- Email: [email protected]
Chemical analysis of powder and set forms of Portland cement, gray ProRoot MTA, white ProRoot MTA, and gray MTA-Angelus
Chemical analysis of powder and set forms of Portland cement, gray ProRoot MTA, white ProRoot MTA, and gray MTA-Angelus Jin-Seon Song, BDS, MS, FRACDS,a Francis K. Mante, DMD, PhD,b William J. Romanow,c and Syngcuk Kim, DDS, PhD,d Philadelphia, PA UNIVERSITY OF PENNSYLVANIA
Objective. To evaluate the chemical composition and crystalline structures of Portland cement, gray ProRoot MTA (gray MTA), white ProRoot MTA (white MTA), and gray MTA-Angelus. Study design. X-ray diffraction analysis was used to identify and characterize crystalline phases, and energy dispersive x-ray spectrometer was used to determine the chemical composition of the test materials. Both powder form and set form were examined. Results. The crystalline structure and chemical composition of gray and white MTA were similar except for the presence of iron in gray MTA. Both were composed mainly of bismuth oxide and calcium silicate oxide. Portland cement was composed mainly of calcium silicate oxide and did not contain bismuth oxide. Gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. There were no noticeable differences in the chemical composition and crystalline structures between the powder and set forms of any of the material tested. Conclusion. Portland cement differed from the MTA by the absence of bismuth ions and presence of potassium ions. Gray MTA contained a significant amount of iron when compared with white MTA. In addition, gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 102:809-15)
Since its introduction and its approval in 1998 by the US Food and Drug Administration, mineral trioxide aggregate (MTA) (ProRoot MTA, Dentsply Tulsa, Tulsa, OK) has been used widely in clinical endodontics. It has been shown to be superior to other materials in terms of sealing ability,1,2 biocompatibility,3-5 and enhancing regeneration of the periradicular tissues.6 It also possesses ideal properties including antimicrobial effect,7,8 radiopacity, dimensional stability, and tolerance to moisture. Clinically, MTA is being used in dental procedures such as vital pulp therapy,9,10 apexification,6,11 repair of root perforation,12,13 root-end filling,14 internal bleaching, and resorption repair. Poten-
a
Department of Endodontics, School of Dental Medicine, University of Pennsylvania. b Director of Biomaterials Restorative Denistry, Department of Restorative Dentistry, University of Pennsylvania. c Undergraduate Instruction & Laboratory Coordinator, Department of Materials Science & Engineering, University of Pennsylvania. d Louis I. Grossman Professor and Chairman, Department of Endodontics, School of Dental Medicine, University of Pennsylvania. Received for publication Nov. 30, 2005; returned for revision Nov. 30, 2005; accepted for publication Nov. 30, 2005. 1079-2104/$ - see front matter © 2006 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2005.11.034
tial uses of MTA in other dental and medical procedures are continually being explored. Some authors have suggested using MTA as an obturating material for the entire root canal system,15 and a possible application of MTA in orthopedic setting has been explored with positive results.16 MTA is based on Portland cement; both gray and white Portland cements are manufactured from similar raw materials except that a fluxing agent is used for production of the white version to remove the ferrite phase during the clinkering process. According to the manufacturer, the principal components of the gray-colored formula are tricalcium silicate, bismuth oxide, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, and calcium sulfate dehydrate, and the white-colored formula lacks the tetracalcium aluminoferrite. Both formulae are 75% Portland cement, 20% bismuth oxide, and 5% gypsum by weight.17,24 Another product, gray MTAAngelus (Angelus Soluções Odontológicas, Londrina, Brazil), consists of 80% Portland cement and 20% bismuth oxide. A number of previous studies have compared MTA with Portland cement and unequivocally indicated that they are similar in chemical composition, if not identical, except for the inclusion of bismuth oxide in MTA.18,19 In vitro20,21 and in vivo22,23 studies have 809
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also shown the Portland cement to exhibit properties similar to MTA. Recently, white MTA has been developed and marketed to replace gray MTA to address esthetic concerns. A number of studies have been performed on this new material to determine if it exhibits the same properties as gray MTA. These studies comparing white and gray MTA have yielded conflicting results in terms of biocompatibility, sealing ability, and ability to induce tissue regeneration. A leakage study by Ferris and Baumgarnter24 and a biocompatibility study by Holland et al.25 have shown them to have similar properties. Camilleri et al.26 reported that osteoblasts had the same biocompatible reaction to both types of MTA. An in vivo study by Menezes et al.10 showed that when white MTA, gray MTA, and white Portland cement were applied as a pulpotomy agent, all the samples resulted in healing of the pulp and a hard tissue bridge formation. However, some in vitro studies, such as by Perez et al.,27 have reported that osteoblastic cell line grown on gray MTA adhered and differentiated better than the cells grown on white MTA. A leakage study by Matt et al.28 showed that gray MTA demonstrated significantly less dye leakage when compared to white MTA. In light of the conflicting findings in comparing the sealing ability, biocompatibility, and tissue-regenerating ability of gray MTA and white MTA between these studies, there is a need to compare the chemical composition of the MTA products available. The purpose of this study was to analyze and compare the chemical composition of Portland cement, gray MTA, white MTA, and gray MTA-Angelus. Both the powder and the set forms were examined. X-ray diffraction (XRD) was used to identify and characterize crystal phases, and an energy dispersive x-ray spectrometer system (EDS) was used to determine the chemical composition of the examined materials. MATERIALS AND METHODS Preparation of the sample (powder) MTA powder was mixed with acetone and applied onto the frosted surface of a glass slide and left in air for 30 seconds until the acetone had evaporated completely, leaving the MTA powder attached to the slide. The prepared slide was mounted onto the XRD apparatus. Three samples of each material, Portland cement, gray MTA, white MTA and gray MTA-Angelus, were investigated by XRD. Preparation of the sample (set) Each MTA sample was mixed with distilled water according to the manufacturer’s direction for use.
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Portland cement sample was also mixed in the same manner. The mix was stored in an incubator at 37°C and 100% humidity for 3 days. The set samples were then mounted onto the XRD apparatus for analysis. XRD analysis The prepared sample material was mounted onto the XRD apparatus (Geigerflex Horizontal diffractometer with a graphite crystal monochrometer; Rigaku/MSC, Woodlands, TX). The x-ray beam angle 2 range was set between 3 degrees (3000) to 70 degrees (70000) and scanned at 2 degrees per minute. The Cu x-ray source was set at accelerating voltage of 45 KV and the current in the electron beam at 30 mA and on continuous scan mode. The peaks on the diffraction pattern were marked using the Rigaku software (version 2.8). Then the peaks were compared and matched with that of the standard material in the powder diffraction file (JCPDS International Center for Diffraction Data 1998, Pennsylvania) using a micro powder diffraction search and matching analysis program. Preparation of the sample for EDS Each sample powder was placed on an aluminum stop with double-sided carbon tape. Carbon coating was applied before running the scanning electron microscopy (SEM). EDS Analytical scanning electron microscopy was performed on JEOL 6400 SEM (Tokyo, Japan). This microscope was equipped with an Oxford energy dispersive x-ray spectrometer (EDS) and wavelength dispersive x-ray spectrometer (WDS). The EDS system was used to determine the chemical composition of the examined materials. RESULTS XRD The chemical composition and its crystal structure of gray and white MTA were similar (Fig. 1, Table I). The only exception was that gray MTA contained significant amount of iron when compared with white MTA. Both materials were composed mainly of bismuth oxide crystalline structure and calcium silicate oxide. Although present, other crystal phases contributed to a very small proportion of the material. Portland cement did not contain bismuth oxide but it was composed of many different crystal phases. Gray MTA-Angelus differed from the gray ProRoot MTA in that it contained less bismuth oxide and more of other crystalline phases, many of which could not be identified (Fig. 1; Table I). For each of the cement types, there were no notice-
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Fig. 1. X-ray diffraction patterns of gray Portland cement, gray MTA, white MTA, and gray MTA-Angelus showing peaks representing the crystal phases present in each material.
able differences in the composition and crystalline structure between powder and set form.
bismuth ions and the presence of potassium ions (Figs. 2-4; Table II).
EDS The chemical composition of Portland cement, gray MTA, and white MTA were very similar. The only difference observed between the 2 types of MTA was the lack of iron ions in white MTA. The Portland cement differed from MTA by the lack of
DISCUSSION Several studies have compared the chemical composition, surface characteristics, sealing ability, biocompatibility, and ability to regenerate original tissues of Portland cement, gray MTA, and white MTA. The surface characteristics of Portland cement and
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3.4 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ⬎ND, None detected.
ND 1.8 1.6 2.1 1.4 1.4 BaZn2(PO4)2 Ca2MgSi2 Ca(SO4)(H2O)2 CaSnO3 Ca3Al2O6 CaAl2Si6O16 5H2O
ND ND ND ND ND ND
38.8 30.1 ND ND 18.6 3.9 ND 1.0 4.2 57.8 30.2 ND ND 3.9 2.7 ND 5.4 ND 56.7 34.1 0.9 0.3 3.7 0.9 1.6 1.7 ND 67.8 21.8 1.4 ND 3.2 1.1 2.3 2.5 ND 58.8 30.3 2.3 ND 5.3 ND 1.0 ND 2.9 Bi2O3 Ca3(SiO4)O Mg3(PO)4 Cu5Si6 O17.7H2O Unknown CaCO3 Ca4P2O9 Ca2SiO4 Ca2MgO. 2AlFeO. 6SiO.2O5
Bismuth oxide Calcium silicate oxide Magnesium phosphate Copper silicate hydrate Unknown Calcium carbonate Calcium phosphate Calcium silicate Calcium magnesium aluminum iron silicate Barium zinc phosphate Calcium magnesium silicate Calcium sulfate hydrate Calcium tin oxide Calcium aluminum oxide Calcium aluminum silicate hydrate
ND 65.7 ND ND 8.5 ND ND 21.7 1.8 ND 72.6 ND ND 6.1 1.0 ND 6.7 5.6
Chemical formula
Portland cement Powder (%)
Portland cement Set (%)
Gray MTA Powder (%)
Gray MTA Set (%)
White MTA Powder (%)
White MTA Set (%)
Gray MTA-Angelus Powder (%)
Song et al.
Component
Table I. X-ray diffraction analysis result showing the chemical composition and semiquantitative crystalline composition of Portland cement, gray MTA, white MTA, and gray MTA-Angelus.
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gray MTA have been shown to be irregular, consisting of either cuboidal discrete crystals or areas of granular material with a coral-like characteristic when viewed under high magnification.16,18,20 This was not the case for the white MTA, which showed different surface roughness when viewed under SEM.27 Holland et al.22 clinically observed 2 differences with these materials: the color and the setting time, which was greater in white MTA. Ferris and Baumgartner24 compared white and gray MTA for their sealing ability of furcal perforation using a bacterial leakage model. Their results demonstrated no difference between the 2 in allowing passage of F. nucleatum. However, a leakage study by Matt et al.28 showed that gray MTA demonstrated significantly less dye leakage than white MTA. Abdullah et al.,20 Holland et al.,22 and Saidon et al.23 showed that the biocompatibility and the potential to promote bone healing of Portland cement are comparable to that of gray MTA in their in vitro studies. There are not many studies published comparing the new white MTA and the extensively studied gray MTA. Perez et al.27 compared their effects on osteoblasts. Under the conditions of their study, primary osteoblasts bound and survived on gray MTA and initially bound to white MTA but did not survive on the surface. On the other hand, Holland et al.22,25 implanted white MTA and gray MTA on the connective tissue of rats and reported that the mechanisms of action of white MTA are very similar to those of gray MTA despite the differences in the material. This study examined the presence and intensity of the peaks from the XRD patterns. Over 50% of the crystalline structure present in ProRoot MTA was in the form of bismuth oxide, and calcium silicate oxide crystalline contributed to approximately 30%. Gray MTAAngelus consisted of about 40% of the bismuth oxide phases and 30% of calcium silicate oxide. This study is in agreement with that by other authors who compared the chemical composition of Portland cement and gray MTA and showed that they contain the same chemical elements except that gray MTA also contains bismuth oxide.18,19,21 This study is also in agreement with that of Diamannti et al.,18 who found that iron oxide was absent in white MTA; however, their observation of absence of calcium sulfate (plaster anhydride) only in gray MTA was not observed in this study. Asgary et al.29 found that white MTA contained significantly less iron oxide as well as aluminum oxide and magnesium oxide than gray MTA. Our results also showed that there was more of the magnesium compound phase in gray MTA than in white MTA. Metal oxides such as
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Fig. 2. Energy dispersive x-ray spectrum of Portland cement.
Fig. 3. Energy dispersive x-ray spectrum of gray MTA.
Fig. 4. Energy dispersive x-ray spectrum of white MTA.
aluminum and iron oxides have been known to cause abnormal tissue reactions equivalent to a chemical insult.31 The effect of iron oxide in gray MTA at this point is not clear. Also, the trace amount of other
compounds detected in the Portland cement and gray MTA-Angelus may or may not play a significant role in the short- and long-term clinical application, and this warrants further studies.
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Table II. Energy dispersive x-ray spectrometer results showing the composition of Portland cement, gray MTA, and white MTA Portland cement
Gray MTA
White MTA
Yes Yes Yes Yes Yes Yes Yes Yes Yes No
Yes Yes No Yes Yes Yes Yes Yes Yes Yes
Yes Yes No Yes Yes No Yes Yes Yes Yes
Ca Si K C O Fe Mg Al S Bi
9.
10.
11.
12.
13.
CONCLUSION The difference observed between the 2 types of MTA was the lack of iron ions in white MTA. They were similarly composed of bismuth oxide and calcium silicate oxide crystalline structures, and other crystalline components comprised a very small proportion of the material. Portland cement differed from MTA by the absence of bismuth ions and presence of potassium ions. In addition, ProRoot MTA appeared to have more homogeneous composition than Portland cement and gray MTA-Angelus. For each of the cement types, there were no noticeable differences in the composition and crystalline structure between powder and set form.30 We thank Dr. Wojciech J Grzesik for reviewing this manuscript and giving us very valuable advice. REFERENCES 1. Wu MK, Kontakiotis E.G., Wesselink PR. Long-term seal provided by some root-end filling materials. J Endod 1998;24:557-60. 2. Torabinejad M, Rastegar AF, Kettering JD, Pitt Ford TR. Bacterial leakage of mineral trioxide aggregate as a root-end filling material. J Endod 1995;21:109-12. 3. Koh ET, McDonald F, Pitt Ford TR, Torabinejad M. Cellular response to mineral trioxide aggregate. J Endod 1998;24:543-7. 4. Torabinejad M, Pitt Ford TR, McKendry DJ, Abedi HR, Miller DA, Kariyawasam SP. Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys. J Endod 1997;23:225-8. 5. Mitchell PJ, Pitt Ford TR, Torabinejad M, McDonald F. Osteoblast biocompatibility of mineral trioxide aggregate. Biomaterials 1997;20:167-73. 6. Shabahang S, Torabinejad M, Boyne P, Abedi H, McMillan P. A comparative study of root-end induction using osteogenic protein-1, calcium hydroxide, and mineral trioxide aggregate in dogs. J Endod 1999;25:1-5. 7. Torabinejad M, Hong CU, Pitt Ford TR, Kettering JD. Antibacterial effects of some root end filling materials. J Endod 1995;21:403-6. 8. Stowe TJ, Sedgley CM, Stowe B, Fenno JC. The effects of chlorohexidine gluconate (0.12%) on the antimicrobial proper-
14.
15.
16.
17. 18.
19.
20.
21.
22.
23.
24. 25.
26.
27.
ties of tooth-colored ProRoot mineral trioxide aggregate. J Endod 2004;30:429-31. Ford TR, Torabinejad M, Abedi HR, Bakland LK, Kariyawasam SP. Using mineral trioxide aggregate as a pulp-capping material. J Am Dent Assoc 1996;127:1491-4. Menezes R, Bramante CM, Letra A, Carvalho VG, Garcia RB. Histologic evaluation of pulpotomies in dog using two types of mineral trioxide aggregate and regular and white Portland cements as wound dressing. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;98:376-9. Hayashi M, Shimizu A, Ebisu S. MTA for obturation of mandibular central incisors with open apices: case report. J Endod 2004;30:120-2. Pitt Ford TR, Torabinejad M, McKendry D, Hong CU, Kariyawasam SP. Use of mineral trioxide for repair of furcal perforations. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:756-62. Nakata TT, Bae KS, Baumgartner JC. Perforation repair comparing mineral trioxide aggregate and amalgam using an anaerobic bacterial leakage model. J Endod 1998;24:4-186. Torabinejad M, Hong CU, Lee SJ, Monsef M, Pitt Ford TR. Investigation of mineral trioxide aggregate for root-end filling in dogs. J Endod 1995;21:603-8. O’Sullivan SM, Hartwell GR. Obturation of a retained primary mandibular second molar using MTA: a case report. J Endod 2001;27:703-5. Koh ET, Torabinejad M, Pitt Ford TR, Brady K, McDonald F. Mineral trioxide aggregate stimulates a biological response in human osteoblasts. J Biomed Mater Res 1997;37:432-9. Literature from the manufacturer. Tulsa (OK): Dentsply Tulsa Dental, Tulsa, OK. Material Safety Data Sheet; 1998. Diamanti E, Kerezoudis NP, Gakis DB, Tsatsas V. Chemical composition and surface characteristics of grey and new white ProRoot MTA. J Endod 2003;Abstract R81. Funteas UR, Wallace JA, Fochtman EW. A comparative analysis of mineral trioxide aggregate and Portland cement. Aust Endod J 2003; 29:43-4. Abdullah D, Ford TR, Papaioannou S, Nicholson J, McDonald F. An evaluation of accelerated Portland cement as a restorative material. Biomaterials 2002;23:4001-10. Estrela C, Bammann LL, Estrela CR, Silva RS, Pecora JD. Antimicrobial and chemical study of MTA, Portland cement, calcium hydroxide paste, Sealapex and Dycal. Braz Dent J 2000;11:3-9. Holland R, Souza V, Nery MJ, Faraco IM Jr, Bernabe PF, Otoboni Filho JA, Dezan E Jr. Reaction of rat tissue to implanted dentin tube filled with mineral trioxide aggregate, Portland cement or calcium hydroxide. Braz Dent J 2001;12:3-8. Saidon J, He J, Zhu Q, Safavi K, Spangberg LS. Cell and tissue reactions to mineral trioxide aggregate and Portland cement. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:483-9. Ferris DM, Baumgartner JC. Perforation repair comparing two types of mineral trioxide aggregate. J Endod 2004;30:422-4. Holland R, Souza V, Nery MJ, Faraco Junior IM, Bernabe PF, Otoboni Filho JA, Dezan Junior E. Reaction of rat connective tissue to implanted dentin filled with a white mineral trioxide aggregate. Braz Dent J 2002;13:23-6. Camilleri J, Montesin F, Papaioannou S, McDonald F, Pitt Ford TR. Biocompatibility of two commercial forms of mineral trioxide aggregate. Int Endod J 2004;37:699-704. Perez AL, Spears R, Gutmann JL, Opperman LA. Osteoblasts and MG-63 osteostcoma cells behave differently when in
OOOOE Volume 102, Number 6 contact with ProRoot MTA and white MTA. Int Endod J 2003;36:564-9. 28. Matt GD, Thorpe JR, Strother JM, McClanahan SB. Comparative study of white and gray mineral trioxide aggregate (MTA) stimulating a one- or two-step apical barrier technique. J Endod 2004;30:876-9. 29. Asgary S, Parirokh M, Eghbal MJ, Brink F. Chemical differences between white and gray mineral trioxide aggregate. J Endod 2005;31:101-3. 30. Torabinejad M, Hong CU, McDonald F, Pitt Ford TR. Physical and chemical properties of a new root-end filling material. J Endod 1995;21: 349-53.
Song et al. 815 31. Steinemann SG. Titanium—the material of choice? Periodontol 2000 1998;17:7-21. Reprint requests: Dr. Syngcuk Kim Department of Endodontics School of Dental Medicine University of Pennsylvania 240 S. 40th Street Philadelphia, PA 19104-6030 [email protected]
Objective. To evaluate the chemical composition and crystalline structures of Portland cement, gray ProRoot MTA (gray MTA), white ProRoot MTA (white MTA), and gray MTA-Angelus. Study design. X-ray diffraction analysis was used to identify and characterize crystalline phases, and energy dispersive x-ray spectrometer was used to determine the chemical composition of the test materials. Both powder form and set form were examined. Results. The crystalline structure and chemical composition of gray and white MTA were similar except for the presence of iron in gray MTA. Both were composed mainly of bismuth oxide and calcium silicate oxide. Portland cement was composed mainly of calcium silicate oxide and did not contain bismuth oxide. Gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. There were no noticeable differences in the chemical composition and crystalline structures between the powder and set forms of any of the material tested. Conclusion. Portland cement differed from the MTA by the absence of bismuth ions and presence of potassium ions. Gray MTA contained a significant amount of iron when compared with white MTA. In addition, gray MTA-Angelus had a lower content of bismuth oxide than ProRoot MTA. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 102:809-15)
Since its introduction and its approval in 1998 by the US Food and Drug Administration, mineral trioxide aggregate (MTA) (ProRoot MTA, Dentsply Tulsa, Tulsa, OK) has been used widely in clinical endodontics. It has been shown to be superior to other materials in terms of sealing ability,1,2 biocompatibility,3-5 and enhancing regeneration of the periradicular tissues.6 It also possesses ideal properties including antimicrobial effect,7,8 radiopacity, dimensional stability, and tolerance to moisture. Clinically, MTA is being used in dental procedures such as vital pulp therapy,9,10 apexification,6,11 repair of root perforation,12,13 root-end filling,14 internal bleaching, and resorption repair. Poten-
a
Department of Endodontics, School of Dental Medicine, University of Pennsylvania. b Director of Biomaterials Restorative Denistry, Department of Restorative Dentistry, University of Pennsylvania. c Undergraduate Instruction & Laboratory Coordinator, Department of Materials Science & Engineering, University of Pennsylvania. d Louis I. Grossman Professor and Chairman, Department of Endodontics, School of Dental Medicine, University of Pennsylvania. Received for publication Nov. 30, 2005; returned for revision Nov. 30, 2005; accepted for publication Nov. 30, 2005. 1079-2104/$ - see front matter © 2006 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2005.11.034
tial uses of MTA in other dental and medical procedures are continually being explored. Some authors have suggested using MTA as an obturating material for the entire root canal system,15 and a possible application of MTA in orthopedic setting has been explored with positive results.16 MTA is based on Portland cement; both gray and white Portland cements are manufactured from similar raw materials except that a fluxing agent is used for production of the white version to remove the ferrite phase during the clinkering process. According to the manufacturer, the principal components of the gray-colored formula are tricalcium silicate, bismuth oxide, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, and calcium sulfate dehydrate, and the white-colored formula lacks the tetracalcium aluminoferrite. Both formulae are 75% Portland cement, 20% bismuth oxide, and 5% gypsum by weight.17,24 Another product, gray MTAAngelus (Angelus Soluções Odontológicas, Londrina, Brazil), consists of 80% Portland cement and 20% bismuth oxide. A number of previous studies have compared MTA with Portland cement and unequivocally indicated that they are similar in chemical composition, if not identical, except for the inclusion of bismuth oxide in MTA.18,19 In vitro20,21 and in vivo22,23 studies have 809
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also shown the Portland cement to exhibit properties similar to MTA. Recently, white MTA has been developed and marketed to replace gray MTA to address esthetic concerns. A number of studies have been performed on this new material to determine if it exhibits the same properties as gray MTA. These studies comparing white and gray MTA have yielded conflicting results in terms of biocompatibility, sealing ability, and ability to induce tissue regeneration. A leakage study by Ferris and Baumgarnter24 and a biocompatibility study by Holland et al.25 have shown them to have similar properties. Camilleri et al.26 reported that osteoblasts had the same biocompatible reaction to both types of MTA. An in vivo study by Menezes et al.10 showed that when white MTA, gray MTA, and white Portland cement were applied as a pulpotomy agent, all the samples resulted in healing of the pulp and a hard tissue bridge formation. However, some in vitro studies, such as by Perez et al.,27 have reported that osteoblastic cell line grown on gray MTA adhered and differentiated better than the cells grown on white MTA. A leakage study by Matt et al.28 showed that gray MTA demonstrated significantly less dye leakage when compared to white MTA. In light of the conflicting findings in comparing the sealing ability, biocompatibility, and tissue-regenerating ability of gray MTA and white MTA between these studies, there is a need to compare the chemical composition of the MTA products available. The purpose of this study was to analyze and compare the chemical composition of Portland cement, gray MTA, white MTA, and gray MTA-Angelus. Both the powder and the set forms were examined. X-ray diffraction (XRD) was used to identify and characterize crystal phases, and an energy dispersive x-ray spectrometer system (EDS) was used to determine the chemical composition of the examined materials. MATERIALS AND METHODS Preparation of the sample (powder) MTA powder was mixed with acetone and applied onto the frosted surface of a glass slide and left in air for 30 seconds until the acetone had evaporated completely, leaving the MTA powder attached to the slide. The prepared slide was mounted onto the XRD apparatus. Three samples of each material, Portland cement, gray MTA, white MTA and gray MTA-Angelus, were investigated by XRD. Preparation of the sample (set) Each MTA sample was mixed with distilled water according to the manufacturer’s direction for use.
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Portland cement sample was also mixed in the same manner. The mix was stored in an incubator at 37°C and 100% humidity for 3 days. The set samples were then mounted onto the XRD apparatus for analysis. XRD analysis The prepared sample material was mounted onto the XRD apparatus (Geigerflex Horizontal diffractometer with a graphite crystal monochrometer; Rigaku/MSC, Woodlands, TX). The x-ray beam angle 2 range was set between 3 degrees (3000) to 70 degrees (70000) and scanned at 2 degrees per minute. The Cu x-ray source was set at accelerating voltage of 45 KV and the current in the electron beam at 30 mA and on continuous scan mode. The peaks on the diffraction pattern were marked using the Rigaku software (version 2.8). Then the peaks were compared and matched with that of the standard material in the powder diffraction file (JCPDS International Center for Diffraction Data 1998, Pennsylvania) using a micro powder diffraction search and matching analysis program. Preparation of the sample for EDS Each sample powder was placed on an aluminum stop with double-sided carbon tape. Carbon coating was applied before running the scanning electron microscopy (SEM). EDS Analytical scanning electron microscopy was performed on JEOL 6400 SEM (Tokyo, Japan). This microscope was equipped with an Oxford energy dispersive x-ray spectrometer (EDS) and wavelength dispersive x-ray spectrometer (WDS). The EDS system was used to determine the chemical composition of the examined materials. RESULTS XRD The chemical composition and its crystal structure of gray and white MTA were similar (Fig. 1, Table I). The only exception was that gray MTA contained significant amount of iron when compared with white MTA. Both materials were composed mainly of bismuth oxide crystalline structure and calcium silicate oxide. Although present, other crystal phases contributed to a very small proportion of the material. Portland cement did not contain bismuth oxide but it was composed of many different crystal phases. Gray MTA-Angelus differed from the gray ProRoot MTA in that it contained less bismuth oxide and more of other crystalline phases, many of which could not be identified (Fig. 1; Table I). For each of the cement types, there were no notice-
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Fig. 1. X-ray diffraction patterns of gray Portland cement, gray MTA, white MTA, and gray MTA-Angelus showing peaks representing the crystal phases present in each material.
able differences in the composition and crystalline structure between powder and set form.
bismuth ions and the presence of potassium ions (Figs. 2-4; Table II).
EDS The chemical composition of Portland cement, gray MTA, and white MTA were very similar. The only difference observed between the 2 types of MTA was the lack of iron ions in white MTA. The Portland cement differed from MTA by the lack of
DISCUSSION Several studies have compared the chemical composition, surface characteristics, sealing ability, biocompatibility, and ability to regenerate original tissues of Portland cement, gray MTA, and white MTA. The surface characteristics of Portland cement and
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3.4 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ⬎ND, None detected.
ND 1.8 1.6 2.1 1.4 1.4 BaZn2(PO4)2 Ca2MgSi2 Ca(SO4)(H2O)2 CaSnO3 Ca3Al2O6 CaAl2Si6O16 5H2O
ND ND ND ND ND ND
38.8 30.1 ND ND 18.6 3.9 ND 1.0 4.2 57.8 30.2 ND ND 3.9 2.7 ND 5.4 ND 56.7 34.1 0.9 0.3 3.7 0.9 1.6 1.7 ND 67.8 21.8 1.4 ND 3.2 1.1 2.3 2.5 ND 58.8 30.3 2.3 ND 5.3 ND 1.0 ND 2.9 Bi2O3 Ca3(SiO4)O Mg3(PO)4 Cu5Si6 O17.7H2O Unknown CaCO3 Ca4P2O9 Ca2SiO4 Ca2MgO. 2AlFeO. 6SiO.2O5
Bismuth oxide Calcium silicate oxide Magnesium phosphate Copper silicate hydrate Unknown Calcium carbonate Calcium phosphate Calcium silicate Calcium magnesium aluminum iron silicate Barium zinc phosphate Calcium magnesium silicate Calcium sulfate hydrate Calcium tin oxide Calcium aluminum oxide Calcium aluminum silicate hydrate
ND 65.7 ND ND 8.5 ND ND 21.7 1.8 ND 72.6 ND ND 6.1 1.0 ND 6.7 5.6
Chemical formula
Portland cement Powder (%)
Portland cement Set (%)
Gray MTA Powder (%)
Gray MTA Set (%)
White MTA Powder (%)
White MTA Set (%)
Gray MTA-Angelus Powder (%)
Song et al.
Component
Table I. X-ray diffraction analysis result showing the chemical composition and semiquantitative crystalline composition of Portland cement, gray MTA, white MTA, and gray MTA-Angelus.
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gray MTA have been shown to be irregular, consisting of either cuboidal discrete crystals or areas of granular material with a coral-like characteristic when viewed under high magnification.16,18,20 This was not the case for the white MTA, which showed different surface roughness when viewed under SEM.27 Holland et al.22 clinically observed 2 differences with these materials: the color and the setting time, which was greater in white MTA. Ferris and Baumgartner24 compared white and gray MTA for their sealing ability of furcal perforation using a bacterial leakage model. Their results demonstrated no difference between the 2 in allowing passage of F. nucleatum. However, a leakage study by Matt et al.28 showed that gray MTA demonstrated significantly less dye leakage than white MTA. Abdullah et al.,20 Holland et al.,22 and Saidon et al.23 showed that the biocompatibility and the potential to promote bone healing of Portland cement are comparable to that of gray MTA in their in vitro studies. There are not many studies published comparing the new white MTA and the extensively studied gray MTA. Perez et al.27 compared their effects on osteoblasts. Under the conditions of their study, primary osteoblasts bound and survived on gray MTA and initially bound to white MTA but did not survive on the surface. On the other hand, Holland et al.22,25 implanted white MTA and gray MTA on the connective tissue of rats and reported that the mechanisms of action of white MTA are very similar to those of gray MTA despite the differences in the material. This study examined the presence and intensity of the peaks from the XRD patterns. Over 50% of the crystalline structure present in ProRoot MTA was in the form of bismuth oxide, and calcium silicate oxide crystalline contributed to approximately 30%. Gray MTAAngelus consisted of about 40% of the bismuth oxide phases and 30% of calcium silicate oxide. This study is in agreement with that by other authors who compared the chemical composition of Portland cement and gray MTA and showed that they contain the same chemical elements except that gray MTA also contains bismuth oxide.18,19,21 This study is also in agreement with that of Diamannti et al.,18 who found that iron oxide was absent in white MTA; however, their observation of absence of calcium sulfate (plaster anhydride) only in gray MTA was not observed in this study. Asgary et al.29 found that white MTA contained significantly less iron oxide as well as aluminum oxide and magnesium oxide than gray MTA. Our results also showed that there was more of the magnesium compound phase in gray MTA than in white MTA. Metal oxides such as
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Song et al. 813
Fig. 2. Energy dispersive x-ray spectrum of Portland cement.
Fig. 3. Energy dispersive x-ray spectrum of gray MTA.
Fig. 4. Energy dispersive x-ray spectrum of white MTA.
aluminum and iron oxides have been known to cause abnormal tissue reactions equivalent to a chemical insult.31 The effect of iron oxide in gray MTA at this point is not clear. Also, the trace amount of other
compounds detected in the Portland cement and gray MTA-Angelus may or may not play a significant role in the short- and long-term clinical application, and this warrants further studies.
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Song et al.
Table II. Energy dispersive x-ray spectrometer results showing the composition of Portland cement, gray MTA, and white MTA Portland cement
Gray MTA
White MTA
Yes Yes Yes Yes Yes Yes Yes Yes Yes No
Yes Yes No Yes Yes Yes Yes Yes Yes Yes
Yes Yes No Yes Yes No Yes Yes Yes Yes
Ca Si K C O Fe Mg Al S Bi
9.
10.
11.
12.
13.
CONCLUSION The difference observed between the 2 types of MTA was the lack of iron ions in white MTA. They were similarly composed of bismuth oxide and calcium silicate oxide crystalline structures, and other crystalline components comprised a very small proportion of the material. Portland cement differed from MTA by the absence of bismuth ions and presence of potassium ions. In addition, ProRoot MTA appeared to have more homogeneous composition than Portland cement and gray MTA-Angelus. For each of the cement types, there were no noticeable differences in the composition and crystalline structure between powder and set form.30 We thank Dr. Wojciech J Grzesik for reviewing this manuscript and giving us very valuable advice. REFERENCES 1. Wu MK, Kontakiotis E.G., Wesselink PR. Long-term seal provided by some root-end filling materials. J Endod 1998;24:557-60. 2. Torabinejad M, Rastegar AF, Kettering JD, Pitt Ford TR. Bacterial leakage of mineral trioxide aggregate as a root-end filling material. J Endod 1995;21:109-12. 3. Koh ET, McDonald F, Pitt Ford TR, Torabinejad M. Cellular response to mineral trioxide aggregate. J Endod 1998;24:543-7. 4. Torabinejad M, Pitt Ford TR, McKendry DJ, Abedi HR, Miller DA, Kariyawasam SP. Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys. J Endod 1997;23:225-8. 5. Mitchell PJ, Pitt Ford TR, Torabinejad M, McDonald F. Osteoblast biocompatibility of mineral trioxide aggregate. Biomaterials 1997;20:167-73. 6. Shabahang S, Torabinejad M, Boyne P, Abedi H, McMillan P. A comparative study of root-end induction using osteogenic protein-1, calcium hydroxide, and mineral trioxide aggregate in dogs. J Endod 1999;25:1-5. 7. Torabinejad M, Hong CU, Pitt Ford TR, Kettering JD. Antibacterial effects of some root end filling materials. J Endod 1995;21:403-6. 8. Stowe TJ, Sedgley CM, Stowe B, Fenno JC. The effects of chlorohexidine gluconate (0.12%) on the antimicrobial proper-
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ties of tooth-colored ProRoot mineral trioxide aggregate. J Endod 2004;30:429-31. Ford TR, Torabinejad M, Abedi HR, Bakland LK, Kariyawasam SP. Using mineral trioxide aggregate as a pulp-capping material. J Am Dent Assoc 1996;127:1491-4. Menezes R, Bramante CM, Letra A, Carvalho VG, Garcia RB. Histologic evaluation of pulpotomies in dog using two types of mineral trioxide aggregate and regular and white Portland cements as wound dressing. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;98:376-9. Hayashi M, Shimizu A, Ebisu S. MTA for obturation of mandibular central incisors with open apices: case report. J Endod 2004;30:120-2. Pitt Ford TR, Torabinejad M, McKendry D, Hong CU, Kariyawasam SP. Use of mineral trioxide for repair of furcal perforations. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:756-62. Nakata TT, Bae KS, Baumgartner JC. Perforation repair comparing mineral trioxide aggregate and amalgam using an anaerobic bacterial leakage model. J Endod 1998;24:4-186. Torabinejad M, Hong CU, Lee SJ, Monsef M, Pitt Ford TR. Investigation of mineral trioxide aggregate for root-end filling in dogs. J Endod 1995;21:603-8. O’Sullivan SM, Hartwell GR. Obturation of a retained primary mandibular second molar using MTA: a case report. J Endod 2001;27:703-5. Koh ET, Torabinejad M, Pitt Ford TR, Brady K, McDonald F. Mineral trioxide aggregate stimulates a biological response in human osteoblasts. J Biomed Mater Res 1997;37:432-9. Literature from the manufacturer. Tulsa (OK): Dentsply Tulsa Dental, Tulsa, OK. Material Safety Data Sheet; 1998. Diamanti E, Kerezoudis NP, Gakis DB, Tsatsas V. Chemical composition and surface characteristics of grey and new white ProRoot MTA. J Endod 2003;Abstract R81. Funteas UR, Wallace JA, Fochtman EW. A comparative analysis of mineral trioxide aggregate and Portland cement. Aust Endod J 2003; 29:43-4. Abdullah D, Ford TR, Papaioannou S, Nicholson J, McDonald F. An evaluation of accelerated Portland cement as a restorative material. Biomaterials 2002;23:4001-10. Estrela C, Bammann LL, Estrela CR, Silva RS, Pecora JD. Antimicrobial and chemical study of MTA, Portland cement, calcium hydroxide paste, Sealapex and Dycal. Braz Dent J 2000;11:3-9. Holland R, Souza V, Nery MJ, Faraco IM Jr, Bernabe PF, Otoboni Filho JA, Dezan E Jr. Reaction of rat tissue to implanted dentin tube filled with mineral trioxide aggregate, Portland cement or calcium hydroxide. Braz Dent J 2001;12:3-8. Saidon J, He J, Zhu Q, Safavi K, Spangberg LS. Cell and tissue reactions to mineral trioxide aggregate and Portland cement. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:483-9. Ferris DM, Baumgartner JC. Perforation repair comparing two types of mineral trioxide aggregate. J Endod 2004;30:422-4. Holland R, Souza V, Nery MJ, Faraco Junior IM, Bernabe PF, Otoboni Filho JA, Dezan Junior E. Reaction of rat connective tissue to implanted dentin filled with a white mineral trioxide aggregate. Braz Dent J 2002;13:23-6. Camilleri J, Montesin F, Papaioannou S, McDonald F, Pitt Ford TR. Biocompatibility of two commercial forms of mineral trioxide aggregate. Int Endod J 2004;37:699-704. Perez AL, Spears R, Gutmann JL, Opperman LA. Osteoblasts and MG-63 osteostcoma cells behave differently when in
OOOOE Volume 102, Number 6 contact with ProRoot MTA and white MTA. Int Endod J 2003;36:564-9. 28. Matt GD, Thorpe JR, Strother JM, McClanahan SB. Comparative study of white and gray mineral trioxide aggregate (MTA) stimulating a one- or two-step apical barrier technique. J Endod 2004;30:876-9. 29. Asgary S, Parirokh M, Eghbal MJ, Brink F. Chemical differences between white and gray mineral trioxide aggregate. J Endod 2005;31:101-3. 30. Torabinejad M, Hong CU, McDonald F, Pitt Ford TR. Physical and chemical properties of a new root-end filling material. J Endod 1995;21: 349-53.
Song et al. 815 31. Steinemann SG. Titanium—the material of choice? Periodontol 2000 1998;17:7-21. Reprint requests: Dr. Syngcuk Kim Department of Endodontics School of Dental Medicine University of Pennsylvania 240 S. 40th Street Philadelphia, PA 19104-6030 [email protected]