0099-2399/95/2104-0177503.00/0 JouRNALOF ENDODONTICS Copyright © 1995 by The American Association of Endodontists
Printed in U.S.A.
VOL. 21, NO. 4, APRIL 1995
In Vivo Evaluation of Root Canal Sealer Distribution David E. Stamos, DDS, MS, James L. Gutmann, DDS, and Bradley H. GetUeman, DDS, MS
MATERIALS AND M E T H O D S
The effectiveness of sealer placement and its distribution in the prepared root canal system by an energized ultrasonic file was evaluated in vivo. One hundred patients had sealer placed into prepared root canals with either the master gutta-percha cone or an ultrasonic file. Before placement of sealer with the file, canals were irrigated, debrided, and flushed with water for 10 s and an energized #20 ultrasonic file at 1.0 mm from the working length. Canals were obturated with gutta-percha using lateral condensation, and evaluations were based on the presence or absence of sealer-filled accessory canals. Chi-square analysis showed that a statistically significant difference existed in the number of radiographically visible accessory canals filled when the ultrasonic file was used to place the sealer.
One hundred patients each received nonsurgical root canal treatment on a single tooth (100 teeth). All participants were chosen at random, regardless of the tooth being treated. Canal treatment was performed by one operator as follows using standardized regimens in all cases through the canal cleaning and shaping phase. All teeth were anesthetized and endodontic access openings were made after rubber dam isolation. Working lengths were determined at 1.0 mm from the radiographic apex. Canal cleaning and shaping were performed with the alternative use of reamers and Hedstrom files to the apical stop. Copious irrigation using 2.6% sodium hypochlorite was delivered to the canal between each file usage. Cases were then randomly subjected to one of two obturation regimens (Tables 1 and 2). Fifty teeth were obturated according to regimen A and 50 were obturated following regimen B. Cavit was placed as a temporary and a posttreatment radiograph was exposed at 60 kV at 0.5 s. Two endodontists other than the operator reviewed all radiographs. These evaluators had been standardized to the criteria for evaluation by having previously reviewed 100 additional cases. The presence or absence of accessory/lateral channels, as depicted by sealer extrusion, was noted and recorded. In the case of disagreements, radiographs were viewed a second time and agreement between the reviewers was reached, or a third reviewer was used to reach consensus.
The effective distribution of root canal sealer/cements throughout the root canal system has been suggested as essential to the best possible root canal seal (1-3). Various methods of sealer placement have been identified or evaluated for this purpose, including lentulo spirals (4-6), files or reamers (3-7), master gutta-percha cones (3, 4, 6), and ultrasonic instruments (5-7). Evaluation of the efficacy of these techniques has occurred on extracted teeth, using serial sectioning, radiographs, specimen clearing, and direct observation. Sealer distribution analysis has included percentages of dentin walls covered, sealer extrusion beyond the apical foramen, and voids in the sealer coverage. Hoen et al. (5) and West et al. (7) have shown that ultrasonic sealer placement resulted in a greater amount of dentin wall coverage, especially in the apical 1 mm. Sealer movement into canal irregularities and accessory canals was noted, but not quantified. Although these findings were statistically significant, they occurred in a controlled, in vitro environment. No studies have evaluated an ultrasonic method of sealer placement in an in vivo setting. The purpose of this study was to compare, in vivo, the efficacy of sealer placement using either a master gutta-percha cone or an energized ultrasonic file.
RESULTS Of the 50 teeth treated with obturation technique A, only 2 teeth or 4% of this sample demonstrated the presence of sealer in an accessory canal. In the teeth obturated with technique B, 12 teeth, or 24%, demonstrated the presence of sealer in accessory canals. These radiographic findings and the tooth type involved are shown in Table 3. Chi-square analysis showed there was a statistically significant difference in the visualization of accessory canals when technique B was used (p < 0.001). DISCUSSION Obturation of the prepared root canal system with gutta-percha and a root canal sealer/cement is the standard of care in contemporary endodontics (8). This combination is essential to achieve the best possible seal of the root canal system, regardless of the
Stamos et al.
Journal of Endodontics
TABLE 1. Obturation technique A 1. Ultrasonic canal debridement (ENAC; The Osada Electric Co., Los Angeles, CA) with H20--power setting at #3 and #20 file placed 1.0 mm from the working length and energized for 10 s in a stationary position 2. Ultrasonic file moved vertically along the canal walls for 50 s 3. Canals dried with paper points 4. Master gutta-percha cone coated with sealer (Grossman's Sealer; Sultan Chemists, Englewood, NJ) and placed to working length 5. Condensation with #25 finger spreader and #20 accessory cones
TABLE 2. Obturation technique B 1. Ultrasonic canal debridement (ENAC; The Osada Electric Co., Los Angeles, CA) with H20--power setting at #3 and #20 file placed 1.0 mm from the working length and energized for 10 s in a stationary position 2. Ultrasonic file moved vertically along the canal walls for 50 s 3. Canals dried with paper points 4. Number 20 ultrasonic file coated with sealer (Grossman's Sealer; Sultan Chemists), placed into the canal and energized for 5 s with a circumferential motion 5. Master gutta-percha cone coated with sealer (Grossman's Sealer) and placed to working length 6. Condensation with #25 finger spreader and #20 accessory cores
TABLE 3. Radiographic findings and sample delineation Obturation Technique
No. of Teeth
Technique A* Technique B'l
% 4 24 28/2=14
debridement technique, especially with sodium hypochlorite prior to sealer placement, may enhance the ohturation of these aberrancies with all methods of obturation, thereby potentially reducing apical leakage. Studies have shown reduced levels of leakage when the smear layer has been removed (13, 14). This would be especially true of vertical condensation with warm gutta-percha and thermoplasticized gutta-percha techniques, the latter of which has been shown to result in the movement of gutta-percha and sealer into the dentinal tubules when the smear layer has been removed (9, 15). The routine occurrence of this movement with lateral condensation, however, has been questioned (16). Previous in vitro studies have presented mixed findings regarding the efficacy of ultrasonic sealer placement. Amato et al. (4) using extracted anterior teeth, Jeffrey et al. (3) using simulated single-canal tooth models, and Wiemann and Wilcox (6) using extracted mandibular incisor teeth have indicated that the method of sealer placement may not be important. On the other hand, Hoen et al. (5) and West et al. (7) both used extracted human mandibular molars and demonstrated that the ultrasonic method of root canal sealer placement covered the canals walls in a more thorough manner, following complete removal of the smear layer. The present in vivo study has shown that following a final debridement procedure with an ultrasonic file and sodium hypochlorite, ultrasonic sealer placement may significantly influence the filling of accessory channels. Variables within all these studies include the type of sealer used, techniques for the use of the ultrasonic unit, the type of unit used, and the nature of the irrigant use.
The informed consent of all human subjects who participated in the experimental investigation reported or described in this article was obtained after the nature of the procedure and possible discomforts and risks had been fully explained. Dr. Stamos is in private practice limited to endodontics, Kansas City, MO. Dr. Gutmann is professor and director, Graduate Endodontic Program, Department of Restorative Sciences, Baylor College of Dentistry, Dallas, TX. Dr. Gettleman is in private practice limited to endodontics, Glendale, AZ. Address requests for reprints to Dr. James L. Gutmann, Department of Restorative Sciences, Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75204.
* x2 - 0.035(p > 0.05),df = 1. 1-x 2 = 28.72(13< 0+001),df = 1.
technique chosen for filling material delivery or condensation. To achieve this goal, thorough cleaning and shaping is necessary, especially as it relates to tissue debris removal from the intricacies of the canal system, such as fins, webs, culs-de-sac, tubules, and accessory canals. Once these aberrant areas are properly cleaned, the movement of sealer and gutta-percha throughout the canal spaces is enhanced (9). Hence, there is a need for techniques to ensure this movement. In this in vivo study, the ultrasonic placement of sealer resulted in its movement into canal intricacies not observed when the master cone only was used for sealer placement and distribution. Based on previous studies (5, 7) and the techniques performed in this study, it is likely that the final ultrasonic cleaning of the canal, prior to sealer placement, resulted in the removal of some of the smear layer which occluded the openings to accessory canals. Many studies have identified the need for sodium hypochlorite solution in conjunction with ultrasonic cleaning to achieve optimal dentin wall cleanliness (10-12). Likewise, final rinses with a chelating agent and alcohol have also been specified (5, 7) to ensure removal of adherent debris and to facilitate drying of the dentinal wails and tubules. Therefore, the use of a final canal
References 1. Uhrich JM, Moser JB, Heuer MA. The theology of selected root canal sealer cements. J Endodon 1978;4:373-9. 2. Evans JT, Simon JHS. Evaluation of the apical seal produced by injected thermoplasticized gutta-perch in the absence of smear layer and root canal sealer. J Endodon 1986;12:101-7. 3. Jeffrey IWM, Saunders WP, Thomas GE. An investigation into the movement of sealer during placement of gutta-perch points. Int Endod J 1986;19:21-8. 4. Amato R, Goldman M, Tenca J, Burk G. A comparison of the efficiency of various delivery methods on sealer distribution [Abstract 6]. J Endodon 1984;19:119. 5. Hoen MM, LaBounty GL, Keller DL. Ultrasonic endodontic sealer placement. J Endodon 1988;14:189-74_ 6. Wiemann AH, Wilcox LR. In vitro evaluation of four methods of sealer placement. J Endodon 1991;17:444-7. 7. West LA, LaBounty GL, Keller DL. Obturation quality utilizing ultrasonic cleaning and sealer placement followed by lateral condensation with guttapercha. J Endodon 1989;15:507-11. 8. American Association of Endodontists. Quality assurance guidelines. Chicago: AAE, 1987. 9. Gutmann JL. Adaptation of thermoplasticized gutta-percha in the absence of the dentinal smear layer, lnt Endod J 1993;26:87-92. 10. Stamos DE, Sadeghi EM, Haasch GC, Gerstein H. An in vitro comparison study to quantitate the debridement ability of hand, sonic, and ultrasonic instrumentation. J Endodon 1987;13:434-40. 11. Mandel E, Machtou P, Friedman S. Scanning etectron microscope observation of canal cleanliness. J Endodon 1990;16:279-83.
Root Canal Sealer Distribution
Vol. 21, No. 4, April 1995 12. Griffiths BM, Stock CJR. The efficiency of irrigants in removing root
canal debris when used with an ultrasonic preparation technique. Int Endod J 1986;19:277-84. 13. Kennedy WA, Walker WA, Gough RW. Smear layer removal effects on apical leakage. J Endodon 1986;12:21-7. 14. Cergneux M, Ciocchi B, Dietschi JM, Holz J. The influence of the smear layer on the sealing ability of canal obturation. Int Endod J 1987;20:
228-32. 15. Michanowicz AE, Czonstkowsky M, Piesco NP. Low-temperature (70°C) injection gutta-percha: a scanning electron microscopic investigation. J Endodon 1986;12:64-7. 16. Baumgardner KR, Krell KV. Ultrasonic condensation of gutta-percha: an in vitro dye penetration and scanning microscopic study. J Endodon 1990;16:253-9.
A Word for the Wise Collecting and speculating on the possible definition of abstruse medicine terms is a harmless pastime. Bezoar, for example, could reasonably be thought to be "a device with which to zo." Alas, its accepted meaning is a hard mass found in the intestine.
My cat, a more prosaic creature, just calls that a hair ball.