root: 2
1 pm root canals: 2
2pm root: 1, maybe 2
2pm root canals: 1, maybe 2
usual # of roots and root canals for max M
roots: 3
root canals: 3, maybe 4 or more
usual # of roots and root canals for mand I
root: 1
root canal: 1, maybe 2
usual # of roots and root canals for mand C
root: 1
root canal: 1
usual # of roots and root canals for mand pm
root:1
root canal: 1, maybe 2
usual # of roots and root canals for mand m
root: 2
root canals: 3, maybe 4 or more
definition of access
drilling a hole through coronal structure to gain entrance into the pulp chamber
3 steps of access
- outline form
- coronal access
- radicular access
requirements of access (4)
- visibility of pulp chamber and all canal orifices from a single vantage point
- straight-line access to mid-root for instrument placement
- complete removal of pulpal roof and pulp horns
- avoidance of unnecessary weakening of tooth
wall of the coronal access should be ____ to the occlual
diverge
why do you diverge the coronal access (3)
- better light
- better visualization
- helps with leak and contamination
access shape of max CI
triangular access, with base at the incisal.
m and d marginal ridges are not invaded or weakened
access shape of max LI
triangular/oval access
*the most difficult of max ant teeth
access shape of max C
triangular/oval access
access shape of mand I
oval access
- very narrow M-D, easy to perforate so be careful.
canals of mand I
40% 2 canals (type II)
60% 1 canal
access shape of mand C
oval access
canals of mand C
78% 1 canal
22% 2 canals
access of max 1 PM
thin oval access
- access is always gained through the O approach on all post teeth
canals of max 1 PM
- 85% 2 canals
- 9% one canal
- 6% three canals
access shape of max 2PM
thin oval
canals of max 2PM
most often type I 1 root, 1 canal (75-85%)
- 15-25% two roots
- 3 roots is really rare
access of mand 1PM
thin oval
canals of mand 1PM
usually 1 root, 1 canal 73.5%
- type IV is 24%
access of mand 2PM
thin oval
canals of mand 2PM
- one root, one canal type I 85.5%
- type III 11.5%
access max 1 M
triangle
apex to palatal should not cross the oblique ridge
canals of the max 1M
4 canals the majority of the time
access of max 2M
similar to the first molar but more compressed MD
(triangle
apex to palatal should not cross the oblique ridge )
access mand 1M
trapezoid preferred
canals of mand 1M
- 4 canals 64%
3 canals 29%
access of mand 2M
- trapezoid/triangle similar to first (trapezoid preferred )
canals of mand 2M
81% 3 canals
11% 4 canals
