The Quantitative Evaluation of Apical Sealing of Four Endodontic Sealers Funda Kont Cobankara, DDS, PhD,* Hasan Orucoglu, DDS, PhD,* Abdülkadir Sengun, DDS, PhD,† and Sema Belli, DDS, PhD* Abstract The aim of this in vitro study was to evaluate the apical seal obtained with four root canal sealers: Rocanal 2, Sealapex, AH Plus, and RC Sealer. Forty root canals were prepared using the step-back technique. The specimens were divided into four groups of 10 samples and obturated by laterally condensed gutta-percha with one of the tested sealers. The computerized fluid filtration method was used for evaluation of apical sealing properties. The quantitative apical leakage of each specimen was measured after 7, 14, and 21 days. Statistical analysis indicated that the apical leakage of all sealers used in this study decreased gradually from 7 days to 21 days (p ⬍ 0.05). Sealapex showed better apical sealing than the other sealers at 7, 14, and 21 days (p ⬍ 0.05). RC Sealer, AH Plus, and Rocanal 2 showed similar apical leakage values at every period (p ⬎ 0.05). (J Endod 2006;32:66 – 68)
Key Words Apical leakage, computerized fluid filtration method, root canal sealers
From the *Department of Endodontics; †Department of Operative Dentistry, Faculty of Dentistry, Selçuk University, Konya, Turkey. Address requests for reprint to Dr. Hasan Oruçoglu, Department of Endodontics, Faculty of Dentistry, Selcuk University Campus 42075, Konya, Turkey. E-mail address: [email protected]
0099-2399/$0 - see front matter Copyright © 2006 by the American Association of Endodontists. doi:10.1016/j.joen.2005.10.019
Cobankara et al.
arious materials have been used in root canal therapy in an attempt to achieve success. But, the most common form of endodontic treatment uses a combination of gutta-percha cones and a sealer (1). Gutta-percha is considered an impermeable core material; therefore, leakage through an obturated root canal is expected to take place at the interfaces between the sealer and dentin or the sealer and gutta-percha, or through voids within the sealer (2). Hence, the sealing quality of a root canal filling also depends on the sealing ability of the sealer (3). A great variety of endodontic sealers is available commercially, and they are divided into many groups according to their chemical composition. Some studies have examined the possibility of adhesive resin as a root canal filling material in root canal treatment (4, 5) and recently, a new polymeric resin– based root canal sealer, RC Sealer, has been introduced to the dental community. Analysis of the sealing ability of endodontic filling materials and techniques have received a great deal of attention. In this connection, leakage studies have been most commonly used. For evaluating the sealing property of root canal filling materials have been used various methods such as colored dye penetration (6), bacterial penetration (7), analysis of radiolabeled tracer penetration (8), and electrochemical method (9). However, a universally accepted method for the evaluation of leakage does not exist yet. Fluid filtration technique is one of the current techniques to quantitate the measurement of microleakage of filling materials (10, 11). The aim of this in vitro study was to compare apical sealing properties of Rocanal 2, Sealapex, AH Plus, and new developed RC Sealer using a computerized fluid filtration method.
Materials and Methods Forty extracted human maxillary anterior teeth were selected. The teeth with caries, cracks, or open apices were excluded. Their external surfaces were cleaned with curettes and were stored in deionized water until use. The crowns were removed with carborundum disks leaving a uniform 15-mm root section. The working lengths were determined by placing a size 10 K-file (Kerr, Romulus, MI) into the root canal until it was visible at the apical foramen and subtracting 1-mm from that length. The coronal 6-mm was flared using Gates Glidden drills (Maillefer, Ballaigues, Switzerland) sizes 2 and 3. The apical portion of the roots was instrumented to size 55 using the step-back technique. Apical patency was confirmed between files using a size 10 K-file. Between each file use, the canals were irrigated with 1 ml of 5.25% NaOCl solution. The canals were dried with paper points, and standardized gutta-percha master cones were fitted with tugback at working length. The specimens were divided into four groups of 10 teeth each and filled with the sealers shown in Table 1 in conjunction with laterally condensed gutta-percha. After obturation, the access cavities were sealed with Cavit-G (ESPE, GmbH, Seefeld, Germany) and the samples were stored in 100% humidity at 37°C for 7 days. Then, the temporary fillings were removed, and the roots were placed into computerized fluid filtration device. An additional four teeth were used for control (two for negative control and two for positive control). The specimens used for the positive control were prepared as described in experimental groups, but root canal spaces were not obturated. In negative control group, a size #10 K-file ⬃1 mm longer than the working length was passed through the apex of each tooth and then totally coated with three layers of nail polish, including the apical foramina.
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Basic Research—Technology TABLE 1. The root canal sealers used in this study Groups
Root Canal Sealers
Rocanal 2 (zinc oxide eugenol based) Sealapex (calcium hydroxide based) AH Plus (epoxy resin based) RC Sealer (polymeric resin based)
La Maison, Dentaire SA, Balzers, Switzerland Kerr Co., Romulus, MI, USA Dentsply, De Trey, Konstanz, Germany Sun Medical Co., Ltd., Shiga, Japan
2 3 4
Measurement of Sealing Properties The sealing qualities of the four different sealers were measured using computerized fluid filtration method described by Orucoglu et al. (12). In this system, during the experiment all the operations were controlled with PC-compatible software (Fluid Filtration’03, Konya, Turkey). The pressure (150 kPa) was maintained constant throughout the experiment by means of a digital air pressure regulator (DP-42 Digital pressure and vacuum sensors Red LED display Sunx Sensors, USA) added to the pressure tank. A 5-min pressurization preload of the system was completed before taking readings. Measurements of fluid movement were automatically made at 2 min during 8 min for each sample by means of PC-compatible software. Leakage quantity was expressed as l/cmH2O/min⫺1. The quality of the seal of each specimen was measured at 7, 14, and 21 days. Between the readings, the samples were stored in isotonic saline solution with 0.2% sodium azide. Statistical Analysis Univariate two-way ANOVA was used to compare the mean leakage values of four root canal sealers for each period. Variables were the root canal sealer and time. Mann-Whitney U tests were used to analyze the leakage of sealers for each period. Wilcoxon Signed Ranks test was used to compare the leakage of each sealer between three periods. The confidence level was used 95% (p ⬍ 0.05).
Results The results of the quantitative evaluation of the sealing properties of the sealers are shown in Table 2. There was a significant difference among variables, which were four root-canal sealers (p ⬍ 0.05) and times in apical leakage (p ⬍ 0.05). The comparison of fluid filtration rates at different time periods according to Wilcoxon Signed Ranks Test indicated that the apical leakage of all sealers used in this study decreased gradually from 7 days to 21 days (p ⬍ 0.05). Sealapex showed less leakage than the other sealers for each study period (p ⬍ 0.05). Although RC Sealer showed the highest leakage at all times, there was no significant difference in the leakage between RC Sealer, AH Plus, and Rocanal 2 (p ⬎ 0.05). The positive controls demonstrated extreme amounts of apical leakage. Mean leakage for the positive controls was observed to be 0.067 ⫾ 0.009 l/cmH2O/min⫺1 150 kPa. The negative controls registered no detectable bubble movement at 150 kPa, for a minimum of 5 min before each data collected began.
Discussion A wide variety of root canal sealers is available commercially. Sealers based on zinc oxide-eugenol (Rocanal 2), calcium hydroxide (Sealapex), epoxy resin (AH Plus), and adhesive resin (RC Sealer) were included in our study. Sealapex is a calcium hydroxide type sealer, in use since the early 1980s. Caicedo and Fraunhofer (13) studied the properties of calcium hydroxide sealers and found that Sealapex showed a significant volu-
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metric expansion during setting. They theorized that this was because of water absorption. This may also increase the solubility of Sealapex. But, an in vitro dye penetration study by Sleder et al. (14) showed that Sealapex is no more soluble than other sealers and that its seal is comparable to TubliSeal (ZnOE-based sealer) at 32 wk. Investigators hypothesized that it can probably be limited surface area of the sealer that is exposed to the tissue fluids in the root canal, a negligible amount of dissolution is occurring. Another in vitro study by Miletic et al. (15) showed that there are no statistically significant differences between Apexit, a calcium hydroxide based sealer, and AH Plus after a 2-wk period. Furthermore, Wu et al. (10) found that Sealapex showed significantly more leakage than AH26 and TubliSeal after storing in water for 1 yr. In our study, Sealapex showed less leakage than other sealers for each study period. The reason for the discrepancy between the findings of the studies may be related to the fact that the different methods are used in them or that relative difference between the materials change over time. Rocanal 2 is a powder-liquid system with a zinc oxide-eugenol base. In an in vitro study, De Almeida et al. (16) observed that leakage with AH Plus was significantly less than that with a ZnOE based sealer. Greater measured leakage for sealers based on ZnOE compared with epoxy resin based sealers was also found by other authors (17, 18). But, in the presented study, there was no significant difference among Rocanal 2, AH Plus, and RC Sealer. However, all of these showed significantly more leakage when compared to the calcium hydroxide-based sealer (Sealapex) for each study period. AH Plus is a sealer based epoxy resin. Some studies report the apical seal of resin-based sealers to be superior to that of other sealers (17, 18). In contrast, other studies have shown that the calcium hydroxide based sealer, Sealapex, provides a significantly better seal than others, including resin-based sealers (19, 20). In our study, AH Plus showed also significantly more leakage when compared to Sealapex but there was no significant difference with Rocanal 2 and RC Sealer based sealers for each period. Components of RC Sealer are Super-Bond Polymer consisting of PMMA and zirconium oxide. Its polymer powder consists of the same constituents with the commercialized Polymer (L-Type radiopaque) of Super-Bond C&B 4-META/MMA-TBB resin, which is known commercially as Super-Bond C&B (Sun Medical Co. Ltd., Moriyama, Shiga, Japan). Super-Bond C&B has been reported to produce consistent and relatively high bond strength, and has been successfully used clinically for nearly two decades (21). This resin has been modified for the special endodontic purpose and it was introduced to endodontic treatment by the name given as RC Sealer. The data are not available with regard to the properties of this material. In our study, there was no significant difference among RC Sealer, Rocanal 2, and AH Plus (p ⬎ 0.05). It is very important to assess leakage not only immediately after sealing but also after some time, because sealing needs to be long lasting to be clinically effective. Smear layer may disintegrate and dissolve with time, creating a void between the root canal wall and sealer (22). Kont TABLE 2. The comparison of fluid filtration rates from different root canal sealers (n ⫽ 10) (Mean ⫾ SD) (l 䡠 min⫺1cm H2O⫺1 ⫻ 10⫺3) Root Canal Sealers Rocanal 2 Sealapex AH Plus RC Sealer
1.52 ⫾ 0.36a,b 0.41 ⫾ 0.20c 1.12 ⫾ 0.31a 2.00 ⫾ 1.56a,b
0.57 ⫾ 0.15a 0.32 ⫾ 0.13b 0.73 ⫾ 0.50a 0.96 ⫾ 0.82a
0.46 ⫾ 0.15a 0.23 ⫾ 0.13b 0.65 ⫾ 0.37a 0.71 ⫾ 0.52a
The means having same superscripts at the same column are not statistically different at p ⬎ 0.05.
Quantitative Evaluation of Apical Sealing
Basic Research—Technology Cobankara et al. (23) found that removal of the smear layer from the root canal walls significantly reduced the leakage of roots obturated with AH26 and Roekoseal sealers. The smear layer was not removed in our study. Also, physical integrity of the sealer matrix may be an important factor in providing resistance to leakage (24, 25). As for in an in vitro study by Wu et al. (26) it was concluded that leakage along root canal spaces filled only with gutta-percha (without sealer) diminishes with time as a result of the swelling of gutta-percha. In the present study, all the tested materials showed decreased leakage after 21 days (p ⬍ 0.05). Kont Cobankara et al. (11) indicated that different root canal sealers (AH Plus, RoekoSeal, Ketac-Endo, and Sultan) showed less leakage after 21 days. De Gee et al. (27) and Wu et al. (28) also indicated that AH26s apical leakage property was diminished by the time. De Gee et al. (27) explained this phenomenon as result of slow setting properties of the materials. For these reasons, it is surely necessary to repeat the leakage measurements after long periods. The fluid filtration technique used in this study provided relatively long-term measurement of leakage on same samples (21 days). Our further study will report 3 months, 6 months, and 1-yr measurements. The results of this in vitro study suggest that: 1. a. The apical leakage of all sealers studied decreased gradually from 7 days to 21 days (p ⬍ 0.05). b. Sealapex showed better apical sealing than those of AH Plus, Rocanal 2, and RC Sealer sealers at 7, 14, and 21 days (p ⬍ 0.05). c. AH Plus, Rocanal 2 and RC Sealer showed similar apical leakage values at every period (p ⬎ 0.05).
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