[ Title ]
An analysis of clinical breakage of root canal instruments.
[Publication ]
Sotokawa T. : An analysis of clinical breakage of root canal instruments,
J Endodon, 14 : 75~82, 1988.
[ Abstract ]
The motive for the present research was to elucidate the causes for instrument failures in order to develop clinical measures to prevent thrir occurrence. Accordingly, for that purpose, a statistical analysis was conducted on K files disposed of at my clinic, with the results showing that such breakages were concentrated among specific K file numbers. In addition, metal fatigue was found to be deeply implicated, based on the results of a scanning electron microscopic analysis of K files that failed during clinical therapy. Moreover, laboratory simulation of various clinical methods of handling demonstrated that metal fatigue and damage in the instrument can be spread more severely depending on the type of filing action.
Cracking in the region of one of the file's edges (20KV; original magnification x1,000).
The fracture surface of a file broken exhibiting little or no macrocopic plastic deformation (20KV; original magnification x270).
The article is quoted in the fourth edition of Dr. Ingle's textbook `ENDODONTICS`.
[Publication ]
Ingle, J.I. and Bakland L. K. :Endodontics fourth edition, 165, Williams & Wilkins, Phila., 1994.
[ Referenced ]
Sotokawa in Japan also studied discarded instruments and indicted metal fatigue as the culprit in breakage and distortion. "First a starting point crack develops on the file's edge and then "metal fatigue fans out from that point, spreading towards the file's axial center". Sotokawa also classified the types of damage to instruments. He found the number 10 file to be the most frequently discarded.
Classification of broken instruments
[ Title ]
Intracanal Breakage of Root Cannal Instruments
[Publication ]
Sotokawa T. : Intracanal Breakage of Root Cannal Instruments, The journal of japan endodomtic association, 10 : 20~27, 1989.
[ Abstract ]
It is an undoubted fact that an occasional breakage of root canal instruments during clinical practice has bothered and frustrated endodontists for a long time. Such an accident has occurred even in the most experienced.
Various methods and instruments have been discussed and suggested for the settlement of this problem. However, in spite of such development, the intracanal breakage still remains an unsolved problem, which seems to have been more complicated.
This paper describes a method which I have recommended, together with other approaches which have been suggested.
Metal case for root canal instruments
[ Title ]
A systematic approach to preventing intracanal breakage of endodontic files
[Publication ]
Sotokawa T. : A systematic approach to preventing intracanal breakage of endodontic files, Endod Dent Traumatol, 6 : 60~62, 1990.
[ Abstract ]
This study was conducted to determine the effectiveness of a method to prevent intracanal breakage of endodontic files. An application schedule with a predetermined number of periods of use for K-files of all sizes was implemented at the author`s clinic for a 3-year period. All the files used under this schedule were discarded after the predetermined periods of use (Table 1), whether they displayed any deformity or not. During the 3 year period, 1933 files (53.7 per month) were discarded after preparation of 3269 root canals. There were 5 file fractures (0.1 per month) compared with 1.4 fractures per month before the adaption of this system. The monthly average of files discarded during the 3-year research period was 53.7. Before the adoption of the trial system, the monthly average of discarded files was 76.5. It is concluded that the experimental system effectively reduced the incidence of intracanal instrument fractures and the total number of files consumed.
Predetermined periods of use for K-files
#08~10 | Until deformity is observed |
#15~30 | 1 month |
#35~45 | 3 months |
#50~60 | 3 months |
#70~120 | 1 year |
[ Title ]
A systematic approach to preventing intracanal breakage of endodontic files
[Publication ]
Sotokawa T. : A systematic approach to preventing intracanal breakage of endodontic files, Meskin L. H., Currier G. F., Kennedy J. E. ets : The Year Book of Dentistry, 162~163, Mosby, St. Louis, 1991.
[ Abstract ]
This article appears in Year Book of Dentistry.
[ Title ]
A systematic approach to preventing intracanal breakage of endodontic files
[ Publication ]
Sotokawa T. : A System for Preventing Instracanal Breakage of Endodontic Files, Japan J Conserv Dent, 36 : 868~873, 1993.
[ Abstract ]
The purpose of the present study was to determine the effectiveness of a system to prevent intracanal breakage of endodontic files.
The experimental system was developed on the basis of the previous study conducted by the author. It consisted of four factors : file-selection, maintenance, -handling (Table 1), and predetermined periods (Table 2) of use for endodontic files of all sizes. The system underwent a four-year clinical trial at the author's clinic.
All the files used under this system were discarded after the predetermined periods of use, regardless of whether they displayed any deformity or not. During the four-year period, 2,872 files were discarded after preparation of 3,864 root canals. File breakage decreased remarkably to one (0.02 per month), compared with the figure attained before adoption of this system (0.14 per month).
It was concluded that the trial system was found to be much more effective against clinical breakage. Adoption of this system would conceivably ensure superior file conditions, allowing the endodontist to perform more efficient root canal therapy with less labor and strain.
Table 1 : Operated technique for preventing intracanal breakage of endodontic instruments.
1) | Discard deformed instruments. |
2) | Forbid continual twisting deformations. |
3) | Forbid counterclockwise twisting deformations. |
Table 2 : Predetermined period of use for endodontic files.
#08 | Until deformity is observed |
#10~20 | 1 month |
#25,30 | 3 months |
#35~45 | 6 months |
#50~130 | 1 year |
[ Title ]
Evaluation of A System for Preventing Intracanal Breakage of Endodontic Files
[ Publication ]
Sotokawa T. : Evaluation of A System for Preventing Intracanal Breakage of Endodontic Files, The Journal of Japan Endodontic Association, Vol.21 No.2, 85~88, 2000.
[ Abstract ]
The present study was carried out to evaluate a system established by the author to prevent intracanal breakage of endodontic files. It consists of four factors : file-selection, file-maintenance, file-handling, and predetermined periods of use for endodontic files of all sizes. The system underwent a seven year clinical use at the author's clinic. During the seven year period, 4,075 files were discarded after preparation of 5,357 root canals (0.76 per root).
No breakage was observed in all the files.
It was concluded that this system was found to be most effective against clinical breakage. Adoption of this system, at both private dental clinics like the author's and larger dental clinics, will save labor in the process of removing the separated instrument fragment from the inside of the root canal.
[ Title ]
Material science of metals dental clinicians need to know for practicing desirable endodontic therapy
[Publication ]
Sotokawa T. : Material science of metals dental clinicians need to know for practicing desirable endodontic therapy, Journal of Japan Endodontic Association, Vol.23 No.1 : p.5~11, 2002.
[ Abstract ]
Root canal instruments are used in various handling methods depending on the location, shape, or conditions of the root canal dentists are treating. The instruments are considered to undergo various complicated deformations as a result of the dynamic differences involved in these actions. To prevent intracanal breakage of root canal instruments, dentists should know the physiochemical properties of the metals used for instruments. The dentists, then, can perform more efficient root canal therapy with less labor and strain. This article presents materials and manufacturing process of root canal instruments, the causes of the intracanal breakage of the instruments , and the terminology in material science metals.
Process of striation
[ Title ]
A method for preventing intracanal breakage of root canal instruments
[Publication ]
Sotokawa T. : A method for preventing intracanal breakage of root canal instruments, Journal of Japan Endodontic Association, Vol.24 No.1,2 : p.1~8, 2003.
[ Abstract ]
The intracanal breakage of root canal instruments has been considered a big problem in endodontic treatment. To prevent the breakage, dentists should apply efficient root canal therapy in their treatment with knowledge of the characteristics of endodontic instruments.
This article is about historical perceptives of intracanal breakage, prevention and prognosis, and the method devised and seven-year-adopted by the author for preventing intracanal breakage of root canal instruments.
The preventive method is applicable for dentists under any clinical situation. The practical application of such a method in their treatment will ensure file conditions, allowing dentists to perform more efficient root canal therapy with less labor and strain.
MAIL : sotokawashika@ozzio.jp