009g-2399/90/1609-0423/$02.00/0 JOURNAL OF ENDODONTICS Copyright 9 1990 by The American Association of Endodontists
Printed in U.S.A,
VOL. 16, NO. 9, SEPTEMBER1990
Comparison of the Sealing Ability of Four Obturation Techniques Henry Anthony Greene, DDS, Marston Wong, DDS, MS, and Timothy A. Ingram III, DDS, MS
the manufacturer, friction created by the plugger and the special one-part canal sealing paste increases the flow of guttapercha into the apical one third of the canal and into the lateral canals. A number of investigators have evaluated the apical seal obtained by these various gutta-percha filling techniques. Benner et al. (7) found no significant difference in apical seals produced by the lateral condensation, warm (vertical) condensation, or McSpadden techniques. EIDeeb et al. (8) evaluated the apical leakage obtained with the same three techniques and found, through linear and volumetric measurements, less dye leakage for the warm gutta-percha technique. Recently, LaCombe et al. (9) compared the apical seal produced by lateral condensation, low (Ultrafil system)- and high (Obtura system)-temperature injection-molded thermoplasticized gutta-percha techniques. Results revealed that lateral condensation of gutta-percha produced significantly less linear leakage than the low- or high-temperature thermoplasticized gutta-percha techniques. However, the spectrophotometric results revealed no significant difference in apical leakage among the three groups. At the present, there are no reports on the quality of the apical seal produced by the Canal Finder system. The purpose of this study was to compare the sealing ability of four different obturation techniques. The Canal Finder system was compared with lateral condensation of guttapercha, the Ultrafil system, and the sectional warm guttapercha technique. Although the Canal Finder has the ability to clean and shape the root canal, the present study only evaluated the system's obturation capability.
This study compared the apical seal produced by four obturation techniques. The Canal Finder system was compared with lateral condensation, the Ultrafil system, and the sectional warm gutta-percha techniques. Forty-two anterior single-rooted teeth were instrumented. Ten teeth were not obturated and served as positive and negative controls. The apical seal was tested for leakage with 0.25% methylene blue dye. The teeth were shaved horizontally and dye penetration was measured with a Boley gauge. Results revealed there was no statistically significant difference among the four obturation techniques.
The ultimate objective of endodontic therapy is complete obturation of the root canal system. Studies (1, 2) have revealed incomplete obliteration of the canal space to be the major cause of endodontic failure. It has been determined that approximately 60% of endodontic failures are due to inadequate obturation of the root canal system (2). Many gutta-percha obturating techniques have been used to obliterate the root canal system. Presently, lateral condensation of gutta-percha and a variety of heat-softened guttapercha filling techniques are the most commonly used obturation techniques. Schilder (3, 4) popularized root canal obturation via the warm gutta-percha method. Yee et al. (5) introduced the injection-molded thermoplasticized gutta-percha concept of obturation. Based on this concept, the Hygenic Corp. developed a low-temperature injection-molded thermoplasticized gutta-percha delivery system (Ultrafil). Among the newer systems for root canal obturation is the Canal Finder system (Endo Technic Corp., Tustin, CA). In addition to being able to clean and shape the canal with this system, the clinician can also use it to facilitate obturation of the canal system. Goldman et al. (6) found that the Canal Finder maintained the original canal configuration more closely than did hand instrumentation. During canal obturation, the Canal Finder technique uses a master point and accessory points, but their placement is facilitated by a motorized handpiece containing a longshanked plugger. The handpiece is started and operated for 7 to l0 s at 6000 to 7000 rpm. The basic movement of the instrument is an up-down lengthwise vibration. According to
MATERIALS AND METHODS Forty-two extracted human maxillary and mandibular anteriors with completely formed apices were utilized in this study. Ten of these teeth, serving as controls, were not obturated. The teeth were divided into six groups for evaluation of the apical seal. Each group had a mixture of maxillary and mandibular anterior teeth. All 42 teeth were free of fractures, free of internal resorption and caries as revealed by radiographs, and contained large and small single patent, straight canals. Each tooth was numbered and assigned to one of the following experimental groups: Group 1 was eight teeth obturated using lateral condensation of gutta-percha and Roth 801 Elite grade sealer (Roth Drug Co., Chicago, IL). Group 2
423
424
Greene et al.
was eight teeth obturated using the Ultrafil system (Hygenic Corp., Akron, OH) and Roth sealer. Group 3 was eight teeth obturated using the Canal Finder system and Endo Technic canal sealer paste. G r o u p 4 was eight teeth obturated using sectional warm gutta-percha technique and Roth sealer. Group 5 was five positive control teeth with canals unfilled and apices open and group 6 was five negative control teeth with canals unfilled and apices closed with Dycal (D. L. Caulk Division, Dentsply International Inc., Milford, DE) and nail polish. The experimental teeth were soaked in 5.25% sodium hypochlorite for 1 h to remove adherent tissue and organic debris, then scraped with a Bard Parker knife, rinsed and stored in distilled water. Lingual access was completed with a straight fissure bur and Gates Glidden burs. The working lengths were determined by radiographs to be approximately 1 mm from the radiographic apex. K files (Sybron/Kerr, Romulus, MI) were used in progressive sizes until the apical preparations ranged from a #30 to #55 file depending on the size of the tooth. The canals were then flared with K files in a step-back fashion. The canal flaring ranged from #45 to #80. During instrumentation, the canals were flooded with 5.25% sodium hypochlorite, which was also used between files. After instrumentation, the canals were irrigated with 5.25% sodium hypochlorite, dried with paper points, and stored in a humidor until obturation. The canals of group 1 were obturated using a lateral con-
FiG 1. Specimen obturated using lateral condensation technique. Note void on the left and dye penetration into the dentin and around the gutta-percha periphery at the 6-mm level (original magnification x20).
Joumal of Endodontics
densation technique. Before obturation, each canal was irrigated with isopropyl alcohol and dried with paper points. A gutta-percha (Sybron/Kerr) master cone was then fitted with tug back at the working length. A thin coat of sealer was placed using a K file one size smaller than the master apical file, and the file was then placed to the working length and then pumped in and out along the canal walls. Following placement of the master cone, lateral condensation of the gutta-percha was accomplished by placing a MA57 spreader (Premier Dental Products Co., Norristown, PA) approximately 2 mm from working length for the initial accessory cone. Group 2 was obturated using the Ultrafil system (Hygenic Corp. Ultrafil Technique Manual). The system consists of an injection syringe, gutta-percha cannulas with a 22-gauge needle attached (equivalent to a #70 file), and a small portable 120-V heater with a preset temperature of 90"C. The canals were irrigated, dried, and coated with Roth sealer as described previously for the lateral condensation technique. The lowtemperature injection syringe with the needle attached was heated for 15 min which allowed the gutta-percha to flow at 70~ The needle was inserted 6 to 8 mm back from the working length of the canals, and the gutta-percha was injected until it backed up into the pulp chamber.
F~G 2. Specimen obturated using Ultrafil system. Note the islands of sealer (white spots) and small voids (black spots) in the gutta-percha. This section at the 5-mm level shows dye penetration into the dentin and surrounding the gutta-percha periphery (original magnification x17).
Vol. 16, No. 9, September 1990
Group 3 was obturated with gutta-percha using the Canal Finder system (Endo Technic Corp. Instruction Manual). The obturating components for this system consist of the Canal Finder contra-angle attachment for the low-speed handpiece, the #30 smooth plugger, and the Endo Technic one-part canal sealing paste. The canals were irrigated and dried as described previously, and the master cone was fitted with tug back, coated with the sealing paste, and then fully seated into the canal. Next, the #30 smooth plugger attached to the contraangle was inserted adjacent to the master cone 2 to 3 mm short of the working length. The handpiece motor (Shorty Low Speed Handpiece; Midwest American/Dental Division of American Hospital Supply Corp., Des Plaines, IL) was then started and operated for 7 to 10 s at approximately 6000 rpm. The handpiece used has a two-speed air motor with a maximum low speed of 6000 rpm in the lower speed range and 30,000 rpm at the upper speed range. Obturation was performed at the maximum speed of the lower speed range. After withdrawing the plugger, an accessory cone coated with a thin layer of sealer was inserted in the canal. This procedure was repeated using the #30 smooth plugger until the canal was completely obturated. Group 4 was obturated using the sectional warm guttapercha technique (10). Again, the canals were irrigated and
FIG 3. Specimen obturated using the Canal Finder system. Note the amount of sealer and lack of well condensed gutta-percha. This section at the 2.8-ram level shows dye penetration 360 degrees around the sealer and almost total dye penetration of the dentin (original magnification x l 6).
Comparison of Obturation Techniques
425
dried as described previously. A plugger with a rubber stop was selected to fit 3 mm short of the working length without binding. Then a master cone was fitted with tug back at the working length and cut into 3- to 4-mm sections. Roth's 801 Elite grade sealer was placed in the canal as described previously for lateral condensation. The plugger was warmed and the apical 3-ram section of gutta-percha was attached to the tip. An alcohol burner was used to slightly soften the attached gutta-percha section prior to carefully inserting the attached gutta-percha into the canal to the working length. The plugger was removed after a rotation in both directions. This procedure was repeated using additional sequential sections of the master cone until the canal obturation reached the level of the pulp chamber. As the canals were obturated coronally, successively larger diameter pluggers were used to condense the gutta-percha. Following obturation of groups 1 to 4, radiographs were taken of the buccal and mesial aspects of each tooth to evaluate the quality of gutta-percha condensation. Those teeth showing radiographic evidence of questionable fillings were redone. Then the access openings were sealed with copal varnish (Plastodent Inc., Bronx, NY) and Tytin amalgam (Sybron/Kerr). These teeth were stored in the humidor for 1 wk to allow the sealer to set (11). The canals of the teeth making up groups 5 and 6 were not obturated. Following closure of the access openings in both groups with copal varnish and amalgam, these teeth were
FIG 4. Specimen obturated using the sectional warm gutta-percha technique. Note void in the top half of gutta-percha and small islands of sealer at bottom periphery at the 9.8-mm level (original magnification xl0).
426
Journal of Endodontics
Greene et al.
stored in the humidor along with groups 1 to 4. The positive controls (group 5) were filled with water (12) before the access openings were sealed with copal varnish and amalgam. A #20 or #40 K file (depending on size of canal) was inserted through the apex to prevent leakage of the water until the teeth were ready for submersion in the methylene blue dye. Following the 1-wk period, the teeth were removed from the humidor. Approximately 1 mm of the apical third of the roots of groups 1 to 4 was gradually removed with a straight fissure bur until the pink of the gutta-percha just appeared. In addition, 1 mm was cut from the apical third of the teeth in groups 5 (positive control) and 6 (negative controls). Apices of the teeth in groups 1 to 4 and 6 were covered with one layer of Dycal. This was done to facilitate exposure of the gutta-percha when later removing the nail polish and wax from the root apices. The methods and materials from this point are similar to those of Spradling and Senia (12). Waxed dental floss was tied around the crowns, after which the teeth were coated with two layers of nail polish, allowing each layer to dry between coats. Each experimental tooth was dipped in melted base-plate wax (flexible base-plate wax; Dentsply, New York, NY) twice. The first layer was hard before the second was applied. The K files inserted through the apices of the positive control group were removed leaving the canal patent. The negative controls were left undisturbed. The experimental teeth were suspended by the dental floss in a closed test tube containing 0.25 % methylene blue dye for 7 days at 37~ After removal from the dye, the teeth were rinsed for 5 min in tap water. Then they were cooled in a refrigerator for 30 min. The nail polish and wax were removed from the teeth with scalers. Then the teeth were stored at room temperature in the humidor until sectioning. All sectioning and measuring was done by the same investigator. Each tooth was coded so that the evaluator could not identify the obturation technique used. A slot was cut on the incisal edge of each experimental tooth to accommodate the Boley gauge during measurement. Each tooth was hand-held with the apex turned upward. The teeth were shaved perpendicular to their long axis with a #57 bur (Midwest American, Des Plaines, IL) in a high-speed handpiece while viewing through a magnification of x2 and x4 under a Parlinda Magnifier 2x-4x (United Kingdom
Design, Hong Kong). The Boley gauge was used to measure each tooth from the incisal slot to the root tip before shaving. After shaving, another measurement, which represented the dye penetration, was taken. The initial measurement and the final measurement were taken three times each and the average was used. The initial measurement minus the second gave the millimeters of dye penetration. Termination of the dye penetration was defined as that point where dye no longer penetrated the gutta-percha, its interface with the dentin wall, or the dentinal tubules. After the data were collected, the coded teeth were identified. The groups were compared using a one-way analysis of variance (ANOVA). RESULTS The positive controls (group 5) showed dye penetration into the canals and dentinal tubules of the teeth. In three of the teeth, the dye penetrated past the cementoenamel junction into the crowns. Dye penetration in the other two teeth covered approximately three fourths of the canal lengths. The negative controls (group 6) did not demonstrate dye penetration. In the experimental groups, obturation of the guttapercha with the Canal Finder system (group 3) showed the least dye penetration while the sectional warm gutta-percha technique (group 4) revealed the most. Obturation with the Ultrafil system (group 2) and the lateral condensation technique (group 1) had the second and third highest mean dye penetration, respectively. Representative photographs Of each experimental group are shown in Figs. 1 to 4. The raw data and the mean of each experimental 'group are listed in Table 1, the range of each group is plotted in Fig.. TABLE 2. Analysis of variance of dye penetration with Canal Finder compared with lateral condensation, Ultrafil, and sectional gutta-percha techniques Source
SS
df
MS
F*
Column Residual Total
8.4 223.3 231.7
3 28 31
2.8 7.97
0.35
* Fo.9s3,28 = 2.95; Fcorn~ted: 0.35 < 2.95. accept Ho (p < 0.05).
TABLE 1. Dye penetration in millimeters for each tooth and group mean penetration Group
1
2
3
4
5
6
Material Tooth
1 2 3 4 5 6 7 8 Mean
Lateral Condensation
Ultrafil
Canal Finder
Sectional Gutta-percha
Positive Control
Negative Control
6.0 10.9 5.8 8.1 5.5 8.4 6.5 9.6
6.3 13.9 13.5 3.4 2.1 5.6 7.8 6.0
7.1 8.7 3.3 5.3 6.6 5.5 10.0 10.1
9.2 10.9 7.8 6.8 3.4 6.8 7.8 9.1
15.4 12.0 12.0 14.5 10.5
0 0 0 0 0
7.6
7.3
7.1
7.7
12.9
0
Vol. 16, No. 9, September 1990
Comparison of Obturation Techniques
5, and the ANOVA shown in Table 2. Using the ANOVA, the significance of the dye penetration was determined where p < 0.05. The results of the ANOVA reveal that there was no significant difference between the means of the groups. DISCUSSION The apices of the experimental teeth were cut back to the level where gutta-percha first appeared in order to ensure direct measurement of the gutta-percha seal, to eliminate variables in apical anatomy, and to eliminate the presence of apical dentin plugs. Harrison and Todd (11) showed that resection of the apical 3 to 4 m m of the root with a bur in a high-speed handpiece does not adversely affect the seal of a well-condensed gutta-percha root canal filling. Although many leakage studies (9, 12-14) allowed penetration of the dye by keeping a patent apical foramen, in the present study, penetration of the dye measured the gutta-percha seal directly since the apical foramen was removed. In regard to the mean dye penetration, the results of this study show similarities and differences to other dye studies. An explanation of the apparent differences may lie in the size of the instrument used to keep the apical foramen open. There appears to be a trend that the larger the file used to maintain patency, the greater the linear leakage. LaCombe et al. (9) used a #10 file to maintain foramen patency and obtained a mean leakage value of 0.5 m m for lateral condensation. E1Deeb (13) used a #15 file to maintain foramen patency and had a mean leakage of 4.45 m m for lateral condensation. Matloff et al. (14) used a #20 file for foramen patency and observed a 6.8-, 7.8-, and 8.2-ram mean leakage for lateral condensation. Spradling and Senia (12) instrumented the teeth to at least a #35 file at the apical foramen and obtained a 10.37-mm mean dye leakage for lateral condensation. From our observations in the present study, the amount of gutta-percha visible would be most likely the diameter of a #35-50 file tip. The mean dye leakage for this study was 7.6 m m for lateral condensation. The 0.25% methylene blue dye was not adjusted to pH 7. Its pH of 4.7 ___ 0.5, although slightly acidic, could have a dissolving effect on the inorganic portion of the tissues, thereby altering the amount of leakage (15). This may in part explain the higher recorded leakage values when compared with other studies if those studies had used adjusted pH dye solutions.
~v
427
Although no significant difference was found among techniques, obturation with the Canal Finder system showed the least mean leakage penetration when compared with the other experimental groups. Interestingly, the specimen with the least leakage (3.3 mm) in this group had very little sealer, but multiple distinct gutta-percha cones were observed (Fig. 6). For the most part though, a c o m m o n observation was the large amount of sealer found and lack of well-condensed gutta-percha (Fig. 7) seen in this group. Peters (16) has demonstrated that obturation techniques with large amounts of sealer will easily dissolve over a period of time.It is possible that the 6000 rpm minimum was not achieved during obturation, and as a result multiple distinct gutta-percha cones were commonly seen. Experimentation on plastic blocks without sealer revealed that the frictional component of the Canal Finder during obturation appeared not to be intense enough to soften gutta-percha to any extent. Apparently the softening effect of the eucalyptus oil in the sealer and the pumping of the spreader for 7 to 10 s provides the condensation required for obturation with the Canal Finder system. Still it is not enough to produce a homogenous mass of gutta-percha. The findings of this current study corroborates the spectrophotometric findings of LaCombe et al. (9) as well as the findings of Michanowicz and Czonstkowsky (17, 18) that the Ultrafil system compares favorably with the lateral condensation technique. It also substantiates findings by Benner et al. (7) who found no significant difference in apical seals
25
2O O J15
Lateral ~ondensation
Ultrafil
Canal Finder
Sectional Gutta-percha
..J
I I I
I
>.
ObtuFation
Material
FIG 5. Range of dye penetration for four groups. Each group contains eight teeth.
FIG 6. Specimen obturated using Canal Finder system. Note the absence of sealer at the canal periphery (voids) and poor condensation at the 2.2-mm level (original magnification x21).
428
Greene et al.
Journal of Endodontics The assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the U.S. Army or Department of Defense. The authors thank Mrs. Shirley Wilkinson for her technical assistance and Mrs. Hattie Greene for her extensive help in manuscript preparation. Dr. Greene is a former senior resident in the Advanced Educational Program in general dentistry (2 years), U.S. Dental Army Activity, Fort Hood, TX. Dr. Wong is chief and mentor of endodontics, Advanced Educational Program in general dentistry (2 years), U.S. Army Dental Activity. Dr. tngram is former chief and mentor of endodontics, Advanced Educational Program in general dentistry (2 years), U.S. Army Dental Activity.
References
FIG 7. Specimen obturated using Canal Finder system. Note the large amount of sealer and lack of good condensation at the 9.2-mm level (original magnification x l 5).
obtained by the lateral condensation or warm (vertical) condensation techniques. CONCLUSIONS Under the conditions of this study, no significant difference in apical leakage was observed among the Canal Finder system, the Ultrafil system, warm gutta-percha, and lateral condensation gutta-percha filling techniques.
1. Dew RP, Ingle JI. Isotope determination of root canal failure. Oral Surg 1955;8:1100-4. 2. Ingle JI, Beveridge EE. Endodontics. 2nd ed. Philadelphia: Lea & Febiger, 1976:34-57. 3. Schilder H. Filling root canals in three dimensions. Dent Clin North Am 1967;11:723-44. 4. Nguyen NT. Obturation of the root canal system, in: Cohen S, Burns RC, eds. Pathways of the pulp. 4th ed. St. Louis: CV Mosby Co., 1987:2106. 5. Yee FS, Madin J, Krakow AA, Gron P. Three-dimensional obturation of the root canal using injection-molded, thermoplasticized dental gutta-percha. J Endodon 1977;3:168-74. 6. Goldman M, Sakurai E, Kronman J, Tenca JI. An in vitro study of the pathfinding ability of a new automated handpiece. J Endodon 1987;13:42933. 7. Benner MD, Peters DD, Grower M, Bernier WE. Evaluation of a new thermoplastic gutta-percha obturation technique using 45Ca. J Endodon 1981 ;7:500-8. 8. EIDeeb ME, Zucker KJ, Messer H. Apical leakage in relation to radiographic density of gutta-percha using different obturation techniques. J Endodon 1985;11:25-9. 9. LaCombe JS, Campbell AD, Hicks ML, Pelleu GB. A comparison of the apical seal produced by two thermoplasticized injectable gutta-percha techniques. J Endodon 1988;14:445-50. 10. Fahid A, Taintor JF. Sectional warm gutta-percha technique. Gen Dent 1985;33:440-4. 11. Harrison JW, Todd MJ. The effect of root resection on the sealing property of root canal obturations. Oral Surg 1980;50:264-72. 12. Spradling PW, Senia SE. The relative sealing ability of paste-type filling materials. J Endodon 1982;8:543-9. 13. EIDeeb ME. The sealing ability of injection-molded thermoplasticized gutta-percha. J Endodon 1985;11:84-6. 14. Matloff IR, Jensen JR, Singer L, Tabibi A. A comparison of methods used in root canal sealabiiity studies. Oral Surg 1982;53:203-8. 15. Antoniazzi JH, Mjor IA, Nygaard-Ostby B. Assessment of the sealing properties of root filling materials. Odontol Tidskr 1968;76:261-71. 16. Peters DD. Two-year in vitro solubility evaluation of four gutta-percha sealer obturation techniques. J Endodon 1986;12:139-45. 17. Michanowicz A, Czonstkowsky M. Sealing properties of an injectionthermoplasticized low-temperature (70~ gutta-percha: a preliminary study. J Endodon 1984;10:563-6. 18. Czonstkowsky M, Michanowicz A, Vazquez JA. Evaluation of an injection of thermoplasticized low-temperature gutta-percha using radioactive isotopes. J Endodon 1985;11:71-4.
Printed in U.S.A,
VOL. 16, NO. 9, SEPTEMBER1990
Comparison of the Sealing Ability of Four Obturation Techniques Henry Anthony Greene, DDS, Marston Wong, DDS, MS, and Timothy A. Ingram III, DDS, MS
the manufacturer, friction created by the plugger and the special one-part canal sealing paste increases the flow of guttapercha into the apical one third of the canal and into the lateral canals. A number of investigators have evaluated the apical seal obtained by these various gutta-percha filling techniques. Benner et al. (7) found no significant difference in apical seals produced by the lateral condensation, warm (vertical) condensation, or McSpadden techniques. EIDeeb et al. (8) evaluated the apical leakage obtained with the same three techniques and found, through linear and volumetric measurements, less dye leakage for the warm gutta-percha technique. Recently, LaCombe et al. (9) compared the apical seal produced by lateral condensation, low (Ultrafil system)- and high (Obtura system)-temperature injection-molded thermoplasticized gutta-percha techniques. Results revealed that lateral condensation of gutta-percha produced significantly less linear leakage than the low- or high-temperature thermoplasticized gutta-percha techniques. However, the spectrophotometric results revealed no significant difference in apical leakage among the three groups. At the present, there are no reports on the quality of the apical seal produced by the Canal Finder system. The purpose of this study was to compare the sealing ability of four different obturation techniques. The Canal Finder system was compared with lateral condensation of guttapercha, the Ultrafil system, and the sectional warm guttapercha technique. Although the Canal Finder has the ability to clean and shape the root canal, the present study only evaluated the system's obturation capability.
This study compared the apical seal produced by four obturation techniques. The Canal Finder system was compared with lateral condensation, the Ultrafil system, and the sectional warm gutta-percha techniques. Forty-two anterior single-rooted teeth were instrumented. Ten teeth were not obturated and served as positive and negative controls. The apical seal was tested for leakage with 0.25% methylene blue dye. The teeth were shaved horizontally and dye penetration was measured with a Boley gauge. Results revealed there was no statistically significant difference among the four obturation techniques.
The ultimate objective of endodontic therapy is complete obturation of the root canal system. Studies (1, 2) have revealed incomplete obliteration of the canal space to be the major cause of endodontic failure. It has been determined that approximately 60% of endodontic failures are due to inadequate obturation of the root canal system (2). Many gutta-percha obturating techniques have been used to obliterate the root canal system. Presently, lateral condensation of gutta-percha and a variety of heat-softened guttapercha filling techniques are the most commonly used obturation techniques. Schilder (3, 4) popularized root canal obturation via the warm gutta-percha method. Yee et al. (5) introduced the injection-molded thermoplasticized gutta-percha concept of obturation. Based on this concept, the Hygenic Corp. developed a low-temperature injection-molded thermoplasticized gutta-percha delivery system (Ultrafil). Among the newer systems for root canal obturation is the Canal Finder system (Endo Technic Corp., Tustin, CA). In addition to being able to clean and shape the canal with this system, the clinician can also use it to facilitate obturation of the canal system. Goldman et al. (6) found that the Canal Finder maintained the original canal configuration more closely than did hand instrumentation. During canal obturation, the Canal Finder technique uses a master point and accessory points, but their placement is facilitated by a motorized handpiece containing a longshanked plugger. The handpiece is started and operated for 7 to l0 s at 6000 to 7000 rpm. The basic movement of the instrument is an up-down lengthwise vibration. According to
MATERIALS AND METHODS Forty-two extracted human maxillary and mandibular anteriors with completely formed apices were utilized in this study. Ten of these teeth, serving as controls, were not obturated. The teeth were divided into six groups for evaluation of the apical seal. Each group had a mixture of maxillary and mandibular anterior teeth. All 42 teeth were free of fractures, free of internal resorption and caries as revealed by radiographs, and contained large and small single patent, straight canals. Each tooth was numbered and assigned to one of the following experimental groups: Group 1 was eight teeth obturated using lateral condensation of gutta-percha and Roth 801 Elite grade sealer (Roth Drug Co., Chicago, IL). Group 2
423
424
Greene et al.
was eight teeth obturated using the Ultrafil system (Hygenic Corp., Akron, OH) and Roth sealer. Group 3 was eight teeth obturated using the Canal Finder system and Endo Technic canal sealer paste. G r o u p 4 was eight teeth obturated using sectional warm gutta-percha technique and Roth sealer. Group 5 was five positive control teeth with canals unfilled and apices open and group 6 was five negative control teeth with canals unfilled and apices closed with Dycal (D. L. Caulk Division, Dentsply International Inc., Milford, DE) and nail polish. The experimental teeth were soaked in 5.25% sodium hypochlorite for 1 h to remove adherent tissue and organic debris, then scraped with a Bard Parker knife, rinsed and stored in distilled water. Lingual access was completed with a straight fissure bur and Gates Glidden burs. The working lengths were determined by radiographs to be approximately 1 mm from the radiographic apex. K files (Sybron/Kerr, Romulus, MI) were used in progressive sizes until the apical preparations ranged from a #30 to #55 file depending on the size of the tooth. The canals were then flared with K files in a step-back fashion. The canal flaring ranged from #45 to #80. During instrumentation, the canals were flooded with 5.25% sodium hypochlorite, which was also used between files. After instrumentation, the canals were irrigated with 5.25% sodium hypochlorite, dried with paper points, and stored in a humidor until obturation. The canals of group 1 were obturated using a lateral con-
FiG 1. Specimen obturated using lateral condensation technique. Note void on the left and dye penetration into the dentin and around the gutta-percha periphery at the 6-mm level (original magnification x20).
Joumal of Endodontics
densation technique. Before obturation, each canal was irrigated with isopropyl alcohol and dried with paper points. A gutta-percha (Sybron/Kerr) master cone was then fitted with tug back at the working length. A thin coat of sealer was placed using a K file one size smaller than the master apical file, and the file was then placed to the working length and then pumped in and out along the canal walls. Following placement of the master cone, lateral condensation of the gutta-percha was accomplished by placing a MA57 spreader (Premier Dental Products Co., Norristown, PA) approximately 2 mm from working length for the initial accessory cone. Group 2 was obturated using the Ultrafil system (Hygenic Corp. Ultrafil Technique Manual). The system consists of an injection syringe, gutta-percha cannulas with a 22-gauge needle attached (equivalent to a #70 file), and a small portable 120-V heater with a preset temperature of 90"C. The canals were irrigated, dried, and coated with Roth sealer as described previously for the lateral condensation technique. The lowtemperature injection syringe with the needle attached was heated for 15 min which allowed the gutta-percha to flow at 70~ The needle was inserted 6 to 8 mm back from the working length of the canals, and the gutta-percha was injected until it backed up into the pulp chamber.
F~G 2. Specimen obturated using Ultrafil system. Note the islands of sealer (white spots) and small voids (black spots) in the gutta-percha. This section at the 5-mm level shows dye penetration into the dentin and surrounding the gutta-percha periphery (original magnification x17).
Vol. 16, No. 9, September 1990
Group 3 was obturated with gutta-percha using the Canal Finder system (Endo Technic Corp. Instruction Manual). The obturating components for this system consist of the Canal Finder contra-angle attachment for the low-speed handpiece, the #30 smooth plugger, and the Endo Technic one-part canal sealing paste. The canals were irrigated and dried as described previously, and the master cone was fitted with tug back, coated with the sealing paste, and then fully seated into the canal. Next, the #30 smooth plugger attached to the contraangle was inserted adjacent to the master cone 2 to 3 mm short of the working length. The handpiece motor (Shorty Low Speed Handpiece; Midwest American/Dental Division of American Hospital Supply Corp., Des Plaines, IL) was then started and operated for 7 to 10 s at approximately 6000 rpm. The handpiece used has a two-speed air motor with a maximum low speed of 6000 rpm in the lower speed range and 30,000 rpm at the upper speed range. Obturation was performed at the maximum speed of the lower speed range. After withdrawing the plugger, an accessory cone coated with a thin layer of sealer was inserted in the canal. This procedure was repeated using the #30 smooth plugger until the canal was completely obturated. Group 4 was obturated using the sectional warm guttapercha technique (10). Again, the canals were irrigated and
FIG 3. Specimen obturated using the Canal Finder system. Note the amount of sealer and lack of well condensed gutta-percha. This section at the 2.8-ram level shows dye penetration 360 degrees around the sealer and almost total dye penetration of the dentin (original magnification x l 6).
Comparison of Obturation Techniques
425
dried as described previously. A plugger with a rubber stop was selected to fit 3 mm short of the working length without binding. Then a master cone was fitted with tug back at the working length and cut into 3- to 4-mm sections. Roth's 801 Elite grade sealer was placed in the canal as described previously for lateral condensation. The plugger was warmed and the apical 3-ram section of gutta-percha was attached to the tip. An alcohol burner was used to slightly soften the attached gutta-percha section prior to carefully inserting the attached gutta-percha into the canal to the working length. The plugger was removed after a rotation in both directions. This procedure was repeated using additional sequential sections of the master cone until the canal obturation reached the level of the pulp chamber. As the canals were obturated coronally, successively larger diameter pluggers were used to condense the gutta-percha. Following obturation of groups 1 to 4, radiographs were taken of the buccal and mesial aspects of each tooth to evaluate the quality of gutta-percha condensation. Those teeth showing radiographic evidence of questionable fillings were redone. Then the access openings were sealed with copal varnish (Plastodent Inc., Bronx, NY) and Tytin amalgam (Sybron/Kerr). These teeth were stored in the humidor for 1 wk to allow the sealer to set (11). The canals of the teeth making up groups 5 and 6 were not obturated. Following closure of the access openings in both groups with copal varnish and amalgam, these teeth were
FIG 4. Specimen obturated using the sectional warm gutta-percha technique. Note void in the top half of gutta-percha and small islands of sealer at bottom periphery at the 9.8-mm level (original magnification xl0).
426
Journal of Endodontics
Greene et al.
stored in the humidor along with groups 1 to 4. The positive controls (group 5) were filled with water (12) before the access openings were sealed with copal varnish and amalgam. A #20 or #40 K file (depending on size of canal) was inserted through the apex to prevent leakage of the water until the teeth were ready for submersion in the methylene blue dye. Following the 1-wk period, the teeth were removed from the humidor. Approximately 1 mm of the apical third of the roots of groups 1 to 4 was gradually removed with a straight fissure bur until the pink of the gutta-percha just appeared. In addition, 1 mm was cut from the apical third of the teeth in groups 5 (positive control) and 6 (negative controls). Apices of the teeth in groups 1 to 4 and 6 were covered with one layer of Dycal. This was done to facilitate exposure of the gutta-percha when later removing the nail polish and wax from the root apices. The methods and materials from this point are similar to those of Spradling and Senia (12). Waxed dental floss was tied around the crowns, after which the teeth were coated with two layers of nail polish, allowing each layer to dry between coats. Each experimental tooth was dipped in melted base-plate wax (flexible base-plate wax; Dentsply, New York, NY) twice. The first layer was hard before the second was applied. The K files inserted through the apices of the positive control group were removed leaving the canal patent. The negative controls were left undisturbed. The experimental teeth were suspended by the dental floss in a closed test tube containing 0.25 % methylene blue dye for 7 days at 37~ After removal from the dye, the teeth were rinsed for 5 min in tap water. Then they were cooled in a refrigerator for 30 min. The nail polish and wax were removed from the teeth with scalers. Then the teeth were stored at room temperature in the humidor until sectioning. All sectioning and measuring was done by the same investigator. Each tooth was coded so that the evaluator could not identify the obturation technique used. A slot was cut on the incisal edge of each experimental tooth to accommodate the Boley gauge during measurement. Each tooth was hand-held with the apex turned upward. The teeth were shaved perpendicular to their long axis with a #57 bur (Midwest American, Des Plaines, IL) in a high-speed handpiece while viewing through a magnification of x2 and x4 under a Parlinda Magnifier 2x-4x (United Kingdom
Design, Hong Kong). The Boley gauge was used to measure each tooth from the incisal slot to the root tip before shaving. After shaving, another measurement, which represented the dye penetration, was taken. The initial measurement and the final measurement were taken three times each and the average was used. The initial measurement minus the second gave the millimeters of dye penetration. Termination of the dye penetration was defined as that point where dye no longer penetrated the gutta-percha, its interface with the dentin wall, or the dentinal tubules. After the data were collected, the coded teeth were identified. The groups were compared using a one-way analysis of variance (ANOVA). RESULTS The positive controls (group 5) showed dye penetration into the canals and dentinal tubules of the teeth. In three of the teeth, the dye penetrated past the cementoenamel junction into the crowns. Dye penetration in the other two teeth covered approximately three fourths of the canal lengths. The negative controls (group 6) did not demonstrate dye penetration. In the experimental groups, obturation of the guttapercha with the Canal Finder system (group 3) showed the least dye penetration while the sectional warm gutta-percha technique (group 4) revealed the most. Obturation with the Ultrafil system (group 2) and the lateral condensation technique (group 1) had the second and third highest mean dye penetration, respectively. Representative photographs Of each experimental group are shown in Figs. 1 to 4. The raw data and the mean of each experimental 'group are listed in Table 1, the range of each group is plotted in Fig.. TABLE 2. Analysis of variance of dye penetration with Canal Finder compared with lateral condensation, Ultrafil, and sectional gutta-percha techniques Source
SS
df
MS
F*
Column Residual Total
8.4 223.3 231.7
3 28 31
2.8 7.97
0.35
* Fo.9s3,28 = 2.95; Fcorn~ted: 0.35 < 2.95. accept Ho (p < 0.05).
TABLE 1. Dye penetration in millimeters for each tooth and group mean penetration Group
1
2
3
4
5
6
Material Tooth
1 2 3 4 5 6 7 8 Mean
Lateral Condensation
Ultrafil
Canal Finder
Sectional Gutta-percha
Positive Control
Negative Control
6.0 10.9 5.8 8.1 5.5 8.4 6.5 9.6
6.3 13.9 13.5 3.4 2.1 5.6 7.8 6.0
7.1 8.7 3.3 5.3 6.6 5.5 10.0 10.1
9.2 10.9 7.8 6.8 3.4 6.8 7.8 9.1
15.4 12.0 12.0 14.5 10.5
0 0 0 0 0
7.6
7.3
7.1
7.7
12.9
0
Vol. 16, No. 9, September 1990
Comparison of Obturation Techniques
5, and the ANOVA shown in Table 2. Using the ANOVA, the significance of the dye penetration was determined where p < 0.05. The results of the ANOVA reveal that there was no significant difference between the means of the groups. DISCUSSION The apices of the experimental teeth were cut back to the level where gutta-percha first appeared in order to ensure direct measurement of the gutta-percha seal, to eliminate variables in apical anatomy, and to eliminate the presence of apical dentin plugs. Harrison and Todd (11) showed that resection of the apical 3 to 4 m m of the root with a bur in a high-speed handpiece does not adversely affect the seal of a well-condensed gutta-percha root canal filling. Although many leakage studies (9, 12-14) allowed penetration of the dye by keeping a patent apical foramen, in the present study, penetration of the dye measured the gutta-percha seal directly since the apical foramen was removed. In regard to the mean dye penetration, the results of this study show similarities and differences to other dye studies. An explanation of the apparent differences may lie in the size of the instrument used to keep the apical foramen open. There appears to be a trend that the larger the file used to maintain patency, the greater the linear leakage. LaCombe et al. (9) used a #10 file to maintain foramen patency and obtained a mean leakage value of 0.5 m m for lateral condensation. E1Deeb (13) used a #15 file to maintain foramen patency and had a mean leakage of 4.45 m m for lateral condensation. Matloff et al. (14) used a #20 file for foramen patency and observed a 6.8-, 7.8-, and 8.2-ram mean leakage for lateral condensation. Spradling and Senia (12) instrumented the teeth to at least a #35 file at the apical foramen and obtained a 10.37-mm mean dye leakage for lateral condensation. From our observations in the present study, the amount of gutta-percha visible would be most likely the diameter of a #35-50 file tip. The mean dye leakage for this study was 7.6 m m for lateral condensation. The 0.25% methylene blue dye was not adjusted to pH 7. Its pH of 4.7 ___ 0.5, although slightly acidic, could have a dissolving effect on the inorganic portion of the tissues, thereby altering the amount of leakage (15). This may in part explain the higher recorded leakage values when compared with other studies if those studies had used adjusted pH dye solutions.
~v
427
Although no significant difference was found among techniques, obturation with the Canal Finder system showed the least mean leakage penetration when compared with the other experimental groups. Interestingly, the specimen with the least leakage (3.3 mm) in this group had very little sealer, but multiple distinct gutta-percha cones were observed (Fig. 6). For the most part though, a c o m m o n observation was the large amount of sealer found and lack of well-condensed gutta-percha (Fig. 7) seen in this group. Peters (16) has demonstrated that obturation techniques with large amounts of sealer will easily dissolve over a period of time.It is possible that the 6000 rpm minimum was not achieved during obturation, and as a result multiple distinct gutta-percha cones were commonly seen. Experimentation on plastic blocks without sealer revealed that the frictional component of the Canal Finder during obturation appeared not to be intense enough to soften gutta-percha to any extent. Apparently the softening effect of the eucalyptus oil in the sealer and the pumping of the spreader for 7 to 10 s provides the condensation required for obturation with the Canal Finder system. Still it is not enough to produce a homogenous mass of gutta-percha. The findings of this current study corroborates the spectrophotometric findings of LaCombe et al. (9) as well as the findings of Michanowicz and Czonstkowsky (17, 18) that the Ultrafil system compares favorably with the lateral condensation technique. It also substantiates findings by Benner et al. (7) who found no significant difference in apical seals
25
2O O J15
Lateral ~ondensation
Ultrafil
Canal Finder
Sectional Gutta-percha
..J
I I I
I
>.
ObtuFation
Material
FIG 5. Range of dye penetration for four groups. Each group contains eight teeth.
FIG 6. Specimen obturated using Canal Finder system. Note the absence of sealer at the canal periphery (voids) and poor condensation at the 2.2-mm level (original magnification x21).
428
Greene et al.
Journal of Endodontics The assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the U.S. Army or Department of Defense. The authors thank Mrs. Shirley Wilkinson for her technical assistance and Mrs. Hattie Greene for her extensive help in manuscript preparation. Dr. Greene is a former senior resident in the Advanced Educational Program in general dentistry (2 years), U.S. Dental Army Activity, Fort Hood, TX. Dr. Wong is chief and mentor of endodontics, Advanced Educational Program in general dentistry (2 years), U.S. Army Dental Activity. Dr. tngram is former chief and mentor of endodontics, Advanced Educational Program in general dentistry (2 years), U.S. Army Dental Activity.
References
FIG 7. Specimen obturated using Canal Finder system. Note the large amount of sealer and lack of good condensation at the 9.2-mm level (original magnification x l 5).
obtained by the lateral condensation or warm (vertical) condensation techniques. CONCLUSIONS Under the conditions of this study, no significant difference in apical leakage was observed among the Canal Finder system, the Ultrafil system, warm gutta-percha, and lateral condensation gutta-percha filling techniques.
1. Dew RP, Ingle JI. Isotope determination of root canal failure. Oral Surg 1955;8:1100-4. 2. Ingle JI, Beveridge EE. Endodontics. 2nd ed. Philadelphia: Lea & Febiger, 1976:34-57. 3. Schilder H. Filling root canals in three dimensions. Dent Clin North Am 1967;11:723-44. 4. Nguyen NT. Obturation of the root canal system, in: Cohen S, Burns RC, eds. Pathways of the pulp. 4th ed. St. Louis: CV Mosby Co., 1987:2106. 5. Yee FS, Madin J, Krakow AA, Gron P. Three-dimensional obturation of the root canal using injection-molded, thermoplasticized dental gutta-percha. J Endodon 1977;3:168-74. 6. Goldman M, Sakurai E, Kronman J, Tenca JI. An in vitro study of the pathfinding ability of a new automated handpiece. J Endodon 1987;13:42933. 7. Benner MD, Peters DD, Grower M, Bernier WE. Evaluation of a new thermoplastic gutta-percha obturation technique using 45Ca. J Endodon 1981 ;7:500-8. 8. EIDeeb ME, Zucker KJ, Messer H. Apical leakage in relation to radiographic density of gutta-percha using different obturation techniques. J Endodon 1985;11:25-9. 9. LaCombe JS, Campbell AD, Hicks ML, Pelleu GB. A comparison of the apical seal produced by two thermoplasticized injectable gutta-percha techniques. J Endodon 1988;14:445-50. 10. Fahid A, Taintor JF. Sectional warm gutta-percha technique. Gen Dent 1985;33:440-4. 11. Harrison JW, Todd MJ. The effect of root resection on the sealing property of root canal obturations. Oral Surg 1980;50:264-72. 12. Spradling PW, Senia SE. The relative sealing ability of paste-type filling materials. J Endodon 1982;8:543-9. 13. EIDeeb ME. The sealing ability of injection-molded thermoplasticized gutta-percha. J Endodon 1985;11:84-6. 14. Matloff IR, Jensen JR, Singer L, Tabibi A. A comparison of methods used in root canal sealabiiity studies. Oral Surg 1982;53:203-8. 15. Antoniazzi JH, Mjor IA, Nygaard-Ostby B. Assessment of the sealing properties of root filling materials. Odontol Tidskr 1968;76:261-71. 16. Peters DD. Two-year in vitro solubility evaluation of four gutta-percha sealer obturation techniques. J Endodon 1986;12:139-45. 17. Michanowicz A, Czonstkowsky M. Sealing properties of an injectionthermoplasticized low-temperature (70~ gutta-percha: a preliminary study. J Endodon 1984;10:563-6. 18. Czonstkowsky M, Michanowicz A, Vazquez JA. Evaluation of an injection of thermoplasticized low-temperature gutta-percha using radioactive isotopes. J Endodon 1985;11:71-4.
