Basic Research—Technology
Influence of Ultrasonic Activation of 4 Root Canal Sealers on the Filling Quality Bruno Martini Guimar~ aes, DDS, MSc, Pablo Andres Amoroso-Silva, DDS, MSc, Murilo Priori Alcalde, DDS, Marina Angelica Marciano, DDS, MSc, Flaviana Bombarda de Andrade, DDS, PhD, and Marco Antonio Hungaro Duarte, DDS, PhD Abstract Introduction: The purpose of this study was to evaluate the effects of ultrasonic activation on the filling quality (intratubular sealer penetration, interfacial adaptation, and presence of voids) of 4 epoxy resin–based sealers. Methods: Eighty-four extracted human canines were divided into 4 groups (n = 20) according to the sealer used to obturate the root canals instrumented with F5 ProTaper instruments (50/05) (Dentsply Maillefer, Ballaigues, Switzerland). The canals were filled by the lateral compaction technique. Previously, the sealers were labeled with rhodamine B dye to allow analysis under a confocal microscope. At the time of obturation, the specimens were divided again into 2 groups (n = 10) according to the ultrasonic activation of the sealers: ultrasonically activated and nonultrasonically activated groups. All samples were sectioned at 2, 4, and 6 mm from the apex. The percentages of voids, gaps, and dentinal sealer penetration segments of the canal were analyzed. Results: Regarding the sealer penetration segments, there was a significant increase for the AH Plus (Dentsply Maillefer), Acroseal (Specialites Septodont, Saint Maur-des-Fosses, France), and Sealer 26 (Dentsply Maillefer) at the 4-mm level and the AH Plus and Sealer 26 at the 6-mm level with ultrasonic activation (P < .05). Concerning the gaps, the ultrasonic activation promoted a smaller presence for all sealers at the 4- and 6-mm levels (P < .05). No statistical significant differences were found for the percentages of voids (P < .05). Conclusions: The use of ultrasonic activation of an epoxy resin–based sealer promoted greater dentinal sealer penetration and less presence of gaps. (J Endod 2014;-:1–5)
Key Words Confocal microscopy, epoxy resin sealers, root canal filling, ultrasound
From the Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of S~ao Paulo, Bauru, S~ao Paulo, Brazil. Address requests for reprints to Dr Bruno Martini Guimar~aes, Al Octavio Pinheiro Brisolla, 9-75-CEP 17012-901, Bauru School of Dentistry, University of S~ao Paulo, Bauru, SP, Brazil. E-mail address: [email protected] 0099-2399/$ - see front matter Copyright ª 2014 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2013.11.016
JOE — Volume -, Number -, - 2014
T
he complete sealing of the root canal system after a biomechanical procedure can determine the long-term success of an endodontic treatment by preventing oral pathogens from colonizing and reinfecting the root and periapical tissues (1, 2). Because gutta-percha does not adhere to the dentinal walls, the sealer must fill the irregularities and the dentinal tubules of the root canal system. Epoxy resin–based sealers were introduced in endodontics by Schroeder (3) and have since been used because of their reduced solubility (4), apical seal (5), and microretention to the root dentin (6). One of these sealers is AH Plus (Dentsply Maillefer, Ballaigues, Switzerland), which has been extensively evaluated for its physicochemical properties, biological response, and interfacial adaptation (7–9). The Adseal (Meta Biomed, Cheongju, South Korea) is another epoxy resin sealer with reports in the literature about its radiopacity value and physical properties (9, 10). Acroseal (Specialites Septodont, Saint Maur-des-Fosses, France) is a sealer that contains 28% calcium hydroxide in its composition. Previous studies have shown its sealing ability, antimicrobial activity against Enterococcus faecalis, and adaptation to the root canal walls (9, 11, 12). Sealer 26 (Dentsply Maillefer) is an epoxy resin– based material containing calcium hydroxide and has also shown good sealing ability and antimicrobial activity (13, 14). Ultrasound is an instrument that was first introduced to endodontics by Richman in 1957. Currently, it has been widely used in different endodontic procedures, ranging from coronal opening to endodontic surgery (15). A greater agitation of irrigating solutions promoted by ultrasound intensifies the penetration in an area of anatomic complexity such as the dentinal tubules and consequently improves the cleaning ability (16). The activation of root canal sealers can possibly favor its penetration inside the dentinal tubules, providing an increase in sealability (17) and antimicrobial effects (18). The effects of ultrasonic activation of the sealer into the root canal and the filling quality have not been explored sufficiently. The aim of this study was to evaluate the effect of ultrasonic activation on 4 epoxy resin–based sealers regarding their filling quality. The null hypothesis that was tested is that ultrasonic activation improves the filling quality of epoxy resin–based sealers.
Materials and Methods Eighty-four maxillary human canines with a root curvature less than 5 were used (19). The ethics committee approved the use of extracted teeth for the research (CEP 079/2011). The crowns were removed at the cementoenamel junction using a 0.3-mm low-speed diamond saw (Isomet, Buehler, Lake Bluff, IL), and the root canal length was established at 15 mm. The working length was established by measuring the penetration of a size 10 K-file (Dentsply Maillefer) until it reached the apical foramen and then subtracting 1 mm. Root canal shaping was performed using ProTaper rotary instruments (Dentsply Maillefer) at the working length until a F5 (50.05) instrument. After the use of each instrument, the canals were irrigated using 2 mL 2.5% sodium hypochlorite. Passive ultrasonic irrigation was performed at the end of the shaping as described by van der Sluis et al (20). A final flush of 2 mL 17% EDTA (pH = 7.7) (Biodin^amica, Ibipor~a, Parana, Brazil) was applied for 3 minutes to eliminate the smear layer. Then, the canals were washed with 5 mL saline solution and dried with paper points (Dentsply Maillefer).
Ultrasonic Activation of 4 Root Canal Sealers
1
Basic Research—Technology The specimens were randomly divided into 4 groups (n = 20) according to the sealer used to obturate the root canals: Group 1: AH Plus (Dentsply Maillefer) Group 2: Acroseal (Septodont, Saint Maur des Fosses, France) Group 3: AdSeal (Meta, Biomed, Cheongju, South Korea) Group 4: Sealer 26 (Dentsply Maillefer) The sealers were manipulated according to the manufacturer’s instructions. To allow visualization under a confocal laser microscope (TCS-SPE; Leica Microsystems GmbH, Mannheim, Germany), the sealers were mixed with fluorescent rhodamine B dye (Sigma-Aldrich, St Louis, MO) to an approximate concentration of 0.1% (21). The sealers were placed in each root canal by using a size 30 rotary lentulo spiral (Dentsply Maillefer), maintaining the instrument 4 mm from the apex. Then, the specimens were divided into 2 groups (n = 10) according to the ultrasonic activation of the sealers: ultrasonically activated (A) and nonultrasonically activated (NA) groups. The activation in group A was performed using a size A nickel-titanium finger spreader (Dentsply Maillefer) adapted into an ultrasonic device (Jet-Sonic Four Plus; Gnatus, Ribeir~ao Preto, SP, Brazil) in ‘‘endo’’ mode (50% potency) using a no. A-120 insert (Gnatus) (Fig. 1). Because the ultrasonic oscillates in a single plane, the spreader was activated for 20 seconds in the buccolingual direction and another 20 seconds in the mesiodistal direction of the root canal, 2 mm short of the working length as a standardization procedure. Next, a 50.02 gutta-percha cone (Dentsply Maillefer) was inserted into the full working length, and the root canal obturation was completed using the lateral compaction technique with a size B finger spreader (Dentsply Maillefer) inserted 2 mm short of the working length and accessory gutta-percha points size 20.02 (Dentsply Maillefer). The cervical portion of the specimens was sealed using a provisional filling material (Coltosol, Coltene, Switzerland). The specimens were stored in 100% humidity at 37 C for 1 week to allow the sealers to set.
Voids Area, Interfacial Adaptation (Gaps), and Segment of Sealer Penetration The samples were sectioned using a 0.3-mm Isomet saw (Buehler, Lake Bluff, IL) at 200 rpm with continuous water cooling to prevent frictional heat. Horizontal sections were performed at the 2-, 4-, and 6-mm levels from the apical foramen and polished with sandpaper (Politriz;
Arotec, Cotia, SP, Brazil). To calculate the void area (mm2) percentages, a stereomicroscope (Stemi 2000C; Carl Zeiss, Jena, Germany) and the Axiovision software (Carl Zeiss) were used (Fig. 2A). First, the total area of each cross-section image of the canal and the visible voids were measured. With both values obtained, the percentage of voids in relation to the total area of each canal section was calculated. The segments of the root canal in which the sealer penetrated into the dentinal tubules, and the interfacial adaptation (gaps) were analyzed on an inverted Leica TCS-SPE confocal laser scanning microscope (Leica Microsystems GmbH) by the similar method described by Moon et al (22). For the correct visualization of all images, the sections were analyzed 10 mm below the surface using the 10 lens. The respective absorption and emission wavelengths for the rhodamine B were set to 540 and 590 nm, respectively. Then, the images were recorded at 100 magnification using the fluorescent mode to a size of 1024 1024 pixels and a scale set to 100 mm (Fig. 2B). Analysis of all images was performed with the Image J V1.46r software (National Institutes of Health, Bethesda, MD). The total circumference of the canal was obtained first. Then, segments of sealer penetration into the dentinal tubules and interfacial adaptation (gaps) of the total circumference were measured, and the values were converted into percentages (Fig. 2C and D).
Statistical Analysis Because of the absence of normal distribution, which was observed using the Shapiro-Wilk test. Statistical analysis was performed by using the nonparametric Kruskal-Wallis and Dunn tests (P < .05). The nonparametric Mann-Whitney test was used to analyze the influence of ultrasonic activation individually in each sealer (P < .05).
Results Median and range of voids, interfacial adaptation (gaps), and dentinal sealer penetration segments of the canal can be found in Table 1. With regard to the sealer penetration segments, there was a significant increase for the AH Plus (Fig. 2E and F), Acroseal, and Sealer 26 at the 4-mm level, and the AH Plus and Sealer 26 at the 6-mm level when the ultrasonic activation was performed (P < .05). Regarding the gaps, the ultrasonic activation promoted a smaller presence for the AH Plus at the 2-mm level and for all sealers at the 4- and 6-mm levels (P < .05). The voids percentage revealed no significant differences between the A or NA groups at all levels (P < .05).
Discussion
Figure 1. Finger spreader adapted into an ultrasonic device using a no. A-120 insert.
2
Guimar~aes et al.
The null hypothesis tested was confirmed because the ultrasonic activation improved the filling quality of the 4 epoxy resin–based sealers. The transmission of acoustic microstreaming energy from an oscillating file by the use of ultrasonic activation can promote the penetration of irrigants in an area of anatomic complexity and the dentinal tubules, resulting in a greater cleaning ability (16). With regard to the intracanal medication, Duarte et al (23) analyzed the influence of ultrasonic activation of calcium hydroxide pastes on the pH and calcium release in simulated external root resorptions. The authors showed that the ultrasonic activation favored a higher pH level and calcium release describing that ultrasonic activation could promote a greater tubular penetration of the calcium hydroxide pastes. In accordance with the results mentioned previously, the present study showed that the ultrasonic activation also favored a greater dentinal sealer penetration and improved the interfacial adaptation between the sealer and the root canal walls, which can promote a higher contact and confinement of microorganisms present in the dentinal tubules (22). JOE — Volume -, Number -, - 2014
Basic Research—Technology
Figure 2. (A and B) Representative correlative stereomicroscopic/confocal pictures of canal filled with Acroseal sealer and lateral compaction technique. A thin layer of sealer is evident just in the confocal picture, which promotes a clear visualization of adaptation without evidence of voids and gaps. (C and D) Segments of the root canal in which the sealer penetrated into the dentinal tubules (white dots) and an evident gap (arrows) at the interfacial adaptation, respectively. (E and F) Representative picture at 4-mm sections of canal filled with AH Plus ultrasonically and nonultrasonically activated, respectively. A remarkable dentinal sealer penetration is evident when the ultrasonic activation was promoted.
The percentage of segments in which the sealer penetrated into the dentinal tubules may be more meaningful and clinically relevant compared with the maximum depth of sealer penetration (24), and it can be considered beneficial for preventing reinfection because of the sealer’s antibacterial activity and by locking the residual microorganisms into the dentinal tubules (22, 25). Additionally, it has been suggested that the sealer inside the tubules promotes a mechanical interlocking, improving the material retention (22, 26). Meanwhile, De-Deus et al (27) reported that there was no significant correlation between the intratubular sealer penetration and the sealing ability. In this study, the sealers were placed by a rotary lentulo spiral for stanJOE — Volume -, Number -, - 2014
dardization procedures. A previous study showed that the distribution of sealer in the canal walls is not affected by the sealer placement method (28), which support the hypothesis that the ultrasonic activation of the sealer could enhance the root filling quality. AH Plus, Acroseal, and Sealer 26 presented a significant increase of segments of sealer penetration at the 4-mm level. AH Plus and Sealer 26 also had a significance difference at the 6-mm level when ultrasonic activation was performed. No significant differences were found at the 2-mm level. These findings are similar to other studies (24, 29, 30), which showed that the sealer penetration in the dentinal tubules was significantly greater in the coronal and middle levels of the root canal
Ultrasonic Activation of 4 Root Canal Sealers
3
4
76.0 (0–100)a 49.7 (0–100)b A different letter in each column represents statistical differences between the ultrasonically activated (A) and nonultrasonically activated (NA) groups for each sealer (P < .05).
0.0 (0–35.5)a 0.0 (0–12.2)a 0.0 (0–8.53)a 7.80 (0–28.0)b 0.0 (0–8.39)a 7.37 (0–24.3)b 0.0 (0–9.61)a 1.37 (0–19.9)a 0.30 (0–2.19)a 0.0 (0–1.66)a 0.0 (0–1.41)a 0.53 (0–3.90)a 0.0 (0–13.6)a 0.83 (0–17.1)a
Guimar~aes et al.
than the apical (31). This could be because of the fact that a superior removal of the smear layer in the coronal and middle levels and the ineffective delivery of irrigant to the apical region of the canal occurs (32). Another factor may be that the apical level contains less tubules, and when present, the diameter is smaller or they are more frequently closed (33). In relation to the interfacial adaptation (gaps), none of the groups showed a total adaptation to the root canal walls. However, the ultrasonic activation promoted a smaller presence of gaps for the AH Plus at the 2-mm level and for all sealers at the 4- and 6-mm levels with a statistical significance (P < .05). The present results are relevant because the gap regions can increase potential microbial leakage (34). Epoxy resin–based sealers like AH Plus are correlated with a higher adhesion to dentin and gutta-percha, and this might explain the appropriate interfacial adaptation of the tested sealers (35). These results are in agreement with previous studies (9, 34). The stereomicroscope analysis revealed voids at all groups (A and NA) and levels, presenting no significant difference between them (P < .05). The ultrasonic activation of the sealer did not seem to influence the presence of voids, which probably is more related to the inability of the lateral compaction technique to allow a homogeneous layer of sealer on the entire root canal wall (36).
39.0 (12.2–100)a 20.8 (0–51)b
30.0 (3.86–97.4)a 23.6 (0–77.3)a 0.0 (0–0)a 0.0 (0–0)a 0.0 (0–7.72)a 10.4 (0–30.7)b 0.0 (0–5.78)a 3.86 (0–50.8)b 0.26 (0–0.96)a 0.14 (0–0.70)a 0.69 (0–12.2)a 0.68 (0–15.7)a
0.29 (0–8.88)a 0.16 (0–13.4)a
2.83 (0–27.2)a 5.25 (0–33.5)a
41.8 (0–77.8)a 0.0 (0–15.4)a
53.3 (27.1–87.8)a 40.9 (18.1–100)a 14.2 (0–46.8)a 0.0 (0–12.7)a 0.0 (0–7.31)a 3.79 (0–23.2)b 0.0 (0–4.62)a 12.8 (0–35.3)b 0.86 (0–5.88)a 0.37 (0–2.25)a 0.0 (0–1.35)a 0.46 (0–2.27)a
0.26 (0–1.65)a 0.27 (0–14.8)a
5.59 (0–18.1)a 11.5 (0–38.7)a
36.7 (0–77.7)a 3.50 (0–42.5)b
55.4 (39.3–100)a 36.5 (0–71.3)b 36.5 (25.0–67.9)a 28.6 (0–55.9)b 0.0 (0–21.7)a 0.0 (0–63.0)a 0.0 (0–24.1)a 10.9 (0–36.3)b 0.0 (0–14.5)a 6.45 (0–35.1)b 0.0 (0–16.3)a 7.96 (0–37.1)b 0.0 (0–4.57)a 0.35(0–2.15)a 0.71 (0–13.3)a 0.0 (0–9.54)a
0.69 (0–24.3)a 0.39 (0–5.97)a
PS 2 mm (%) Gap 6 mm (%) Gap 4 mm (%) Gap 2 mm (%) Voids 6 mm (%) Voids 4 mm (%) Voids 2 mm (%)
AH Plus A NA Acroseal A NA ADSeal A NA Sealer 26 A NA
TABLE 1. Median and Range of Voids, Interfacial Adaptation (gaps), and Dentinal Sealer Penetration Segments of the Canal (PS)
PS 4 mm (%)
PS 6 mm (%)
Basic Research—Technology
Conclusions The use of ultrasonic activation of an epoxy resin–based sealer promoted greater dentinal sealer penetration and less presence of gaps.
Acknowledgments Supported by the State of S~ao Paulo Research Foundation FAPESP (2011/03973-4). The authors deny any conflicts of interest related to this study.
References 1. Buckley M, Spangberg LS. The prevalence and technical quality of endodontic treatment in an American subpopulation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:92–100. 2. Bouillaguet S, Shaw L, Barthelemy J, et al. Long-term sealing ability of Pulp Canal Sealer, AH-Plus, GuttaFlow and Epiphany. Int Endod J 2008;41:219–26. 3. Schroeder A. Endodontics: Science and Practice—A Textbook for Student and Practioner. Chicago: Quintessence; 1981. 4. Carvalho-Junior JR, Guimaraes LF, Correr-Sobrinho L, et al. Evaluation of solubility, disintegration, and dimensional alterations of a glass ionomer root canal sealer. Braz Dent J 2003;14:114–8. 5. Sousa-Neto MD, Passarinho-Neto JG, Carvalho-Junior JR, et al. Evaluation of the effect of EDTA, EGTA and CDTA on dentin adhesiveness and microleakage with different root canal sealers. Braz Dent J 2002;13:123–8. 6. Tagger M, Tagger E, Tjan AH, et al. Measurement of adhesion of endodontic sealers to dentin. J Endod 2002;28:351–4. 7. Leonardo MR, Flores DS, de Paula ESFW, et al. A comparison study of periapical repair in dogs’ teeth using RoekoSeal and AH plus root canal sealers: a histopathological evaluation. J Endod 2008;34:822–5. 8. Duarte MA, Ordinola-Zapata R, Bernardes RA, et al. Influence of calcium hydroxide association on the physical properties of AH Plus. J Endod 2010;36:1048–51. 9. Marciano MA, Guimaraes BM, Ordinola-Zapata R, et al. Physical properties and interfacial adaptation of three epoxy resin-based sealers. J Endod 2011;37:1417–21. 10. Tasdemir T, Yesilyurt C, Yildirim T, et al. Evaluation of the radiopacity of new root canal paste/sealers by digital radiography. J Endod 2008;34:1388–90. 11. de Vasconcelos BC, Bernardes RA, Duarte MAH, et al. Apical sealing of root canal fillings performed with five different endodontic sealers: analysis by fluid filtration. J Appl Oral Sci 2011;19:324–8. 12. Pinheiro CR, Guinesi AS, Pizzolitto AC, et al. In vitro antimicrobial activity of Acroseal, Polifil and Epiphany against Enterococcus faecalis. Braz Dent J 2009;20:107–11. 13. Oliveira AC, Tanomaru JM, Faria-Junior N, et al. Bacterial leakage in root canals filled with conventional and MTA-based sealers. Int Endod J 2011;44:370–5. 14. Cavalcanti AL, Limeira FI, Sales EA, et al. In vitro antimicrobial activity of root canal sealers and calcium hydroxide paste. Contemp Clin Dent 2010;1:164–7.
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Basic Research—Technology 15. Plotino G, Pameijer CH, Grande NM, et al. Ultrasonics in endodontics: a review of the literature. J Endod 2007;33:81–95. 16. Wiseman A, Cox TC, Paranjpe A, et al. Efficacy of sonic and ultrasonic activation for removal of calcium hydroxide from mesial canals of mandibular molars: a microtomographic study. J Endod 2011;37:235–8. 17. Wu MK, de Gee AJ, Wesselink PR. Effect of tubule orientation in the cavity wall on the seal of dental filling materials: an in vitro study. Int Endod J 1998;31:326–32. 18. Heling I, Chandler NP. The antimicrobial effect within dentinal tubules of four root canal sealers. J Endod 1996;22:257–9. 19. Schneider SW. A comparison of canal preparations in straight and curved root canals. Oral Surg Oral Med Oral Pathol 1971;32:271–5. 20. van der Sluis LW, Shemesh H, Wu MK, et al. An evaluation of the influence of passive ultrasonic irrigation on the seal of root canal fillings. Int Endod J 2007;40:356–61. 21. D’Alpino PHP, Pereira JC, Svizero NR, et al. Use of fluorescent compounds in assessing bonded resin-based restorations: a literature review. J Dent 2006;34:623–34. 22. Moon YM, Kim HC, Bae KS, et al. Effect of laser-activated irrigation of 1320-nanometer Nd:YAG laser on sealer penetration in curved root canals. J Endod 2012;38: 531–5. 23. Duarte MA, Balan NV, Zeferino MA, et al. Effect of ultrasonic activation on pH and calcium released by calcium hydroxide pastes in simulated external root resorption. J Endod 2012;38:834–7. 24. Bolles JA, He J, Svoboda KK, et al. Comparison of Vibringe, EndoActivator, and needle irrigation on sealer penetration in extracted human teeth. J Endod 2013;39: 708–11. 25. Kokkas AB, Boutsioukis A, Vassiliadis LP, et al. The influence of the smear layer on dentinal tubule penetration depth by three different root canal sealers: an in vitro study. J Endod 2004;30:100–2.
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26. White RR, Goldman M, Lin PS. The influence of the smeared layer upon dentinal tubule penetration by plastic filling materials. J Endod 1984;10:558–62. 27. De-Deus G, Brandao MC, Leal F, et al. Lack of correlation between sealer penetration into dentinal tubules and sealability in nonbonded root fillings. Int Endod J 2012;45: 642–51. 28. Hall MC, Clement DJ, Dove SB, et al. A comparison of sealer placement techniques in curved canals. J Endod 1996;22:638–42. 29. Balguerie E, van der Sluis L, Vallaeys K, et al. Sealer penetration and adaptation in the dentinal tubules: a scanning electron microscopic study. J Endod 2011;37: 1576–9. 30. Chadha R, Taneja S, Kumar M, et al. An in vitro comparative evaluation of depth of tubular penetration of three resin-based root canal sealers. J Conserv Dent 2012;15:18–21. 31. Chandra SS, Shankar P, Indira R. Depth of penetration of four resin sealers into radicular dentinal tubules: a confocal microscopic study. J Endod 2012;38: 1412–6. 32. Kara Tuncer A, Tuncer S. Effect of different final irrigation solutions on dentinal tubule penetration depth and percentage of root canal sealer. J Endod 2012;38: 860–3. 33. Mjor IA, Smith MR, Ferrari M, et al. The structure of dentine in the apical region of human teeth. Int Endod J 2001;34:346–53. 34. De-Deus G, Reis C, Di Giorgi K, et al. Interfacial adaptation of the Epiphany selfadhesive sealer to root dentin. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:381–6. 35. Lee KW, Williams MC, Camps JJ, et al. Adhesion of endodontic sealers to dentin and gutta-percha. J Endod 2002;28:684–8. 36. Wu MK, Ozok AR, Wesselink PR. Sealer distribution in root canals obturated by three techniques. Int Endod J 2000;33:340–5.
Ultrasonic Activation of 4 Root Canal Sealers
5
Influence of Ultrasonic Activation of 4 Root Canal Sealers on the Filling Quality Bruno Martini Guimar~ aes, DDS, MSc, Pablo Andres Amoroso-Silva, DDS, MSc, Murilo Priori Alcalde, DDS, Marina Angelica Marciano, DDS, MSc, Flaviana Bombarda de Andrade, DDS, PhD, and Marco Antonio Hungaro Duarte, DDS, PhD Abstract Introduction: The purpose of this study was to evaluate the effects of ultrasonic activation on the filling quality (intratubular sealer penetration, interfacial adaptation, and presence of voids) of 4 epoxy resin–based sealers. Methods: Eighty-four extracted human canines were divided into 4 groups (n = 20) according to the sealer used to obturate the root canals instrumented with F5 ProTaper instruments (50/05) (Dentsply Maillefer, Ballaigues, Switzerland). The canals were filled by the lateral compaction technique. Previously, the sealers were labeled with rhodamine B dye to allow analysis under a confocal microscope. At the time of obturation, the specimens were divided again into 2 groups (n = 10) according to the ultrasonic activation of the sealers: ultrasonically activated and nonultrasonically activated groups. All samples were sectioned at 2, 4, and 6 mm from the apex. The percentages of voids, gaps, and dentinal sealer penetration segments of the canal were analyzed. Results: Regarding the sealer penetration segments, there was a significant increase for the AH Plus (Dentsply Maillefer), Acroseal (Specialites Septodont, Saint Maur-des-Fosses, France), and Sealer 26 (Dentsply Maillefer) at the 4-mm level and the AH Plus and Sealer 26 at the 6-mm level with ultrasonic activation (P < .05). Concerning the gaps, the ultrasonic activation promoted a smaller presence for all sealers at the 4- and 6-mm levels (P < .05). No statistical significant differences were found for the percentages of voids (P < .05). Conclusions: The use of ultrasonic activation of an epoxy resin–based sealer promoted greater dentinal sealer penetration and less presence of gaps. (J Endod 2014;-:1–5)
Key Words Confocal microscopy, epoxy resin sealers, root canal filling, ultrasound
From the Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of S~ao Paulo, Bauru, S~ao Paulo, Brazil. Address requests for reprints to Dr Bruno Martini Guimar~aes, Al Octavio Pinheiro Brisolla, 9-75-CEP 17012-901, Bauru School of Dentistry, University of S~ao Paulo, Bauru, SP, Brazil. E-mail address: [email protected] 0099-2399/$ - see front matter Copyright ª 2014 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2013.11.016
JOE — Volume -, Number -, - 2014
T
he complete sealing of the root canal system after a biomechanical procedure can determine the long-term success of an endodontic treatment by preventing oral pathogens from colonizing and reinfecting the root and periapical tissues (1, 2). Because gutta-percha does not adhere to the dentinal walls, the sealer must fill the irregularities and the dentinal tubules of the root canal system. Epoxy resin–based sealers were introduced in endodontics by Schroeder (3) and have since been used because of their reduced solubility (4), apical seal (5), and microretention to the root dentin (6). One of these sealers is AH Plus (Dentsply Maillefer, Ballaigues, Switzerland), which has been extensively evaluated for its physicochemical properties, biological response, and interfacial adaptation (7–9). The Adseal (Meta Biomed, Cheongju, South Korea) is another epoxy resin sealer with reports in the literature about its radiopacity value and physical properties (9, 10). Acroseal (Specialites Septodont, Saint Maur-des-Fosses, France) is a sealer that contains 28% calcium hydroxide in its composition. Previous studies have shown its sealing ability, antimicrobial activity against Enterococcus faecalis, and adaptation to the root canal walls (9, 11, 12). Sealer 26 (Dentsply Maillefer) is an epoxy resin– based material containing calcium hydroxide and has also shown good sealing ability and antimicrobial activity (13, 14). Ultrasound is an instrument that was first introduced to endodontics by Richman in 1957. Currently, it has been widely used in different endodontic procedures, ranging from coronal opening to endodontic surgery (15). A greater agitation of irrigating solutions promoted by ultrasound intensifies the penetration in an area of anatomic complexity such as the dentinal tubules and consequently improves the cleaning ability (16). The activation of root canal sealers can possibly favor its penetration inside the dentinal tubules, providing an increase in sealability (17) and antimicrobial effects (18). The effects of ultrasonic activation of the sealer into the root canal and the filling quality have not been explored sufficiently. The aim of this study was to evaluate the effect of ultrasonic activation on 4 epoxy resin–based sealers regarding their filling quality. The null hypothesis that was tested is that ultrasonic activation improves the filling quality of epoxy resin–based sealers.
Materials and Methods Eighty-four maxillary human canines with a root curvature less than 5 were used (19). The ethics committee approved the use of extracted teeth for the research (CEP 079/2011). The crowns were removed at the cementoenamel junction using a 0.3-mm low-speed diamond saw (Isomet, Buehler, Lake Bluff, IL), and the root canal length was established at 15 mm. The working length was established by measuring the penetration of a size 10 K-file (Dentsply Maillefer) until it reached the apical foramen and then subtracting 1 mm. Root canal shaping was performed using ProTaper rotary instruments (Dentsply Maillefer) at the working length until a F5 (50.05) instrument. After the use of each instrument, the canals were irrigated using 2 mL 2.5% sodium hypochlorite. Passive ultrasonic irrigation was performed at the end of the shaping as described by van der Sluis et al (20). A final flush of 2 mL 17% EDTA (pH = 7.7) (Biodin^amica, Ibipor~a, Parana, Brazil) was applied for 3 minutes to eliminate the smear layer. Then, the canals were washed with 5 mL saline solution and dried with paper points (Dentsply Maillefer).
Ultrasonic Activation of 4 Root Canal Sealers
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Basic Research—Technology The specimens were randomly divided into 4 groups (n = 20) according to the sealer used to obturate the root canals: Group 1: AH Plus (Dentsply Maillefer) Group 2: Acroseal (Septodont, Saint Maur des Fosses, France) Group 3: AdSeal (Meta, Biomed, Cheongju, South Korea) Group 4: Sealer 26 (Dentsply Maillefer) The sealers were manipulated according to the manufacturer’s instructions. To allow visualization under a confocal laser microscope (TCS-SPE; Leica Microsystems GmbH, Mannheim, Germany), the sealers were mixed with fluorescent rhodamine B dye (Sigma-Aldrich, St Louis, MO) to an approximate concentration of 0.1% (21). The sealers were placed in each root canal by using a size 30 rotary lentulo spiral (Dentsply Maillefer), maintaining the instrument 4 mm from the apex. Then, the specimens were divided into 2 groups (n = 10) according to the ultrasonic activation of the sealers: ultrasonically activated (A) and nonultrasonically activated (NA) groups. The activation in group A was performed using a size A nickel-titanium finger spreader (Dentsply Maillefer) adapted into an ultrasonic device (Jet-Sonic Four Plus; Gnatus, Ribeir~ao Preto, SP, Brazil) in ‘‘endo’’ mode (50% potency) using a no. A-120 insert (Gnatus) (Fig. 1). Because the ultrasonic oscillates in a single plane, the spreader was activated for 20 seconds in the buccolingual direction and another 20 seconds in the mesiodistal direction of the root canal, 2 mm short of the working length as a standardization procedure. Next, a 50.02 gutta-percha cone (Dentsply Maillefer) was inserted into the full working length, and the root canal obturation was completed using the lateral compaction technique with a size B finger spreader (Dentsply Maillefer) inserted 2 mm short of the working length and accessory gutta-percha points size 20.02 (Dentsply Maillefer). The cervical portion of the specimens was sealed using a provisional filling material (Coltosol, Coltene, Switzerland). The specimens were stored in 100% humidity at 37 C for 1 week to allow the sealers to set.
Voids Area, Interfacial Adaptation (Gaps), and Segment of Sealer Penetration The samples were sectioned using a 0.3-mm Isomet saw (Buehler, Lake Bluff, IL) at 200 rpm with continuous water cooling to prevent frictional heat. Horizontal sections were performed at the 2-, 4-, and 6-mm levels from the apical foramen and polished with sandpaper (Politriz;
Arotec, Cotia, SP, Brazil). To calculate the void area (mm2) percentages, a stereomicroscope (Stemi 2000C; Carl Zeiss, Jena, Germany) and the Axiovision software (Carl Zeiss) were used (Fig. 2A). First, the total area of each cross-section image of the canal and the visible voids were measured. With both values obtained, the percentage of voids in relation to the total area of each canal section was calculated. The segments of the root canal in which the sealer penetrated into the dentinal tubules, and the interfacial adaptation (gaps) were analyzed on an inverted Leica TCS-SPE confocal laser scanning microscope (Leica Microsystems GmbH) by the similar method described by Moon et al (22). For the correct visualization of all images, the sections were analyzed 10 mm below the surface using the 10 lens. The respective absorption and emission wavelengths for the rhodamine B were set to 540 and 590 nm, respectively. Then, the images were recorded at 100 magnification using the fluorescent mode to a size of 1024 1024 pixels and a scale set to 100 mm (Fig. 2B). Analysis of all images was performed with the Image J V1.46r software (National Institutes of Health, Bethesda, MD). The total circumference of the canal was obtained first. Then, segments of sealer penetration into the dentinal tubules and interfacial adaptation (gaps) of the total circumference were measured, and the values were converted into percentages (Fig. 2C and D).
Statistical Analysis Because of the absence of normal distribution, which was observed using the Shapiro-Wilk test. Statistical analysis was performed by using the nonparametric Kruskal-Wallis and Dunn tests (P < .05). The nonparametric Mann-Whitney test was used to analyze the influence of ultrasonic activation individually in each sealer (P < .05).
Results Median and range of voids, interfacial adaptation (gaps), and dentinal sealer penetration segments of the canal can be found in Table 1. With regard to the sealer penetration segments, there was a significant increase for the AH Plus (Fig. 2E and F), Acroseal, and Sealer 26 at the 4-mm level, and the AH Plus and Sealer 26 at the 6-mm level when the ultrasonic activation was performed (P < .05). Regarding the gaps, the ultrasonic activation promoted a smaller presence for the AH Plus at the 2-mm level and for all sealers at the 4- and 6-mm levels (P < .05). The voids percentage revealed no significant differences between the A or NA groups at all levels (P < .05).
Discussion
Figure 1. Finger spreader adapted into an ultrasonic device using a no. A-120 insert.
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The null hypothesis tested was confirmed because the ultrasonic activation improved the filling quality of the 4 epoxy resin–based sealers. The transmission of acoustic microstreaming energy from an oscillating file by the use of ultrasonic activation can promote the penetration of irrigants in an area of anatomic complexity and the dentinal tubules, resulting in a greater cleaning ability (16). With regard to the intracanal medication, Duarte et al (23) analyzed the influence of ultrasonic activation of calcium hydroxide pastes on the pH and calcium release in simulated external root resorptions. The authors showed that the ultrasonic activation favored a higher pH level and calcium release describing that ultrasonic activation could promote a greater tubular penetration of the calcium hydroxide pastes. In accordance with the results mentioned previously, the present study showed that the ultrasonic activation also favored a greater dentinal sealer penetration and improved the interfacial adaptation between the sealer and the root canal walls, which can promote a higher contact and confinement of microorganisms present in the dentinal tubules (22). JOE — Volume -, Number -, - 2014
Basic Research—Technology
Figure 2. (A and B) Representative correlative stereomicroscopic/confocal pictures of canal filled with Acroseal sealer and lateral compaction technique. A thin layer of sealer is evident just in the confocal picture, which promotes a clear visualization of adaptation without evidence of voids and gaps. (C and D) Segments of the root canal in which the sealer penetrated into the dentinal tubules (white dots) and an evident gap (arrows) at the interfacial adaptation, respectively. (E and F) Representative picture at 4-mm sections of canal filled with AH Plus ultrasonically and nonultrasonically activated, respectively. A remarkable dentinal sealer penetration is evident when the ultrasonic activation was promoted.
The percentage of segments in which the sealer penetrated into the dentinal tubules may be more meaningful and clinically relevant compared with the maximum depth of sealer penetration (24), and it can be considered beneficial for preventing reinfection because of the sealer’s antibacterial activity and by locking the residual microorganisms into the dentinal tubules (22, 25). Additionally, it has been suggested that the sealer inside the tubules promotes a mechanical interlocking, improving the material retention (22, 26). Meanwhile, De-Deus et al (27) reported that there was no significant correlation between the intratubular sealer penetration and the sealing ability. In this study, the sealers were placed by a rotary lentulo spiral for stanJOE — Volume -, Number -, - 2014
dardization procedures. A previous study showed that the distribution of sealer in the canal walls is not affected by the sealer placement method (28), which support the hypothesis that the ultrasonic activation of the sealer could enhance the root filling quality. AH Plus, Acroseal, and Sealer 26 presented a significant increase of segments of sealer penetration at the 4-mm level. AH Plus and Sealer 26 also had a significance difference at the 6-mm level when ultrasonic activation was performed. No significant differences were found at the 2-mm level. These findings are similar to other studies (24, 29, 30), which showed that the sealer penetration in the dentinal tubules was significantly greater in the coronal and middle levels of the root canal
Ultrasonic Activation of 4 Root Canal Sealers
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76.0 (0–100)a 49.7 (0–100)b A different letter in each column represents statistical differences between the ultrasonically activated (A) and nonultrasonically activated (NA) groups for each sealer (P < .05).
0.0 (0–35.5)a 0.0 (0–12.2)a 0.0 (0–8.53)a 7.80 (0–28.0)b 0.0 (0–8.39)a 7.37 (0–24.3)b 0.0 (0–9.61)a 1.37 (0–19.9)a 0.30 (0–2.19)a 0.0 (0–1.66)a 0.0 (0–1.41)a 0.53 (0–3.90)a 0.0 (0–13.6)a 0.83 (0–17.1)a
Guimar~aes et al.
than the apical (31). This could be because of the fact that a superior removal of the smear layer in the coronal and middle levels and the ineffective delivery of irrigant to the apical region of the canal occurs (32). Another factor may be that the apical level contains less tubules, and when present, the diameter is smaller or they are more frequently closed (33). In relation to the interfacial adaptation (gaps), none of the groups showed a total adaptation to the root canal walls. However, the ultrasonic activation promoted a smaller presence of gaps for the AH Plus at the 2-mm level and for all sealers at the 4- and 6-mm levels with a statistical significance (P < .05). The present results are relevant because the gap regions can increase potential microbial leakage (34). Epoxy resin–based sealers like AH Plus are correlated with a higher adhesion to dentin and gutta-percha, and this might explain the appropriate interfacial adaptation of the tested sealers (35). These results are in agreement with previous studies (9, 34). The stereomicroscope analysis revealed voids at all groups (A and NA) and levels, presenting no significant difference between them (P < .05). The ultrasonic activation of the sealer did not seem to influence the presence of voids, which probably is more related to the inability of the lateral compaction technique to allow a homogeneous layer of sealer on the entire root canal wall (36).
39.0 (12.2–100)a 20.8 (0–51)b
30.0 (3.86–97.4)a 23.6 (0–77.3)a 0.0 (0–0)a 0.0 (0–0)a 0.0 (0–7.72)a 10.4 (0–30.7)b 0.0 (0–5.78)a 3.86 (0–50.8)b 0.26 (0–0.96)a 0.14 (0–0.70)a 0.69 (0–12.2)a 0.68 (0–15.7)a
0.29 (0–8.88)a 0.16 (0–13.4)a
2.83 (0–27.2)a 5.25 (0–33.5)a
41.8 (0–77.8)a 0.0 (0–15.4)a
53.3 (27.1–87.8)a 40.9 (18.1–100)a 14.2 (0–46.8)a 0.0 (0–12.7)a 0.0 (0–7.31)a 3.79 (0–23.2)b 0.0 (0–4.62)a 12.8 (0–35.3)b 0.86 (0–5.88)a 0.37 (0–2.25)a 0.0 (0–1.35)a 0.46 (0–2.27)a
0.26 (0–1.65)a 0.27 (0–14.8)a
5.59 (0–18.1)a 11.5 (0–38.7)a
36.7 (0–77.7)a 3.50 (0–42.5)b
55.4 (39.3–100)a 36.5 (0–71.3)b 36.5 (25.0–67.9)a 28.6 (0–55.9)b 0.0 (0–21.7)a 0.0 (0–63.0)a 0.0 (0–24.1)a 10.9 (0–36.3)b 0.0 (0–14.5)a 6.45 (0–35.1)b 0.0 (0–16.3)a 7.96 (0–37.1)b 0.0 (0–4.57)a 0.35(0–2.15)a 0.71 (0–13.3)a 0.0 (0–9.54)a
0.69 (0–24.3)a 0.39 (0–5.97)a
PS 2 mm (%) Gap 6 mm (%) Gap 4 mm (%) Gap 2 mm (%) Voids 6 mm (%) Voids 4 mm (%) Voids 2 mm (%)
AH Plus A NA Acroseal A NA ADSeal A NA Sealer 26 A NA
TABLE 1. Median and Range of Voids, Interfacial Adaptation (gaps), and Dentinal Sealer Penetration Segments of the Canal (PS)
PS 4 mm (%)
PS 6 mm (%)
Basic Research—Technology
Conclusions The use of ultrasonic activation of an epoxy resin–based sealer promoted greater dentinal sealer penetration and less presence of gaps.
Acknowledgments Supported by the State of S~ao Paulo Research Foundation FAPESP (2011/03973-4). The authors deny any conflicts of interest related to this study.
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