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Apical extrusion of debris using two hand and two rotary instrumentation techniques
0099-2399/98/2403-0180503.00/0 JOURNALOF ENDODONTICS Copyright © 1998 by The American Association of Endodontists
Printed in U.S.A.
VOL. 24, NO. 3, MARCH1998
Apical Extrusion of Debris Using Two Hand and Two Rotary Instrumentation Techniques Sarina A. Reddy, DDS, and M. Lamar Hicks, DDS, MS
The purpose of this study was to investigate the quantity of apical debris produced in vitro using two hand and two rotary instrumentation techniques. Sixty minimally curved, mature human mandibular premolars with single canals were divided into 4 groups of 15 teeth each and prepared using step-back instrumentation with K-files, balanced force with Flex-R files, Lightspeed nickeltitanium instruments, or .04 taper ProFile Series 29 rotary nickel-titanium files. Debris extruded through the apical foramen during instrumentation was collected on preweighed filters. The mean weight of extruded debris for each group was statistically analyzed using a Kruskal Wallis one-way analysis of variance and a Mann-Whitney U rank sum tested. Although all instrumentation techniques produced apically extruded debris, stepback instrumentation produced significantly more debris than the other methods (p < 0.0001). There was no difference between balanced force hand instrumentation and the two rotary nickel-titanium instrumentation methods (p > 0.05). Hand or engine-driven instrumentation that uses rotation seems to reduce significantly the amount of debris extruded apically when compared with a push-pull (filing) technique. Decreased apical extrusion of debris has strong implications for a decreased incidence of postoperative inflammation and pain.
However, the amount of apical debris created by rotary nickeltitanium instruments has not been investigated. Vande Visse and Brilliant (5) first quantified the amount of debris apically extruded during instrumentation. They found that instrumentation with irrigant produced extrusion, whereas instrumentation without irrigant produced no collectible debris. Martin and Cunningham (8) found less extruded debris when instrumentation was confined to the canal and when an endosonic instrument was used. Fairbourn et al. (7) found sonic instrumentation extruded the least amount of debris, followed by cervical flaring and ultrasonic instrumentation. Conventional hand filing produced the most debris. Ruiz-Hubard et al. (6) compared conventional step-back instrumentation to crown down pressureless technique in both curved and straight canals in plastic blocks. They found that less debris was apically extruded using the crown-down pressureless technique in curved and straight canals when compared with stepback instrumentation. McKendry (3) found less apical debris when using balanced forced technique, compared with sonic or step-back techniques. The sonic and step-back groups did not differ significantly. A1-Omari and Dummer (4) compared eight different hand instrumentation techniques and found that step-back instrumentation with circumferential and anticurvature filing had the most apical extrusion, whereas crown-down pressureless and balanced force techniques produced the least amount of debris. A common finding in the aforementioned studies is that pushpull instrumentation (filing) produces more apical debris than instrumentation techniques that incorporate a rotational force. This leads to the hypothesis that engine-driven rotary instruments will produce less debris than hand filing techniques. The purpose of this study was to investigate the quantity of apical debris produced in vitro using step-back instrumentation, balanced force technique, and two engine-driven rotary instrumentation techniques using nickel-titanium instruments.
In an effort to obtain complete debridement of the root canal system, debris such as dentina] filings, necrotic pulp tissue, bacteria or irrigants may be extruded into the periradicular tissue. This debris may lead to postoperative pain and discomfort (1, 2). Studies show that almost all instrumentation techniques produce apical debris to some degree (3-8). Using an instrumentation technique that minimizes apical extrusion would be advantageous to both the practitioner and the patient. Investigators studying the amount of apical debris extruded during instrumentation have examined hand instrumentation (38), sonic instrumentation (6-8) and the use of irrigation (5).
MATERIALS AND METHODS Sixty extracted human mandibular premolars with patent single canals and completely formed apices were used in this study. The teeth were sterilized in an autoclave and stored in a 0.05% thymol solution. The teeth selected met the criteria of similar root curvature, root length, and canal size at the working length. All teeth were radiographed and the degree of root curvature determined using the method of Schneider (9). Only teeth with minimal (0 to
180
Vol. 24, No. 3, March 1998
Apically Extruded Dentinal Debris
181
10 degrees) curvature were included. All of the teeth were decoronated so the roots were of similar length. Canal patency was established with a #15 file. The working length was determined by placing a #15 file in the canal so it was flush apically with the external surface of the root, then pulling back 1 mm. The first file to bind at the working length was recorded. The only teeth used were those that had canals in which a #20 or #25 file bound at the working length. The external root surface of all teeth was debrided with a periodontal curette. Any pulp tissue was removed with a barbed broach. The teeth were randomly assigned to 1 of 4 groups of 15 teeth each. All canals, regardless of technique, were irrigated with 2 ml of 2.5% sodium hypochlorite after each instrument using a 28-gauge needle. The needle was placed as far into the canal as possible without binding.
Step-back Filing Technique (Group 1) All files used in group 1 (10) were K-flex files (Caulk, Milford, DE). The apical preparation was made by starting with the first file to bind at the working length. Each file was used in a push-pull filing motion until it was loose in the canal before the next size file was used. The apical preparation was enlarged to a #55 file. Then, progressive filing was completed using four successively larger files, each at a length 1 mm shorter than the previous file. The coronal two-thirds of the canal was prepared using a circumferential filing motion with the last file used.
Balanced Force Technique (Group 2) All files used in group 2 (11) were Flex-R files (Union Broach, York, PA). The teeth were instrumented using the "balanced force" concept as described by Roane et al. (11). Instrumentation began with a file one size larger than the first file that bound at the working length. This technique was conducted to an apical preparation size of a #55 file, as suggested by Roane et al. (11).
Lightspeed Rotary Instrument Technique (Group 3) After the working length was established in group 3 teeth with a #15 K-file, the size of the canal at the working length was measured with a Lightspeed instrument to ensure that it did not exceed a size 25. The nickel-titanium instruments were used in a 1/1 handpiece (Aseptico, K_irkland, WA) powered by an electric motor (Aseptico, Kirkland, WA) at a constant speed of 2000 rpm. The canals were successively instrumented to the working length up to a #55 instrument. Then, a step-back technique was used up to a #100 Lightspeed instrument.
FIG 1. Photograph of glass microanalysis filtration system. (,,4)Acrylic block with tooth in place. (B) Vacuum flask. (Arrowhead) Collecting filter held in vice. (Arrow) Tooth root embedded in acrylic block.
0.465 at the tip. No hand instrumentation was used after determining the working length. For all groups, the operator was shielded from the root by an acrylic block (Fig. 1). Upon completion of instrumentation, the apically extruded debris (Fig. 2) was washed off the root apex with absolute alcohol from a wash bottle and collected on a preweighed 25 mm Durapore filter (Millipore, Bedford, MA) with a pore size of 65 /xm placed in a glass microanalysis filtration device (Millipore) (Fig. 1). After drying for 6 to 7 days, the samples were weighed on a Mettler microbalance (Mettler Instrumente, Greisensee, Switzerland) to 0.01 rag. The weight of the debris was determined by subtracting the weight of the filter from the weight of the filter plus the dried debris. All instrumentation and weighing was done by one operator. The mean weight of extruded debris for each group was analyzed statistically using a Kruskal-Wallis one-way analysis of variance and a Mann-Whitney U rank sum test. The confidence level was set at 0.05.
ProFile .04 Taper Series 29 Rotary Instrument Technique (Group 4)
RESULTS
After the working length was established in group 4 teeth with a #15 K-file, they were instrumented according to the manufacturer's directions. The rotary nickel-titanium files (Tulsa Dental Products, Tulsa, OK) were used in a 16/1 gear reduction handpiece (Aseptico) powered by an electric motor (Aseptico) at a constant speed of 300 rpm. The final instrument used at the full working length was a #7 ProFile .04 Taper, which is equivalent to ISO size
The mean weight, range, and standard deviation for each instrumentation group are presented in Table 1. Data were analyzed using a Kruskal-Wallis one-way analysis of variance to determine whether a significant difference in the amount of apically extruded debris existed among the groups. Because data were distributed abnormally, a nonparametric test, the Mann-Whitney U rank sum test, was used to compare the groups to each other. This analysis
182
Reddy and Hicks
Journal of Endodontics
FIG 2. Representative examples of apically extruded debris produced by different instrumentation techniques. (A) Step-back. (/3) Balanced force. (C) .04 taper ProFile Series 29. (D) Lightspeed. showed that step-back instrumentation (group 1) produced significantly more debris (p < 0.0001) than any other method of instrumentation. The difference in the amount of debris produced among groups 2, 3, and 4 was not significant.
DISCUSSION The results of this study demonstrate that all of the instrumentation methods tested produce apically extruded debris in vitro.
Apically Extruded Dentinal Debris
Vol. 24, No. 3, March 1998 TABLE 1. Analysis of apically extruded debris produced by two hand and two rotary instrumentation methods Instrumentation Group
Mean Weight (mg)
SD
Range (mg)
Group 1 Step-back
2.58*
1.87
0.11-7.03
Group 2 Balanced force
0.53
0.45
0.05-1.26
Group 3 ProFile .04
0.46
0.36
0.00-0.98
Group 4 Lightspeed
0.39
0.32
0.00-0.96
* Significantly different from the other groups, Mann-Whitney U rank sum test, p < 0.0001.
Regardless of instrumentation method, all of the apically extruded debris produced was dentin debris from instrumentation and not pulpal remnants. The pulp tissue was removed before instrumentation to eliminate a variable. To increase the probability that the amount of dentinal debris produced was a result of instrumentation, a standardized tooth model was used to decrease the number of variables. The teeth used for this study were carefully selected according to tooth type, canal size at the working length, and canal curvature. In addition, the teeth were decoronated to keep the root canals similar in length and to create an easy reference point for the working length. This ensured that the amount of debris produced apically was due to the instrumentation method and not to tooth morphology. The results of this study agree with McKendry (3) and Al-Omari and Dummer (4) that step-back instrumentation produced more apically extruded debris than the balanced force technique. Stepback instrumentation also produced significantly more debris than either of the rotary nickel-titanium instrumentation techniques. A comparison of these hand instrumentation techniques to engine k driven nickel-titanium instrumentation had not been previously reported. The hypothesis that engine-driven rotary nickel-titanium instruments will produce less debris than hand filing techniques was only partially supported. Although it was expected that step-back filing would produce more debris than the other groups, it was not expected that the balanced force technique would produce such small amounts of apically extruded debris that it would be statistically similar to the engine-driven rotary techniques. A probable explanation for these results is that groups 2, 3, and 4 all incorporate rotation during instrumentation, which tends to pull dentinal debris into the flutes of the file and directs it toward the coronal aspect of the canal. In contrast, the push-pull or filing action of the step-back technique tends to push more debris apically. The K-file acts as a plunger to force the debris ahead of the file, through the patent apical foramen, and out into what would be the periradicular area.
In the clinical situation, the debris extruded apically would enter
183
the periradicular tissue. In addition to dentinal debris, bacteria, intracanal irrigants, or intracanal medicaments can be forced into the periradicular tissues and produce postinstrumentation inflammation and pain. Seltzer et al. (2) reported that dentin debris in the periapical area was associated with persistent inflammation. Totneck et al. (12) reported similar findings in the incisors of young primates. Instrumentation that involves rotational movement, such as the balanced force technique and the Lightspeed and ProFile Series 29 systems, decreases the amount of debris forced apically thus leading to a decreased potential for periradicular tissue irritation and postoperative sequella. In conclusion, incorporating rotational movement in hand instrumentation (as with the balanced force technique) or with engine-powered instrumentation (as with the Lightspeed and ProFile Series 29) is recommended to reduce the amount of apically extruded debris. We thank Tulsa Dental Products, Lightspeed Technologies, Inc., and the I. B. Bender Research Fund, Albert Einstein Medical Center for their support of this study. We also thank Dr. Richard Titlebaum for his encouragement and technical support, Dr. Semih Erhan for his assistance with the filtration system, Dr. Leonard Braitman for statistical analysis, and Ms. Brenda Vaden for her assistance in preparing the manuscript. Dr. Reddy is a former resident and Dr. Hicks is chairman and program director, I. B. Bender Division of Endodontics, Department of Dental Medicine, Albert Einstein Medicine Center, Philadelphia, PA. Address requests for reprints to Dr. M. Lamar Hicks, Chairman and Program Director, I. B. Bender Division of Endodontics, Department of Dental Medicine, Albert Einstein Medical Center, 5501 Old York Road, Philadelphia, PA 19141-3098.
References 1. Seltzer S, Naidorf IJ. Flare-ups in endodontics: etiological factors. J Endodon 1985;11:472-8. 2. Seltzer S, Soltanoff W, Sinai I, Goldenberg A, Bender I. Biologic aspects of endodontics. Part II1. Periapical tissue reactions to root canal instrumentation. Oral Surg 1968;26:534-9. 3. McKendry DJ. Comparison of balanced forces, endosonic, and stepback filing instrumentation techniques: quantification of extruded apical debris. J Endodon 1990;16:24-7. 4. AI-Omari MAO, Dummer PMH. Canal blockage and debris extrusion with eight preparation techniques. J Endodon 1995;21:154-8. 5. Vande Visse JE, Brilliant JD. Effect of irrigation on the production of extruded material at the root apex during instrumentation. J Endodon 1975; 1:243-6. 6. Ruiz-Hubard EL, Gutmann JL, Wagner MJ. A quantitative assessment of canal debris forced periapically during root canal instrumentation using two different techniques. J Endodon 1987;12:554-8. 7. Fairboum DR, McWalter GM, Montgomery S. The effect of four preparation techniques on the amount of apically extruded debris. J Endodon 1987;13:102-8. 8. Martin H, Cunningham WT. The effect of endosonic and hand manipulation on the amount of root canal material extruded. Oral Surg 1982;53: 611-3. 9. Schneider SW. A comparison of canal preparations in straight and curved root canals. Oral Surg 1971;32:271-5. 10. West JD, Roane JB, Goerig AD. Cleaning and shaping of the root canal system. In: Cohen S, Burns RC, eds. Pathways of the pulp. 6th ed. St. Louis: Mosby-Year Book, 1994:181-93. 11. Roane JB, Sabala CL, Duncanson MG. The "balanced force" concept for instrumentation of curved canals. J Endodon 1985;11:203-11. 12. Torneck CD, Smith JS, Grindall P. Biologic effects of endodontic procedures on developing incisor teeth. I}1. Effect of debridement and disinfection procedures in the treatment of experimentally induced pulp and periapical disease. Oral Surg 1973;35:532-40.
Printed in U.S.A.
VOL. 24, NO. 3, MARCH1998
Apical Extrusion of Debris Using Two Hand and Two Rotary Instrumentation Techniques Sarina A. Reddy, DDS, and M. Lamar Hicks, DDS, MS
The purpose of this study was to investigate the quantity of apical debris produced in vitro using two hand and two rotary instrumentation techniques. Sixty minimally curved, mature human mandibular premolars with single canals were divided into 4 groups of 15 teeth each and prepared using step-back instrumentation with K-files, balanced force with Flex-R files, Lightspeed nickeltitanium instruments, or .04 taper ProFile Series 29 rotary nickel-titanium files. Debris extruded through the apical foramen during instrumentation was collected on preweighed filters. The mean weight of extruded debris for each group was statistically analyzed using a Kruskal Wallis one-way analysis of variance and a Mann-Whitney U rank sum tested. Although all instrumentation techniques produced apically extruded debris, stepback instrumentation produced significantly more debris than the other methods (p < 0.0001). There was no difference between balanced force hand instrumentation and the two rotary nickel-titanium instrumentation methods (p > 0.05). Hand or engine-driven instrumentation that uses rotation seems to reduce significantly the amount of debris extruded apically when compared with a push-pull (filing) technique. Decreased apical extrusion of debris has strong implications for a decreased incidence of postoperative inflammation and pain.
However, the amount of apical debris created by rotary nickeltitanium instruments has not been investigated. Vande Visse and Brilliant (5) first quantified the amount of debris apically extruded during instrumentation. They found that instrumentation with irrigant produced extrusion, whereas instrumentation without irrigant produced no collectible debris. Martin and Cunningham (8) found less extruded debris when instrumentation was confined to the canal and when an endosonic instrument was used. Fairbourn et al. (7) found sonic instrumentation extruded the least amount of debris, followed by cervical flaring and ultrasonic instrumentation. Conventional hand filing produced the most debris. Ruiz-Hubard et al. (6) compared conventional step-back instrumentation to crown down pressureless technique in both curved and straight canals in plastic blocks. They found that less debris was apically extruded using the crown-down pressureless technique in curved and straight canals when compared with stepback instrumentation. McKendry (3) found less apical debris when using balanced forced technique, compared with sonic or step-back techniques. The sonic and step-back groups did not differ significantly. A1-Omari and Dummer (4) compared eight different hand instrumentation techniques and found that step-back instrumentation with circumferential and anticurvature filing had the most apical extrusion, whereas crown-down pressureless and balanced force techniques produced the least amount of debris. A common finding in the aforementioned studies is that pushpull instrumentation (filing) produces more apical debris than instrumentation techniques that incorporate a rotational force. This leads to the hypothesis that engine-driven rotary instruments will produce less debris than hand filing techniques. The purpose of this study was to investigate the quantity of apical debris produced in vitro using step-back instrumentation, balanced force technique, and two engine-driven rotary instrumentation techniques using nickel-titanium instruments.
In an effort to obtain complete debridement of the root canal system, debris such as dentina] filings, necrotic pulp tissue, bacteria or irrigants may be extruded into the periradicular tissue. This debris may lead to postoperative pain and discomfort (1, 2). Studies show that almost all instrumentation techniques produce apical debris to some degree (3-8). Using an instrumentation technique that minimizes apical extrusion would be advantageous to both the practitioner and the patient. Investigators studying the amount of apical debris extruded during instrumentation have examined hand instrumentation (38), sonic instrumentation (6-8) and the use of irrigation (5).
MATERIALS AND METHODS Sixty extracted human mandibular premolars with patent single canals and completely formed apices were used in this study. The teeth were sterilized in an autoclave and stored in a 0.05% thymol solution. The teeth selected met the criteria of similar root curvature, root length, and canal size at the working length. All teeth were radiographed and the degree of root curvature determined using the method of Schneider (9). Only teeth with minimal (0 to
180
Vol. 24, No. 3, March 1998
Apically Extruded Dentinal Debris
181
10 degrees) curvature were included. All of the teeth were decoronated so the roots were of similar length. Canal patency was established with a #15 file. The working length was determined by placing a #15 file in the canal so it was flush apically with the external surface of the root, then pulling back 1 mm. The first file to bind at the working length was recorded. The only teeth used were those that had canals in which a #20 or #25 file bound at the working length. The external root surface of all teeth was debrided with a periodontal curette. Any pulp tissue was removed with a barbed broach. The teeth were randomly assigned to 1 of 4 groups of 15 teeth each. All canals, regardless of technique, were irrigated with 2 ml of 2.5% sodium hypochlorite after each instrument using a 28-gauge needle. The needle was placed as far into the canal as possible without binding.
Step-back Filing Technique (Group 1) All files used in group 1 (10) were K-flex files (Caulk, Milford, DE). The apical preparation was made by starting with the first file to bind at the working length. Each file was used in a push-pull filing motion until it was loose in the canal before the next size file was used. The apical preparation was enlarged to a #55 file. Then, progressive filing was completed using four successively larger files, each at a length 1 mm shorter than the previous file. The coronal two-thirds of the canal was prepared using a circumferential filing motion with the last file used.
Balanced Force Technique (Group 2) All files used in group 2 (11) were Flex-R files (Union Broach, York, PA). The teeth were instrumented using the "balanced force" concept as described by Roane et al. (11). Instrumentation began with a file one size larger than the first file that bound at the working length. This technique was conducted to an apical preparation size of a #55 file, as suggested by Roane et al. (11).
Lightspeed Rotary Instrument Technique (Group 3) After the working length was established in group 3 teeth with a #15 K-file, the size of the canal at the working length was measured with a Lightspeed instrument to ensure that it did not exceed a size 25. The nickel-titanium instruments were used in a 1/1 handpiece (Aseptico, K_irkland, WA) powered by an electric motor (Aseptico, Kirkland, WA) at a constant speed of 2000 rpm. The canals were successively instrumented to the working length up to a #55 instrument. Then, a step-back technique was used up to a #100 Lightspeed instrument.
FIG 1. Photograph of glass microanalysis filtration system. (,,4)Acrylic block with tooth in place. (B) Vacuum flask. (Arrowhead) Collecting filter held in vice. (Arrow) Tooth root embedded in acrylic block.
0.465 at the tip. No hand instrumentation was used after determining the working length. For all groups, the operator was shielded from the root by an acrylic block (Fig. 1). Upon completion of instrumentation, the apically extruded debris (Fig. 2) was washed off the root apex with absolute alcohol from a wash bottle and collected on a preweighed 25 mm Durapore filter (Millipore, Bedford, MA) with a pore size of 65 /xm placed in a glass microanalysis filtration device (Millipore) (Fig. 1). After drying for 6 to 7 days, the samples were weighed on a Mettler microbalance (Mettler Instrumente, Greisensee, Switzerland) to 0.01 rag. The weight of the debris was determined by subtracting the weight of the filter from the weight of the filter plus the dried debris. All instrumentation and weighing was done by one operator. The mean weight of extruded debris for each group was analyzed statistically using a Kruskal-Wallis one-way analysis of variance and a Mann-Whitney U rank sum test. The confidence level was set at 0.05.
ProFile .04 Taper Series 29 Rotary Instrument Technique (Group 4)
RESULTS
After the working length was established in group 4 teeth with a #15 K-file, they were instrumented according to the manufacturer's directions. The rotary nickel-titanium files (Tulsa Dental Products, Tulsa, OK) were used in a 16/1 gear reduction handpiece (Aseptico) powered by an electric motor (Aseptico) at a constant speed of 300 rpm. The final instrument used at the full working length was a #7 ProFile .04 Taper, which is equivalent to ISO size
The mean weight, range, and standard deviation for each instrumentation group are presented in Table 1. Data were analyzed using a Kruskal-Wallis one-way analysis of variance to determine whether a significant difference in the amount of apically extruded debris existed among the groups. Because data were distributed abnormally, a nonparametric test, the Mann-Whitney U rank sum test, was used to compare the groups to each other. This analysis
182
Reddy and Hicks
Journal of Endodontics
FIG 2. Representative examples of apically extruded debris produced by different instrumentation techniques. (A) Step-back. (/3) Balanced force. (C) .04 taper ProFile Series 29. (D) Lightspeed. showed that step-back instrumentation (group 1) produced significantly more debris (p < 0.0001) than any other method of instrumentation. The difference in the amount of debris produced among groups 2, 3, and 4 was not significant.
DISCUSSION The results of this study demonstrate that all of the instrumentation methods tested produce apically extruded debris in vitro.
Apically Extruded Dentinal Debris
Vol. 24, No. 3, March 1998 TABLE 1. Analysis of apically extruded debris produced by two hand and two rotary instrumentation methods Instrumentation Group
Mean Weight (mg)
SD
Range (mg)
Group 1 Step-back
2.58*
1.87
0.11-7.03
Group 2 Balanced force
0.53
0.45
0.05-1.26
Group 3 ProFile .04
0.46
0.36
0.00-0.98
Group 4 Lightspeed
0.39
0.32
0.00-0.96
* Significantly different from the other groups, Mann-Whitney U rank sum test, p < 0.0001.
Regardless of instrumentation method, all of the apically extruded debris produced was dentin debris from instrumentation and not pulpal remnants. The pulp tissue was removed before instrumentation to eliminate a variable. To increase the probability that the amount of dentinal debris produced was a result of instrumentation, a standardized tooth model was used to decrease the number of variables. The teeth used for this study were carefully selected according to tooth type, canal size at the working length, and canal curvature. In addition, the teeth were decoronated to keep the root canals similar in length and to create an easy reference point for the working length. This ensured that the amount of debris produced apically was due to the instrumentation method and not to tooth morphology. The results of this study agree with McKendry (3) and Al-Omari and Dummer (4) that step-back instrumentation produced more apically extruded debris than the balanced force technique. Stepback instrumentation also produced significantly more debris than either of the rotary nickel-titanium instrumentation techniques. A comparison of these hand instrumentation techniques to engine k driven nickel-titanium instrumentation had not been previously reported. The hypothesis that engine-driven rotary nickel-titanium instruments will produce less debris than hand filing techniques was only partially supported. Although it was expected that step-back filing would produce more debris than the other groups, it was not expected that the balanced force technique would produce such small amounts of apically extruded debris that it would be statistically similar to the engine-driven rotary techniques. A probable explanation for these results is that groups 2, 3, and 4 all incorporate rotation during instrumentation, which tends to pull dentinal debris into the flutes of the file and directs it toward the coronal aspect of the canal. In contrast, the push-pull or filing action of the step-back technique tends to push more debris apically. The K-file acts as a plunger to force the debris ahead of the file, through the patent apical foramen, and out into what would be the periradicular area.
In the clinical situation, the debris extruded apically would enter
183
the periradicular tissue. In addition to dentinal debris, bacteria, intracanal irrigants, or intracanal medicaments can be forced into the periradicular tissues and produce postinstrumentation inflammation and pain. Seltzer et al. (2) reported that dentin debris in the periapical area was associated with persistent inflammation. Totneck et al. (12) reported similar findings in the incisors of young primates. Instrumentation that involves rotational movement, such as the balanced force technique and the Lightspeed and ProFile Series 29 systems, decreases the amount of debris forced apically thus leading to a decreased potential for periradicular tissue irritation and postoperative sequella. In conclusion, incorporating rotational movement in hand instrumentation (as with the balanced force technique) or with engine-powered instrumentation (as with the Lightspeed and ProFile Series 29) is recommended to reduce the amount of apically extruded debris. We thank Tulsa Dental Products, Lightspeed Technologies, Inc., and the I. B. Bender Research Fund, Albert Einstein Medical Center for their support of this study. We also thank Dr. Richard Titlebaum for his encouragement and technical support, Dr. Semih Erhan for his assistance with the filtration system, Dr. Leonard Braitman for statistical analysis, and Ms. Brenda Vaden for her assistance in preparing the manuscript. Dr. Reddy is a former resident and Dr. Hicks is chairman and program director, I. B. Bender Division of Endodontics, Department of Dental Medicine, Albert Einstein Medicine Center, Philadelphia, PA. Address requests for reprints to Dr. M. Lamar Hicks, Chairman and Program Director, I. B. Bender Division of Endodontics, Department of Dental Medicine, Albert Einstein Medical Center, 5501 Old York Road, Philadelphia, PA 19141-3098.
References 1. Seltzer S, Naidorf IJ. Flare-ups in endodontics: etiological factors. J Endodon 1985;11:472-8. 2. Seltzer S, Soltanoff W, Sinai I, Goldenberg A, Bender I. Biologic aspects of endodontics. Part II1. Periapical tissue reactions to root canal instrumentation. Oral Surg 1968;26:534-9. 3. McKendry DJ. Comparison of balanced forces, endosonic, and stepback filing instrumentation techniques: quantification of extruded apical debris. J Endodon 1990;16:24-7. 4. AI-Omari MAO, Dummer PMH. Canal blockage and debris extrusion with eight preparation techniques. J Endodon 1995;21:154-8. 5. Vande Visse JE, Brilliant JD. Effect of irrigation on the production of extruded material at the root apex during instrumentation. J Endodon 1975; 1:243-6. 6. Ruiz-Hubard EL, Gutmann JL, Wagner MJ. A quantitative assessment of canal debris forced periapically during root canal instrumentation using two different techniques. J Endodon 1987;12:554-8. 7. Fairboum DR, McWalter GM, Montgomery S. The effect of four preparation techniques on the amount of apically extruded debris. J Endodon 1987;13:102-8. 8. Martin H, Cunningham WT. The effect of endosonic and hand manipulation on the amount of root canal material extruded. Oral Surg 1982;53: 611-3. 9. Schneider SW. A comparison of canal preparations in straight and curved root canals. Oral Surg 1971;32:271-5. 10. West JD, Roane JB, Goerig AD. Cleaning and shaping of the root canal system. In: Cohen S, Burns RC, eds. Pathways of the pulp. 6th ed. St. Louis: Mosby-Year Book, 1994:181-93. 11. Roane JB, Sabala CL, Duncanson MG. The "balanced force" concept for instrumentation of curved canals. J Endodon 1985;11:203-11. 12. Torneck CD, Smith JS, Grindall P. Biologic effects of endodontic procedures on developing incisor teeth. I}1. Effect of debridement and disinfection procedures in the treatment of experimentally induced pulp and periapical disease. Oral Surg 1973;35:532-40.