Policies, Access & Working Length. Flashcards
More points are lost in Lab to — than anything else
Most FAILURES on WREBs & ADEC are due to —
POOR ACCESS
POOR ACCESS
Access Procedure - Outline
- You may draw your outline
form on the tooth - Create outline form just
through enamel with number
2 round or 330 bur HS - At this point bur is
somewhat perpendicular to
lingual surface of tooth - Stay shallow at this point.
Just through enamel < 1mm.
Access Procedure - Penetration
* Penetrate pulp chamber roof
with bur angled approaching
parallel to long axis of root in
center of outline form.
- You should reach the pulp in
most cases by — mm. – if not,
call for instructor help.
7
Confirm Pulp canal entry with
endodontic explorer DG16:
PUSH
Un-roof Pulp Chamber with
brushing out-strokes. Take
care not to gouge axial walls.
* Remove obstructions & smooth
the walls
- Irrigate well (NaOCl)
(3)
– Vision
– Remove Debris
– Begin Disinfection
Access Procedure - Refining
* Refine access prep with
Safe
ended diamond bur or Endo–Z
bur to help provide straight-line
access to mid-root. ( Mostly in
molar access).
* The non-cutting tip is simply a
pilot.
After ACCESS, your
next big task is
Working Length
The correct WL is:
1.0mm.
SHORT of the CANAL EXIT
If you DON’T get the WL
right; you will likely result
in a
POOR OUTCOME
How do you FIND the Canal Exit?
* In your HAND; Look at it
(3)
– Observe the canal exit
– Measure before you MOUNT tooth
– Measure before you MOUNT tooth
How do you FIND the Canal Exit?
* In the MOUTH; Start w/ Average Length
(3)
– Chart
– Apex Locator (if possible)
– Radiograph (with #15 file in canal)
APEX LOCATOR:
In use on a patient in the
Clinic
Apex Locator is not applicable in Lab
(No PDL in extracted teeth)
Place a #15 hand file in the
access and extend it in the
canal to the estimated canal
length
Take a radiograph and
adjust until you determine
the correct Working Length
Why do we use a #15 FILE to radiograph?
The GOAL for the WL is 1mm.short of the canal exit. This places the WL in close
proximity to the
natural Apical Constriction
WL
- Too SHORT:
The canal is NOT well CLEANED
WL
- Too LONG:
Even ¼ of a mm. long of the
constriction – we have created a
“BLOW-OUT” which guarantees
incomplete compaction at the apex
and an explosion of sealer in the
PA tissues.
About WL
* MUST HAVE a Reliable Reference Point
– Select a solid, reproducible location on the tooth
* Tip of incisal edge (anteriors)
* Tip of cusp for which the canal is named (molars)
– Don’t reduce it after WL is determined
– No need to reconfirm unless something
has changed.
Reliable Reference Point
when determined
write it down
Cleaning and Shaping:
– Access to the Pulp Chamber
FACILITATES:
(6)
– Locating the Canals
– Negotiating the Canals
– Gaining Patency
– Establishing Working Length
– Maintaining Apical Constriction
– A GOOD OUTCOME
***Proper — is arguably the single most
important requisite contributing to routine
endodontic success.
Access
skipped
Poor ACCESS yields PROBLEMS:
- You will NOT have a predictable result
- You will routinely miss canals
- You will NOT be able to clean properly
- You will NOT be able to shape completely
- You will NOT be able to fill adequately
- *** You will easily create problems and make your RCT far more difficult, dangerous and time-consuming than it needs to be.
Dr. Riley Mess-up
“Coke bottle” shape
Most simply defined, access involves drilling
a hole through coronal structure to gain
entrance into the pulp chamber.
* You are thinking: “Any fool can drill a hole
into the pulp” . . . But can they?
There is nothing so fool-proof that a
sufficiently talented fool cannot foul it up
OBJECTIVE of ACCESS
Create effective
SHAPE:–
(4)
SMOOTH
– CONSTANTLY TAPERING
– RESPECTING THE SHAPE
OF THE NATURAL CANAL
– CONSTRICTING NEAR THE
TERMINUS OF THE ROOT
AVOID:
- “Coke Bottle” effect
(canal is bigger than the cervical
access at some more apical point
in the canal)
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 & pulp horns
- Avoidance of unnecessary weakening of tooth
- Visibility
Visibility of pulp
chamber and all
canal orifices
from a single
vantage point
= “DRAW”
- Straight-line Access to Mid-root – Straight-line access to mid-root is required for (2)
instruments & obturating materials (Without regard to the long axis of the tooth)
skipped
Cross-hatched area of secondary dentin should be removed to create better access to
mesial root (this is also called a dentin triangle). A .25/.12 rotary file may be used to remove this
impediment to treatment.
3 Steps of Access***
(3)
- Outline Form (2 dimensional surface shape)
- Coronal Access (Extending into pulp)
- Radicular Access (Adjustments to allow
easy straight-line entry to mid-root of
each canal) *
1.Outline Form:
The 2 dimensional plan for the initial opening (Could be traced onto crown)
While canal anatomy & tooth damage somewhat determine shape, size and location of initial entry into tooth – there is an “Ideal” to be mastered ***
First Shape the Outline Form in a shallow (1/2 to 1mm) fashion ( #4 round for molars, #2 for PM and Anteriors)
2.Coronal Access:
To allow unobstructed visualization of the pulpal floor and ALL canal orifices from a single vantage point . . .
You should reach the pulp at 7mm or less. Mark your bur at 7mm
Extend your bur within the Outline Form to remove Pulpal Roof.
Pulpal FLOOR should NOT be touched by access bur.
Walls of the coronal
access should
DIVERGE to the
occlusal (B)
(3)
- better light
- better visualization
- Your temporary
restoration which is
placed between visits
will not be easily
dislodged to Leak &
Contaminate***
- Radicular Access:
To allow straight-line access to midroot for all shaping instruments and obturation materials ( observe canal path- not long axis of tooth)
Flare into canals to remove obstructions and make instrument placement simple and foolproof without looking.
Facilitates “Crown-Down” procedure.
The ESSENCE of ACCESS
* Think of Access as creating the mouth of a
funnel which directs the files to the center
of the canal in a smooth & unobstructed
manner. You will place a file
into each canal
hundreds of times.
Hand files generally require —-
before going to next larger size file *
100 strokes/file
Access: Planning for success
* Common canal
configurations***
– Type I:
– Type II:
– Type III:
– Type IV:
one canal from
pulp chamber to apex
2 canals from pulp
chamber, join prior to apex
2 canals from pulp
chamber to apex
one canal from
pulp chamber divides prior
to apex (most difficult to
treat)
Access: Maxillary Central Incisor
- Triangular access (base
of triangle at incisal)
“Incisal compromise”
Total straight-line access on anteriors would involve access from the facial and create a weakening of the incisal edge and an esthetic issue.***
Access: Maxillary Lateral Incisor
- Triangular/Oval Access
- Thinner root than central
(narrower access M-D
narrower pulp horns) - Root often curves to distal
- Apex tips to palatal (most
difficult of max. ant. teeth) - “Incisal Compromise”
on all anterior teeth
Access: Maxillary Canine
- Triangular/Oval access
- Canal narrower M-D than
F-L - One root (larger and
longer than lateral) - Type I canal (most max.
anteriors)
Tooth root tips toward
palate at apex
Access: Mandibular Incisors
- Oval access
- Root wider F-L than M-D
- Very narrow M-D (easy to perforate to side of root)
- One canal 60% Two canals 40%
- When two canals-mostly Type II Benjamin and Dowson
- Must extend access toward incisal to locate lingual
canal) LOOK at XR-also adjacent teeth. - Cervical access will miss Lingual canal
Access: Mandibular Canine
- Oval access* If one root usually very wide
F - L - Type I, II, or IV canals - I
mostly - Vertucci 78% 1 canal
22% 2 canals
Access :
Common errorsLine up penetration in 2 planes:
M-D & F-L
Visualize cervical cross section
Perforations often spell the demise of the tooth =
iatrogenic error
Access : Common ErrorsInadequate access compromises shaping:
(2)
*induces unnecessary bending of file
*creates apical transportation of canal
Access: Maxillary 1st Premolar
- Thin Oval Access (width of #4)
- thin M-D root
- Two canals most prevalent
– 85% two canals
– 9% one canal
– 6% three canals
Carnes and Skidmore - Canal orifices lie under respective
cusp tips
***Access always gained through the —
approach on all posterior teeth.
occlusal
Access: Maxillary Second Premolar
- Access: thin oval
- Usually one root, 1 canal
(type I), 85.5 % - Type III, 11.5 %
- Three canals less than 1%
Another study Vertucci
98% one canal 2% two
Max. 1st Molar Access– 4 Canals 95%*
Access = Triangle –
apex to palatal: should
not cross oblique ridge
4 canals most of the time
5 canals 2.4%
*Kulild JC, Peters DD: Incidence and
configuration of canal systems in the
mesiobuccal root of maxillary first and
second molars, J Endod, vol 17, no. 8
Aug 91
“MB root has 2 canals more than 90%
of the time & over 70 % of these end in
2 apical POE’s”
Access Maxillary Second Molar
(similar to 1st – more compressed M-D)
Access: Triangle
Access : Mandibular 1st Molar
Access: Trapezoid preferred
Mesial and distal walls
of preparation lean to-
ward the mesial. (i)
Prep does not cross
distal triangular ridges
4 or 3 canals
64% 3 canals
29% 4 canals
Bjorndal and Skidmore
Access: Mandibular 2nd Molar
Access: Trapezoid/Triangle Similar to 1st
3 canals 81%
4 canals 11%
Weine
Are the 2 canals
which you found
CENTERED?
C-Shaped Canal =
REFER
2-8% Cooke & Cox et.al.
Common Access Errors:
M/M Premolars
All Perforations are MENTAL
ERRORS *
Get your perception RIGHT :
Line it up in 2 planes (Know
where the root angles)
STAY FOCUSED*
— is the WORST error you can make at access ***
Perforation
