Lecture 1: Working Length & Access Flashcards
When, why and how to refer your potential problems describes:
case selection
Most non-complicated cases follow:
one basic RCT technique
LEO:
Lesion of endodontic origin
What are our objectives with endo cases?
- correctly DIAGNOSE disease as LEO
- PERFORM quality NS endodontic therapy
- RESTORE & DOCUMENT healed outcome
What will cause your endodontic treatment to FX & fail?
lack of placing mandatory crown
Endo treatment is considered an extreme service to the patient as we:
- relieve acute pain
- retain otherwise lost natural tooth
More points are lost in lab to ____ than anything else
poor access
Most failures on WREBs & AEDC are due to:
poor access
What is the first step of access procedure?
Draw outline form on tooth
The shape of the outline form of the tooth is dependent on:
anatomy of the pulp chamber
After drawing the outline form on the tooth, what step is next?
Create outline form just through enamel with number 2 round bur or 330 bur on high speed
What layer should be drilled through when creating outline form?
Just through the enamel
What burs and what speed may be used when creating the outline form?
2 round bur or #330 bur on high speed
When creating the outline form the bur is somewhat _____ to the _____ surface of the tooth
perpendicular; lingual
When creating the outline form its important to stay ____ at this point; just through the enamel at less than_____mm
shallow; 1mm
After the outline form is created the next step to the access procedure is:
penetration
During the penetration step of access procedure, penetrate the pulp chamber roof with _____ approaching _____ in center of outline form
bur angled; parallel to long axis of root
During the penetration step of access procedure, penetrate the ___ with the bur angled approaching parallel to long axis of the root in the _____ of the outline form
pulp chamber roof; center
During the penetration step of access procedure, you should reach the pulp in most cases by:
7mm
(if not ask for help- never go beyond 7mm)
During the penetration step of access procedure, how should you confirm the pulp canal entry?
With endodontic explorer; DG16 (push)
Do confirm pulp canal entry during the penetration step of access procedure, you should NEVER look for canals with:
a bur
What step of access procedure follows penetration?
Un-roofing
Un-roof pulp chamber with:
brushing out strokes
When un-roofing the pulp chamber with brushing-out strokes, be careful not to:
Gouge axial walls
When un-roofing the pulp chamber, remove ____ & smooth ____
obstructions; the walls
When un-roofing, irrigate well with NaOCl for:
- vision
- removal of debris
- begin disinfection
Following the un-roofing step of the access procedure, we:
refine
Refine the access prep with ____ or ____ to help provide straight-line access to mid-root (mostly in molar access)
Safe ended diamond bur; Endo-Z bur
The Endo-Z bur is the ____ one
gold
Why do we use the safe endo diamond bur or endo-Z bur during the refining step of access procedure?
To help provide straight-line access to mid-root
During the refining step of access procedure, the non-cutting tip of the bur (safe end of diamond bur or endo-Z bur) is simply:
A pilot
Do NOT JAM the Endo-Z bur INTO the canal. This is a:
side cutting instrument only
After ACCESS your next big task is:
working length
The correct working length=
1 mm short of the canal exit
If you do NOT get the ____ right; you will likely result in a poor outcome
working length
Incorrect working length may instigate:
apical periodontitis
How you find the canal exit in your hand? (2)
- look at the canal exit
- measure BEFORE you mount the tooth
How do you find the canal exit in the mouth?
- start with average length
- chart
- apex locator (if possible)
- radiograph with #15 file in canal
Average root length central incisor:
maxillary: 22.5
mandibular: 20.7
Average root length lateral incisor:
maxillary: 22.0
mandibular: 21.1
Average root length canine:
maxillary: 26.5
mandibular: 25.6
Average root length first premolar:
maxillary: 20.6
mandibular: 21.6
Average root length second premolar:
maxillary: 21.5
mandibular: 22.3
Average root length first molar:
maxillary: 20.8
mandibular: 21.0
Average root length second molar:
maxillary: 20.0
mandibular: 19.8
Usual number of roots & canals for maxillary incisors (teeth #7,#8,#9,#10):
one root, one canal
Usual number of roots & canals for maxillary canines (teeth #6, #11):
one root, one canal
Usual number of roots & canals for maxillary first premolars (teeth #5, #12):
two roots, two canals
Usual number of roots & canals for maxillary second premolars (teeth #4, #13):
Usually one, possibly two
Usually one, possibly two
Usual number of roots & canals for maxillary molars (teeth #1,#2,#3,#14,#15,#16):
Three roots, sometimes three but probably four or more
Usual number of roots & canals for mandibular incisors (teeth #23,#24,#25,#26):
One root, one canal possibly two
Usual number of roots & canals for mandibular canines (teeth #22,#27):
One root, one canal
Usual number of roots & canals for mandibular premolars (teeth #20,#21, #28, #29):
One root, one canal, possibly two
Usual number of roots & canals for mandibular molars (teeth #17,#18,#19,#30,#31,#32):
Two roots, three canals possibly 4 or more
How do we determine the correct working length in clinic?
apex locator
To determine the correct working length, place a _____ hand file in the access & extend it in the canal to the estimated canal length
15 hand file
Everything you do following an inaccurate working length is:
wrong
The goal for WL is:
1 mm short of the canal exit
The goal for WL is 1mm short of the canal exit, this placed WL in close proximity to :
the natural apical constriction
What happens if you WL is too short?
The canal is NOT well cleaned
What happens if you WL is too long?
Results in “Blow out” which guarantees:
- incomplete compaction at the apex
- an explosion of sealer in the PA tissues
In regards to WL, your reference point should be: (2)
- easy to see
- easy to reproduce
When selecting a reliable reference point for anterior teeth you should use the:
tip of incisal edge
When selecting a reliable reference point for posterior teeth you should use:
tip of cusp for which the canal is named
T/F: It is okay to reduce your reference point after WL is determined
False- don’t reduce it after WL is determined
What is the first step after diagnosis?
access
Access to the pulp chamber facilitates: (6)
- locating the canals
- negotiating the canals
- gaining patently
- establishing WL
- maintaining apical constriction
- a good outcome
Arguable the single most important requisite contributing to routine endodontic success:
proper access
Poor access yields problems such as: (5)
- No predictable result
- routinely missed canals
- unable to properly clean
- unable to shape completely
- unable to fill adequately
Access involves:
drilling a hole through coronal structure to gain entrance into the pulp chamber
The objective of access is to create an effective shape, this includes: (4)
- smooth
- constantly tapering
- respecting shape of natural canal
- constricting near terminus of root
What is considered the “coke bottle effect” with access?
Canal is bigger than the cervical access at some more apical point in the canal
List the requirements of access: (4)
- visibility of pulp chamber and ALL canal orfices from a SINGLE vantage point
- straight-line access to mid-root for instrument placement
- complete removal of pulpal roof & pulp horns
- avoidance of unnecessary weakening of tooth
What do we mean when referring to “visibility” as a requirement of access?
Visibility of pulp chamber and ALL canal orfices from a SINGLE vantage point
Visibility of pulp chamber and ALL canal orfices from a SINGLE vantage point =
draw
Why is straight-line access to mid-root a requirement to access?
Straight-line access to mid-root is required for instruments and obdurating materials (without regard to long axis of tooth)
Cross-hatched area of secondary dentin that should be removed to create better access to the mesial root:
dentin triangle
What may be used to remove the dentin triangle to create better access to the mesial root?
.25/.12 rotary file
Why is it important to preserve tooth structure during access?
to avoid unnecessary weakening of tooth
What are the three main steps to access?
- outline form (2D surface shape)
- coronal access (extending into pulp)
- radicular access (adjustments to allow easy straight-line entry to mid-root of each canal)
The 2D plan for the initial opening (could be traced onto crown):
outline form
To allow unobstructed visualization of the pulpal floor and ALL canal orfices from a single vantage point:
coronal access
During coronal access you should reach the pulp at ____ or less
7mm
T/F: The pulpal floor should NOT be touched by access bur
true
Walls of the coronal access should _____ to the occlusal
diverge
Walls of the coronal access should DIVERGE to the occlusal because: (3)
- better light
- better visualization
- temp restoration placed between visits will not be easily dislodged to leak & contaminate
To allow straight-line access to mid-root for all shaping instruments and obturation materials (observe canal path- not long access of tooth):
radicular access
Facilitates “crown-down” procedure
Radicular access
T/F: Hand files generally require 10 strokes/file before going to the next larger size file
False- generally require 100 strokes/file
Common canal configurations:
-One canal from pulp chamber to apex
Type I
Common canal configurations:
-Two canals from pulp chamber join prior to apex
Type II
Common canal configurations:
-Two canals from pulp chamber to apex
Type III
Common canal configurations:
-One canal from pulp chamber divides prior to apex
Type IV
Which type of canal configuration is the most difficult to treat?
Type IV
Label the type of canal configuration seen below:
Type I
Label the type of canal configuration seen below:
Type II
Label the type of canal configuration seen below:
Type III
Label the type of canal configuration seen below:
Type IV
What is the shape of access for a maxillary central incisor?
triangular access (base of triangle at incisal)
T/F: For access with a maxillary central incisor, the angles of the triangle are slightly rounded
true
For a maxillary central incisor what is the measurement of the triangle on all sides?
about 3 mm
Total straight-line access on anteriors would involve access from the facial and create weakening of the incisal edge and an esthetic issue, this is called:
incisal compromise
“Incisal compromise” is when total straight-line access on anteriors would involve access from the facial and create a:
weakening of the incisal edge and esthetic issue
What is the shape of access of a maxillary lateral incisor?
triangular/oval
The maxillary lateral incisor has a thinner root than the central incisor meaning:
narrower access M-D and narrower pulp horns
When accessing a maxillary lateral incisor, its important to note that the root curves to the _____ and the apex tips to the ____
distal; palatal
Due to the apex tipping to the palatal, what is the most difficult maxillary anterior tooth to access?
lateral incisor
Phenomenon on all anterior teeth in regards to access:
Incisal compromise
What is the shape of access for a mandibular canine?
Oval access
If the mandibular canine has one root, its usually very wide:
F-L
What type of canals can be seen in a mandibular canine? What type is seen most often?
Type I, II or IV; Type I most common
According to Vertucci, ____% of mandibular canines have one canal, whereas ___% have two canals
78% ; 22%
T/F: it is more common for a mandibular canine to have two canals than one canal
False- one canal is much more prevalent
To avoid common errors of access, you should: (2)
- line up penetration in two planes (MD & FL)
- visualize cervical cross section
A common iatrogenic error that often spell the demise of the tooth:
perforations
List some common errors of access: (6)
- too large
- skewed to distal
- too small & round
- too cervically placed
- pulp horns not cleaned
- straight-line access to mid-root is inhibited
Inadequate access compromises ____
shaping
Inadequate access induces:
bending of th efile
Inadequate access creates ____ of canal
apical transportation
Access is ALWAYS gained through _____ approach on ALL posterior teeth
occlusal
What is the shape of access for a maxillary first premolar?
thin (MD) oval access
The thin oval shaped access for a maxillary premolar should be the width of:
4 round bur
Most commonly in a maxillary first premolar we see ____ canals
two
List the prevalence of the following canals for a maxillary first premolar:
____% two canals
_____% one canal
_____% three canals
85% two canals
9% one canal
6% three canals
What is the shape of access for a maxillary second premolar?
Thin oval
The thin oval shape of access for a maxillary second premolar should be the width of:
4 round bur
Most often we see the maxillary second premolar have a type _____ canal with ____ root ____ canal (75-85%)
Type _____, ____ & ____ are less frequent
Type I; 1 root 1 canal
Type II, III, IV
How often do we see two roots for a maxillary second premolar? How often do we see three roots?
2 roots: 15-25% of time
3 roots: rare
In a maxillary second premolar, if one canal is found but is not in the center FL, then we should assume:
2 canals present
In regards to a maxillary second premolar we should beware of type ____ because they are very hard to shape, clean & fill
Type IV
What is the shape of access for a mandibular first premolar?
Thin oval
Mandibular first premolars usually have _____ root(s) and ____ canals ____% of the time.
one root, one canal (73.5%)
Mandibular first premolars usually have 1 root and 1 canal 73.5% of the time. They have type IV canals ___% of the time. They have three canals ____% of the time.
24%; less than 1%
What is the shape of access for a mandibular second premolar?
Thin oval
The mandibular second premolar usually has ____ root(s), ____ canals, ____%
one root; one canal (85.5%) Type I
95% of the time, the maxillary first molar has ____ canals
4
What is the shape of access for a maxillary first molar?
Triangle- apex to palatal
The triangular shaped access with the apex to the palatal for a maxillary first molar should NOT cross the:
oblique ridge
T/F: The maxillary first molar has four canals most of the time, but if not has five canals
True
The access to the maxillary second molar is similar to _____ but more _____
maxillary first molar; more compressed MD
What is the shape of access for a maxillary second molar?
triangle
What is the shape of access for a mandibular first molar?
Trapezoid
When accessing a mandibular first molar, the mesial and distal walls of th preparation lean towards the:
mesial
The access prep for a mandibular first molar, does not cross:
distal triangular ridges
T/F: Most often, the mandibular first molar has four canals followed by three canals
False- three canals most often, followed by four canals
What is the shape of access for a mandibular second molar?
Trapezoid/triangle (similar to mandibular first molar)
T/F: Most often, the mandibular second molar has four canals followed by three canals
False- three canals most often, followed by four canals
When a mandibular second molar has two centered canals, we call this ______. When this occurs ____
C-shaped; REFER
T/F: At UMKC, all second molars are done by advanced endo
true
How should we line up the bur when accessing a tooth:
in two planes
What is the WORST error you can make with access?
Perforation
