Virginia Technique
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Endodontic Instrumentation With the Virginia Technique Frederick R. Liewehr, DDS, MS
Root Canal I nstrumentation
Aim After instrumentation the root canal space should be free of bacteria. This should be achieved without excessively weakening the root or affecting the ability to adequately restore the tooth.
Early endodontic access preparation
(No longer practiced at VCU)
Goerig "Step-down" technique •
Flaring the coronal portion of canal before instrumenting to apex
•
Allows deeper penetration of the irrigant
•
Eliminates coronal interferences with the files
Christie WH, Peikoff MD. Conservative treatment of apical foramen. J Canad Dent Assn 1980;3:187
Goerig "Step-down" technique •
Reduces canal curvatures allowing straighter access to the apex
•
Removes the bulk of radicular tissue without penetrating apex
•
Ideal emergency treatment
I nitial opening • • •
Traditional openings were too small, in the wrong areas Canals were missed Tooth structure misdirected files
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Let the tooth dictate your access – Simply enlarge access to match pulp chamber
Messing JJ, Stock CJR. A Colour Atalas of Endodontics
Access improved
Traditional anterior cingulum access
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Frequent result – perforation!
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Missed lingual canal
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Again - simply enlarge access to match pulp chamber
Messing JJ, Stock CJR. A Colour Atalas of Endodontics
Access improved
I nitial opening Need straight-line access to the apical 1/3
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
File types and techniques
Stainless Steel K-Files • Square blank twisted to produce the • • •
spiral shaped cutting edges Flexible in small sizes Stiffness increases rapidly in larger sizes Can be pre-curved
• Excellent for pathfinding, bypassing obstructions and dealing with procedural accidents •Can cause transportation and perfs
Stainless Steel Hedstrom Files • Round blank cut to produce very sharp cutting edges • Very aggressive, fast dentin removal • Must NEVER be twisted into canal • Insert and cut by pulling outward • Somewhat less strong than K-files due to cut edges
Nickel Titanium Files • I ncreased flexibility • Conforms to canal curvature • Memory – straight! • Cannot precurve • Too flexible for pathfinding, bypassing obstacles, etc.
Stainless Steel K-File
Kink
Nickel Titanium
No kink
This can be good or bad, depending on what you are trying to accomplish • If you are instrumenting a canal, the file tends to stay centered – good… • If you are trying to bypass an instrument or ledge, the file tends to stay centered – bad!
Taper No, this is not crown and bridge!
What is Taper? D16
D1
0.02 taper
0.32 mm diameter increase
D16
D1
0.06 taper
Taper is expressed in mm diameter increase per mm length
0.96 mm diameter increase
How much is enough? • Schilder said we need to develop a continuously tapering form for debridement and resistance form • Black’s principles, modified by Ingle and Bakland, said our form must be dictated by the internal anatomy of the canal • Some canals do NOT have a continuously tapering form
• So, the taper we select must match the anatomy of the canal.
Some canals have a lot of taper…
1 2 3 4
Distance from apex
Size
Taper
1mm
40
2mm
60
.20
3mm
100
.40
4mm
110
.10
5mm
100
-.10
6mm
110
.10
7mm
130
.20
8mm
150
.20
5 6
Average taper = 0.157 mm/mm
7 8
Some canals have very little Distance from apex
Size
Taper
1mm
30
2mm
30
0
3mm
30
0
4mm
30
0
5mm
30
0
6mm
35
.05
7mm
45
.10
8mm
55
.10
9mm
60
.05
10mm
50
-.10
Average taper = 0.027 mm/mm
The problem with excessive taper Binds here
Not here
Files tend to bind and cut coronally, where they are largest, and not apically where we think they are binding, leaving the coronal portion overinstrumented and weak, and the apical portion underinstrumented and infected.
The problem with excessive taper
All files with a long cutting edge exhibit taper, and the modern trend is to more and more taper. This, however, is not appropriate for all canals. For those canals a non-tapered (LightSpeed), or minimally tapered (0.02) file must be used
Misconception about Ni-Ti • “Superflexibility” somehow negates characteristics of other metals – Increasing size -> increasing stiffness – Increasing taper -> increasing stiffness
• Reality – There is no magic!
Do those look flexible to you?
How do we create taper if we don’t use very tapered instruments?
Step - Back Technique
Taper = 0.05
By increasing file size in “steps” of 1mm as you “back out” coronally
Proper taper • The appropriate taper for a canal is that which it had initially • Occasionally we have to increase the taper slightly to allow for our obturation technique • Any dentin we remove, however, will weaken the tooth • So, we must err toward conservatism
Proper taper • For most molars and some premolars, rotary files having 0.04 and and 0.06 taper will produce approximately the correct taper • Excessive taper will cause strip perforations • Insufficient taper is not really a problem • So, err toward less taper
Proper file size • Some rotary systems are available with only small tip sizes (e.g. <40) • This is due to an erroneous belief that: – All canals are tapering – All canals are small at the apex
• Research shows that these assumptions are not true • Therefore, the apical portion may need to be prepared with hand instruments or LightSpeed
Taper?
Proper file size • In rotary systems that are available with tip sizes >40, tapers larger than 0.02 can lead to excessive coronal sizes and resulting strip perfs
Principles & Practice of Endodontics, Walton & Torabinejad, Saunders, 2002
But I thought more taper was better? • 0.06 taper means the file size enlarges by 0.06 mm/mm • If the tip size is 40, and • The length is 16mm, then • 16 x 0.06 = 0.96 • Add to tip size 40 = size 136 • A GT 0.12 would be 40 + 1.92 = size 231!
Proper file size Since file taper should match canal taper – The only reason to exceed the natural taper is to facilitate GP cone placement – In larger canal sizes, this is no problem
• Therefore, in teeth with large canals, less tapered files are indicated Canal is BIG and almost straight!
Proper file size • This means that in many maxillary anteriors and many premolars rotary instruments are not indicated or needed • It is often faster to instrument teeth with large canals with Hedstrom files than with rotary instruments!
Be sure you instrument to a large enough size apically!
Why is the preparation size important?
Bacteria!
Apical size chart Tooth
Initial file size
Final file size
MAXILLARY ARCH Central
45
60
Lateral
40 (30 if curved)
55 (45 if curved)
Canine
45
60
Premolar
B: 25, P: 30; 1 canal: 40
B: 40, P: 45; 1 canal: 55
Molar
MB: 25, DB: 25, P: 40
MB: 40, DB: 40, P: 55
Anterior
B: 25, L: 25; 1 canal 40
B: 40, L: 40; 1 canal 55
Canine
40
55
Premolar
B: 25, L: 30; 1 canal 45
B: 40, L: 45; 1 canal 60
Molar
MB: 25, ML: 25, D: 40
MB: 40, ML: 40, D: 55
MANDIBULAR ARCH
• Based on morphological studies • Not a rule but a starting point • Adjust for each individual tooth
Clinical Procedures
Clinical Procedures
1. Determine canal configuration
Clinical Procedures 1a. Estimate working length
Expose a parallel X- Ray
Clinical Procedures Pre-op film employs the XCP instrument to produce a parallel radiograph
Why parallel?
Clinical Procedures Parallel films have the least distortion and allow measurements to be made with reasonable accuracy
Clinical Procedures Paralleling requires a film holder Bisecting angle reduces but does not eliminate distortion
a Purple – tooth plane Red – Film plane Light blue – bisecting angle
b
A - with instrument B – without instrument
Do not fixate on the apex only!
Evaluate root curvature!
Clinical Procedures 1b. Estimate canal curvature
http://www.gearjammin.com/twisty/
Clinical Procedures
Do NOT use rotaries in highly curved canals!
Clinical Procedures 1c. Determine canal form
http://www.holylandmarket.com/html/731.htm
Determine canal form Small
Medium
Large
Rotary - OK
Rotary - OK
Rotary - NO
Clinical Procedures
2. Obtain straight line access
What burs do we need? • #4 or #6 high-speed round carbide
• D11-T equivalent diamond or Endo-Z bur
Access the chamber…
Then let the internal anatomy dictate your outline form
I nitial opening •
Remove caries and defective restorations
•
High speed round #4 or 6 for penetration into pulp chamber
•
Aim for largest canal
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Watch for procedural errors!
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
I nitial opening •
After penetration, enlarge by cutting on withdrawal
•
Locate largest canal, follow road map on chamber floor
•
Endo explorer to locate canals
Cohen S, Burns RC. Pathways of the Pulp, 7th Ed.
X Incorrect
Anteriors Correct
Penetrate, then cut on withdrawal
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Posteriors
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Penetrate, then cut on withdrawal
Enlargement •
Access preparation is a dynamic process
•
Conservation of tooth structure is SECONDARY to convenience form
•
Access opening should NEVER bind or guide instruments
Binding
Oops!
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Remove the cervical bulge! Pull up
Then smooth
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Completed access •
Continuously tapering, conical form desired
•
Use a 1 DT diamond for outline form Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Clinical Procedures
3. Explore canal patency
Clinical Procedures
Pass a small, precurved file to the apex
Clinical Procedures
4. Estimate canal size (use chart + x-ray)
Apical Size Chart Tooth
Initial file size
Final file size
MAXILLARY ARCH Central
45
60
Lateral
40 (30 if curved)
55 (45 if curved)
Canine
45
60
Premolar
B: 25, P: 30; 1 canal: 40
B: 40, P: 45; 1 canal: 55
Molar
MB: 25, DB: 25, P: 40
MB: 40, DB: 40, P: 55
Anterior
B: 25, L: 25; 1 canal 40
B: 40, L: 40; 1 canal 55
Canine
40
55
Premolar
B: 25, L: 30; 1 canal 45
B: 40, L: 45; 1 canal 60
Molar
MB: 25, ML: 25, D: 40
MB: 40, ML: 40, D: 55
MANDIBULAR ARCH
Notice the variation in canal size
Rotaries are not designed for large canals!
Clinical Procedures
5. Establish initial working length (IWL)
I nitial working length • •
Study pre-op radiographs to determine the approximate length to the apex Subtract 4mm; this is the IWL
IWL 4mm
Rotary technique • NEVER force a rotary instrument • Use only light pressure (similar to writing) • Use intermittent tapping motion • Listen to handpiece, reduce pressure if it slows down (this does NOT work in non-battery powered handpieces) • Always use a torque-reverse handpiece
Rotary technique • All instrumentation is PASSIVE • Instruments are chosen because they very nearly fit to length (1-2mm) • As they rotate, they clean and smooth • 3 sizes allows sufficient dentin removal for mechanical disinfection and smoothing without weakening the tooth
Clinical Procedures
6. Prepare coronal 1/3 with orifice shapers
Clinical Procedures Prepare coronal 1/3 with Orifice Shapers: Initial working length minus 4mm (apex – 8 mm) Begin with size that nearly reaches the IWL – 4 mm passively, increase 3 sizes (less if too much binding occurs)
Coronal Flaring: Orifice Shapers
STRAIGHT-LINE ACCESS
IWL - 4 IWL
Clinical Procedures Irrigation & RC Prep are essential!
Why irrigate and recapitulate?
Mud here… Causes perf here And failure here!
Recapitulation and Apical clearing • Canal is like a snow globe • An absorbent point would remove the liquid but not the snow • It would pack into the bottom of the globe, or apex of the tooth • Snow, or dentinal “mud”, must be removed mechanically
Clinical Procedures Instrument with a “tapping” motion Light pressure (like writing with a pen) NO MORE THAN 1MM AT A TIME !!!!!!!
Clinical Procedures Prepare coronal 1/3 with Orifice Shapers: Initial Working Length minus 4 mm Irrigation & RC Prep
Instrument with a “pecking” motion Light pressure (like writing with a pen) NO MORE THAN 1MM AT A TIME !!!!!!!
Small to large orifice openers until largest at approximately IWL - 4
Important note! • The Virginia technique is PASSIVE • NEVER force an instrument • If it doesn’t tap easily to the IWL-4, accept the new, shorter length • Continue to tap the instruments only as far as they go without causing the handpiece to autoreverse
Very large, non-tapered canals • If you can insert all the orifice openers to the IWL-4 or beyond, the canal is too large for rotary instrumentation with a long cutting edge instrument like a ProFile • Hand instrumentation or the LightSpeed system should be used • Consult your instructor before proceeding
Clinical Procedures 7. Prepare mid 1/3 with 0.06 tapers
0.06 taper files
Clinical Procedures Prepare coronal 2/3 with 0.06 tapers Select size that passively almost reaches IWL, instrument 3 sizes more Endpoint is the Initial Working Length
IWL
Clinical Procedures 8. Determine the exact length to foramen
How long should we go?
The Apical Foramen Cementum
Minor foramen
Dentin
Mesial view of an anterior tooth
"Natural" constriction in the apical area 0.25 to 0.5 from the radiographic apex = MINOR FORAMEN
The Apical Foramen Cementum
0.5 to 1 mm
Dentin Note: File is long, but it looks short on the radiograph!
Mesial view of an anterior tooth
Standard radiographic view
Instrument Length
Aim: As close to minor foramen as possible. Realize that the radiographic apex is not necessarily the anatomic apex!
Instrument Length
Ideal
Instrument Length
Final Working length will be ~1mm from radiographic apex
Instrument Length
Can I "feel“ the apex? - Only useful with crown-down technique - Not reliable - Use only in conjunction with
other techniques
How about apex locators?
Studies suggest ever-increasing accuracy Still remain technique-sensitive Do not work in all cases Useful adjunct, but can be difficult to interpret Need a combination of techniques for accuracy
Radiographic Determination Still the “gold standard”!
“Endo Ray” instrument allows paralleling radiograph with instruments in place
Radiographic Determination
Ideal placement
Radiographic Determination
Short
Long
Shift shot
• Always make 2 radiographs from slightly different angles • Aids in overcoming 2-D limitation
Radiographic Determination
Hedstrom and K files make canal identification easy!
Clinical Procedures 9. Prepare apical 1/3 with 0.04 ISO tapers from small to large
Prepare the apical 1/ 3
Working length
Instrumentation of the apical 1/3 Coat a 0.04 hand file the same size as the file you used to take your FWL radiograph with RC Prep Place it to the FWL using a watch-winding motion Rotate it clockwise until it is loose in the canal
Instrumentation of the apical 1/3 Irrigate copiously Coat the next larger file with RC Prep Work it to the FWL using a watch-winding motion Rotate it clockwise until it is loose in the canal
Instrumentation of the apical 1/3 Continue to repeat these steps for three file sizes. Recapitulate – after irrigating, replace the original file size to the FWL and watch wind to place if necessary. Then irrigate. This will remove any accumulated dentinal “mud”
Instrumentation of the apical 1/3 Now, begin step back as follows: Place the next larger size in the same fashion, but only to the FWL – 1mm. Work the file in the same fashion as previously
Instrumentation of the apical 1/3 Repeat this twice, with the next larger size, to FWL –2 and FWL –3 This will give you a “step back” taper
Instrumentation of the apical 1/3 Finally, recapitulate, irrigate, and smooth the steps by using the last size you took to the FWL in an up-anddown filing motion This file size is your master apical file, which will dictate the size of your master gutta percha cone
Important note… • Instrumentation near the apex is dangerous • Many endodontists complete the apical 1/3 entirely with hand instruments • However, the use of carefully controlled rotaries can result in a smoother transition • Once you have sufficient experience, the alternate technique for finishing should provide a smoother preparation
Instrumentation of the apical 1/3: alternative to step-back • After instrumenting to the WL for three file sizes past the file used to determine your FWL, instead of the stepback, simply: • Place the next larger size 0.04 taper Profile in the handpiece and gently tap it to the WL • Be careful not to pass the WL!
Remember: • NEVER attempt to instrument a canal with a rotary instrument that you have not already instrumented to the FWL with at least a size 25 hand instrument
Remember: • Always use any instrument, hand or rotary, with RC Prep for lubrication • Be sure to irrigate copiously after each file
Remember: • Apical clearing is NOT recapitulation! • It consists of: – Drying the canal – Rotating (by hand) without pressure the last size file used (master apical file)
Irrigate copiously, dry, apically clear, and you are…
Root Canal I nstrumentation
Aim After instrumentation the root canal space should be free of bacteria. This should be achieved without excessively weakening the root or affecting the ability to adequately restore the tooth.
Early endodontic access preparation
(No longer practiced at VCU)
Goerig "Step-down" technique •
Flaring the coronal portion of canal before instrumenting to apex
•
Allows deeper penetration of the irrigant
•
Eliminates coronal interferences with the files
Christie WH, Peikoff MD. Conservative treatment of apical foramen. J Canad Dent Assn 1980;3:187
Goerig "Step-down" technique •
Reduces canal curvatures allowing straighter access to the apex
•
Removes the bulk of radicular tissue without penetrating apex
•
Ideal emergency treatment
I nitial opening • • •
Traditional openings were too small, in the wrong areas Canals were missed Tooth structure misdirected files
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Let the tooth dictate your access – Simply enlarge access to match pulp chamber
Messing JJ, Stock CJR. A Colour Atalas of Endodontics
Access improved
Traditional anterior cingulum access
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Frequent result – perforation!
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Missed lingual canal
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Again - simply enlarge access to match pulp chamber
Messing JJ, Stock CJR. A Colour Atalas of Endodontics
Access improved
I nitial opening Need straight-line access to the apical 1/3
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
File types and techniques
Stainless Steel K-Files • Square blank twisted to produce the • • •
spiral shaped cutting edges Flexible in small sizes Stiffness increases rapidly in larger sizes Can be pre-curved
• Excellent for pathfinding, bypassing obstructions and dealing with procedural accidents •Can cause transportation and perfs
Stainless Steel Hedstrom Files • Round blank cut to produce very sharp cutting edges • Very aggressive, fast dentin removal • Must NEVER be twisted into canal • Insert and cut by pulling outward • Somewhat less strong than K-files due to cut edges
Nickel Titanium Files • I ncreased flexibility • Conforms to canal curvature • Memory – straight! • Cannot precurve • Too flexible for pathfinding, bypassing obstacles, etc.
Stainless Steel K-File
Kink
Nickel Titanium
No kink
This can be good or bad, depending on what you are trying to accomplish • If you are instrumenting a canal, the file tends to stay centered – good… • If you are trying to bypass an instrument or ledge, the file tends to stay centered – bad!
Taper No, this is not crown and bridge!
What is Taper? D16
D1
0.02 taper
0.32 mm diameter increase
D16
D1
0.06 taper
Taper is expressed in mm diameter increase per mm length
0.96 mm diameter increase
How much is enough? • Schilder said we need to develop a continuously tapering form for debridement and resistance form • Black’s principles, modified by Ingle and Bakland, said our form must be dictated by the internal anatomy of the canal • Some canals do NOT have a continuously tapering form
• So, the taper we select must match the anatomy of the canal.
Some canals have a lot of taper…
1 2 3 4
Distance from apex
Size
Taper
1mm
40
2mm
60
.20
3mm
100
.40
4mm
110
.10
5mm
100
-.10
6mm
110
.10
7mm
130
.20
8mm
150
.20
5 6
Average taper = 0.157 mm/mm
7 8
Some canals have very little Distance from apex
Size
Taper
1mm
30
2mm
30
0
3mm
30
0
4mm
30
0
5mm
30
0
6mm
35
.05
7mm
45
.10
8mm
55
.10
9mm
60
.05
10mm
50
-.10
Average taper = 0.027 mm/mm
The problem with excessive taper Binds here
Not here
Files tend to bind and cut coronally, where they are largest, and not apically where we think they are binding, leaving the coronal portion overinstrumented and weak, and the apical portion underinstrumented and infected.
The problem with excessive taper
All files with a long cutting edge exhibit taper, and the modern trend is to more and more taper. This, however, is not appropriate for all canals. For those canals a non-tapered (LightSpeed), or minimally tapered (0.02) file must be used
Misconception about Ni-Ti • “Superflexibility” somehow negates characteristics of other metals – Increasing size -> increasing stiffness – Increasing taper -> increasing stiffness
• Reality – There is no magic!
Do those look flexible to you?
How do we create taper if we don’t use very tapered instruments?
Step - Back Technique
Taper = 0.05
By increasing file size in “steps” of 1mm as you “back out” coronally
Proper taper • The appropriate taper for a canal is that which it had initially • Occasionally we have to increase the taper slightly to allow for our obturation technique • Any dentin we remove, however, will weaken the tooth • So, we must err toward conservatism
Proper taper • For most molars and some premolars, rotary files having 0.04 and and 0.06 taper will produce approximately the correct taper • Excessive taper will cause strip perforations • Insufficient taper is not really a problem • So, err toward less taper
Proper file size • Some rotary systems are available with only small tip sizes (e.g. <40) • This is due to an erroneous belief that: – All canals are tapering – All canals are small at the apex
• Research shows that these assumptions are not true • Therefore, the apical portion may need to be prepared with hand instruments or LightSpeed
Taper?
Proper file size • In rotary systems that are available with tip sizes >40, tapers larger than 0.02 can lead to excessive coronal sizes and resulting strip perfs
Principles & Practice of Endodontics, Walton & Torabinejad, Saunders, 2002
But I thought more taper was better? • 0.06 taper means the file size enlarges by 0.06 mm/mm • If the tip size is 40, and • The length is 16mm, then • 16 x 0.06 = 0.96 • Add to tip size 40 = size 136 • A GT 0.12 would be 40 + 1.92 = size 231!
Proper file size Since file taper should match canal taper – The only reason to exceed the natural taper is to facilitate GP cone placement – In larger canal sizes, this is no problem
• Therefore, in teeth with large canals, less tapered files are indicated Canal is BIG and almost straight!
Proper file size • This means that in many maxillary anteriors and many premolars rotary instruments are not indicated or needed • It is often faster to instrument teeth with large canals with Hedstrom files than with rotary instruments!
Be sure you instrument to a large enough size apically!
Why is the preparation size important?
Bacteria!
Apical size chart Tooth
Initial file size
Final file size
MAXILLARY ARCH Central
45
60
Lateral
40 (30 if curved)
55 (45 if curved)
Canine
45
60
Premolar
B: 25, P: 30; 1 canal: 40
B: 40, P: 45; 1 canal: 55
Molar
MB: 25, DB: 25, P: 40
MB: 40, DB: 40, P: 55
Anterior
B: 25, L: 25; 1 canal 40
B: 40, L: 40; 1 canal 55
Canine
40
55
Premolar
B: 25, L: 30; 1 canal 45
B: 40, L: 45; 1 canal 60
Molar
MB: 25, ML: 25, D: 40
MB: 40, ML: 40, D: 55
MANDIBULAR ARCH
• Based on morphological studies • Not a rule but a starting point • Adjust for each individual tooth
Clinical Procedures
Clinical Procedures
1. Determine canal configuration
Clinical Procedures 1a. Estimate working length
Expose a parallel X- Ray
Clinical Procedures Pre-op film employs the XCP instrument to produce a parallel radiograph
Why parallel?
Clinical Procedures Parallel films have the least distortion and allow measurements to be made with reasonable accuracy
Clinical Procedures Paralleling requires a film holder Bisecting angle reduces but does not eliminate distortion
a Purple – tooth plane Red – Film plane Light blue – bisecting angle
b
A - with instrument B – without instrument
Do not fixate on the apex only!
Evaluate root curvature!
Clinical Procedures 1b. Estimate canal curvature
http://www.gearjammin.com/twisty/
Clinical Procedures
Do NOT use rotaries in highly curved canals!
Clinical Procedures 1c. Determine canal form
http://www.holylandmarket.com/html/731.htm
Determine canal form Small
Medium
Large
Rotary - OK
Rotary - OK
Rotary - NO
Clinical Procedures
2. Obtain straight line access
What burs do we need? • #4 or #6 high-speed round carbide
• D11-T equivalent diamond or Endo-Z bur
Access the chamber…
Then let the internal anatomy dictate your outline form
I nitial opening •
Remove caries and defective restorations
•
High speed round #4 or 6 for penetration into pulp chamber
•
Aim for largest canal
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Watch for procedural errors!
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
I nitial opening •
After penetration, enlarge by cutting on withdrawal
•
Locate largest canal, follow road map on chamber floor
•
Endo explorer to locate canals
Cohen S, Burns RC. Pathways of the Pulp, 7th Ed.
X Incorrect
Anteriors Correct
Penetrate, then cut on withdrawal
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Posteriors
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Penetrate, then cut on withdrawal
Enlargement •
Access preparation is a dynamic process
•
Conservation of tooth structure is SECONDARY to convenience form
•
Access opening should NEVER bind or guide instruments
Binding
Oops!
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Remove the cervical bulge! Pull up
Then smooth
Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Completed access •
Continuously tapering, conical form desired
•
Use a 1 DT diamond for outline form Ingle JI, Beveridge EE. Endodontics 2nd Ed.
Clinical Procedures
3. Explore canal patency
Clinical Procedures
Pass a small, precurved file to the apex
Clinical Procedures
4. Estimate canal size (use chart + x-ray)
Apical Size Chart Tooth
Initial file size
Final file size
MAXILLARY ARCH Central
45
60
Lateral
40 (30 if curved)
55 (45 if curved)
Canine
45
60
Premolar
B: 25, P: 30; 1 canal: 40
B: 40, P: 45; 1 canal: 55
Molar
MB: 25, DB: 25, P: 40
MB: 40, DB: 40, P: 55
Anterior
B: 25, L: 25; 1 canal 40
B: 40, L: 40; 1 canal 55
Canine
40
55
Premolar
B: 25, L: 30; 1 canal 45
B: 40, L: 45; 1 canal 60
Molar
MB: 25, ML: 25, D: 40
MB: 40, ML: 40, D: 55
MANDIBULAR ARCH
Notice the variation in canal size
Rotaries are not designed for large canals!
Clinical Procedures
5. Establish initial working length (IWL)
I nitial working length • •
Study pre-op radiographs to determine the approximate length to the apex Subtract 4mm; this is the IWL
IWL 4mm
Rotary technique • NEVER force a rotary instrument • Use only light pressure (similar to writing) • Use intermittent tapping motion • Listen to handpiece, reduce pressure if it slows down (this does NOT work in non-battery powered handpieces) • Always use a torque-reverse handpiece
Rotary technique • All instrumentation is PASSIVE • Instruments are chosen because they very nearly fit to length (1-2mm) • As they rotate, they clean and smooth • 3 sizes allows sufficient dentin removal for mechanical disinfection and smoothing without weakening the tooth
Clinical Procedures
6. Prepare coronal 1/3 with orifice shapers
Clinical Procedures Prepare coronal 1/3 with Orifice Shapers: Initial working length minus 4mm (apex – 8 mm) Begin with size that nearly reaches the IWL – 4 mm passively, increase 3 sizes (less if too much binding occurs)
Coronal Flaring: Orifice Shapers
STRAIGHT-LINE ACCESS
IWL - 4 IWL
Clinical Procedures Irrigation & RC Prep are essential!
Why irrigate and recapitulate?
Mud here… Causes perf here And failure here!
Recapitulation and Apical clearing • Canal is like a snow globe • An absorbent point would remove the liquid but not the snow • It would pack into the bottom of the globe, or apex of the tooth • Snow, or dentinal “mud”, must be removed mechanically
Clinical Procedures Instrument with a “tapping” motion Light pressure (like writing with a pen) NO MORE THAN 1MM AT A TIME !!!!!!!
Clinical Procedures Prepare coronal 1/3 with Orifice Shapers: Initial Working Length minus 4 mm Irrigation & RC Prep
Instrument with a “pecking” motion Light pressure (like writing with a pen) NO MORE THAN 1MM AT A TIME !!!!!!!
Small to large orifice openers until largest at approximately IWL - 4
Important note! • The Virginia technique is PASSIVE • NEVER force an instrument • If it doesn’t tap easily to the IWL-4, accept the new, shorter length • Continue to tap the instruments only as far as they go without causing the handpiece to autoreverse
Very large, non-tapered canals • If you can insert all the orifice openers to the IWL-4 or beyond, the canal is too large for rotary instrumentation with a long cutting edge instrument like a ProFile • Hand instrumentation or the LightSpeed system should be used • Consult your instructor before proceeding
Clinical Procedures 7. Prepare mid 1/3 with 0.06 tapers
0.06 taper files
Clinical Procedures Prepare coronal 2/3 with 0.06 tapers Select size that passively almost reaches IWL, instrument 3 sizes more Endpoint is the Initial Working Length
IWL
Clinical Procedures 8. Determine the exact length to foramen
How long should we go?
The Apical Foramen Cementum
Minor foramen
Dentin
Mesial view of an anterior tooth
"Natural" constriction in the apical area 0.25 to 0.5 from the radiographic apex = MINOR FORAMEN
The Apical Foramen Cementum
0.5 to 1 mm
Dentin Note: File is long, but it looks short on the radiograph!
Mesial view of an anterior tooth
Standard radiographic view
Instrument Length
Aim: As close to minor foramen as possible. Realize that the radiographic apex is not necessarily the anatomic apex!
Instrument Length
Ideal
Instrument Length
Final Working length will be ~1mm from radiographic apex
Instrument Length
Can I "feel“ the apex? - Only useful with crown-down technique - Not reliable - Use only in conjunction with
other techniques
How about apex locators?
Studies suggest ever-increasing accuracy Still remain technique-sensitive Do not work in all cases Useful adjunct, but can be difficult to interpret Need a combination of techniques for accuracy
Radiographic Determination Still the “gold standard”!
“Endo Ray” instrument allows paralleling radiograph with instruments in place
Radiographic Determination
Ideal placement
Radiographic Determination
Short
Long
Shift shot
• Always make 2 radiographs from slightly different angles • Aids in overcoming 2-D limitation
Radiographic Determination
Hedstrom and K files make canal identification easy!
Clinical Procedures 9. Prepare apical 1/3 with 0.04 ISO tapers from small to large
Prepare the apical 1/ 3
Working length
Instrumentation of the apical 1/3 Coat a 0.04 hand file the same size as the file you used to take your FWL radiograph with RC Prep Place it to the FWL using a watch-winding motion Rotate it clockwise until it is loose in the canal
Instrumentation of the apical 1/3 Irrigate copiously Coat the next larger file with RC Prep Work it to the FWL using a watch-winding motion Rotate it clockwise until it is loose in the canal
Instrumentation of the apical 1/3 Continue to repeat these steps for three file sizes. Recapitulate – after irrigating, replace the original file size to the FWL and watch wind to place if necessary. Then irrigate. This will remove any accumulated dentinal “mud”
Instrumentation of the apical 1/3 Now, begin step back as follows: Place the next larger size in the same fashion, but only to the FWL – 1mm. Work the file in the same fashion as previously
Instrumentation of the apical 1/3 Repeat this twice, with the next larger size, to FWL –2 and FWL –3 This will give you a “step back” taper
Instrumentation of the apical 1/3 Finally, recapitulate, irrigate, and smooth the steps by using the last size you took to the FWL in an up-anddown filing motion This file size is your master apical file, which will dictate the size of your master gutta percha cone
Important note… • Instrumentation near the apex is dangerous • Many endodontists complete the apical 1/3 entirely with hand instruments • However, the use of carefully controlled rotaries can result in a smoother transition • Once you have sufficient experience, the alternate technique for finishing should provide a smoother preparation
Instrumentation of the apical 1/3: alternative to step-back • After instrumenting to the WL for three file sizes past the file used to determine your FWL, instead of the stepback, simply: • Place the next larger size 0.04 taper Profile in the handpiece and gently tap it to the WL • Be careful not to pass the WL!
Remember: • NEVER attempt to instrument a canal with a rotary instrument that you have not already instrumented to the FWL with at least a size 25 hand instrument
Remember: • Always use any instrument, hand or rotary, with RC Prep for lubrication • Be sure to irrigate copiously after each file
Remember: • Apical clearing is NOT recapitulation! • It consists of: – Drying the canal – Rotating (by hand) without pressure the last size file used (master apical file)
Irrigate copiously, dry, apically clear, and you are…
