Cleaning and Shaping 2: Curved Canals Flashcards
Are most canals straight or curved?
Curved
Can wave one canal file be autoclaved?
No
Should you curve SS file before putting it in canal?
Yes
The new shaping routine with greatly improved modern files
and electric torque control motors should virtually eliminate
_____ and ______
ledging and canal transportation.
Beyond ___ degrees of curvature, it is very difficult; refer
30 degrees
Radiographs will generally
show ___ and _____ curves.
mesial and distal
____ and _____ curves will
NOT generally be seen:
Facial and lingual
_______ configuration may reveal
apex curving severely to Facial or L.
“Bulls eye”
________ etc. is one of the MAIN
REASONS that we selected the current
technique in which hand files used are
generally no larger than #15
Transportation,
____ is the smaller part of the
funnel created by the apical failure to
follow the curved canal
Elbow
s our shaping proceeded to the larger sizes of SS hand files above #15 (previously necessary to cleaning and shaping): a geometric progression - Increase in \_\_\_\_ - Decrease in \_\_\_\_\_\_
Stiffness*
Flexibility*
The above characteristics of SS hand files as sizes increase work to dramatically straighten out the canal curvature resulting in: \_\_\_\_ and \_\_\_\_\_\_
Ledges & Blockages*
Canal Transportation*
Transportation of apex occurs within
the root. The result is called a ____
Zip
As SS hand files increase in diameter beyond the flexible #08-15 files,
they increase greatly in stiffness & decrease greatly in flexibility
______ adaptation to the natural curve of the canal.
resisting
If there is a severe curve in the canal –
especially if the curve occurs in the apical
1/3 and a _________ was not
perfected and the operator tries to PUSH
or Force the Wave One Gold file to WL
very smooth glide path
_____ can still OCCUR
• By allowing the Vortex Blue finishing files
to rotate at or slightly short of WL for
more than 1 moment*
Transportation
KEEP THE VORTEX BLUE FILE _____
using a smooth in-out motion in the canal
while flexing it on the out stroke to smooth
and further flare the walls.
MOVING
When we place a straight SS hand file in a curved canal:
• Physics dictates it must track the OUTSIDE (convex) wall of the canal at some point. What does this do?
• Tends to gouge and attack the outsidewall of the canal creating the a _____ ,which can be the first step to ____ or ______
Ledge; Blockage or Transportation
When we place a straight SS hand file in a curved canal:
• Physics dictates it must track the ______ wall of the canal at some point. What does this do?
• Tends to gouge and attack the outside wall of the canal creating the a Ledge,which can be the first step to Blockageor Transportation
OUTSIDE (convex)
If we keep Pushing & Grinding on the file, we can eventually force it through the root to create a _______
Perforation
The Curved File is to be oriented correctly to \_\_\_\_\_ or \_\_\_\_\_ the curvature of the canal , introduced in a gentle watch-winding motion and then flexed in a rasping pull motion with circumferential filing after the path is negotiated.
coincide or slightly exceed
\_\_\_\_\_ and \_\_\_\_\_\_ • Are the biggest issues and are the reasons we changed to modern Ni-Ti files, expensive motors and a new technique.
Ledging & Transportation
\_\_\_\_\_ files are STRAIGHT – BUT: – Extremely Flexible* but will transport if inattentive & pushed* – Super-Elastic* and Expensive* • Not pathfinders • Will only follow a smooth glide path*
Ni-Ti
TO AVOID BLOCKAGE:______
IRRIGATE
TO AVOID LEDGING: ________
CURVE & INSERT FILES
CORRECTLY AND IRRIGATE
TO AVOID FILE SEPARATION: ____________
SINGLE USE FILES
INSPECT & DON’T SKIP SIZES OR FORCE
Bend every file in a gentle curve _____ entering canal.
before
f you successfully negotiate a difficult curve (tight resistance), spend lots of time flexing & working with the _____ file before moving to the next larger size*** “100 strokes”
small
if a LEDGE is created or if we encounter LOOSE RESISTANCE to apical advancement (= A CURVE), we modify the curvature to include the very terminal flute of the SMALL FILE to about a \_\_ degree curve to bypass the curve toward the inner wall or to scout for the direction of the CURVE
45
Most Common Causes of _______:
- Failure to RECAPITULATE***
- Failure to Gain and Maintain Patency
- Failure to recognize LOSS OF LENGTH ledge/blockage/curve
- Dentin mud is harder than dentin
Blockage:
Occurs when files used are either too large or too
aggressively used for a small or thin walled canal.
• Commonly the distal of the mesial root of lower molars,
MF of upper molars , 2 canal max. PM .
Strip Perf
What 3 locations do strip perf most commonly occur?
distal of the mesial root of lower molars,
MF of upper molars , 2 canal max. PM .
MB1 and MB2 (Maxillary Molars) (__% two
canals)
95%
DF and DL of Mandibular Molars (Join ___ %
Type II)
60%
MF and ML of Mandibular Molars (Join ___%
Type II)
40%
Maxillary 1st Premolars (___% have two roots)
85%
If we 1st create a smooth glide path in the
MB canal. The .25-.12 rotary file
can be inserted ____ mm into the canal and
while rotating at 500 rpm be carefully
uprighted to remove the dentin triangle and
align the access to a more advantageous
path to the canal – thereby making it much
easier to shape the apical curvature.
3-4mm
If we 1st create a smooth glide path in the
MB canal. The .25-.12 rotary file
can be inserted 3-4mm into the canal and
while rotating at 500 rpm be carefully
______ to remove the dentin triangle and
align the access to a more advantageous
path to the canal – thereby making it much
easier to shape the apical curvature.
uprighted
What file is used to refine straight line access in an incident of high cervical break by uprighting?
Vortex .25/.12
What is the main reason files break/separate?
Pushing too hard
The larger the instrument or the tighter the curve, the greater the stretching on the outer diameter of the curved instrument and the greater the compression on the inner diameter of the curve = ________
Torsional Stress
Additionally, greater acceleration of the curve results in increased stress from stretching and compressing resulting in increased _________
Cyclic Fatigue.
Attempting to take a rotary file through a \_\_\_\_\_\_\_\_\_ is an almost certain prelude to instrument separation
convergence
of canals
T/F: If you feel as if you need to PUSH the rotary file to get it to advance, go back and smooth or carefully enlarge the glide path with a small properly curved hand file.
True
Anytime obturation is
not yet accomplished,
this is an indication for
__________
intracanal medication.
What needs to be placed over layer of CaOH every time it is used in a canal?
Cotton
____ is currently the singular most popular intra-canal medication to use for disinfection of canal btwn visits
CaOH
CaOH is placed about _______ in relation to WL; and where does it stop?
2 mm short of WL; Fill the canal not chamber
____ is a great temp for anterior teeth with light occlusion
- Not good for 2 surface restorations
- CAN’T BE USED ON VITAL TEETH
- COmes from the tube or jar ready to place in tooth without mixing; seals better than IRM but deteriorates rapidly
Cavit
______: temp material 1-4 week seal duration = stronger
- Can be used when 2 or more surfaces are missing
IRM
_____ is reccommended to seal obturated canal against leakage following successful RCT completion while awaiting perm restoration
Vitrebond
How do you close the RCT if post is used later?
NO vitrebond
Place temp restoration over cotton pellet
If treatment plan calls for crown, how do you close up tooth after RCT?
No Cotton over obturation
Place Temp on it
In the anteriors , how do you restore a tooth with. minimal structure loss?
Vitrebond and composite
In the anteriors , how do you restore a tooth with.significant structure loss?
Crown or Post and Crown
In the posterior , how do you restore a tooth with. minimal structure loss?
Crown
In the posterior , how do you restore a tooth with significant structure loss?
Crown and post
Do posts strengthen or weaken tooth?
Weaken; provide retention
