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X-Ray Diffraction Analysis of Various Calcium Silicate-Based Materials
J Dent Hyg Sci 2022;22:191-8
Published online September 30, 2022;
© 2022 Korean Society of Dental Hygiene Science.

So-Youn An1 , Myung-Jin Lee2 , and Youn-Soo Shim3,†

1Department of Pediatric Dentristry & Wonkwang Bone Regeneration Research Institute, College of Dentistry, Wonkwang University, Daejeon 35233, 2Department of Dental Hygiene, Baekseok University, Cheonan 31065, 3Department of Dental Hygiene, Sunmoon University, Asan 31460, Korea
Correspondence to: Youn-Soo Shim,
Department of Dental Hygiene, Sunmoon University, 70, Sunmoon-ro 221beon-gil, Tangjeong-myeon, Asan 31460, Korea
Tel: +82-41-530-2740, Fax: +82-41-530-2726, E-mail:
Received September 1, 2022; Revised September 14, 2022; Accepted September 19, 2022.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: The purpose of this study was to evaluate the composition of the crystal phases of various calcium silicate-based materials (CSMs): ProRoot white MTA (mineral trioxide aggregate) (WMTA), Ortho MTA (OM), Endocem MTA (EM), Retro MTA (RM), Endocem Zr (EN-Z), BiodentineTM (BD), EZ-sealTM (EZ), and OrthoMTA III (OM3).
Methods: In a sample holder, 5 g of the powder sample was placed and the top surface of the material was packed flat using a sterilized glass slide. The prepared slides were mounted on an X-ray diffraction (XRD) instrument (D8 Advance; Bruker AXS GmbH, Germany). The X-ray beam 2θ angle range was set at 10∼90° and scanned at 1.2° per minute. The Cu X-ray source set to operate at 40 kV and 40 mA in the continuous mode. The peaks in the diffraction pattern of each sample were analyzed using the software Diffrac (version 2.1). Then, the peaks were compared and matched with those of standard materials in the corresponding Powder Diffraction File (PDF-2, JCPDS International Center for Diffraction Data). A powder samples of the materials were analyzed using XRD and the peaks in diffraction pattern were compared to the Powder Diffraction File data.
Results: Eight CSMs showed a similar diffraction pattern because their main component was calcium silicate. Eight CSMs showed similar diffraction peaks because calcium silicate was their main component. Two components were observed to have been added as radiopacifiers: bismuth oxide was detected in WMTA, OM, and EM while zirconium oxide was detected in RM, EN-Z, BD, EZ, and OM3. Unusual patterns were detected for the new material, OM3, which had strong peaks at low angles.
Conclusion: It was caused by the presence of Brushite, which is believed to have resulted in crystal growth in a particular direction for a specific purpose.
Keywords : Calcium silicate, Mineral trioxide aggregate, Root canal filling materials, X-ray diffraction analysis


Mineral trioxide aggregate (MTA) was developed at Loma Linda University in the 1990s for use as a root filling material1). It has been approved by the U.S. Food and Drug Administration (FDA) and marketed as ProRoot MTA (Tulsa Dental Products, Tulsa, OK, USA)2). MTA was originally developed as a root end filling material, but its range of applications has been extended due to its excellent biocompatibility, sealing ability, and induction of hard tissue formation. It is used in various root canal treatment methods such as pulp capping, pulpotomy, apexogenesis, open apex to apical barrier formation, root perforation repair and canal filling3-5).

ProRoot MTA was the first commercially available and most widely used MTA-based material worldwide and has shown excellent biocompatibility in many previous studies6). However, ProRoot MTA is limited by long setting time, poor handling, and discoloration of teeth7,8). Manufacturers have developed a variety of MTA-like materials namely, calcium silicate-based materials (CSMs) by varying the composition of the material to compensate for the drawbacks of the original MTA. As shown in Table 1, various CSM products are marketed in Korea with the approval of Ministry of Food and Drug Safety (MFDS).

Other Root Canal Filling Materials Approved by Ministry of Food and Drug Safety (Classification Number: C10040.01)

No. Item permission number Product name Model name Manufacture/importer
1 00-90 METAPEX and 1 other Meta Biomed
2 00-136 METAPASTE and 2 others Meta Biomed
3 00-721 VITAPEX Shinhung
4 04-261 PROROOT MTA A040500000100 and 4 others Dentsply Sirona Korea
5 05-988 CALCIPEX II Shinhung
6 09-968 ORTHO MTA BioMTA
7 10-800 820 MTA-Angelus Gray 1 g and 3 others Osstem Implant
8 10-853 MTA WHITW 1G and 3 others Sambudental
10 12-1133 RetroMTA-Ortho MTA II RetroMTA-OrthoMTA II BioMTA
13 14-2165 RetroMTA-Ortho MTA II BIODENTINE Shinwon dental
14 14-1792 MTA Cem, MTA, MTA Seal MTA cem and 2 others NEXOBIO
15 14-1858 Evofill Cartridge 23 g and 1 other DiaDent
15 15-883 EZ-seal EZ-seal EZEKIEL
17 16-4273 MTA Cem MTA Cem 1.0 and 2 others NEXOBIO
18 16-4707 Well-Root PT VERICOM
19 17-4592 OrthoMTA III-1 BioMTA
20 18-4131 ApexCal 598607AN and 1 other Ivoclar Vivadent
21 18-4240 MTA 10 and 3 others GENOSS
22 18-4353 New MTA Cem MTA Cem 0.14 and 1 other IL-CHUNG Dental
23 18-4410 New MTA Cem S IL-CHUNG Dental
24 18-4613 ApexCal 598607AN and 1 other META VISION
25 18-4956 DIA-ROOT BIO MTA 0.5 g DiaDent
26 19-4152 DIA-ROOT BIO MTA 0.5 g DiaDent

MTA: mineral trioxide aggregate.

X-ray diffraction (XRD) is a useful analytical technique for cement research. Major crystalline products can be identified in cement samples using XRD4). The highlight of this technique is that, for single crystalline phases, the XRD pattern is characterized by a unique set of peaks with a specific diffracted intensity (y-axis) and diffracted angle (x-axis). The measured peak set can be compared with the Powder Diffraction Data File (PDF) of interest, provided by the International Center for Diffraction Data (ICDD) database, to identify a specific material5).

In the early stages of the use of MTAs, XRD was used to compare the components of ProRoot MTA with those of Portland cement or newly released MTA products3-5,9). The main components of MTA are tricalcium silicate, tricalcium aluminates, calcium silicate and bismuth oxide4). In another study reported that the presence of bismuth oxide, calcium silicate, calcium carbonate, calcium phosphate, and calcium silicate in MTA samples9). However, research on the components of various CSM products that have been used in Korea recently is lacking.


The purpose of this study was to find an exact match for experimental peaks with known data available on the ICDD database in order to verify the presence or absence of certain materials in the investigated sample and clarify the difference in the chemical compositions of various CSM products used in Korea using XRD analysis.

Materials and Methods

1.Ethics statement

This study did not receive IRB as a material subject.

2.Study design

This study examined eight CSMs approved by the MFDS and used clinically in Korea as alternative root canal fillings: ProRoot white MTA (WMTA; Densply, Tulsa, OK, USA), Ortho MTA (OM; BioMTA, Seoul, Korea), Endocem MTA (EM; MARUCHI, Wonju, Korea), Retro MTA (RM; BioMTA), Endocem Zr (EN-Z; MARUCHI), BiodentineTM (BD; Septodont, St.Maur-des- Fosses, France), EZ-sealTM (EZ; EZEKIEL, Taean, Korea), OrthoMTA III (OM3; BioMTA). Of these, OM3 is a new material not yet been released although it has been approved by the MFDS. In a sample holder, 5 g of the powder sample was placed and the top surface of the material was packed flat using a sterilized glass slide. The prepared slides were mounted on an XRD instrument (D8 Advance; Bruker AXS GmbH, Karlsruhe, Germany). The X-ray beam 2q angle range was set at 10∼90° and scanned at 1.2° per minute. The Cu X-ray source set to operate at 40 kV and 40 mA in the continuous mode.

3.Statistical methods

Each material has a characteristic diffraction pattern. Because cement is made up of several compounds, each sample can produce several peaks. The peaks in the diffraction pattern of each sample were analyzed using the software Diffrac.Suite Eva software (version 2.1; Bruker, Billerica, MA, USA). Then, the peaks were compared and matched with those of standard materials in the corresponding Powder Diffraction File (PDF-2, JCPDS ICDD).


The XRD pattern of each sample is shown in Fig. 1. Similar XRD patterns appeared for the eight materials because they are all based on calcium silicate. Alite (Ca3SiO5) was predominant in most of the seven materials. In EZ, belite (Ca2SiO4) was detected. Bismuth oxide (Bi2O3) was detected as a radiopacifier in WMTA, OM, and EM, which were released earlier. Zirconium oxide (ZrO2) was detected in the remaining materials: RM, EN-Z, BD, EZ, and OM3.

Fig. 1. X-ray diffraction patterns of calcium silicate-based materials showing peaks that represent the crystal phases present in each material. (A) ProRoot white MTA, (B) Ortho MTA, (C) Endocem MTA, (D) Retro MTA, (E) Endocem Zr, (F) BiodentineTM, (G) EZ-sealTM, (H) OrthoMTA III. MTA: mineral trioxide aggregate.

In EM, aluminum bismuth oxide (Al2Bi24O39) and mayenite (Ca12Al14O33) were detected. In addition, calcium carbonate (CaCO3) was detected in BD, and bassanite (2CaSO4∙H2O) was identified in EZ.

The new material, OM3, which has not yet been commercialized, showed a strong peak at a low 2q angle of 11.7°, unlike other materials. This was observed due to the presence of Brushite (CaHPO4∙2H2O).


MTA consists of Type 1 Portland cement containing 20 w% bismuth oxide for radiopacity, and for the first time, ProRoot MTA was commercially manufactured5). Type 1 Portland cement contains four major phases; alite, belite, tricalcium aluminate (Ca3Al2O6), and calcium alminoferrite (Ca2AlFeO5)10). Among them, alite and belite are the main phases in MTA2,5,11,12). Alite is the most important phase showing seven polymorphic crystal phases depending on the temperature, composition, or presence of impurities13). It has the advantage of undergoing hydration relatively quickly, reducing the setting time13,14). Belite is generally a b-polymorph, and its hydration reaction is relatively slow5,14). As a result, alite contributes to the strength for up to 28 days, while belite provides strength in the later stages10). Instead of undergoing a slow reaction, belite releases silicon ions during the reaction, shows high apatite formation activity and good bioactivity14). Camilleri et al.11) reported that gray MTA contained both alite and belite, whereas white MTA contained only alite without belite. In this study, alite was identified as the main component in seven materials including WMTA, and belite was the main component in EZ only. RM and EN-Z had similar components to those of EZ except calcium silicate. The setting time for RM and EN-Z were 2 minutes and 30 seconds and 4 minutes, respectively, while EZ required a relatively long setting time of approximately 60 minutes15,16). Because of concerns of wash out, it is thought that alite was preferred for shortening the setting time and increase the initial strength.

Tricalcium aluminate had the fastest hydration rate among the main components of Portland cement and is thus, important for shortening setting time and improving initial compressive strength by promoting the hydration process therein10,14). However, it is rarely included in MTA due to concerns about the safety over the use of aluminum. Song et al.9) reported that tricalcium aluminate was found in Portland cement but not in gray and white MTA. Similarly, in this study, tricalcium aluminate was not identified in any of the eight CSMs. Calcium aluminoferrite was not identified in the eight CSMs examined in this study, either. Since the ferrite phase contributes to dark colors in Portland cement, a white MTA with a reduced ferrite phase is preferred to improve aesthetic aspects4). The resulting strength is lower, but the slight decrease in compressive strength is not a significant issue because the MTA does not receive direct occlusal load when used as the root end-filling material4). Radiopacifiers are added to biomaterials to increase their radiopacity, making it easy to distinguish materials from anatomical structures in radiographs17). Bismuth oxide was used as the first radiopacifier in MTA18). In this study, bismuth oxide was identified in WMTA, OM and EM. However, zirconium oxide was detected, instead of bismuth oxide, in RM, EN-Z, BD, EZ, and OM3.

The use of zirconium oxide instead of bismuth oxide as a radiopaque material has many advantages. Among heavy metals, bismuth is unusual in that its toxicity is sign-ificantly lower than that of its neighboring metals in the periodic table, such as lead and thallium. However, it exhibits toxic properties and negatively affects the growth and proliferation of human dental pulp cells and reduces the biocompatibility of MTA7,19). Because bismuth oxide is dissolved in an acidic environment, when MTA is placed in an acidic environment such as inflammatory tissues, bismuth oxide is released and affects the precipitation of calcium hydroxide7). Bismuth oxide also has the disadvantage of delaying the setting reaction and causing tooth discoloration20-22). Due to these disadvantages of bismuth oxide, alternative radiopacifiers such as gold powder, silver alloy, zirconium oxide, and calcium tungstate have been proposed14,17).

Zirconium oxide has been used as a biomaterial in dental and orthopedic fields because of its excellent physical properties and biocompatibility17,21). Zirconium oxide is a radiopaque due to its high atomic number and can be used as a radiopacifier in place of bismuth oxide17). Nanoparticles of zirconium oxide accelerate the setting time because they accelerate the degree of hydration of Portland cement and do not compromise the bio-compatibility20,21). In terms of tooth discoloration, MTA containing zirconium oxide causes less discoloration than MTA containing bismuth oxide22).

In this study, aluminum bismuth oxide (Al2Bi24O39) and mayenite (Ca12Al14O33) were included only in EM. Han et al.20) also reported that EM showed a higher aluminum content than WMTA. This is due to the presence of pozzolan cement: the increase in aluminum content contributes to the reduction in the setting time20). Aluminum is rare, but it is likely to cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations23). In addition, studies have reported that aluminum is associated with Parkinson’s and Alzheimer’s diseases14). In fact, the aluminum contained in MTA has never been proven to be harmless to humans, but due to concerns about the inclusion of aluminum, manufacturers may have excluded aluminum-related components from their latest released products.

BD contains calcium carbonate (CaCO3) as a filler material in powder components24). In this study, calcium carbonate was identified only in BD. Camilleri et al.25) suggested that calcium carbonate acts as a nucleation site, forming reaction rims and improving hydration around them, thus resulting in dense microstructures. Therefore, BD shows a higher density and less porosity than conventional MTA. In addition, its physical properties are superior to those of the conventional MTA and its strength is similar to that of dentin, so it can be used as a core material24,26). Commercially available CSMs have similar constituents: therefore, their XRD patterns also exhibited similar features. OM3 is a product that is yet remains to be introduced to the market after MFDS approval. Unlike other materials, a strong peak was observed at a low 2q angle of 11.7°. As a result of matching with the PDF provided by ICDD, it was conidered to have been caused by brushite (CaHPO4∙2H2O) grown in a specific crystal direction for a specific purpose. Brushite is a phosphate mineral and the precursor of hydroxyapatite (HA, Ca5(PO4)3OH)27). HA is the major inorganic mineral in natural bones. Calcium and phosphate ions, which can accelerate bone growth and healing, are released during the transformation of Brushite into HA27). Other studies regarding Brushite cement have also shown that it is biocompatible and has great potential as a bone substitute and can act as a reservoir for calcium and phosphate ions in the re-mineralization of hard tissues28,29). Brushite cements have excellent bioresorbability and can be absorbed under physiological conditions such that newly produced woven bones replace Brushite cements28,29). OM3 may have been prepared with this advantage in mind.


There is a limit to the research conducted by selecting products centered on materials currently used in dental clinic.


Eight CSMs showed similar diffraction peaks because calcium silicate was their main component. Two components were observed to have been added as radiopacifiers: bismuth oxide was detected in WMTA, OM, and EM while zirconium oxide was detected in RM, EN-Z, BD, EZ, and OM3. Unusual patterns were detected for the new material, OM3, which had strong peaks at low angles. This was caused by the presence of Brushite, which is believed to have resulted in crystal growth in a particular direction for a specific purpose. The number of MTA materials used in clinical fields is increasing, and there are differences between countries where they are used. Therefore, there is a limit to generalizing the product used as a research object to all products used in clinical practice.


Modified or newly developed materials from existing ones can be widely used if they overcome the weaknesses of previous products. In fact, MTA has been successfully modified in Portland cement and is widely used clinically. Careful research is needed before new materials with different components can be applied to clinical settings and investigations should be undertaken to verify if they can replace existing materials. In this study, OM3, a new material, was found to have add new components that were different from previous CSMs. OM3 should be investigated and evaluated to check whether its physical properties and biocompatibility are superior to that of existing materials and whether it can replace currently used materials. In the future, research on more diverse products will be needed.


This work was supported by the Sunmoon University University Research Grant of 2022.

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Ethical Approval

This study did not receive IRB as a material subject.

Author contributions

Conceptualization: So-Youn An and Youn-Soo Shim. Data acquisition: Myung-Jin Lee. Formal analysis: Youn-Soo Shim and Myung-Jin Lee. Funding: Youn-Soo Shim. Supervision: Youn-Soo Shim. Writing–original draft: So-Youn An. Writing–review & editing: Youn-Soo Shim.

Data availability

The calcium silicate-based materials (CSMs) of MTA data can be obtained here:

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