Lecture 1: Working Length & Access Flashcards
When, why, & 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 three 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 fracture and 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 & ADEC are due to:
poor access
What is the first step in access procedure?
Outline (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 the enamel with number 2 round or 330 bur on high speed
What layer should be drilled through when creating the outline form?
just through the enamel
What burs and what speed may be used when creating the outline form?
2 round bur or #330 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 the 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, penetration the ___ with the bur angled approaching parallel to long axis of the root in the ___ of outline form.
pulp chamber roof; center
During the penetration step of the 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 the access procedure, how should you confirm pulp canal entry?
with endodontic explorer; DG16 (push)
To confirm pulp canal entry, during the penetration step of the 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; walls
When un-roofing, irrigate well with:
NaOCl
When un-roofing, irrigate well with NaOCl for:
- vision
- removal of debris
- begin disinfection
Following the unroofing 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 or Endo-Z bur
The Endo-Z bur is the ___ one
gold one
Why do we use the Safe ended diamond bur or Endo-Z bur during the refining step of the 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 ended 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
WL
Incorrect WL may instigate:
apical periodontitis
How do you find the canal exit in your hand?
- 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 1st PM:
maxillary: 20.6
mandibular: 21.6
Average root length 2nd PM:
maxillary: 21.5
mandibular: 22.3
Average root length 1st molar:
maxillary: 20.8
mandibular 21.0
Average root length 2nd molar:
maxillary: 20.0
mandibular: 19.8
Usual # of roots & canals for maxillary incisors: (Teeth #7,#8, #9, #10)
one root; one canal
Usual # of roots & canals for maxillary canines: ( Teeth #6, & #11)
one root; one canal
Usual # of roots & canals for maxillary first premolars (Teeth #5 & #12)
two roots; two canals
Usual # of roots & canals for maxillary 2nd premolars: (Teeth #4 & #13)
Usually 1 root; one 1 canal
(possibly two on both)
Usual # of roots & canals for maxillary molars: (Teeth #1,2,3,14,15,16)
usually 3 roots and 3 canals (probably 4 or more)
Usual # of roots & canals for mandibular incisors (Teeth #,23,24,,25,26)
Usually 1 root: 1 canal (potentially 2 canals)
Usual # of roots & canals for mandibular canines (Teeth # 22, 27)
Usually 1 root; 1 canal
Usual # of roots & canals for mandibular premolars (Teeth #20, 21, 28,29)
usually 1 root; 1 canal (possibly 2 canals)
Usual # of roots & canals for mandibular molars: (teeth #17,18, 19, 30, 31, 32)
Usually 2 roots; 3 or possibly 4 or more canal
In clinic, how do we determine the correct working length?
apex locator
To determine the correct working length, place a ____ hand file in the access and extend it into 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:
1.0 mm short of the canal exit
The goal for WL is 1.0 mm short of the canal exit. This places WL in close proximately to the:
natural apical constriction
What happens if your working length is too short?
The canal is NOT well cleaned
What happens if your working length is too long?
Results in “blow out” which guarantees:
1. incomplete compaction at the apex
2. an explosion of sealer in the PA tissues
In regards to working length, your reference point should be: (2)
- easy to see
- easy to reproduce
When selecting a reliable reference point for anterior teeth, you should use:
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 working length is determined
false- don’t reduce it after working length is determined
What is the first step after diagnosis?
access
Access to the pulp chamber facilitates: (6)
- locating the canals
- negotiating the canals
- gaining patency
- establishing working length
- maintaining apical constriction
- a good outcome
Arguably 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 effective shape, this include: (4)
- smooth
- constantly tapering
- respecting shape of natural canal
- constricting near terminus of root
What is 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 offices from a SINGLE vantage point
- Straight-line access to mid-root for instrument placement
- Complete removal of pulpal roof and pulp horns
- Avoidance of unecessary weakening of tooth
What do we mean when referring to “visibility” as a requirement of access?
visibility of pulp chamber and ALL canal offices from a SINGLE vantage point
visibility of pulp chamber and ALL canal offices from a SINGLE vantage point =
draw
Why is straight-line access to mid-root a requirement or access?
straight-line access to mid-root is requirement for instruments & obturating materials (without regard to long axis of the 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 3 main steps to access?
- Outline form (2D surface shape)
- Coronal access (extending into pulp)
- Radicular acesso (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 canna offices from a single vantage point:
Coronal access
During coronal access, you should reach the pulp at ____ mm 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 axis 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 1
Common canal configurations:
2 canals from pulps chamber, join prior to apex
Type 2
Common canal configurations:
2 canals from pulp chamber to apex
Type 3
Common canal configurations:
One canal from pulp chamber divides prior to apex
Type 4
Which type of canal configuration is the most difficult to treat?
Type 4
Label the type of canal configuration seen below:
Type 1
Label the type of canal configuration seen below:
Type 2
Label the type of canal configuration seen below:
Type 3
Label the type of canal configuration seen below:
Type 4
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 access with 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 a 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 an esthetic issue
What is the shape of access for 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 regard to access:
incisal compromise
What is the shape of access for a mandibular canine?
oval
If the mandibular canine has one root, its usually vey wide:
F-L
What type of canals can be seen in a mandibular canine? What type do we see most often?
Type I, II, or IV; Type I most common
According to vertucci, ____% of mandibular canines have 1 canal, whereas ____% have 2 canals
78%; 22%
T/F: It is more common for a mandibular canal to have 2 canals, than 1 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 the file
Inadequate access creates ___ of the canal
apical transportation
Access is ALWAYS gained through ____ approach on ALL posterior teeth
occlusal
What is the shape of access for a maxillary 1st premolar
Thin oval access (MD)
The thin oval shaped access of a maxillary first 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 widget of:
4 round bur
Most often we see the maxillary second premolar have a Type ___ canal, ____root & ____canal (75-85%) of the time.
Type ___, ____, & ____ are less frequent
Type 1; 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%; 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 2nd premolar, we should be aware of type ___, because they are very hard to shape, clean & fill.
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 ___ roots and ___ canals ____% of the time
1 root; 1 canal (85.5%) Type 1
95% of the time, the maxillary first molar has ___ canals
4
What is the shape of access for a maxillary 1st 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 4 canals most of the time but if not, has 5 canals
True
The access to the maxillary second molar is similar to the ___ but more ___
Similar to maxillary 1st molar but more compressed MD
What is the shape of access for a maxillary second molar?
triangle
What is the shape of access for a mandibular 1st molar?
Trapezoid
When accessing a mandibular first molar, the mesial and distal walls of the preparation lean toward the:
mesial
The access prep for a mandibular first molar does NOT cross:
distal triangular ridges
T/F: Most often , the mandibular 1st molar has 4 canals followed by 3 canals.
False- 3 canals most often, followed by 4 canals
What is the shape of access for a mandibular 2nd molar?
Trapezoid/Triangle (similar to mandibular 1st)
T/F: Most often, the mandibular 2nd molar has 4 canals, followed by 3 canals
False- 3 canals most often, followed by 4 canals
When a mandibular 2nd molar has two centered canals, were call this ____. When this occurs, ____.
C-shaped; REFER
T/F: At UMKC, all 2nd molars are done by advanced endo
True
How should we line up the bur when accessing a tooth?
In 2 planes
What is the WORST error you can make with access?
Perforation
