6. 1. Increased chance of instrument separation
2. Increased degree of torsional stress to the
instruments and the tooth.
7. Aggravated by the narrow mesio-distal dimensions
of the canal and the greater taper of the rotating
NiTi instruments
8. 1. Increased chance of instrument separation
2. Increased degree of torsional stress to the
instruments and the tooth.
3. Requires crown-down preparations and straight
line access.
9.
10. 1. Increased chance of instrument separation
2. Increased degree of torsional stress to the
instruments and the tooth.
3. Requires crown-down preparations and straight
line access.
4. Both procedures remove excess tooth structure
in the mesio-distal plane.
11. The role of mechanical instrumentation in the cleaning or root canals. Zvi Metzger,
Michael Solomonov, Anda Kfir. Endodontic Topics 2013;29:87-109.
12.
13. 1. Increased chance of instrument separation
2. Increased degree of torsional stress to the
instruments and the tooth.
3. Requires crown-down preparations and straight line
access.
4. Both procedures remove excess tooth structure in
the mesio-distal plane.
5. Not effective in cleansing in the bucco-lingual
plane.
14.
15.
16. 1. Increased chance of instrument separation
2. Increased degree of torsional stress to the
instruments and the tooth.
3. Requires crown-down preparations and straight
line access.
4. Both procedures remove excess tooth structure in
the mesio-distal plane.
5. Not effective in cleansing in the bucco-lingual
plane.
6. Produces dentinal micro-cracks.
17.
18. 1. Increased chance of instrument separation
2. Increased degree of torsional stress to the
instruments and the tooth.
3. Requires crown-down preparations and straight
line access.
4. Both remove excess tooth structure in the mesio-
distal plane.
5. Not effective in cleansing in the bucco-lingual
plane.
6. Produces dentinal micro-cracks.
7. With a non cutting tip and flutes that drive the
instrument apically, increased amounts of debris
are driven apically.
19. The same rotating fluted design that draws the
instrument beyond the apex will also drive the debris
in front of the tip beyond the confines of the root.
21. When tooth structure is excessively removed in
the mesio-distal plane in teeth where the pulp is
very thin in that plane, the roots become weaker.
22. 8. Reduces resistance to vertical fractures.
9. Gives the canal a shape that increases the
masticatory stresses.
23. Again, a result of excessive removal of tooth
structure in the thinner mesio-distal plane.
24. 8. Reduces resistance to vertical fractures.
9. Gives the canal a shape that increases the
masticatory stresses.
10. Only for single usage.
25. 8. Reduces resistance to vertical fractures.
9. Gives the canal a shape that increases the
masticatory stresses.
10. Only for single usage.
11. Very expensive.
26. 8. Reduces resistance to vertical fractures.
9. Gives the canal a shape that increases the
masticatory stresses.
10. Only for single usage.
11. Very expensive.
12. Increases procedural stress.
27. When the dentist must be constantly conscious of
the impact of the procedures on the integrity of
the instrument rather than the integrity of the
root, it underlines the fact that he/she is using a
poorly conceived product.
28. 8. Reduces resistance to vertical fractures.
9. Gives the canal a shape that increases the
masticatory stresses.
10. Only for single usage.
11. Very expensive.
12. Increases procedural stress.
13. Still dependent upon the K-file for the glide
path.
29. K-files are used manually for the creation of the
glide path producing hand fatigue and tend to
impact debris apically in curved canals resulting in
loss of length before rotary NiTi is employed.
30. And that brings us to a far safer, more efficient, less
expensive approach to endodontic instrumentation
that virtually eliminates hand fatigue and
separation while preserving far more tooth
structure.
31. Now let us consider 30º reciprocation of modified
reamers oscillating at 3000-4000 cycles per
minute.
32. 1. Use of modified reamers rather than K-files that
encounter less resistance making the shaping
procedure faster.
34. Relieved Vertically Fluted Instrument
K-File
We use these instruments rather than k-
files.
Comparing relieved vertically fluted
instruments to k-files we
observe the following:
1. Fewer flutes on the 16 mm of working
length of a relieved vertically fluted
instrument than on a k-file
approximately 16 flutes versus 30.
35. Consequences of fewer flutes:
1. There is less engagement along length.
2. Relieved vertically fluted instruments
are more flexible than files because they
are less work hardened and thinner in cross
section.
3. The flutes are more vertically oriented.K-File
Relieved Vertically Fluted Instrument
36. Relieved Vertically Fluted Instrument
K- File
Consequences of less engagement:
1. Less resistance along the shank as we
negotiate apically.
Consequences of greater flexibility:
1. Able to negotiate curved canals with
less chance of distortion.
Consequences of more vertically oriented
flutes:
1. Able to cut dentin along canal length
when the motion of the instrument is
either horizontal rotation or
reciprocation.
37. Taken together, the consequences of greater flexibility, less
engagement and more efficient cutting along length produce
a superior tactile perception along length and at the tip
of the instrument.
38. The consequences of superior tactile perception:
1. Allows the safe incorporation of a cutting tip.
The consequences of a cutting tip:
1. The ability to pierce pulpal tissue rather than
impact it apically.
2. The ability to distinguish between a tight
canal and hitting a wall when used in a
watchwinding motion or a reciprocating
handpiece.
39. The incorporation of the reciprocating
handpiece allows a 30º arc of motion
oscillating at 3000-4000 cpm.
A 30º arc of motion represents 1/12 of
a circle or 5 minutes on the face of a
clock.
The motion is so limited it virtually eliminates the 2 major
factors that cause rotary NiTi files to break and unwind,
namely, torsional stress and cyclic fatigue.
40. 1. Use of modified reamers rather than K-files that
encounter less resistance making the shaping
procedure faster.
2. No hand fatigue after the initial instrument goes
to the apex.
41.
42.
43. 1. Use of modified reamers rather than K-files that
encounter less resistance making the shaping
procedure faster.
2. No hand fatigue after the initial instrument goes
to the apex.
3. Virtually no chance of instrument separation
during the full shaping of the canal.
44. A 30º arc of motion virtually eliminates torsional
stress and cyclic fatigue in turn eliminating
instrument separation and dentinal micro-cracks.
45. 1. Use of reamers rather than K-files that
encounter less resistance making the shaping
procedure faster.
2. No hand fatigue after the initial instrument
goes to the apex.
3. Virtually no chance of instrument separation
during the full shaping of the canal.
4. Far less tooth structure sacrificed in the mesio
-distal plane.
46. Rarely, if ever, do we exceed an 04 taper, thus
preserving dentin in the mesio-distal plane while
removing more tissue in the bucco-lingual plane.
Nor is straight-line access necessary.
47. 1. Use of reamers rather than K-files that
encounter less resistance making the shaping
procedure faster.
2. No hand fatigue after the initial instrument
goes to the apex.
3. Virtually no chance of instrument separation
during the full shaping of the canal.
4. Far less tooth structure sacrificed in the mesio
-distal plane.
5. Greater debris removal in the bucco-lingual
plane.
48.
49. 1. Use of reamers rather than K-files that
encounter less resistance making the shaping
procedure faster.
2. No hand fatigue after the initial instrument
goes to the apex.
3. Virtually no chance of instrument separation
during the full shaping of the canal.
4. Far less tooth structure sacrificed in the mesio
-distal plane.
5. Greater debris removal in the bucco-lingual
plane.
6. No dentinal micro-cracks.
51. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
52. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
9. Used multiple times.
53. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
9. Used multiple times.
10. Relatively inexpensive.
54. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
9. Used multiple times.
10. Relatively inexpensive.
11. Far less procedural stress.
55. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
9. Used multiple times.
10. Relatively inexpensive.
11. Far less procedural stress.
12. Faithfully follows the glidepath created by
the most flexible 02 tapered stainless steel
reamers.
56. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
9. Used multiple times.
10. Relatively inexpensive.
11. Far less procedural stress.
12. Faithfully follows the glidepath created by
the most flexible 02 tapered stainless steel
reamers.
13. Pushes far less debris over the apex because
of a cutting tip and not being drawn into the
depths of the canal.
57. 7. Less reduction in resistance to vertical
fracture.
8. Lesser tapered preparations making the
tooth more resistant to masticatory forces.
9. Used multiple times.
10. Relatively inexpensive.
11. Far less procedural stress.
12. Faithfully follows the glidepath created by
the most flexible 02 tapered stainless steel
reamers.
13. Pushes far less debris over the apex
because of a cutting tip and not being
drawn into the depths of the canal.
14. Superior measurement control.
63. You have been presented with a detailed rationale for
modified reamers over K-files, 30º reciprocation
oscillating at 3000-4000 cycles per minute rather than
continuous or interrupted rotations and the
predominant use of stainless steel 02 tapered
instruments rather than greater tapered NiTi that will
increase the quantity and quality of the remaining
dentin while increasing the speed and safety of your
procedures.
64. The relieved reamers combined with the 30º
reciprocating handpiece are commercially known as
the SafeSider Instruments and oscillate in the
handpiece called the Endo-Express.
65. For further information on learning these
techniques call the offices of Dr. Barry Musikant.
The office number is 212-582-8161 and the
address is 119 West 57th Street NYC, NY.
Our E-mail address is mdkdendo@aol.com
For those interested in reviewing supporting
research it is available on request.
Editor's Notes
Relieved reamers have fewer and more vertically oriented flutes than those on a K-file
Fewer flutes mean less engagement along length. Fewer flutes also mean a more flexible instrument. Fewer flutes most importantly mean more vertically oriented flutes.
Less engagement means less resistance as the instrument negotiates apically. Greater flexibility means the instrument negotiates curves with less resistance. More vertically oriented flutes cut the dentin more efficiently when used with a watch winding motion or in the 30º reciprocating handpiece.
When you have instruments designed to negotiate to the apex more efficiently, have greater flexibility and shave dentin away more effectively, we produce instruments that have a better tactile perception meaning the dentist is better able to determine whether or not the tip of the instrument is hitting a solid object or is simply in a tight canal. In the former situation there is no immediate tugback. In the latter, tugback never disappears. Making this distinction is critical in knowing when to advance an instrument already in the canal and one that must be removed, prebent at the tip and then manually negotiated around an abrupt curve.
Superior tactile perception coupled to a reciprocating form of motion allows for a cutting tip that will pierce rather impact pulpal tissue
The 30º reciprocating arc of motion mimics manual motion that virtually eliminates the torsional stress and cyclic fatigue that leads to instrument separation when using rotary NiTi.
The reamers both relieved and unrelieved that we recommend fit into the handpiece. This design allows the same instrument to be used either manually or in the reciprocating handpeice.
a video of the reciprocating handpiece demonstrating the short arc of motion.
The reason the technique represents simple, predictable sequencing is because if used as indicated, breakage is not a problem and superior tactile perception tells the dentist if and when the instruments must be prebent to either negotiate around impediments or highly curved canals without causing any distortions.
We generally make a glidepath thru a 20 (yellow) going 0.5 mm beyond the apex and then use the tapered peeso within 6 mm of the apex. This is followed by the 25 also going 0.5 mm beyond the apex. The 30 and 35 go to the apex as measured by the apex locator, the 40 1 mm shorter and the 25/06 (pink) gain goes 0.5 mm beyond the apex. All these instruments can be used either manually or in the reciprocating handpiece.
We generally make a glidepath thru a 20 (yellow) going 0.5 mm beyond the apex and then use the tapered peeso within 6 mm of the apex. This is followed by the 25 also going 0.5 mm beyond the apex. The 30 and 35 go to the apex as measured by the apex locator, the 40 1 mm shorter and the 25/06 (pink) gain goes 0.5 mm beyond the apex. All these instruments can be used either manually or in the reciprocating handpiece.
