INTRODUCTION

Calcium silicate-based cements {mineral trioxide aggregate (MTA) lookalike materials} are cements or root canal sealers that have been made based on a composition of calcium and silicate. Due to promising results obtained by MTA and its excellent sealing ability, biocompatibility, and clinical applications for pulp capping in primary and permanent teeth, root-end filling, perforation repair, and apical plug for teeth with open apices, researchers have been encouraged to investigate materials with similar favorable properties while being less expensive as well as fewer of the current drawbacks of the original MTA (Parirokh & Torabinejad 2010a, b; Torabinejad & Parirokh 2010). Since 75% of MTA is composed of Portland cement (PC) (Parirokh & Torabinejad 2010a), some investigators introduced their novel formulations as PC-based materials. These investigators claimed that their new materials had a similar composition to MTA with some modifications that may improve some of the properties such as handling characteristics, lower setting time, prevention of tooth discoloration, and higher radiopacity. In this chapter, several materials, mostly composed of calcium and silicate (main components of PC) that are commercially available, are discussed. In addition, several new formulations of experimental calcium silicate-based cements are briefly introduced.

PORTLAND CEMENT (PC)

High cost has been claimed to be one of the major drawbacks for MTA (Parirokh & Torabinejad 2010b). Since PC is an inexpensive material and is chemically similar to MTA, some researchers have suggested PC as an acceptable substitute material for MTA.

Chemical composition

Except for the bismuth oxide component, PC and MTA have a similar main composition of tricalcium and dicalcium silicate, which during hydration, produce calcium silicate hydrate gel and calcium hydroxide (CH). However, MTA showed lack of potassium, and less calcium dialuminate, and calcium sulfate unhydrated compared to type I PC (Parirokh & Torabinejad 2010a).

Despite the similarity, several differences are reported between the materials in terms of setting expansion, chemical composition, surface chemical composition, porosity, compressive strength, radiopacity, calcium ion release, and particle size. Several investigators have tried to add various amounts of bismuth oxide (as radiopacifiers) to PC. However, an increase in porosity, solubility, and degradation of the material were observed with increasing amounts of bismuth oxide. Moreover, because of the presence of more flaws in the composition of bismuth oxide and PC, the mixture showed a higher amount of cracks in the set material (Parirokh & Torabinejad 2010a).

Despite similarities in the composition of white and gray ProRoot MTA to white and gray PC (Asgary et al. 2009b; Parirokh & Torabinejad 2010a), both types of ProRoot MTA showed significantly lower levels of arsenic compared to white and gray PC. In addition, gray PC showed significantly higher lead concentrations than gray and white ProRoot MTA and white PC. Also the amounts of chromium, copper, manganese, and zinc in gray PC were significantly higher compared to white PC and gray and white ProRoot MTA (Chang et al. 2010). The amount of trace elements released from PC in both physiologic solution (Hank’s balanced solution: HBSS) and acidic environment was higher than that in several calcium silicate-based materials such as BioAggregate (BA), Biodentine (BD), tricalcium silicate, and Angelus MTA (AMTA). PC had higher concentrations of chromium, lead, and arsenic compared to AMTA (Camilleri et al. 2012). Despite having no significant difference in amounts of arsenic in their composition, white PC and AMTA released higher amounts of arsenic than ProRoot MTA when the samples were either placed in water or synthetic body fluid. Gray PC not only has significantly higher levels of lead, arsenic, and chromium in its material composition compared to AMTA and ProRoot MTA, but it also releases significantly higher amounts of these elements in water or synthetic body fluid (Schembri et al. 2010). The amounts of arsenic in all types of white PC are not the same. One investigation showed that despite the presence of 4.7 ± 0.36 ppm type III arsenic in white PC from one manufacturer (Irajazinho; Votorantim Cimentos, Rio Branco, SP, Brazil), another manufacture’s white PC (Juntalider; Brasilatex Ltda, Diadema, SP, Brazil) had lower detectable levels of type III arsenic in its composition (De-Deus et al. 2009a).

Physical properties

It has been suggested that the presence of iron and manganese in MTA may be the cause of tooth discoloration after treatment (Asgary et al. 2005; Dammaschke et al. 2005; Parirokh & Torabinejad 2010b). Recently however, the discoloration potential of MTA has been attributed to the presence of bismuth in the material’s composition (Krastl et al. 2013; Vallés et al. 2013). An investigation showed that PC had significantly lower discoloration potential compared to gray ProRoot MTA, while no significant difference was measured against white ProRoot MTA. The contamination of white ProRoot MTA and PC with blood resulted in the cements’ discoloration with no significant difference between the tested materials (Lenherr et al. 2012).

There are some controversies regarding the solubility of PC. Early investigations reported a high solubility of PC compared to MTA (Parirokh & Torabinejad 2010a). One investigation reported that AMTA had higher solubility than modified PC (75% PC + 20% bismuth oxide + 5% calcium sulfate) (Vivan et al. 2010). According to ISO 6876/2001, white ProRoot MTA showed significantly higher solubility compared to white PC. When the white PC and white ProRoot MTA was stored in either water or HBSS, the latter material showed significantly higher liquid uptake. Both white PC and white ProRoot MTA showed expansion in contact with HBSS. White PC released calcium, aluminum, and silicon in higher amounts in HBSS compared to the water (Camilleri 2011). Washout resistance of PC was higher when the material was stored in both distilled water and HBSS compared to AMTA (Formosa et al. 2013).

Several criteria have been introduced for evaluating a material’s bioactivity such as: releasing calcium ions, electroconductivity, production of CH, formation of an interfacial layer between the cement and dentinal wall, and formation of apatite crystals over the material’s surface in a synthetic tissue fluid environment (Parirokh et al. 2007; Asgary et al. 2009a; Parirokh et al. 2009; Parirokh & Torabinejad 2010a, 2010b). PC showed an alkaline pH and the production of portlandite (CH) after hydration (Camilleri 2008; Gonçalves et al. 2010; Massi et al. 2011; Formosa et al. 2012). However, a long-term investigation showed that formation of CH throughout a one-year period after setting in PC was significantly lower compared to ProRoot MTA. Maturation of structure and hydration mechanism is not obvious in PC compared to ProRoot MTA throughout the one-year period of time (Chedella & Berzins 2010). This suggests that MTA is more bioactive than PC (Formosa et al. 2012).

The particle size of white PC is significantly larger than white ProRoot MTA (Asgary et al. 2011b) and, after hydration, the crystalline particles in white MTA were smaller than those present in white PC (Asgary et al. 2004).

White and gray PC did not fulfill the requirement of ANSI/ADA specification 57 for radiopacity (Borges et al. 2011). According to ANSI/ADA specification number 57/2000 and ISO 6876/2001, each root canal sealing material should have radiopacity equal to 3 mm aluminum, which is enough for MTA, but PC did not exhibit this amount of radiopacity. Several investigations have been performed to evaluate the effect of adding different opacifiers to various properties of PC (Camilleri 2010; Camilleri et al. 2011b; Cutajar et al. 2011; Formosa et al. 2012).

Bioactivity of white PC has been confirmed by precipitation and formation of the interfacial layer between the cement and the root dentin in separate in vitro investigations (Parirokh & Torabinejad 2010a). PC showed bioactivity when placed in a synthetic body fluid such as HBSS (Formosa et al. 2012), Dulbecco’s phosphate-buffered saline (Gandolfi et al. 2010), or phosphate-buffered saline (PBS) (Reyes-Carmona et al. 2010). Both white and gray PC showed calcium ion release (Gonçalves et al. 2010; Massi et al. 2011). The formation of apatite crystals took different amounts of time when various physiologic solutions were used (Gandolfi et al. 2010).

The push-out bond strength of PC was reported to be significantly lower than that of AMTA and ProRoot MTA following storage of the materials in PBS (Reyes-Carmona et al. 2010).

From the physical and chemical properties, the major differences between MTA and PC are the presence of bismuth oxide, lower levels of calcium aluminate and calcium sulfate, lower solubility, and smaller particle size of MTA compared to PC (Parirokh & Torabinejad 2010a).

Antibacterial activity

There are a few reports regarding the antibacterial activity of PC and MTA. Some investigators reported no antibacterial activity of PC and MTA against several bacterial species, whereas others showed that PC, like MTA, has antibacterial and antifungal properties against Enterococcus faecalis, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Psuedomonas aeruginosa, and Candida albicans (Parirokh & Torabinejad 2010a).

Sealing ability

White and gray ProRoot MTA showed similar dye penetration compared to white and gray PC when used as root-end filling materials (Rekab & Ayoubi 2010; Shahi et al. 2011). When used as perforation repair material, white PC showed significantly less protein leakage compared to white and gray ProRoot MTA (Shahi et al. 2009).

Biocompatibility

Cell culture studies

Investigations that compared PC and MTA reported different results regarding cell viability, proliferation, and migration. Several cell culture investigations revealed no significant differences between the tested PC and MTA (Parirokh & Torabinejad 2010a). Moreover, an investigation reported that white PC with 15% bismuth oxide (similar to white AMTA) showed no genotoxicity or cytotoxicity in murine fibroblast cell culture (Zeferino et al. 2010). In contrast, addition of bismuth oxide to PC powder at all ratios resulted in significantly lower cell viability compared to the control during early evaluation time (Parirokh & Torabinejad 2010a). PC did not affect cell viability or induce expression of osteonectin and dentin sialophosphoprotein mRNAs in human dental pulp cell culture (Min et al. 2007). Both ProRoot MTA- and PC-induced expression of collagen, fibronectin, and transforming growth factor (TGF) β1 in periodontal fibroblast cell culture (Fayazi et al. 2011). However, ProRoot MTA showed significantly higher cell proliferation and migration compared to PC in human bone marrow-derived mesenchymal stem cells (D’Antò et al. 2010). Varying results in cell culture investigations, despite the use of similar materials, might be because of the employment of various cell types, the choice of study duration, use of a fresh or cured material, frequency of changing the medium, the use of direct contact or extract of MTA, and the concentration of the material in the cell culture media (Torabinejad & Parirokh 2010).

Subcutaneous implantation

Subcutaneous implantation of dentin tubes filled with PC promotes mineralization between PC and the dentinal tube. However, PC showed significantly lower biomineralization compared to AMTA mainly after 30 and 60 days (Dreger et al. 2012). Another subcutaneous implantation study showed that both white and gray ProRoot MTA were more biocompatible compared to white and gray PC (Shahi et al. 2010). Subcutaneous implantation of PC showed a similar reaction to AMTA by inducing moderate inflammation at 7 days followed by a reduction in the number of inflammatory cells as well as signs of mineralization by presence of Von Kossa positive structures at longer time intervals (Viola et al. 2012).

In vivo investigations

Animal investigations reported no significant difference between white ProRoot MTA and white PC as pulp capping agents in terms of the calcified bridge thickness over the capping area. However, both materials were significantly superior compared to CH in that regard (Parirokh & Torabinejad 2010b; Al-Hezaimi et al. 2011a). Another investigation used a combination of Emdogain with either white PC or white ProRoot MTA as pulp capping agents. Results showed that there was no significant difference between reparative dentin thicknesses with either of the combinations (Al-Hezaimi et al. 2011b).

Clinical applications

A human investigation using AMTA and PC for pulpotomy in carious primary molars reported successful clinical and radiographic outcomes up to 24 months after treatment. However, more pulp canal obliteration was observed in the teeth that were treated with PC compared to the gray AMTA (Sakai et al. 2009).

Limitations

1. Separate investigations reported scarce results regarding the composition of PC (De-Deus et al. 2009a; Parirokh & Torabinejad 2010a). Since PC is manufactured widely around the world, it is difficult if not impossible to evaluate the purity of all manufacturers’ compositions.
2. PC had higher concentrations of chromium, lead, and arsenic, is acid-soluble, and leaches out in HBSS compared to AMTA (Camilleri et al. 2012). In addition, PC contains higher concentrations of heavy metals such as copper, manganese, and strontium, which are known to be toxic, compared to white ProRoot MTA (Parirokh & Torabinejad 2010a). One of the major concerns about using PC is the amount of lead and arsenic in its composition that are released from the material into the surrounding tissues (Schembri et al. 2010). Because of some reports regarding the high solubility of some types of PC and the release of toxic elements into the surrounding tissues, its long-term safety is questioned (Parirokh & Torabiejad 2010a). In addition, gray PC showed significantly higher lead concentrations than gray and white ProRoot MTA, as well as white PC. Moreover, the amount of cadmium, chromium, copper, manganese, and zinc in gray PC were significantly higher compared to white PC and gray and white ProRoot MTA. Finally, the amount of arsenic in gray and white PC is significantly higher than that in both white and gray ProRoot MTA (Chang et al. 2010).
3. Another concern for PC’s higher solubility is the fact that the material might degrade after one of its clinical applications and therefore jeopardize the seal of the material (Borges et al. 2010; Parirokh & Torabinejad 2010a).
4. Lower compressive strength of some types of PC compared to white and gray MTA might be important for some of the clinical applications of MTA such as repairing perforations and pulp capping because these procedures need materials with sufficient compressive strength during mastication (Parirokh & Torabinejad 2010a).
5. Excessive setting expansion of a material, particularly as a root-end filling substance, might result in a cracked tooth, which is undesirable. The scarcity of results regarding setting expansion of PC is another concern for the use of the material as an MTA substitute for root-end filling (Parirokh & Torabinejad 2010a).
6. Carbonation of PC in inflamed tissue results in lower tensile strength and resiliency of the material, which might cause cracks and buckle under mastication force instead of deforming, particularly in some clinical applications of MTA such as perforation repair or pulp capping (Parirokh & Torabinejad 2010a).
7. MTA as a medical material is manufactured under intensive supervision to ensure its composition and to prevent contamination. The material is approved by the US Food and Drug Administration (FDA) for use in humans (Parirokh & Torabinejad 2010a).
8. PC produces a significantly lower amount of portlandite after setting, compared to white ProRoot MTA, up to 1 year after hydration, which may affect long-term efficacy of the material (Chedella & Berzins 2010).
9. Biomineralization by MTA-based materials is more effective than PC, which is crucial for a biomaterial (Dreger et al. 2012).

In conclusion, despite some similarity in chemical composition and physical properties between white and gray MTA with white and gray PC, there have been several limitations that prevent practitioners from using PC as a substitute for MTA.

ANGELUS MTA

Angelus MTA (MTA-Angelus, Angelus, Londrina, PR, Brazil) was developed in Brazil. Similar to ProRoot MTA (Asgary et al. 2005; Parirokh et al. 2005) the material is marketed in both forms of white and gray AMTA. Unfortunately, most articles do not mention the type of AMTA used; therefore, they are combined as AMTA in this chapter.

Chemical composition

AMTA is composed of 80% PC and 20% bismuth oxide. Compared to gray ProRoot MTA, gray AMTA contains a lower amount of bismuth oxide and magnesium phosphate, but a higher amount of calcium carbonate, calcium silicate, and barium zinc phosphate. Furthermore, AMTA contains less carbon, oxygen, and silica than gray ProRoot MTA, but more calcium. In addition, AMTA showed the presence of aluminum and the absence of iron, in contrast to gray ProRoot MTA, which exhibited the opposite. The amount of bismuth oxide in crystalline structures of gray ProRoot MTA is greater than that in gray AMTA. Based on present available data, AMTA has a different chemical composition compared to gray ProRoot MTA (Parirokh & Torabinejad 2010a). The amount of aluminum oxide in AMTA was reported to be more than twice as high that in white ProRoot MTA (Asgary et al. 2009b).

De-Deus and associates (2009a) have shown that both gray ProRoot MTA and gray AMTA had a below-the-limit amount of arsenic (<2 mg/kg-ISO 9917–1/2007) in their compositions, whereas the white ProRoot MTA (3.3 ± 0.46 ppm) and white AMTA (6.5 ± 0.56 ppm) had a higher than permitted amount of arsenic in their compositions. AMTA and white ProRoot MTA and white PC had similar amounts of metallic ions. The amount of acid-soluble level of arsenic in both white ProRoot MTA and AMTA is higher than the ISO 9917–1/2007 specification. AMTA released significantly less chromium compared to ProRoot MTA in synthetic body fluid. However, the amount of arsenic released in AMTA is significantly higher than that in white ProRoot MTA when the samples are either kept in water or synthetic body fluid (Schembri et al. 2010). Investigations (Monteiro Bramante et al. 2008; Parirokh & Torabinejad 2010a; Schembri et al. 2010; Camilleri et al. 2012) on arsenic and trace elements in the composition of MTA resulted in variations to ISO 9917–1/2007. The method of detecting acid-soluble elements in MTA was different in separate investigations and it may be the reason for reporting different amounts of arsenic and other trace elements in various types of MTA. Despite an acid-extractable arsenic level higher than ISO 9917–1/2007 (Schembri et al. 2010; Camilleri et al. 2012), Camilleri and associates (2012) concluded that AMTA is safe to be used in dentistry.

Physical properties

Some of the physical properties of AMTA, such as setting time and range of particles, are different from those of ProRoot MTA. However, there are similarities in pH and calcium ion release between these materials (Parirokh & Torabinejad 2010a).

Several discoloration reports regarding MTA have used either white or gray AMTA in their case reports, clinical trials, or in vitro investigations (Bortoluzzi et al. 2007; Moore et al. 2011; Ioannidis et al. 2013). Valles and associates (2013) attributed MTA discoloration to the formation of metallic bismuth under light irradiation. Discoloration potential of white and gray AMTA has been investigated (Ioannidis et al. 2013). Results showed that gray AMTA produced significantly greater discoloration compared to white AMTA. Gray AMTA’s discoloration effect was observed after one month, whereas detectable discoloration in white AMTA samples was observed by human eyes after three months. Both types of AMTA reduced lightness, redness, and yellowness in human teeth. A recent in vitro investigation suggested that conditioning coronal dentinal tubules with dentin bonding agents prior to placing either gray or white AMTA as an orifice barrier inside the root canal may prevent future tooth discoloration (Akbari et al. 2012).

Both white and gray AMTA showed an alkaline pH following mixture. However, the latter material showed higher alkalinity up to 168 hours after mixing. The amount of calcium ions released in gray AMTA is higher than that in white AMTA up to 72 hours after mixing (de Vasconcelos et al. 2009). White AMTA showed an alkaline pH, lower calcium ion release, as well as lower initial and final setting time compared to PC (Massi et al. 2011; Hungaro Duarte et al. 2012). The AMTA solubility values meet the requirement of solubility described by ASNI/ADA specification 57/2000 (Borges et al. 2012). However, the material solubility did not fulfill the requirements that are determined by the International Standard Organization 6876/2001 (Parirokh & Torabinejad 2010a).

Microhardness of AMTA could be affected by the method of mixing. The best average of microhardness at 4 days following mixing was obtained for white and gray AMTA when both materials were mixed with ultrasonic vibration. However, at 28 days after mixing, white AMTA that triturated with amalgamator and gray AMTA that mixed with ultrasonic vibration obtained the best average of microhardness (Nekoofar et al. 2010). No temperature rise was observed up to 400 minutes following gray AMTA mixing. The porosity of the gray AMTA is reported to be about 28% and the size of pores was 2.5 µm. The compressive strength of gray AMTA was about 34 MPa after 15 days (Oliveira et al. 2010).

The resistance to displacement of AMTA was significantly higher than that of PC (Reyes-Carmona et al. 2010). In a long-term study, fracture resistance of teeth with immature roots that were filled with AMTA was significantly higher than that of teeth filled with CH after one year. However, no significant difference was found between gray AMTA and ProRoot MTA in that study (Tuna et al. 2011).

Fracture resistance of teeth with immature roots that were filled with gray AMTA was significantly greater than that of teeth filled with CH after 1 year. However, no significant difference was found between AMTA and white ProRoot MTA in the same period of time (Tuna et al. 2011).

According to the manufacturers’ data sheets for AMTA, the absence of dehydrated calcium sulfate lowers the material setting time to 10 minutes. The setting time of AMTA (14.28 ± 0.49 min) is lower than white and gray ProRoot MTA (Parirokh & Torabinejad 2010a).

Results regarding radiopacity of various types of MTA showed that both types of gray and white AMTA have lower radiopacity than white and gray ProRoot MTA. Gray and white forms of AMTA had a higher number of dissimilar particles compared to white and gray ProRoot MTA (Parirokh & Torabinejad 2010a).

Antibacterial activity

AMTA showed some antibacterial and antifungal activities (Parirokh & Torabinejad 2010a). AMTA showed similar antifungal activity as ProRoot MTA. Despite no killing effect on C. albicans after one hour, both of the materials showed fungicidal activity at 24 hours and 48 hours (Kangarlou et al. 2012).

Sealing ability

AMTA showed reasonable sealing ability and marginal adaptation in several investigations (Torabinejad & Parirokh 2010).

Biocompatibility properties

Cell culture studies

White AMTA showed low or no genotoxicity and cytotoxicity in separate investigations on murine fibroblast cell culture, L929 mouse fibroblasts, fibroblasts (3 T3), odontoblast-like cells, and human dermal fibroblast (Gomes-Filho et al. 2009c; Lessa et al. 2010; Zeferino et al. 2010; Damas et al. 2011; Hirschman et al. 2012; Silva et al. 2012). A cell culture study that used L929 mouse fibroblast cells showed that AMTA did not inhibit cell viability or induce interleukin (IL)-6 cytokine (with no significant difference compared to the control). However, AMTA significantly increased the release of IL-1β compared to the control (Gomes-Filho et al. 2009c). Comparing the effects of ProRoot MTA and AMTA on human periodontal fibroblasts, the former showed better biocompatibility (Samara et al. 2011). AMTA showed gelatinolytic activity for matrix metalloproteinase-2 (Silva et al. 2012). Both white ProRoot MTA and AMTA showed similar human dermal fibroblast viability of greater than or equal to 91.8%. (Damas et al. 2011).

Anti-inflammatory effects of gray AMTA have been confirmed by reducing mRNA expression for CC5, IL-1α, and interferon-γ (Parirokh & Torabinejad 2010a). Immune cells produced greater amounts of TGF-β1, IL-1β, macrophage inflammatory protein-2 (MIP-2), and Leukotriene-B4 in the presence of AMTA (Torabinejad & Parirokh 2010).

Subcutaneous implantation

Separate investigations on AMTA subcutaneous implantation showed a moderate inflammatory reaction at seven days that was similar to the control at longer time intervals (30 and 60 days) and subsided in terms of reduced intensity of inflammatory cells. Mineralized structures were seen in close contact with the implanted material at 30 days following the material implantation (Gomes-Filho et al. 2009a, b, 2012; Viola et al. 2012). Biomineralization of AMTA was significantly higher than that of PC (Dreger et al. 2012).

Intraosseous implantation

AMTA produced a mild inflammatory reaction and dystrophic calcification following implantation of the material inside the socket of extracted teeth in rats. In conclusion, AMTA was tolerated well by the rats’ alveolar socket (Gomes-Filho et al. 2010, 2011).

In vivo investigations

Animal investigations using AMTA as pulp capping and root-filling materials reported successful outcomes (Parirokh & Torabinejad 2010b). Perforation repair in rat maxillary molar teeth with AMTA resulted in a significant reduction in the width of periodontal space and osteoclasts’ number at 60 days (da Silva et al. 2011). A histologic investigation on dogs’ teeth showed no significant difference among AMTA, super EBA, and IRM as root-end filling material, although AMTA was the most biocompatible material tested in terms of periapical tissue response (Wälivaara et al. 2012). Another investigation on rats’ avulsed teeth with extended extraoral dry time conditions compared white AMTA and CH as root canal filling materials. Results showed that despite no significant difference between CH and white AMTA, the latter material induced more new bone deposition and less inflammatory tissue reaction after 80 days (Marão et al. 2012).

Clinical applications

Several case reports illustrated successful use of AMTA for repairing resorptive defects, perforations, root-end filling materials, pulp capping, revitalization with triple antibiotics paste, and filling a root canal in a tooth with root fracture (Kvinnsland et al. 2010; Parirokh & Torabinejad 2010b; Yilmaz et al. 2010; dos Santos et al. 2011; Shetty & Xavier 2011; Lenzi & Trope 2012; Vier-Pelisser et al. 2012; Carvalho et al. 2013).

All human investigations that used AMTA as pulp capping agent in caries-free intact teeth showed favorable pulp response (Parirokh & Torabinejad 2010b; Zarrabi et al. 2010).

In a clinical and radiographic investigation on placing either white AMTA or white ProRoot MTA as an apical plug in 22 maxillary incisors, no significant difference was found between two groups up to an average of 23.4 months follow-up time. In this study, four out of five teeth that showed coronal discoloration following treatment were treated with AMTA (Moore et al. 2011).

In conclusion, despite promising reports of using AMTA through several case reports and case series, the limited amount of evidence-based investigations may be of concern to clinicians using the material for various clinical applications that have been tested for MTA.

BIOAGGREGATE (BA)

BioAggregate (BA) also referred to as DiaRoot (DiaDent) BioAggregate (Innovative Bioceramix, Vancouver, BC, Canada) (De-Deus et al. 2009b; Hashem & Wanees Amin 2012) is a material that was introduced for perforation repair, root-end filling, as well as pulp capping.

Chemical composition

The material is composed of fine nanoparticle size, aluminum-free powder that is mixed with deionized water to form a bioceramic paste. BA is composed of a powder (mixed with H₂O) consisting of SiO₂ (13.70%), P₂O₅ (3.92%), CaO (63.50%), and Ta₂O₅ (17%). The manufacturer adds tantalum oxide (Ta₂O₅) to the powder as radiopacifier (Camilleri et al. 2012). In addition, CH was detected in the set form of BA, similar to white ProRoot MTA (Park et al. 2010; Grech et al. 2013). BA has chromium in a similar amount to PC in material composition. In addition, BA has a higher amount of acid-extractable arsenic accepted by ISO 9917–1/2007 (2 mg/kg) and also shows an acceptable amount of lead in its composition. However, the material released negligible amount of trace elements (Camilleri et al. 2012).

Physical properties

BA has an alkaline pH after setting (Zhang et al. 2009a; Grech et al. 2013). BA and white ProRoot MTA showed bioactivity and precipitate apatite crystals when the materials are kept in PBS for up to two months (Shokouhinejad et al. 2012a; Grech et al. 2013). BA showed significantly less resistance to displacement compared to AMTA when the samples were kept in PBS. However, when the samples were exposed to an acidic environment for four days, BA’s push-out bond strength had not been influenced, whereas AMTA’s resistance to displacement significantly decreased. Surprisingly, if the exposed samples to acid kept in PBS for 30 days, the AMTA bond resorted and the samples showed significantly higher push-out bond strength compared to the BA samples in the same storage conditions (Hashem & Wanees Amin 2012). Fracture resistance of teeth with immature roots that were filled with BA was significantly greater than that of the teeth filled with CH after 1 year. However, no significant difference was found between AMTA, ProRoot MTA, and BA for the same period of time (Tuna et al. 2011).

Antibacterial activity

Both ProRoot MTA and BA killed E. faecalis with no significant difference between the materials. Interestingly, the set cement killed bacteria more quickly compared to the freshly mixed materials. Adding dentin powder to the BA cement increased its antibacterial activity (Zhang et al. 2009a).

Sealing ability

BA showed significantly lower dye leakage (El Sayed & Saeed 2012), whereas no significant glucose penetration was observed compared to white ProRoot MTA (Leal et al. 2011).

Biocompatibility

Cell culture studies

Results of a human periodontal ligament (PDL) fibroblast cell culture study reported that both ProRoot MTA and BA were able to differentiate the PDL cells as well as induce alkaline phosphates and collagen I gene expression (Yan et al. 2010). Another investigation on osteoblast cells reported that both materials were nontoxic. However, BA induced a significant increase in the expression of collagen type I, osteocalcin, and osteopontin genes compared to white ProRoot MTA on the second and third day of the study (Yuan et al. 2010). No significant difference regarding cell viability was reported between white ProRoot MTA and BA when they were exposed to human mononuclear cell culture (derived from bone marrow) (De-Deus et al. 2009b).

In conclusion, BA is a material with fine particle size, bioactivity, certain antibacterial properties, and no reported toxicity. However, so far, all investigations on BA have been laboratory studies. One will need to see in vivo and evidence-based investigations to determine the material’s efficacy in clinical applications.

BIODENTINE (BD)

Biodentine (Septodont, Saint-Maur-des-Fosse´s Cedex, France) is a powder/liquid material.

Chemical composition

The powder consists mainly of SiO2 (16.90%), CaO (62.90%), ZrO2 (5.47%), and the liquid is composed of Na (15.8%), Mg (5%), Cl (34.7), Ca (23.6%), and H₂O (20.9%) (Camilleri et al. 2012). The hydration of BD results in calcium silicate hydrate and CH that leach into the surrounding solution (Grech et al. in press). In one investigation, the amount of lead that leached into an acidic environment from BD was higher than that for AMTA, PC, BA, and tricalcium silicate. The amount of released arsenic from BD, however, was the same as that from BA and PC in the same environment. The amount of chromium released from BD in an acidic environment is lower than that from BA and PC. Despite the presence of high lead some investigators have concluded that BD is safe for use in dentistry (Camilleri et al. 2012).

Physical properties

Biodentine has an alkaline pH and is bioactive by releasing calcium ions when stored in HBSS (Grech et al. 2013). When BD is used as a root canal filling material, the amount of calcium and silicate uptake by the root dentin was significantly higher than that of the control and white ProRoot MTA specimens (Han & Okiji 2011). BD showed a significant adverse influence on flexural strength of dentin after two and three months of exposure (Sawyer et al. 2012). Prolonged contact of BD with dentin resulted in biodegradation of the collagen matrix (Leiendecker et al. 2012).

Biocompatibility and clinical applications

In an in vitro investigation, BD, white ProRoot MTA, and CH significantly elevated the secretion of TGFβ1 of the whole pulp following use as pulp capping agents. Moreover, an early form of reparative dentin was observed in the teeth capped with BD (Laurent et al. 2012).

Similar to those for BA, so far, all investigations on BD were conducted in vitro. More investigations, particularly in vivo, are needed to determine its effectiveness in clinical situations.

iROOT

iRoot (Innovative BioCeramix Inc., Vancouver, Canada) has been introduced in three forms: iRoot Sp, iRoot BP, and iRoot BP Plus. These forms have been introduced for use in root filling, root repair (iRoot BP and iRoot BP plus), and root canal sealer (iRoot Sp) materials (http://www.ibioceramix.com/iRootSP.html).

iRoot SP is an injectable, ready-to-use, insoluble, radiopaque white paste that needs moisture to initiate and complete its setting.

Chemical composition

iRoot SP is a calcium silicate aluminum-free-based root canal sealer that has a very similar composition to WMTA (http://www.ibioceramix.com/iRootSP.html). The root canal should not be completely free of moisture when iRoot Sp is used as a root canal sealer (Nagas et al. 2012).

Physical properties

The manufacturer has introduced the material as a root filling material that can be used with or without gutta-percha (Nagas et al. 2012). iRoot SP shows a significantly higher bond to dentin compared to MTA Fillapex and Epiphany (Sağsen et al. 2011; Nagas et al. 2012). The higher bond strength has been attributed to the smaller particle size, level of viscosity, and minimal shrinkage during setting period. The smaller particle size and high level of viscosity increase the flow of the material into the dentinal tubules, other anatomic structures of the root canal space, when gutta-percha is used as the root canal filling material (Shokouhinejad et al. 2013). In a study of three conditions of dry, wet, and slightly moist canal, the latter condition provided the highest bond strength between iRoot SP and the dentinal wall of the root canal space (Nagas et al. 2012). Placement of CH inside the root canal prior to using iRoot SP as a root canal sealer improves its bond strength to dentin (Amin et al. 2012). The results of another study have shown that using iRoot SP with gutta-percha improves resistance to fracture in simulated open apex teeth (Ulusoy et al. 2011). iRoot SP showed an alkaline pH up to 7 days after setting and was capable of killing E. faecalis in an antibacterial investigation (Zhang et al. 2009b).

iRoot BP is an injectable, ready-to-use white paste for root repair and root filling. The manufacturer claims that iRoot BP and iRoot BP Plus are insoluble, radiopaque, do not shrink during setting, and need moisture to set (http://www.ibioceramix.com/products.html). However, the results of a recent investigation showed that iRoot SP was very soluble and did not fulfill ANSI/ADA Specification 57/2000 requirement (Borges et al. 2012). The difference between iRoot BP and iRoot BP Plus is the consistency of the materials. iRoot BP is an injectable premixed paste while iRoot BP Plus is a premixed putty material (http://www.ibioceramix.com/products.html).

Biocompatibility

Results of a cell culture investigation on human osteoblast cells showed that iRoot BP Plus showed significantly lower viability compared to white ProRoot MTA (De-Deus et al. 2012). Another cell culture study on L929 cells showed fresh iRoot Sp had significantly higher toxicity compared to ProRoot MTA in a filter diffusion test, whereas the extracts of both materials were nontoxic (Zhang et al. 2010).

Recently, the manufacturer introduced iRoot FS as the next generation of root canal filling and repair materials with fast setting properties and the same characteristics of calcium silicate-based, aluminum-free materials that are insoluble, radiopaque, do not shrink during setting, and need moisture for setting (http://www.ibioceramix.com/products.html).

In conclusion, iRoot is a bioactive, alkaline material, high toxicity with certain antibacterial properties. However, so far, the material efficacy in clinical procedures has not been investigated.

CALCIUM ENRICHED MIXTURE (CEM) CEMENT

Calcium enriched mixture (CEM) cement (BioniqueDent, Tehran, Iran) is a powder/liquid material.

Chemical composition

CEM cement is composed of CaO (51.81%), SiO2 (6.28%), Al₂O3 (0.95%), MgO (0.23%), SO₃ (9.48%), P₂O₅ (8.52%), Na₂O (0.35%), Cl (0.18%), and H&C (22.2%) (Asgary et al. 2008c). It has been shown that lime is the major component of CEM cement. The concentrations of other constituents in CEM cement are different from those in ProRoot MTA, AMTA, and white and gray PC, except for some trace elements (Asgary et al. 2009b).

Physical properties

CEM cement and white ProRoot MTA have no significant difference in pH (10.61 versus 10.71), working times (4.5 min versus 5 min), or dimensional changes (0.075 versus 0.085 mm). However, there were significant differences between the materials’ setting times, film thickness, and flow (Asgary et al. 2008c). CEM cement produces an alkaline pH and releases calcium in a similar manner to white ProRoot MTA (Asgary et al. 2008c; Amini Ghazvini et al. 2009). In addition, CEM cement releases significantly higher levels of phosphate compared to PC and white ProRoot MTA during the first hour after mixing (Amini Ghazvini et al. 2009). CEM cement radiopacity is reported to be 2.227 mm Al, which is lower than that of ProRoot MTA (5.009 mm Al) and AMTA (5.589 mm Al) (Torabzadeh et al. 2012). CEM cement’s radiopacity did not fulfill the requirement of ANSI/ADA specification number 57/2000 and ISO 6876/2001 each for endodontic sealing materials (3 mm Al). The particle size of CEM cement is between 0.5 to 30 µm (Soheilipour et al. 2009). The percentage of the particle size between 0.5 and 2.5 µm diameter in CEM cement is significantly higher than that in white ProRoot MTA and white PC (Asgary et al. 2011b). The effect of using CH, ProRoot MTA, and CEM cement on flexural strength of bovine root dentin after 30 days showed that all tested materials significantly decreased flexural strength compared to the control. However, there was no significant difference among the tested materials in that regard (Sahebi et al. 2012). Shear bond strength of either CEM cement or ProRoot MTA to composite resin did not improve following acid etching. Therefore, the investigators encourage covering the bioactive materials used for vital pulp therapy such as CEM cement or MTA with resin modified glass ionomer before restoring the teeth with composite resin (Oskoee et al. 2011). Obturating the simulated open apex teeth with either white MTA or CEM cement significantly increases their resistance to fracture after six months. However, no significant difference was found between the materials tested (Milani et al. 2012). Push-out bond strength of CEM cement as root-end filling material was comparable with white ProRoot MTA. Both materials showed higher resistance to displacement when the root-end preparation was performed with ultrasonic tec/>