- Email: [email protected]
Evaluation of pH and Calcium Ion Release of Root-end Filling Materials Containing Calcium Hydroxide or Mineral Trioxide Aggregate
Basic Research—Technology
Evaluation of pH and Calcium Ion Release of Root-end Filling Materials Containing Calcium Hydroxide or Mineral Trioxide Aggregate ´ rio Tanomaru-Filho, PhD,* Frederico Bordini Chaves Faleiros, MS,* Ma Juliana Nogueira Sac¸aki, DDS,* Marco Antonio Hungaro Duarte, PhD,† and Juliane Maria Guerreiro-Tanomaru, PhD* Abstract Introduction: To evaluate calcium ion release and pH of Sealer 26 (S26) (Dentsply, Rio de Janeiro, RJ, Brazil), white mineral trioxide aggregate (MTA), Endo CPM Sealer (CPM1) (EGEO SRL Bajo licencia MTM Argentina SA, Buenos Aires, Argentina), Endo CPM Sealer in a thicker consistency (CPM 2), and zinc oxide and eugenol cement (ZOE). Methods: Material samples (n = 10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 3, 6, 12, 24, and 48 hours and 7, 14, and 28 days, the water pH was determined with a pH meter, and calcium release was assessed by atomic absorption spectrophotometry. An empty tube was used as the control group. Results: The control group presented a pH value of 6.9 at all studied periods and did not show the presence of calcium ion. S26 presented greater hydroxyl ion release up to 12 hours (p < 0.05). From 24 hours until 28 days, S26, MTA, CPM1, and CPM2 had similar results. In all periods, ZOE presented the lowest hydroxyl ion release. CPM1, followed by CPM2, released the most calcium ions until 24 hours (p < 0.05). Between 48 hours and 7 days, CPM1 and CPM2 had the highest release. A greater calcium ion release was observed for CPM2, followed by CPM1 at 14 days and for S26, CPM1, and CPM2 at 28 days. ZOE released the least calcium ions in all periods. Conclusion: Sealer 26, MTA, and Endo CPM sealer at normal or thicker consistency release hydroxyl and calcium ions. Endo CPM sealer may be an alternative as root-end filling material. (J Endod 2009;35:1418–1421)
Key Words Calcium, mineral trioxide aggregate, pH, root canal filling, root-end filling material
From the *Department of Restorative Dentistry, Araraquara Dental School, Sa˜o Paulo State University, UNESP, Araraquara, SP, Brazil; and †Department of Dentistry, Bauru Dental School, University of Sa˜o Paulo, USP, Bauru, SP, Brazil. Address requests for reprints to Dr Ma´rio Tanomaru Filho, Rua Humaita´, 1680, Caixa Postal 331, Centro, 14801-903 Araraquara, SP, Brazil. E-mail address: [email protected]. 0099-2399/$0 - see front matter Copyright ª 2009 American Association of Endodontists. doi:10.1016/j.joen.2009.07.009
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etrograde obturation consists in the preparation and filling of an apical cavity with an appropriate material (1). The ideal endodontic filling material should be biocompatible and able to induce mineralized tissue formation. These properties are dependent on the cement’s ability to release hydroxyl and calcium ions (2–4). Calcium hydroxide or calcium oxide–containing cements have been suggested as obturating materials because of their ability to dissociate into calcium and hydroxyl ions, resulting in a higher pH in the adjacent medium and inducing mineralized tissue formation (2–6). Sealer 26 (S26) (Dentsply, Rio de Janeiro, RJ, Brazil) is an epoxy resin–based endodontic sealer containing calcium hydroxide. It has been reported to release less hydroxyl and calcium ions compared with calcium hydroxide–based materials (3, 7). However, when this material is used in retrograde fillings, a greater amount of powder is incorporated into the mix, resulting in a larger quantity of calcium hydroxide in the manipulated material (8). Mineral trioxide aggregate (MTA), a retrograde obturation material composed of tricalcium silicate, tricalcium aluminate, and other mineral trioxides, shows adequate sealing ability in retrograde obturations (9, 10) and in the treatment of root perforations (11). This material is also biocompatible when used in retrograde obturation (12, 13) and root canal perforations (14). MTA contains calcium oxide and promotes alkaline pH (6, 15) and, according to Holland et al (16, 17), presents a similar mechanism of action to calcium hydroxide. However, placing MTA into the retrograde cavity is a technically challenging procedure. For this reason, additives such as calcium chloride have been added to MTA with the goal of improving its consistency (18–20). Endo CPM Sealer (EGEO SRL Bajo licencia MTM Argentina SA, Buenos Aires, Argentina) is an endodontic cement with calcium oxide developed from MTA. This material features satisfactory plasticity, adherence, and flowability while maintaining the biological properties of MTA (21). S26 is an epoxy resin–based endodontic sealer containing calcium hydroxide that can be used in retrograde obturation. By increasing its powder/resin ratio, this sealer acquires greater consistency, which facilitates the insertion of the material into the rootend cavity (8). Similarly, Endo CPM Sealer may also be handled with the consistency of a root canal filling material or in a higher proportion of powder in order to allow its use as a retrograde filling material. Because this is a new MTA-based material, it is certainly beneficial to evaluate its physical and chemical properties when manipulated both in the recommended consistency for root canal filling or with a higher powder/liquid ratio and compare its performance with other retrograde filling materials. The aim of the present study was to evaluate the calcium ion release and pH of S26 manipulated as a retrograde material, MTA, and Endo CPM Sealer (CPM) conventionally manipulated or with a higher powder/liquid ratio.
Material and Methods The following materials containing calcium hydroxide or calcium oxide were evaluated (Table 1). For pH and calcium ion release evaluation, 10 samples were prepared from each material studied. Fifty polyethylene tubes measuring 1 cm in length and 1.5 mm in diameter were filled with the cements to be evaluated.
JOE — Volume 35, Number 10, October 2009
Basic Research—Technology TABLE 1. Materials Used in the Study, Their Composition and Their Origin Material Sealer 26 White MTA
Endo CPM Sealer Zinc oxide and eugenol
Composition
Manufacturer
Calcium hydroxide, bismuth oxide, tetramine hexamethylene, titanium dioxide, bisphenol epoxy resin Silicon dioxide, Potassium oxide, aluminum oxide, sodium oxide, iron oxide, sulfur trioxide, calcium oxide, bismuth oxide, magnesium oxide, insoluble residues of calcium oxide, potassium and sodium per sulphate, and crystalline silica Mineral trioxide aggregate, silicon dioxide, calcium carbonate, bismuth trioxide, barium sulfate, barium proplenglycol angin, propylenglycol, sodium citrate, calcium chloride, calcium oxide. Powder: zinc oxide Liquid: eugenol
Dentsply, Rio de Janeiro, RJ, Brazil
S26 was manipulated in a 5:1 powder/resin ratio, according to Tanomaru-Filho et al (8). MTA was handled in a powder/liquid ratio of 0.33 g/1 g (20). CPM1 was manipulated according to a preliminary study in the proportion of 0.20 g of powder to 0.05 mL of liquid (4:1 in mass), which is considered adequate for use as a root canal filling material. The same cement was evaluated in a higher proportion powder/liquid proportion (0.30 g of powder to 0.05 mL of liquid, 6:1 in mass) (CPM2) determined by another preliminary study and recommended for its use as a retrograde filling material. Zinc oxide and eugenol (ZOE) cement was manipulated in a 1 g/0.2 g ratio (22). Immediately after manipulating the materials and filling the tubes, these were placed in lidded flasks (JProlab, Sa˜o Jose´ dos Pinhais, PR, Brazil) containing 10 mL of neutral pH distilled water and kept in an oven at 37 C. After 2, 6, 12, 24, and 48 hours and 7, 14, and 28 days, the water was assessed for pH and calcium ion release. The pH of the water in which an empty tube was immersed was measured in all studied periods (control). The tubes containing the cements were placed in new flasks with 10 mL of distilled water for further analyses in the different time periods.
Analyses of pH and Calcium Release Measurements of pH were performed with an UltraBasic pH Meter (Denver Instrument Company, Arvada, CO) previously calibrated using substances with pH values of 4, 7, and 10. Ca++ release was monitored with an H1170 Hilger and Watts Atomspeck atomic absorption spectrophotomer (Rank Precision Industries Ltd. Analytical Division, London, United Kingdom) equipped
Angelus, Londrina, PR, Brazil
Egeo SRL, under the license of MTM Argentina SA, Buenos Aires, Argentine Dentsply, Rio de Janeiro, RJ, Brazil
with a calcium atom-specific hollow cathode lamp (wavelength = 422.7 nm and current = 20 mA), a 0.7-nm slit, and a 5.0-cm burner length. Ca++ ion release readings were compared with a standard curve obtained by diluting calcium at 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 15.0, 20.0, and 25.0 ppm (Calcium Standard Solution; Merck, Darmstadt, Germany) in ultrapure water.
Statistical Analysis Data were subjected to statistical analysis (analysis of variance) and individual comparisons were performed by using the TukeyKramer method at a significance level of p < 0.05.
Results The water of the flasks in which an empty tube was immersed presented a pH of 6.9 and did not show the presence of calcium ion. The mean pH values for the cements evaluated in the different experimental periods are depicted in Table 2. S26 presented the highest pH readings compared with the other cements in the initial periods (3, 6, and 12 hours). No significant differences were observed between S26, MTA, and CPM1 and CPM2 at 24 hours. After 48 hours, pH readings for MTA and Endo CPM1 and CPM2 were similar (p > 0.05) and higher than the pH of S26. After 7 days, all materials had similar pH readings, except for ZOE, which showed lower values (p < 0.05). At 14 days, MTA, CPM1, and CPM2 had the highest pH readings. At 28 days, all materials had similar results, except for ZOE. In all experimental periods, ZOE had the lowest pH reading values (p < 0.05).
TABLE 2. Mean and Standard Deviation of Hydroxide Ions (pH) Released from the Materials Studied after Different Periods of Time 3h 6h 12 h 24 h 48 h 7d 14 d 28 d
S26
MTA
CPM 1
CPM 2*
ZOE
10.47 0.18 (A) 9.617 0.22 (A) 9.120 0.14 (A) 8.425 0.1 (A) 8.185 0.16 (B) 8.173 0.1 (A) 8.258 0.11 (AB) 7.800 0.1 (A)
9.918 0.22 (B) 9.139 0.24 (B) 8.745 0.14 (B) 8.628 0.19 (A) 8.555 0.1 (A) 8.198 0.03 (A) 8.213 0.1 (BC) 7.845 0.22 (A)
9.496 0.17 (C) 9.138 0.3 (B) 8.805 0.16 (B) 8.570 0.23 (A) 8.616 0.14 (A) 8.098 0.08 (AB) 8.014 0.1 (C) 7.745 0.21 (A)
9.386 0.25 (C) 8.881 0.31 (B) 8.736 0.21 (B) 8.392 0.41 (A) 8.621 0.4 (A) 8.028 0.08 (B) 8.027 0.09 (C) 7.904 0.07 (A)
7.286 0.28 (D) 7.609 0.31 (C) 7.232 0.17 (C) 7.043 0.19 (B) 7.377 0.21 (C) 7.359 0.22 (C) 7.090 0.33 (D) 7.270 0.18 (B)
(A,B,C,D) In each period, means values followed by different labels are statistically different (p < 0.05). *Thicker consistency.
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pH and Calcium Ion Release of Root-end Filling Materials
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Basic Research—Technology TABLE 3. Mean and Standard Deviation of Calcium (mg%) Released from the Materials Studied after Different Periods of Time 3h 6h 12 h 24 h 48 h 7d 14 d 28 d
S26
MTA
CPM 1
CPM 2*
ZOE
0.118 0.13 (C) 1.513 1.13 (BC) 0.249 0.08 (CD) 0.730 0.07 (C) 0.389 0.19 (B) 0.170 0.09 (C) 0.229 0.05 (C) 1.575 0.32 (A)
0 (C) 0.782 0.56 (CD) 0.102 0.06 (D) 0.777 0.13 (C) 0.494 0.09 (B) 0.519 0.06 (B) 0.303 0.07 (C) 1.06 0.21 (B)
4.135 0.52 (A) 4.473 1.4 (A) 2.186 0.21 (A) 3.775 0.25 (A) 1.848 0.13 (A) 1.175 0.14 (A) 0.536 0.14 (A) 1.474 0.31 (A)
1.808 0.67 (B) 2.276 1.26 (B) 1.313 0.34 (B) 2.733 0.48 (B) 1.926 0.27 (A) 1.314 0.18 (A) 0.704 0.15 (B) 1.367 0.46 (AB)
0 (C) 0.219 0.03 (D) 0 (D) 0.145 0.04 (D) 0.152 0.11 (C) 0.007 0.02 (D) 0 (D) 0 (C)
(A,B,C,D) In each period, means values followed by different labels are statistically different (p < 0.05). *Thicker consistency.
Table 3 shows the mean calcium ion release values for the cements in the different experimental periods. At 3 hours, only CPM1 and CPM2 released calcium ions, with higher readings for this CPM1 (p < 0.05). At 6, 12, and 24 hours, CPM1 had higher calcium ion release, followed by CPM2. At 48 hours and at 7 days, CPM1 and CPM2 released the highest amount of calcium ions with similar readings (p > 0.05). After 7 and 14 days, calcium release readings were higher for CPM1 and CPM2, followed by MTA and S26, with the lowest readings for ZOE (G5) (p < 0.05). At 28 days, S26, CPM1, and CPM2 had a similar calcium release (p > 0.05), which was higher than MTA. Again, ZOE presented the lowest readings among all materials (p < 0.05).
Discussion The methodology used in this study consists in filling standardized tubes with the materials to be tested and immersing in distilled water. After that, the pH is determined in the resulting solution with a pH meter (23). Santos et al (15) used tubes measuring 10 mm in length by 1 mm in diameter in a study designed to assess the pH and calcium ion release by MTA and an experimental dental cement. Sealer 26 is an epoxy resin-based sealer containing calcium hydroxide that showed satisfactory biological properties in a study involving retrograde obturations in dogs’ teeth with periapical lesions (8). Regarding the pH readings of the various cements, in the first 12 hours Sealer 26 had the highest pH among all materials tested, indicating a faster release of hydroxyl ions. After 24 hours, no statistically significant difference was observed between S26, MTA, CPM1, and CPM2. These results may be because of the availability of calcium hydroxide in the composition of Sealer 26, in addition to the longer setting time of this cement. In MTA-based materials, the chemical reaction that takes place during setting results in the formation of calcium hydroxide, which subsequently dissociates into calcium and hydroxyl ions. Similar results were reported by Duarte et al (7), who also observed higher pH values for Sealer 26 in the initial readings. Furthermore, the incorporation of a greater amount of powder when manipulating Sealer 26 in a thicker consistency contributes for the greater availability of calcium hydroxide in the material. The pH readings for MTA are similar to those found by Duarte et al (6) for the same material. These authors reported slightly higher pH values for white MTA when compared with Pro Root MTA. Calcium chloride, which is added to some MTA-based cements with the purpose of accelerating the setting reaction (18, 20, 24), is included in the formulation of Endo CPM Sealer. According to Wiltbank 1420
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et al (24), the addition of calcium chloride to MTA or to Portland cement did not alter the pH in comparison with a control material. Bortoluzzi et al (25) reported that the presence of calcium chloride could significantly increase the mean pH readings but only immediately after manipulation of the material. In the present study, no significant differences were observed between the pH of MTA and Endo CPM Sealer. Tay et al (26) described the calcium phosphate phases produced after the immersion of set Portland cement in phosphate-buffered saline solution. The authors observed that the pH changes occurred in two stages, with the release of hydroxyl ions during the precipitation of calcium phosphate. The results from the present study indicated that Endo CPM Sealer in normal consistency released significantly more calcium ions than the other cements in almost all periods, except at 48 hours, when it had similar readings to Endo CPM Sealer in thicker consistency and at 28 days, when it performed similarly to S26 and MTA. Bortoluzzi et al (25) studied the addition of calcium chloride to Pro Root MTA, MTA Angelus, and Portland cements and found greater calcium ion release in cements containing calcium chloride. Thus, the presence of calcium chloride in the composition of Endo CPM Sealer may explain our results. Our findings show favorable potential for the MTA-based material Endo CPM Sealer in retrograde obturations. The thicker consistency obtained by manipulating the cement in a greater powder/liquid ratio facilitates its insertion into the retrograde cavity. Additional physical, chemical, and biological features of this material should be evaluated to further substantiate its indication as a retrograde obturation material.
Conclusions The considerable release of hydroxyl ions was observed for Sealer 26 and the MTA-based materials evaluated, particularly for Sealer 26 in the initial experimental periods. Moreover, calcium ion release was shown for Endo CPM Sealer in normal and thicker consistencies. Endo CPM sealer may be an alternative as root-end filling material.
References 1. Tobo´n-Arroyave SI, Restrepo-Pe´rez MM, Arismendi-Echavarrı´a JA, et al. Ex vivo microscopic assessment of factors affecting the quality of apical seal created by root-end fillings. Int Endod J 2007;40:590–602. 2. Holland R, Souza V. Ability of a new calcium hydroxide root canal filling material to induce hard tissue formation. J Endod 1985;11:535–43. 3. Silva LAB, Leonardo MR, Silva RS, et al. Calcium hydroxide root canal sealers: evaluation of pH, calcium ion concentration and conductivity. Int Endod J 1997;30: 205–9.
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Basic Research—Technology 4. Holland R, Souza V, Nery MJ, et al. Calcium salts deposition in rat connective tissue after the implantation of calcium hydroxide-containing sealers. J Endod 2002;28: 173–6. 5. Eldeniz AU, Erdemir A, Kurtoglu F, et al. Evaluation of pH and calcium ion release of Acroseal sealer in comparison with Apexit and Sealapex sealers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:86–91. 6. Duarte MA, Demarchi ACO, Yamashita JC, et al. pH and calcium ion release of 2 root-end filling materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;36:610–5. 7. Duarte MA, Demarchi ACO, Giaxa MH, et al. Evaluation of pH and calcium ion release of three root canal sealers. J Endod 2000;26:389–90. 8. Tanomaru-Filho M, Luis MR, Leonardo MR, et al. Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 102:127–32. 9. Torabinejad M, Higa RJ, McKendry DJ, et al. Dye leakage of four root end filling materials: effects of blood contamination. J Endod 1994;20:159–63. 10. Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregate when used as a root end filling material. J Endod 1993;19:591–5. 11. Lee SJ, Monsef M, Torabinejad M. Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations. J Endod 1993;19:541–4. 12. Camilleri J, Pitt Ford TR. Mineral trioxide aggregate: a review of the constituents and biological properties of the material. Int Endod J 2006;39:747–54. 13. Felippe WT, Felippe MC, Rocha MJ. The effect of mineral trioxide aggregate on the apexification and periapical healing of teeth with incomplete root formation. Int Endod J 2006;39:2–9. 14. Holland R, Bisco Ferreira L, de Souza V, et al. Reaction of the lateral periodontium of dogs’ teeth to contaminated and noncontaminated perforations filled with mineral trioxide aggregate. J Endod 2007;33:1192–7.
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15. Santos AD, Moraes JCS, Arau´jo EB, et al. Physico-chemical properties of MTA and a novel experimental cement. Int Endod J 2005;38:443–7. 16. Holland R, Souza V, Nery MJ, et al. Reaction of rat connective tissue to implanted dentin tube filled with mineral trioxide aggregate and calcium hydroxide. J Endod 1999;25:161–6. 17. Holland R, Souza V, Nery MJ, et al. Reaction of rat connective tissue to implanted dentin tube filled with mineral trioxide aggregate, Portland Cement and calcium hydroxide. Braz Dent J 2001;12:3–8. 18. Kogan P, He J, Glickman GN, et al. The effects of various additives on setting properties of MTA. J Endod 2006;32:569–72. 19. Ber BS, Hatton JF, Stewart GP. Chemical modification of Pro Root MTA to improve handling characteristics and decrease setting time. J Endod 2007;33:1231–4. 20. Fridland M, Rosado R. Mineral trioxide aggregate (MTA) solubility and porosity with different water-to-powder ratios. J Endod 2003;29:814–7. 21. Gomes-Filho JE, Watanabe S, Bernabe´ PF, et al. A mineral trioxide aggregate sealer stimulated mineralization. J Endod 2009;35:256–60. 22. Bernabe´ PF, Holland R, Morandi R, et al. Comparative study of MTA and other materials in retrofilling of pulpless dog’s teeth. Braz Dent J 2005;16:149–55. 23. Anthony DR, Gordon TM, del Rio CE. The effect of three vehicles on the pH of calcium hydroxide. Oral Surg Oral Med Oral Pathol 1982;54:560–5. 24. Wiltbank KB, Schwartz SA, Schindler WG. Effect of selected accelerants on the physical properties of mineral trioxide aggregate and Portland cement. J Endod 2007;33: 1235–8. 25. Bortoluzzi EA, Broon NJ, Duarte MAH, et al. The use of a setting accelerator and its effect on pH and calcium ion release of mineral trioxide aggregate and White Portland Cement. J Endod 2006;32:1194–7. 26. Tay FR, Pashley DH, Rueggeberg FA, et al. Calcium phosphate phase transformation produced by the interaction of the portland cement component of white mineral trioxide aggregate with a phosphate-containing fluid. J Endod 2007;33:1347–51.
pH and Calcium Ion Release of Root-end Filling Materials
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Evaluation of pH and Calcium Ion Release of Root-end Filling Materials Containing Calcium Hydroxide or Mineral Trioxide Aggregate ´ rio Tanomaru-Filho, PhD,* Frederico Bordini Chaves Faleiros, MS,* Ma Juliana Nogueira Sac¸aki, DDS,* Marco Antonio Hungaro Duarte, PhD,† and Juliane Maria Guerreiro-Tanomaru, PhD* Abstract Introduction: To evaluate calcium ion release and pH of Sealer 26 (S26) (Dentsply, Rio de Janeiro, RJ, Brazil), white mineral trioxide aggregate (MTA), Endo CPM Sealer (CPM1) (EGEO SRL Bajo licencia MTM Argentina SA, Buenos Aires, Argentina), Endo CPM Sealer in a thicker consistency (CPM 2), and zinc oxide and eugenol cement (ZOE). Methods: Material samples (n = 10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 3, 6, 12, 24, and 48 hours and 7, 14, and 28 days, the water pH was determined with a pH meter, and calcium release was assessed by atomic absorption spectrophotometry. An empty tube was used as the control group. Results: The control group presented a pH value of 6.9 at all studied periods and did not show the presence of calcium ion. S26 presented greater hydroxyl ion release up to 12 hours (p < 0.05). From 24 hours until 28 days, S26, MTA, CPM1, and CPM2 had similar results. In all periods, ZOE presented the lowest hydroxyl ion release. CPM1, followed by CPM2, released the most calcium ions until 24 hours (p < 0.05). Between 48 hours and 7 days, CPM1 and CPM2 had the highest release. A greater calcium ion release was observed for CPM2, followed by CPM1 at 14 days and for S26, CPM1, and CPM2 at 28 days. ZOE released the least calcium ions in all periods. Conclusion: Sealer 26, MTA, and Endo CPM sealer at normal or thicker consistency release hydroxyl and calcium ions. Endo CPM sealer may be an alternative as root-end filling material. (J Endod 2009;35:1418–1421)
Key Words Calcium, mineral trioxide aggregate, pH, root canal filling, root-end filling material
From the *Department of Restorative Dentistry, Araraquara Dental School, Sa˜o Paulo State University, UNESP, Araraquara, SP, Brazil; and †Department of Dentistry, Bauru Dental School, University of Sa˜o Paulo, USP, Bauru, SP, Brazil. Address requests for reprints to Dr Ma´rio Tanomaru Filho, Rua Humaita´, 1680, Caixa Postal 331, Centro, 14801-903 Araraquara, SP, Brazil. E-mail address: [email protected]. 0099-2399/$0 - see front matter Copyright ª 2009 American Association of Endodontists. doi:10.1016/j.joen.2009.07.009
1418
Tanomaru-Filho et al.
R
etrograde obturation consists in the preparation and filling of an apical cavity with an appropriate material (1). The ideal endodontic filling material should be biocompatible and able to induce mineralized tissue formation. These properties are dependent on the cement’s ability to release hydroxyl and calcium ions (2–4). Calcium hydroxide or calcium oxide–containing cements have been suggested as obturating materials because of their ability to dissociate into calcium and hydroxyl ions, resulting in a higher pH in the adjacent medium and inducing mineralized tissue formation (2–6). Sealer 26 (S26) (Dentsply, Rio de Janeiro, RJ, Brazil) is an epoxy resin–based endodontic sealer containing calcium hydroxide. It has been reported to release less hydroxyl and calcium ions compared with calcium hydroxide–based materials (3, 7). However, when this material is used in retrograde fillings, a greater amount of powder is incorporated into the mix, resulting in a larger quantity of calcium hydroxide in the manipulated material (8). Mineral trioxide aggregate (MTA), a retrograde obturation material composed of tricalcium silicate, tricalcium aluminate, and other mineral trioxides, shows adequate sealing ability in retrograde obturations (9, 10) and in the treatment of root perforations (11). This material is also biocompatible when used in retrograde obturation (12, 13) and root canal perforations (14). MTA contains calcium oxide and promotes alkaline pH (6, 15) and, according to Holland et al (16, 17), presents a similar mechanism of action to calcium hydroxide. However, placing MTA into the retrograde cavity is a technically challenging procedure. For this reason, additives such as calcium chloride have been added to MTA with the goal of improving its consistency (18–20). Endo CPM Sealer (EGEO SRL Bajo licencia MTM Argentina SA, Buenos Aires, Argentina) is an endodontic cement with calcium oxide developed from MTA. This material features satisfactory plasticity, adherence, and flowability while maintaining the biological properties of MTA (21). S26 is an epoxy resin–based endodontic sealer containing calcium hydroxide that can be used in retrograde obturation. By increasing its powder/resin ratio, this sealer acquires greater consistency, which facilitates the insertion of the material into the rootend cavity (8). Similarly, Endo CPM Sealer may also be handled with the consistency of a root canal filling material or in a higher proportion of powder in order to allow its use as a retrograde filling material. Because this is a new MTA-based material, it is certainly beneficial to evaluate its physical and chemical properties when manipulated both in the recommended consistency for root canal filling or with a higher powder/liquid ratio and compare its performance with other retrograde filling materials. The aim of the present study was to evaluate the calcium ion release and pH of S26 manipulated as a retrograde material, MTA, and Endo CPM Sealer (CPM) conventionally manipulated or with a higher powder/liquid ratio.
Material and Methods The following materials containing calcium hydroxide or calcium oxide were evaluated (Table 1). For pH and calcium ion release evaluation, 10 samples were prepared from each material studied. Fifty polyethylene tubes measuring 1 cm in length and 1.5 mm in diameter were filled with the cements to be evaluated.
JOE — Volume 35, Number 10, October 2009
Basic Research—Technology TABLE 1. Materials Used in the Study, Their Composition and Their Origin Material Sealer 26 White MTA
Endo CPM Sealer Zinc oxide and eugenol
Composition
Manufacturer
Calcium hydroxide, bismuth oxide, tetramine hexamethylene, titanium dioxide, bisphenol epoxy resin Silicon dioxide, Potassium oxide, aluminum oxide, sodium oxide, iron oxide, sulfur trioxide, calcium oxide, bismuth oxide, magnesium oxide, insoluble residues of calcium oxide, potassium and sodium per sulphate, and crystalline silica Mineral trioxide aggregate, silicon dioxide, calcium carbonate, bismuth trioxide, barium sulfate, barium proplenglycol angin, propylenglycol, sodium citrate, calcium chloride, calcium oxide. Powder: zinc oxide Liquid: eugenol
Dentsply, Rio de Janeiro, RJ, Brazil
S26 was manipulated in a 5:1 powder/resin ratio, according to Tanomaru-Filho et al (8). MTA was handled in a powder/liquid ratio of 0.33 g/1 g (20). CPM1 was manipulated according to a preliminary study in the proportion of 0.20 g of powder to 0.05 mL of liquid (4:1 in mass), which is considered adequate for use as a root canal filling material. The same cement was evaluated in a higher proportion powder/liquid proportion (0.30 g of powder to 0.05 mL of liquid, 6:1 in mass) (CPM2) determined by another preliminary study and recommended for its use as a retrograde filling material. Zinc oxide and eugenol (ZOE) cement was manipulated in a 1 g/0.2 g ratio (22). Immediately after manipulating the materials and filling the tubes, these were placed in lidded flasks (JProlab, Sa˜o Jose´ dos Pinhais, PR, Brazil) containing 10 mL of neutral pH distilled water and kept in an oven at 37 C. After 2, 6, 12, 24, and 48 hours and 7, 14, and 28 days, the water was assessed for pH and calcium ion release. The pH of the water in which an empty tube was immersed was measured in all studied periods (control). The tubes containing the cements were placed in new flasks with 10 mL of distilled water for further analyses in the different time periods.
Analyses of pH and Calcium Release Measurements of pH were performed with an UltraBasic pH Meter (Denver Instrument Company, Arvada, CO) previously calibrated using substances with pH values of 4, 7, and 10. Ca++ release was monitored with an H1170 Hilger and Watts Atomspeck atomic absorption spectrophotomer (Rank Precision Industries Ltd. Analytical Division, London, United Kingdom) equipped
Angelus, Londrina, PR, Brazil
Egeo SRL, under the license of MTM Argentina SA, Buenos Aires, Argentine Dentsply, Rio de Janeiro, RJ, Brazil
with a calcium atom-specific hollow cathode lamp (wavelength = 422.7 nm and current = 20 mA), a 0.7-nm slit, and a 5.0-cm burner length. Ca++ ion release readings were compared with a standard curve obtained by diluting calcium at 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 15.0, 20.0, and 25.0 ppm (Calcium Standard Solution; Merck, Darmstadt, Germany) in ultrapure water.
Statistical Analysis Data were subjected to statistical analysis (analysis of variance) and individual comparisons were performed by using the TukeyKramer method at a significance level of p < 0.05.
Results The water of the flasks in which an empty tube was immersed presented a pH of 6.9 and did not show the presence of calcium ion. The mean pH values for the cements evaluated in the different experimental periods are depicted in Table 2. S26 presented the highest pH readings compared with the other cements in the initial periods (3, 6, and 12 hours). No significant differences were observed between S26, MTA, and CPM1 and CPM2 at 24 hours. After 48 hours, pH readings for MTA and Endo CPM1 and CPM2 were similar (p > 0.05) and higher than the pH of S26. After 7 days, all materials had similar pH readings, except for ZOE, which showed lower values (p < 0.05). At 14 days, MTA, CPM1, and CPM2 had the highest pH readings. At 28 days, all materials had similar results, except for ZOE. In all experimental periods, ZOE had the lowest pH reading values (p < 0.05).
TABLE 2. Mean and Standard Deviation of Hydroxide Ions (pH) Released from the Materials Studied after Different Periods of Time 3h 6h 12 h 24 h 48 h 7d 14 d 28 d
S26
MTA
CPM 1
CPM 2*
ZOE
10.47 0.18 (A) 9.617 0.22 (A) 9.120 0.14 (A) 8.425 0.1 (A) 8.185 0.16 (B) 8.173 0.1 (A) 8.258 0.11 (AB) 7.800 0.1 (A)
9.918 0.22 (B) 9.139 0.24 (B) 8.745 0.14 (B) 8.628 0.19 (A) 8.555 0.1 (A) 8.198 0.03 (A) 8.213 0.1 (BC) 7.845 0.22 (A)
9.496 0.17 (C) 9.138 0.3 (B) 8.805 0.16 (B) 8.570 0.23 (A) 8.616 0.14 (A) 8.098 0.08 (AB) 8.014 0.1 (C) 7.745 0.21 (A)
9.386 0.25 (C) 8.881 0.31 (B) 8.736 0.21 (B) 8.392 0.41 (A) 8.621 0.4 (A) 8.028 0.08 (B) 8.027 0.09 (C) 7.904 0.07 (A)
7.286 0.28 (D) 7.609 0.31 (C) 7.232 0.17 (C) 7.043 0.19 (B) 7.377 0.21 (C) 7.359 0.22 (C) 7.090 0.33 (D) 7.270 0.18 (B)
(A,B,C,D) In each period, means values followed by different labels are statistically different (p < 0.05). *Thicker consistency.
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Basic Research—Technology TABLE 3. Mean and Standard Deviation of Calcium (mg%) Released from the Materials Studied after Different Periods of Time 3h 6h 12 h 24 h 48 h 7d 14 d 28 d
S26
MTA
CPM 1
CPM 2*
ZOE
0.118 0.13 (C) 1.513 1.13 (BC) 0.249 0.08 (CD) 0.730 0.07 (C) 0.389 0.19 (B) 0.170 0.09 (C) 0.229 0.05 (C) 1.575 0.32 (A)
0 (C) 0.782 0.56 (CD) 0.102 0.06 (D) 0.777 0.13 (C) 0.494 0.09 (B) 0.519 0.06 (B) 0.303 0.07 (C) 1.06 0.21 (B)
4.135 0.52 (A) 4.473 1.4 (A) 2.186 0.21 (A) 3.775 0.25 (A) 1.848 0.13 (A) 1.175 0.14 (A) 0.536 0.14 (A) 1.474 0.31 (A)
1.808 0.67 (B) 2.276 1.26 (B) 1.313 0.34 (B) 2.733 0.48 (B) 1.926 0.27 (A) 1.314 0.18 (A) 0.704 0.15 (B) 1.367 0.46 (AB)
0 (C) 0.219 0.03 (D) 0 (D) 0.145 0.04 (D) 0.152 0.11 (C) 0.007 0.02 (D) 0 (D) 0 (C)
(A,B,C,D) In each period, means values followed by different labels are statistically different (p < 0.05). *Thicker consistency.
Table 3 shows the mean calcium ion release values for the cements in the different experimental periods. At 3 hours, only CPM1 and CPM2 released calcium ions, with higher readings for this CPM1 (p < 0.05). At 6, 12, and 24 hours, CPM1 had higher calcium ion release, followed by CPM2. At 48 hours and at 7 days, CPM1 and CPM2 released the highest amount of calcium ions with similar readings (p > 0.05). After 7 and 14 days, calcium release readings were higher for CPM1 and CPM2, followed by MTA and S26, with the lowest readings for ZOE (G5) (p < 0.05). At 28 days, S26, CPM1, and CPM2 had a similar calcium release (p > 0.05), which was higher than MTA. Again, ZOE presented the lowest readings among all materials (p < 0.05).
Discussion The methodology used in this study consists in filling standardized tubes with the materials to be tested and immersing in distilled water. After that, the pH is determined in the resulting solution with a pH meter (23). Santos et al (15) used tubes measuring 10 mm in length by 1 mm in diameter in a study designed to assess the pH and calcium ion release by MTA and an experimental dental cement. Sealer 26 is an epoxy resin-based sealer containing calcium hydroxide that showed satisfactory biological properties in a study involving retrograde obturations in dogs’ teeth with periapical lesions (8). Regarding the pH readings of the various cements, in the first 12 hours Sealer 26 had the highest pH among all materials tested, indicating a faster release of hydroxyl ions. After 24 hours, no statistically significant difference was observed between S26, MTA, CPM1, and CPM2. These results may be because of the availability of calcium hydroxide in the composition of Sealer 26, in addition to the longer setting time of this cement. In MTA-based materials, the chemical reaction that takes place during setting results in the formation of calcium hydroxide, which subsequently dissociates into calcium and hydroxyl ions. Similar results were reported by Duarte et al (7), who also observed higher pH values for Sealer 26 in the initial readings. Furthermore, the incorporation of a greater amount of powder when manipulating Sealer 26 in a thicker consistency contributes for the greater availability of calcium hydroxide in the material. The pH readings for MTA are similar to those found by Duarte et al (6) for the same material. These authors reported slightly higher pH values for white MTA when compared with Pro Root MTA. Calcium chloride, which is added to some MTA-based cements with the purpose of accelerating the setting reaction (18, 20, 24), is included in the formulation of Endo CPM Sealer. According to Wiltbank 1420
Tanomaru-Filho et al.
et al (24), the addition of calcium chloride to MTA or to Portland cement did not alter the pH in comparison with a control material. Bortoluzzi et al (25) reported that the presence of calcium chloride could significantly increase the mean pH readings but only immediately after manipulation of the material. In the present study, no significant differences were observed between the pH of MTA and Endo CPM Sealer. Tay et al (26) described the calcium phosphate phases produced after the immersion of set Portland cement in phosphate-buffered saline solution. The authors observed that the pH changes occurred in two stages, with the release of hydroxyl ions during the precipitation of calcium phosphate. The results from the present study indicated that Endo CPM Sealer in normal consistency released significantly more calcium ions than the other cements in almost all periods, except at 48 hours, when it had similar readings to Endo CPM Sealer in thicker consistency and at 28 days, when it performed similarly to S26 and MTA. Bortoluzzi et al (25) studied the addition of calcium chloride to Pro Root MTA, MTA Angelus, and Portland cements and found greater calcium ion release in cements containing calcium chloride. Thus, the presence of calcium chloride in the composition of Endo CPM Sealer may explain our results. Our findings show favorable potential for the MTA-based material Endo CPM Sealer in retrograde obturations. The thicker consistency obtained by manipulating the cement in a greater powder/liquid ratio facilitates its insertion into the retrograde cavity. Additional physical, chemical, and biological features of this material should be evaluated to further substantiate its indication as a retrograde obturation material.
Conclusions The considerable release of hydroxyl ions was observed for Sealer 26 and the MTA-based materials evaluated, particularly for Sealer 26 in the initial experimental periods. Moreover, calcium ion release was shown for Endo CPM Sealer in normal and thicker consistencies. Endo CPM sealer may be an alternative as root-end filling material.
References 1. Tobo´n-Arroyave SI, Restrepo-Pe´rez MM, Arismendi-Echavarrı´a JA, et al. Ex vivo microscopic assessment of factors affecting the quality of apical seal created by root-end fillings. Int Endod J 2007;40:590–602. 2. Holland R, Souza V. Ability of a new calcium hydroxide root canal filling material to induce hard tissue formation. J Endod 1985;11:535–43. 3. Silva LAB, Leonardo MR, Silva RS, et al. Calcium hydroxide root canal sealers: evaluation of pH, calcium ion concentration and conductivity. Int Endod J 1997;30: 205–9.
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Basic Research—Technology 4. Holland R, Souza V, Nery MJ, et al. Calcium salts deposition in rat connective tissue after the implantation of calcium hydroxide-containing sealers. J Endod 2002;28: 173–6. 5. Eldeniz AU, Erdemir A, Kurtoglu F, et al. Evaluation of pH and calcium ion release of Acroseal sealer in comparison with Apexit and Sealapex sealers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:86–91. 6. Duarte MA, Demarchi ACO, Yamashita JC, et al. pH and calcium ion release of 2 root-end filling materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;36:610–5. 7. Duarte MA, Demarchi ACO, Giaxa MH, et al. Evaluation of pH and calcium ion release of three root canal sealers. J Endod 2000;26:389–90. 8. Tanomaru-Filho M, Luis MR, Leonardo MR, et al. Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 102:127–32. 9. Torabinejad M, Higa RJ, McKendry DJ, et al. Dye leakage of four root end filling materials: effects of blood contamination. J Endod 1994;20:159–63. 10. Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregate when used as a root end filling material. J Endod 1993;19:591–5. 11. Lee SJ, Monsef M, Torabinejad M. Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations. J Endod 1993;19:541–4. 12. Camilleri J, Pitt Ford TR. Mineral trioxide aggregate: a review of the constituents and biological properties of the material. Int Endod J 2006;39:747–54. 13. Felippe WT, Felippe MC, Rocha MJ. The effect of mineral trioxide aggregate on the apexification and periapical healing of teeth with incomplete root formation. Int Endod J 2006;39:2–9. 14. Holland R, Bisco Ferreira L, de Souza V, et al. Reaction of the lateral periodontium of dogs’ teeth to contaminated and noncontaminated perforations filled with mineral trioxide aggregate. J Endod 2007;33:1192–7.
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15. Santos AD, Moraes JCS, Arau´jo EB, et al. Physico-chemical properties of MTA and a novel experimental cement. Int Endod J 2005;38:443–7. 16. Holland R, Souza V, Nery MJ, et al. Reaction of rat connective tissue to implanted dentin tube filled with mineral trioxide aggregate and calcium hydroxide. J Endod 1999;25:161–6. 17. Holland R, Souza V, Nery MJ, et al. Reaction of rat connective tissue to implanted dentin tube filled with mineral trioxide aggregate, Portland Cement and calcium hydroxide. Braz Dent J 2001;12:3–8. 18. Kogan P, He J, Glickman GN, et al. The effects of various additives on setting properties of MTA. J Endod 2006;32:569–72. 19. Ber BS, Hatton JF, Stewart GP. Chemical modification of Pro Root MTA to improve handling characteristics and decrease setting time. J Endod 2007;33:1231–4. 20. Fridland M, Rosado R. Mineral trioxide aggregate (MTA) solubility and porosity with different water-to-powder ratios. J Endod 2003;29:814–7. 21. Gomes-Filho JE, Watanabe S, Bernabe´ PF, et al. A mineral trioxide aggregate sealer stimulated mineralization. J Endod 2009;35:256–60. 22. Bernabe´ PF, Holland R, Morandi R, et al. Comparative study of MTA and other materials in retrofilling of pulpless dog’s teeth. Braz Dent J 2005;16:149–55. 23. Anthony DR, Gordon TM, del Rio CE. The effect of three vehicles on the pH of calcium hydroxide. Oral Surg Oral Med Oral Pathol 1982;54:560–5. 24. Wiltbank KB, Schwartz SA, Schindler WG. Effect of selected accelerants on the physical properties of mineral trioxide aggregate and Portland cement. J Endod 2007;33: 1235–8. 25. Bortoluzzi EA, Broon NJ, Duarte MAH, et al. The use of a setting accelerator and its effect on pH and calcium ion release of mineral trioxide aggregate and White Portland Cement. J Endod 2006;32:1194–7. 26. Tay FR, Pashley DH, Rueggeberg FA, et al. Calcium phosphate phase transformation produced by the interaction of the portland cement component of white mineral trioxide aggregate with a phosphate-containing fluid. J Endod 2007;33:1347–51.
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