Endodontic Instruments
Usage of ideal instruments is essential in endodontics and every detail related to the types, usage, care in using them and lot more is discussed here.
1. What does D1 indicate?
D1 is the diameter at the tip of the instrument in hundredths of a mm.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 356
2. What are the standardized norms for endodontic instruments?
The diameter at the tip is D1 and that at the end of the cutting edge is D16. The difference in the diameter from D1 to D16 is 0.32mm. The taper of the instruments is consistent, 0.02mm. The D1/D16 distance is also constant, 16mm so that the working portion of the instrument is always the same.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 356,357
3. What are the variable lengths of the instruments available?
Short instruments (21mm) for the molars, standard (25mm) and long (31mm) for canines and any long roots.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 357
4. What accounts for the differences in the three lengths of the instruments?
The difference in the length is at the distance between the most coronal cutting flute and the handle, which is the shaft or the non working portion of the instrument.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 357
5. How are the colors standardized?
The colors are repeated every six instruments with the exception of the first three of the series.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 357
6. Why are stainless steel instruments preferred nowadays?
Stainless steel instruments are a mixture of pure iron 74% and chromium 18% which prevents corrosion and nickel 8% which confers elasticity to the alloy. So they are preferred nowadays.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 361
7. Why should the barbed broach be used cautiously?
If the barbed broach engages the canal wall and rotated to hook the pulp, it gets fractured. Also when the broach is placed excessively deep, the hooks bend in towards the shaft. While withdrawal, the hooks engage the dentin and bend outwards causing fracture of the instrument. So these broaches have to be used only once with utmost caution.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 373
8. Where are barbed broaches truly indicated?
Barbed broaches are truly indicated in large and straight canals.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 373
9. How is the size of the broach important?
Depending on the case, the broach of suitable size is selected. Too much small broach will cause tearing and mashing of the pulp without hooking it and too large broach will engage the dentinal which may get fractured also.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 373
10. What are the uses of barbed broach?
The barbed broach is used to remove the pulp tissue, food residue or cotton pellets used as medication.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 373
11. What are Gates Glidden Drills?
Gates Glidden Drills are stainless steel instruments with a long shank and eliptical extremity that is flame shaped and guiding non cutting tip.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 373
12. How are Gates Glidden drills standardized?
They are available in 6 sizes and marked with circular notches, no.1 has one notch and no.2 has two notches and so on. No. 1 has a maximum diameter of 0.50mm at the widest part of the elliptical portion and it increases by 0.20mm for each successive size. The length of the cutting part increases progressively with the caliber.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 375
13. What are the uses of GG Drills?
GG Drills are used for the preparation of the coronal third of the canal and for eliminating interferences.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 376
14. How is the Gates Glidden Drill used in the canal?
The Gates Glidden drills are used passively on withdrawl from the canal with a brush like circumferential movement and their use must always be preceeded by preflaring of the canal using hand instruments.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 376
15. Why are GG drills not used actively?
GG drills when used actively will lead to ledge formation and dangerous structural weakening in curved and thin canals causing stripping.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 376
16. How do Peeso reamers differ from GG drills?
Peeso reamers are also steel instruments similar to GG drills but they differ in that the blades spread over a wide surface and the shape is cylindrical.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 377
17. What are the similar features in GG Drill and Peeso reamer?
Both are stainless steel instruments for contra angled handpiece. The design of the blade is radial lands type and the tip is non cutting in both.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 377
18. How are Peeso reamers used?
Peeso reamers are used in the preparation of post space in canals already enlarged or in retreatment to remove the obturating material much faster.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 377
19. Why are Peeso reamers used carefully?
The active part of the instrument is extended and hence the cutting action is very aggressive which can actually cause root stripping. So it is used carefully.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 377
20. How do the sizes of Peeso reamers vary?
The peeso reamers also have notches corresponding to the sizes from 1-6. No.1 has a maximum diameter of 0.7mm which increases by 0.2mm for each successive size until reaching 1.7mm for the instrument.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 377
21. What are line angle axxess burs? ( LA Axxess burs)
The LA axxess burs are steel burs for the low speed handpiece specifically designed for the elimination of interferences in the pulp chamber and coronal one third of the canal.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 377
22. What are Race instruments?
Race are instruments with alternating cutting edges characterized by a triangular cross section, cutting blades, non working tip and alternating cutting angles that reduce the risk of screw in, canal blockage and reduces the working torque of the instruments.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 393
23. What are the advantages of the alternating cutting edges in the Race?
The alternating cutting edges reduce the risk of screw in, canal blockage and reduces the working torque of the instruments.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 393
24. Why are K files considered as the ideal instrument for exploring endodontic anatomy?
The K files are the most used endodontic instruments, made by twisting a steel wire with square cross section. The cross section increases its resistance to torsion and flexion making it particularly useful in initial negotiation of the canal. The four point contact of the blades against the canal walls also improves the tactile perception of the operator. So they are considered to be the ideal instruments for exploring the endodontic anatomy.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 362,363
25. What is the inconvenience produced while working with K type file and how to overcome it?
The K file produces a large amount of dentinal debris that can block the spirals of the files thus decreasing their cutting efficiency. The push and pull action can push the debris apically thereby blocking the foramen. To prevent this, the file should work on withdrawal, the debris frequently rinsed away and alternative irrigation is done.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 363
26. What are K flex files?
The K flex files are hybrid instruments that can integrate the force and versatility of the K file and cutting aggression of Headstroem file. It has a rhomboidal cross section that increases the flexibility in larger diameters also.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 363
27. How do Flex o files differ from K files?
K Flexofiles differ from the K files in the cross section and the instrument tip. The tip of the flexo files is rounded with a blunted transitional angle making it safer during shaping the curved canals and their cross is triangular. Whereas the K files have a quadrangular design and the tip of the file is cutting and has an aggressive transition angle causing ledging when used in curved canals.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 363
28. How does the cross section of the flexo files make it better than K files?
The triangular cross section is less bulky than the K files and it increases its flexibility. The three angles of contact with the dentinal walls reduce the friction and favour penetration in an apical direction. Also this cross section gives increased space for the dentinal debris to be removed and so there is less tendency for causing apical plugging.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 363
29. What is Unifile?
The Unifile has a cross section of a ‘S’ obtained by machining a double helix on the long axis of the round wire.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 364
30. How does a S file differ from Unifile?
Both the S file and the Unifile have a ‘S’ configuration in cross section but S file has a constant angle of spirals throughout the working length and a spiral depth which increases from the tip to the handle.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 364
31. What are C+ files?
They are files devised to facilitate the location of the canal orifices and initial exploration of calcified canals. They have a robust quadrangular cross section that makes the instrument resistant to deformation, thereby allowing to exert more pressure during insertion into the canal. The tip is pyramidal that favors its penetration in calcified canals.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 365,366
32. How are ultrasonic files used?
The ultrasonic files were used previously for canal shaping but because of their tendency to make ledges in the canal walls and their structural fragility, they are currently used passively to activate the irrigating solution before canal obturation.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 366
33. Why are GG drills considered as important aids for endodontists?
GG drills are important aids for endodontists since they eliminate the coronal interferences and prepare the coronal one third of the canal.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 376
34. What is Pro taper system?
The Protaper system consists of 6 instruments that are divided into 2 groups of 3 instruments each – shapers with marking SX, S1 and S2 and finishers with markings F1, F2 and F3.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 390
35. What are shapers and finishers in protaper system?
The shapers are instruments for eliminating coronal interferences and to create a smooth pathway for the finishing instruments. The finishers are meant for finalizing the shape created by the shapers and for giving a definitive taper and diameter to the canal.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 390
36. How are the Protaper shapers used in the canal?
The shapers are not forced into the canal and used in increasing order from smallest to the largest in a pre enlarged canal. They are used in lateral cutting action (ie) brushing action that is very useful for removing the coronal interferences.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 392
37. How are the finishers used in the canal?
The finishers have a greater taper and diameter and must be used with a rapid insertion and withdrawl without excessive pressure.
Ref: Endodontics,Arnaldo Castelluci,IL Tridente, vol II; 392