**4. Bioactivity**

Bioactive materials can be used to repair diseases or damage to bone tissue and can remain in place indefinitely. An indication of bioactivity is the ability to develop a stable binding with living tissues in contact with simulated body fluid solution [22] via deposition of hydroxyapatite on the surface of a substrate [23].

The bioactivity of endodontic bioceramic materials was confirmed in the Bioaggregate [21], EndoSequence Root Repair Material [21], Pro RootMTA [21], and iRoot SP [24].

After the SCR closure, direct contact between the obturator material and the periapical tissues occurs, such as the periodontal ligament (PDL) and the bone, making a three-dimensional hermetic sealing to prevent recurrent infections of the periapical space, both of endodontic or coronal origin. This seal may be mechanical with materials that provide an airtight seal, but may also be of biological origin. In this case, the filling material induces the formation of hard tissue through the cells of the periodontal ligament, isolating the root canal from the surrounding tissues and stimulating the healing processes of damaged apical tissues [25].

According to Camps et al. [26], tricalcium silicate-based materials have a recognized bioactivity property, that is, the ability to induce hard tissue formation in both the dental pulp in the periapical region. In this regard, interactions of newly developed tricalcium silicate (BioRoot, Septodont, Saint Maur Des Fosses, France)

with apical tissue were compared with a standard zinc oxide-eugenol cement (Pulp Channel Sealer [PCS]; SybronEndo Orange, CA). Cell viability was investigated by direct contact between human periodontal ligament (PDL) cells and BioRoot or PCS. For this, the extracted human incisors were sectioned at the enamel-cement junction; root canals were prepared, sterilized, and filled with lateral condensation with both materials. The root apexes were submerged in the culture medium for 24 h. These conditioned media were used to investigate their effects on human PDL cells. BioRoot had less toxic effects on PDL cells than PCS and induced a higher secretion of angiogenic and osteogenic growth factors than PCS. Given the results of the present study, it is suggested that calcium silicate cement (BioRoot) has a higher bioactivity than zinc oxide eugenol cement (PCS) in human PDL cells.

According to Niu et al. [27], a particularity of tricalcium silicate-based materials is their potential to express bioactivity, which is considered an important property for bone binding capacity. In this sense, Moinzadeh et al. [28] conducted a study to evaluate the interaction of EndoSequence BC RRM (Brasseler USA, Savannah, GA) in contact with simulated blood and tissue fluids, as these materials come into direct contact with the periapical region. These materials are hydrophilic; therefore, its properties improve in the presence of moisture, either from the periodontal ligament or dentinal tubules. However, specific environmental conditions may modify the material configuration. The reaction of tricalcium silicate with tissue fluids led to the formation of calcium hydroxide, and this was evident in the mass in contact with water and Hank's balanced salt solution. In this case, there was also the formation of globular crystals synonymous with hydroxyapatite formation. The material in contact with blood had a non-crystalline surface with additional peaks of calcium, phosphorus, and chlorine. However, in vitro material evaluation may not be representative of the clinical situation, because carbon dioxide present in the bloodstream leads to the formation of calcium carbonate rather than hydroxyapatite reported in in vitro studies.

### **5. Cytotoxicity**

All endodontic treatment will be impaired if the sealing cement is irritating to the tissues of the periapical region, causing larger inflammation or promoting large tissue necrosis, which may lead to reduction in apical repair capacity. Hence, the great importance of knowing the biocompatibility and cytotoxicity of obturator cements [21]. The cytotoxicity of endodontic cements can cause cell degeneration and delay healing due to the direct contact of the cements with the periapical tissues [29]. Cements with satisfactory biocompatibility must have low or no toxicity to the periapical tissues.

When compared to their cytotoxicity, some bioceramic cements exhibit minimal levels of cytotoxicity (EndoSequence Root Repair Material) and Mineral Trioxide Aggregate (MTA) [11]. In a study by Fayyad [30] that compared cytotoxicity, some bioceramic cements exhibited minimal levels of cytotoxicity (EndoSequence Root Repair Material) and Mineral Trioxide Aggregate (MTA) of two materials, BioAggregate and iRoot (Innovative Bioceramix, IBC, Vancouver, Canada) on human fibroblast MRC-5 cells found that both showed acceptable biocompatibility and that the cytotoxic effect of the materials was concentration dependent.

According to Candeiro et al. [12], comparing the characteristics of biodegradable EndoSequence sealer with AH Plus, bioceramic cement presented lower cytotoxicity and was unlikely to damage the genetic information inside a cell compared to AH Plus.

The results involving the biological response of MTA Fillapex (Angelus, Londrina, Brazil) seem to be conflicting. This cement showed high cytotoxicity and

**183**

**7. Color change**

*Bioceramic Cements in Endodontics*

human osteoblast cells [29].

**6. Antimicrobian activity**

*DOI: http://dx.doi.org/10.5772/intechopen.89015*

genotoxicity, shortly after the manipulation. Another study reported that when implanted into subcutaneous tissue in rats for a period of 90 days, it remained toxic [31]. However, another study has shown that despite these initial toxic effects in the early stage the cytotoxicity of Fillapex MTA decreases over time, exhibiting activity adequate to the stimulation of the formation of hydroxyapatite crystals in cultured

some studies have shown that cytotoxicity levels are identical.

eliminating residual microorganisms within the dentinal tubules [33].

According to Damas et al. [2], bioceramic cements have several applications and

Much research has been conducted proving the relationship between microorganisms and periodontitis, as well as the presence of endodontic biofilm in the process of periapical diseases. Thus, during root canal treatment, the main objective is sanitation through chemical-mechanical preparation [32], which may be associated with intra-canal medication, ending with the three-dimensional obturation. As is known, the total eradication of bacteria in all root spaces is not always achieved due to the limitation of the mechanical action of the instruments. Ideally, the obturator materials should have an antimicrobial component to assist in the process of

Bukhari and Karabucak [34] carried out a study to test the antibacterial activity of bioceramic cement compared to AH Plus (Dentsply International Inc., York, PA) in a biofilm composed of 8-week-old *Enterococcus faecalis* adhered to surfaces using a model of dentin infection. The surfaces of the unirradicular intact extracted canals were infected by *E. faecalis* biofilm. Cement AH Plus and EndoSequence BC Sealer (Brasseler USA, Savannah, GA) were placed on the wall of the root canal of the specimens during a period of 24 h and another of 2 weeks in humid conditions at 37°C. Infected samples incubated without shutter cement for similar periods were used as negative controls. In order to test the sealing cements, the specimens were labeled with fluorescence viability staining and confocal laser scanning microscopy to evaluate the proportions of dead and living bacteria in the canal walls during the determined periods. The EndoSequence BC Sealer significantly killed more *E. faecalis* in biofilm bound to channel surfaces when compared to AH Plus and control at both time points (P, 0.05–0.0005). In this sense, they concluded that the EndoSequence BC Sealer exhibited significant antimicrobial ability in the presence of dentin for up to 2 weeks in an 8 week old *E. faecalis* biofilm, compared to the AH Plus cement.

The aim of endodontic interventions is to prevent and treat apical periodontitis. However, the esthetic result is equally important, especially in the anterior region. Pulpal therapy procedures, such as direct pulp capping, repair of perforations, and regenerative endodontics involve the placement of materials in the coronal third of the tooth, which may have potential for discoloration [35]. In this sense, Kohli et al. [36] carried out a study with the objective of evaluating the in vitro tooth discoloration induced by bioceramic materials, EndoSequence RRM and BD in comparison with other materials used during endodontic treatment, such as gray MTA (GMDTA, Dentsply, York, PA, USA). The aim of this study was to evaluate in vitro the biomarker-induced coronal tooth discoloration, EndoSequence RRM and BD, in comparison with other materials used during endodontic treatment, such as gray MTA (GMTA); MTA white (WMTA, Dentsply), triple antibiotic paste

*Bioceramic Cements in Endodontics DOI: http://dx.doi.org/10.5772/intechopen.89015*

*Oral Diseases*

reported in in vitro studies.

**5. Cytotoxicity**

periapical tissues.

with apical tissue were compared with a standard zinc oxide-eugenol cement (Pulp Channel Sealer [PCS]; SybronEndo Orange, CA). Cell viability was investigated by direct contact between human periodontal ligament (PDL) cells and BioRoot or PCS. For this, the extracted human incisors were sectioned at the enamel-cement junction; root canals were prepared, sterilized, and filled with lateral condensation with both materials. The root apexes were submerged in the culture medium for 24 h. These conditioned media were used to investigate their effects on human PDL cells. BioRoot had less toxic effects on PDL cells than PCS and induced a higher secretion of angiogenic and osteogenic growth factors than PCS. Given the results of the present study, it is suggested that calcium silicate cement (BioRoot) has a higher bioactivity than zinc oxide eugenol cement (PCS) in human PDL cells.

According to Niu et al. [27], a particularity of tricalcium silicate-based materials is their potential to express bioactivity, which is considered an important property for bone binding capacity. In this sense, Moinzadeh et al. [28] conducted a study to evaluate the interaction of EndoSequence BC RRM (Brasseler USA, Savannah, GA) in contact with simulated blood and tissue fluids, as these materials come into direct contact with the periapical region. These materials are hydrophilic; therefore, its properties improve in the presence of moisture, either from the periodontal ligament or dentinal tubules. However, specific environmental conditions may modify the material configuration. The reaction of tricalcium silicate with tissue fluids led to the formation of calcium hydroxide, and this was evident in the mass in contact with water and Hank's balanced salt solution. In this case, there was also the formation of globular crystals synonymous with hydroxyapatite formation. The material in contact with blood had a non-crystalline surface with additional peaks of calcium, phosphorus, and chlorine. However, in vitro material evaluation may not be representative of the clinical situation, because carbon dioxide present in the bloodstream leads to the formation of calcium carbonate rather than hydroxyapatite

All endodontic treatment will be impaired if the sealing cement is irritating to the tissues of the periapical region, causing larger inflammation or promoting large tissue necrosis, which may lead to reduction in apical repair capacity. Hence, the great importance of knowing the biocompatibility and cytotoxicity of obturator cements [21]. The cytotoxicity of endodontic cements can cause cell degeneration and delay healing due to the direct contact of the cements with the periapical tissues [29]. Cements with satisfactory biocompatibility must have low or no toxicity to the

When compared to their cytotoxicity, some bioceramic cements exhibit minimal levels of cytotoxicity (EndoSequence Root Repair Material) and Mineral Trioxide Aggregate (MTA) [11]. In a study by Fayyad [30] that compared cytotoxicity, some bioceramic cements exhibited minimal levels of cytotoxicity (EndoSequence Root Repair Material) and Mineral Trioxide Aggregate (MTA) of two materials, BioAggregate and iRoot (Innovative Bioceramix, IBC, Vancouver, Canada) on human fibroblast MRC-5 cells found that both showed acceptable biocompatibility

According to Candeiro et al. [12], comparing the characteristics of biodegradable EndoSequence sealer with AH Plus, bioceramic cement presented lower cytotoxicity and was unlikely to damage the genetic information inside a cell compared to AH Plus. The results involving the biological response of MTA Fillapex (Angelus, Londrina, Brazil) seem to be conflicting. This cement showed high cytotoxicity and

and that the cytotoxic effect of the materials was concentration dependent.

**182**

genotoxicity, shortly after the manipulation. Another study reported that when implanted into subcutaneous tissue in rats for a period of 90 days, it remained toxic [31]. However, another study has shown that despite these initial toxic effects in the early stage the cytotoxicity of Fillapex MTA decreases over time, exhibiting activity adequate to the stimulation of the formation of hydroxyapatite crystals in cultured human osteoblast cells [29].

According to Damas et al. [2], bioceramic cements have several applications and some studies have shown that cytotoxicity levels are identical.

#### **6. Antimicrobian activity**

Much research has been conducted proving the relationship between microorganisms and periodontitis, as well as the presence of endodontic biofilm in the process of periapical diseases. Thus, during root canal treatment, the main objective is sanitation through chemical-mechanical preparation [32], which may be associated with intra-canal medication, ending with the three-dimensional obturation. As is known, the total eradication of bacteria in all root spaces is not always achieved due to the limitation of the mechanical action of the instruments. Ideally, the obturator materials should have an antimicrobial component to assist in the process of eliminating residual microorganisms within the dentinal tubules [33].

Bukhari and Karabucak [34] carried out a study to test the antibacterial activity of bioceramic cement compared to AH Plus (Dentsply International Inc., York, PA) in a biofilm composed of 8-week-old *Enterococcus faecalis* adhered to surfaces using a model of dentin infection. The surfaces of the unirradicular intact extracted canals were infected by *E. faecalis* biofilm. Cement AH Plus and EndoSequence BC Sealer (Brasseler USA, Savannah, GA) were placed on the wall of the root canal of the specimens during a period of 24 h and another of 2 weeks in humid conditions at 37°C. Infected samples incubated without shutter cement for similar periods were used as negative controls. In order to test the sealing cements, the specimens were labeled with fluorescence viability staining and confocal laser scanning microscopy to evaluate the proportions of dead and living bacteria in the canal walls during the determined periods. The EndoSequence BC Sealer significantly killed more *E. faecalis* in biofilm bound to channel surfaces when compared to AH Plus and control at both time points (P, 0.05–0.0005). In this sense, they concluded that the EndoSequence BC Sealer exhibited significant antimicrobial ability in the presence of dentin for up to 2 weeks in an 8 week old *E. faecalis* biofilm, compared to the AH Plus cement.

#### **7. Color change**

The aim of endodontic interventions is to prevent and treat apical periodontitis. However, the esthetic result is equally important, especially in the anterior region. Pulpal therapy procedures, such as direct pulp capping, repair of perforations, and regenerative endodontics involve the placement of materials in the coronal third of the tooth, which may have potential for discoloration [35]. In this sense, Kohli et al. [36] carried out a study with the objective of evaluating the in vitro tooth discoloration induced by bioceramic materials, EndoSequence RRM and BD in comparison with other materials used during endodontic treatment, such as gray MTA (GMDTA, Dentsply, York, PA, USA). The aim of this study was to evaluate in vitro the biomarker-induced coronal tooth discoloration, EndoSequence RRM and BD, in comparison with other materials used during endodontic treatment, such as gray MTA (GMTA); MTA white (WMTA, Dentsply), triple antibiotic paste

(TAP), and AH Plus sealant (AH+, Dentsply). Visual discoloration was observed in all specimens in the GMTA, WMTA, and TAP groups over 7 days, which increased over time. Significant coronary tooth discoloration was caused by TAP, GMTA, and WMTA, but not by BD, RRM or RRMF at the end of the experiment.

Discoloration of the crown such as the one present in the MTA is one of the disadvantages of restorative cement used in dentistry. This has to be taken into account when repairing furcation injuries or in cases where pulp protection is required. According to the literature, the bismuth oxide present in the MTA composition reacts with the residual sodium hypochlorite that remains inside the dentinal tubules after mechanical chemical preparation, resulting in dark precipitations and staining of the tooth. In the composition of the EndoSequence, the zirconia oxide is the opacifier used, preventing the unwanted darkening [37].

According to Kholi et al. [36], the bio-based materials Biodentine (Septodont, Saint-Maur-des-Fosses, France), ERRM, EndoSequence, ERRM putty (Brasseler, Savannah, GA), RMF, EndoSequence ERRM fast set paste (Brasseler), and AH+, AH Plus sealer (Dentsply), when left in the pulp chamber for periods of up to 6 months do not induce color change in the tooth structure. Alsubait et al. [37] compared the potential for discoloration of the Endosequence Bioceramic Root Repair Material Fast Putty Set (ERRM) and ProRootMTA (PMTA) by placing them on the crown of extracted human teeth for a period of 4 months and found progressive discoloration in teeth when treated with PMTA, whereas those with ERRM had no change in color stability.

## **8. Mechanism of action**

The bioceramic cement is hydrophilic; therefore, it uses water present in the dentin tubules to initiate the firming reaction. The hydration of the material decreases the working time, consequently the amount of water mixed can reduce the time required; but the bioceramics only harden when present in a humid environment. After hydration, the calcium silicate gel and the calcium hydroxide are produced by the calcium silicate present in the mixture. Calcium hydroxide reacts with phosphate ions and produces hydroxyapatite and water. The continuous interaction of calcium silicate and water leads to the formation of hydrated calcium silicate [38]. The amount of water in the reaction is a critical factor in controlling the rate of hydration. The pH is similar when compared to the reaction time of calcium hydroxide. As this is highly alkaline, it reaches a value of 12.8 during the placement time, decreasing progressively over a period of 1 week [2]. The pH is affected by the release of calcium ions and by alkalinizing the medium, a condition that can influence the repair, besides promoting the mineralization process and its concentration. The release of hydroxyl ions can alter the dissociation [12].

Candeiro et al. [12] carried out a study with the purpose of evaluating the physicochemical properties of a bioceramic. Radiopacity, pH, calcium ion release, and flowability were studied and compared with AH Plus® cement (resin-based cement). The radiopacity and flow were evaluated by using ISO 6876/2001 standards. For the analysis of the radiopacity, metal discs with 10 mm diameter and 1 mm thickness were used and were covered with sealer cement. The flowability test was performed with 0.005 ml of cement on a glass plate. The release of calcium ions and pH were evaluated in periods of 3, 24, 72, 180, and 240 h with a spectrometer and pH meter, respectively. Radiopacity was then found to be significantly lower than AH Plus®, pH analysis, and calcium ion release were significantly higher than AH Plus®, and it was demonstrated that there were no significant differences in

**185**

*Bioceramic Cements in Endodontics*

*DOI: http://dx.doi.org/10.5772/intechopen.89015*

very favorable values for a sealant cement.

(BC-RRM) showed similar sealing ability.

adaptation in this region [19, 40, 41].

**10. Resistance of union**

**9. Marginal adaptation/sealing capacity**

flowability. Thus, the bioceramics present values of radiopacity and fluidity within the limits of ISO standards and the other physicochemical properties analyzed show

According to Shokouhinejad et al. [39], the marginal adaptation of the EndoSequence Root Repair Material (ERRM) was similar to that of the MTA. However, bioceramic-based cements when compared with resin-based cements (AH PLUS) exhibited more regions containing gaps. Bioceramic endodontic cements also showed infiltration results similar to MTA. In relation to sealing and its ability, the Bioceramic Root-end Repair (BCRR) is equivalent to the MTA [13]. Antunes et al. [14] reported that MTA and BioCeramic Root Repair Material

To what concerns bioceramics and the hydration of the material during the setting process, the formation of hydroxyapatite crystals occurs between the surface of the material and the dentin wall, which can provide adequate sealing and marginal

The ability of a root canal sealer to adhere intra-radicular dentin through micromechanical retention or resistance to friction is advantageous in maintaining the integrity of the sealant interface and dentin during mechanical stresses caused by flexion of the teeth, surgical procedures or preparation of the space for intra radicular retainers [42]. It has been shown that the release of calcium and hydroxyl ions from calcium silicate-containing material results in the formation of a layer of hydroxyapatite when it comes in contact with the fluids of the dentinal tubules. The formation of this interfacial layer develops a chemical bond between calcium and dentin walls [43]. Therefore, it is expected that the bioceramic cements, which are based on a calcium silicate composition, have the potential to chemically adhere to the dentin. Shokouhinejad et al. [44] conducted an investigation to compare the bond strength of bioceramic (EndoSequence BC Sealer) and resin cement AH Plus in the presence and absence of smear layer. Uniradicular ex vivo specimens were used in this experiment using 5.25% sodium hypochlorite and 17% EDTA protocols for smear layer removal and in the other specimens no debris removal protocol, only 5.25% sodium hypochlorite irrigation. The modes of adhesion strength and failure were evaluated. No statistically significant differences were found between the groups filled with gutta percha and AH Plus sealant and gutta percha and bioceramic sealant. The presence or absence of smear layer does not appear to signifi-

Antunes et al. [14] evaluated the sealing capacity of MTA cement and EndoSequence BC RRM-Fast Set Putty in an ex vivo study, in roots of 60 instrumented lower central incisors, which were sectioned in the apical region and ultrasonic tip retroinstruments, and using a new model of bacterial nutrient infiltration. Retrograde obturation was performed with the MTA and BC-RRM Putty in two sets of teeth. In the MTA group, 50% of viable species were detected while in the Putty BC-RRM group, 28% of the samples were positive for cultured bacteria. However, in the comparison analysis of the quantitative or presence/absence of bacteria, no significant difference was identified between the groups, leading the authors to

conclude that the cements studied have similar sealing capacity.

cantly affect the bond strength of filler materials.

*Oral Diseases*

no change in color stability.

**8. Mechanism of action**

dissociation [12].

(TAP), and AH Plus sealant (AH+, Dentsply). Visual discoloration was observed in all specimens in the GMTA, WMTA, and TAP groups over 7 days, which increased over time. Significant coronary tooth discoloration was caused by TAP, GMTA, and

Discoloration of the crown such as the one present in the MTA is one of the disadvantages of restorative cement used in dentistry. This has to be taken into account when repairing furcation injuries or in cases where pulp protection is required. According to the literature, the bismuth oxide present in the MTA composition reacts with the residual sodium hypochlorite that remains inside the dentinal tubules after mechanical chemical preparation, resulting in dark precipitations and staining of the tooth. In the composition of the EndoSequence, the zirconia oxide is

According to Kholi et al. [36], the bio-based materials Biodentine (Septodont, Saint-Maur-des-Fosses, France), ERRM, EndoSequence, ERRM putty (Brasseler, Savannah, GA), RMF, EndoSequence ERRM fast set paste (Brasseler), and AH+, AH Plus sealer (Dentsply), when left in the pulp chamber for periods of up to 6 months do not induce color change in the tooth structure. Alsubait et al. [37] compared the potential for discoloration of the Endosequence Bioceramic Root Repair Material Fast Putty Set (ERRM) and ProRootMTA (PMTA) by placing them on the crown of extracted human teeth for a period of 4 months and found progressive discoloration in teeth when treated with PMTA, whereas those with ERRM had

The bioceramic cement is hydrophilic; therefore, it uses water present in the dentin tubules to initiate the firming reaction. The hydration of the material decreases the working time, consequently the amount of water mixed can reduce the time required; but the bioceramics only harden when present in a humid environment. After hydration, the calcium silicate gel and the calcium hydroxide are produced by the calcium silicate present in the mixture. Calcium hydroxide reacts with phosphate ions and produces hydroxyapatite and water. The continuous interaction of calcium silicate and water leads to the formation of hydrated calcium silicate [38]. The amount of water in the reaction is a critical factor in controlling the rate of hydration. The pH is similar when compared to the reaction time of calcium hydroxide. As this is highly alkaline, it reaches a value of 12.8 during the placement time, decreasing progressively over a period of 1 week [2]. The pH is affected by the release of calcium ions and by alkalinizing the medium, a condition that can influence the repair, besides promoting the mineralization process and its concentration. The release of hydroxyl ions can alter the

Candeiro et al. [12] carried out a study with the purpose of evaluating the physicochemical properties of a bioceramic. Radiopacity, pH, calcium ion release, and flowability were studied and compared with AH Plus® cement (resin-based cement). The radiopacity and flow were evaluated by using ISO 6876/2001 standards. For the analysis of the radiopacity, metal discs with 10 mm diameter and 1 mm thickness were used and were covered with sealer cement. The flowability test was performed with 0.005 ml of cement on a glass plate. The release of calcium ions and pH were evaluated in periods of 3, 24, 72, 180, and 240 h with a spectrometer and pH meter, respectively. Radiopacity was then found to be significantly lower than AH Plus®, pH analysis, and calcium ion release were significantly higher than AH Plus®, and it was demonstrated that there were no significant differences in

WMTA, but not by BD, RRM or RRMF at the end of the experiment.

the opacifier used, preventing the unwanted darkening [37].

**184**

flowability. Thus, the bioceramics present values of radiopacity and fluidity within the limits of ISO standards and the other physicochemical properties analyzed show very favorable values for a sealant cement.
