Microstructural and elemental characterization of novel bioactive glass bioceramic sealer using Fourier transform infrared and X-ray diffraction analysis

Abstract

Introduction:

The success of endodontic therapy is primarily determined by effective root canal obturation and complete bacterial eradication. Recently, bioceramic sealers have gained significant attention in root canal treatments due to their bioactive and biocompatible properties. This study aims to characterize a novel bioactive glass-based bioceramic sealer, utilizing X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy to evaluate its bioactivity and hydroxyapatite-forming potential.

Methodology:

Characterization of the material involved XRD to identify crystalline phases, while FTIR was employed to detect functional groups. The synthesized powder was sieved and pressed into discs for FTIR analysis, with XRD analysis conducted on the sieved powder.

Results:

XRD analysis revealed nanoscale crystalline features, indicating a complex multiphase composition. FTIR identified silicate networks, hydroxyl groups, and carbonate species, supporting the material’s bioactivity and its potential to form hydroxyapatite.

Conclusion:

The bioactive glass-based bioceramic sealer shows strong potential for dental and orthopedic use. Its nanoscale crystalline structure and silicate network enhance bioactivity and mechanical strength, while hydroxyl and carbonate groups promote tissue integration and hydroxyapatite formation. Further in vivo and in vitro studies are needed to confirm its clinical effectiveness.

INTRODUCTION

The success of endodontic treatment relies on the thorough three-dimensional obturation of the root canal system and the complete elimination of bacteria.[1] In addition to meticulous cleaning and shaping of the root canal, the use of appropriate endodontic sealers is crucial for the success of root canal therapy.[2]

Various types of root canal sealers are available that help achieve a hermetic seal within the root canal space.[3] The ideal properties of an endodontic sealer include complete bacterial eradication, the creation of a void-free environment, bioactivity, and osteogenic potential.[4]

While resin-based sealers have been traditionally used, bioceramic sealers are gaining popularity due to their bioactive properties as root canal sealers.[5] Bioceramic sealers are known for their biocompatibility, minimal cytotoxicity, and dimensional stability.[6] Bioactivity is an important property associated with bioceramic materials.[7]

Bioactive glass, first developed in the 1960s, is well recognized for its ability to bond with bone, thereby enhancing its osteogenic potential.[8] Due to these properties, bioactive glass has been extensively utilized in orthopedic surgery. More recently, it has been discovered that bioactive glass can form hydroxyapatite, making it suitable for applications in the oral environment as well.[9] Commercially available products, such as BioRoot RCS and Nishika Bioceramic sealers, incorporate 45S bioactive glass particles to enhance the osteogenic potential of bioceramic sealers.[10] However, the use of 45S bioactive glass is associated with certain limitations, including increased viscosity and reduced working time.[11]

To address these limitations, a novel bioactive glass-based bioceramic sealer has been developed in a powder-liquid system. This new formulation includes 53S bioactive glass particles, along with calcium oxide, silicon oxide, and phosphorus pentoxide. The liquid component consists of calcium chloride dissolved in distilled water to aid in dissolving the powder and forming a cohesive mixture. The characterization of this new bioceramic sealer has been performed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. XRD analysis helps identify the crystalline phases within the powder that are conducive to hydroxyapatite formation, while FTIR is employed to detect the functional groups and chemical bonds in the material, providing insight into its chemical and physiological interactions within the oral environment.[12]

In recent years, the demand for biomaterials that demonstrate not only sealing efficacy but also bioactive and regenerative properties has significantly increased. Bioactive glass-based sealers have emerged as a pivotal innovation in this regard, offering a multifunctional approach to root canal therapy. Unlike traditional materials, which primarily act as passive fillers, bioactive glass-based sealers interact dynamically with their environment to stimulate tissue regeneration and create a robust barrier against microbial infiltration.[13] These materials promote hydroxyapatite formation, which is critical for establishing a chemical bond with dentin and enhancing the long-term success of endodontic treatment.[14] Moreover, the release of calcium and phosphate ions during the setting process contributes to the repair of periapical tissues and fosters an antibacterial environment.[15] However, challenges such as managing the material’s viscosity, ensuring adequate working time, and achieving consistent clinical outcomes still remain.[16] Addressing these issues requires not only advanced material formulations but also a deeper understanding of the structural and functional attributes of these sealers. This study endeavors to bridge these gaps by investigating the novel 53S bioactive glass-based bioceramic sealer, thereby contributing to the growing body of knowledge aimed at enhancing both material performance and clinical application.

This study aims to characterize the new bioactive glass-based bioceramic sealer with BioRoot RCS, a commercially available bioceramic sealer using XRD and FTIR techniques. The analysis of its crystalline structure and chemical composition of both the novel as well as the commercially available product will allow us to assess the bioactive potential, suitability for clinical use, and potential of the novel material to be used on a commercial scale. The findings from this research will contribute to the development of more bioactive and efficient endodontic sealers, ultimately enhancing the effectiveness of root canal therapy and improving patient outcomes.

METHODOLOGY

The study obtained the scientific review board approval with the Application no.: SRB/SDC/ENDO-2303/24/277.

Sample preparation

The preparation of samples for XRD and FTIR spectroscopy was a critical step in accurately characterizing the novel product as well as BioRoot RCS. The novel bioactive glass-based bioceramic sealer consisted of a powder and a liquid. The powder component of the bioactive glass-based sealer was formulated by precisely weighing and homogenizing its constituents. The formulation included 53S bioactive glass particles (30 wt%), calcium silicate (30 wt%), zirconia dioxide (25 wt%), calcium carbonate (10 wt%), and alginic acid powder (5 wt%), which acted as a binder. The dry ingredients were thoroughly mixed using a high-speed mechanical mixer to ensure uniform dispersion and compositional homogeneity.

The liquid component was prepared by dissolving 2.5 g of calcium chloride (CaCl₂) in 50 mL of distilled water. The solution was stirred continuously for 10 min using a magnetic stirrer to obtain a 5% CaCl₂ aqueous solution, which functioned as the setting liquid for the sealer.

Sample preparation for X-ray diffraction analysis

Prior to XRD analysis, the powder and liquid components were mixed in a 1:1 weight ratio, forming a uniform paste. The paste was then transferred into molds and allowed to set at 37°C for 24 h to simulate physiological conditions. Following the setting process, the hardened samples were crushed into a fine powder using a mortar and pestle. The powdered specimens were subsequently dried at 60°C for 24 h to eliminate residual moisture before XRD evaluation.

The XRD process began with the synthesis of the sealer powder using a sol-gel technique. The synthesized powder obtained from both the samples was then dried in an oven at 60°C for 24 h to eliminate any residual solvents and moisture that could interfere with subsequent analyses.[13] This drying step was essential to stabilize the samples and ensure consistency.

After drying, the resultant xerogels obtained needed to be ground into a fine powder to achieve a homogeneous consistency. This grinding process was carried out manually using a mortar and pestle, with careful attention to achieve a uniform particle size. Uniformity in particle size is crucial for producing representative and reproducible data during XRD and FTIR analyses.[14]

Following the grinding process, the two sample powder was sieved through a 45 µm mesh to ensure that only particles of uniform size were selected for further analysis. Sieving enhances the precision of characterization by removing larger, unground particles that could otherwise distort the results.

The sieved powder was then carefully loaded into sample holders for XRD examination. It was important to evenly distribute the powder in a compact layer within the sample holder. An even surface provides better diffraction patterns, allowing for clearer and more accurate data.[15] If the powder is unevenly distributed or loosely packed, X-ray beams may scatter, resulting in lower-quality data. Ensuring a tightly packed sample holder facilitates consistent X-ray interaction with the sample, which is essential for accurate phase identification.

For FTIR analysis, the sieved powder obtained from the two samples was used to prepare thin discs. This was achieved by compressing the powders using a hydraulic press, applying stable pressure to form flat, smooth discs. This step is crucial, as a homogeneous disc surface ensures consistent interaction between infrared light and the sample. Variations in the absorption spectra caused by surface defects on the discs could compromise the precise identification of functional groups and chemical bonds in the sealer.

X-ray diffraction analysis

XRD analysis was conducted using a diffractometer equipped with Cu Kα radiation, where the wavelength (λ) was set at 1.5406 Å. The scanning process covered a range from 10° to 80° 2 θ, with a step size of 0.02° and a count time of 1 s per step. This approach enabled a detailed examination of the crystalline structure of the sealer. The qualitative phase analysis was performed by interpreting the obtained XRD patterns to identify the various crystalline phases present within the sealer material.

Fourier transform infrared spectroscopy analysis

FTIR spectroscopy was carried out using a spectrometer across a wavelength range of 4000–400/cm. Spectral data were collected utilizing an attenuated total reflectance (ATR) accessory, which enhances the accuracy of surface measurements. The resulting FTIR spectra were subsequently analyzed to identify the functional groups and chemical bonds present in the sealer material, providing insights into its chemical composition and potential interactions within the oral environment.

RESULTS

X-ray diffraction analysis-novel bioactive glass-based sealer

The XRD analysis of the sample revealed a total of 25 diffraction peaks, with two prominent high-intensity peaks observed at 28.337° and 28.413°. The XRD pattern of the synthesized bioactive glass-based bioceramic root canal sealer revealed the presence of multiple crystalline phases consistent with its composition.

The diffraction peaks indicate the presence of calcium silicate (Ca₂SiO₄), zirconia (ZrO₂), and calcium carbonate (CaCO₃), along with an amorphous bioactive glass phase. The most intense peak observed at 28.337° is characteristic of calcium silicate (larnite), confirming its dominant crystalline phase. Peaks at 31.747° and 34.171° correspond to tetragonal zirconia (t-ZrO₂), while additional peaks at 28.413° may indicate monoclinic zirconia (m-ZrO₂). The presence of CaCO₃ (calcite) is suggested by peaks at 39.703°, 43.264°, and 45.007°, contributing to the overall mineralogical profile of the material.

The broad diffraction signals at 24.170° and 35.460° suggest the presence of an amorphous phase, likely associated with the bioactive glass component (SiO₂-CaO-P₂O₅). The combination of crystalline and amorphous phases is essential for the material’s bioactivity and sealing properties, ensuring adequate mechanical stability while promoting ion release for biological interaction [Figure 1].

Figure 1.

X-ray diffraction analysis of novel bioactive glass-based bioceramic sealer

Fourier transform infrared spectroscopy analysis-novel bioactive glass-based sealer

The FTIR spectrum of the bioglass powder revealed several distinct peaks corresponding to various functional groups and structural components within the material.

• Hydroxyl groups: A prominent peak at 3641.90/cm indicates the presence of surface-bound hydroxyl groups or adsorbed water. This is typical for bioglass materials due to their high surface area and reactivity, which facilitates the adsorption of moisture or the formation of hydroxyl groups on the surface

• Carbonate species: Peaks observed at 1418.33/cm and 1793.55/cm are indicative of carbonate species within the bioglass. These carbonates may have been introduced during the synthesis or processing stages of the material

• Silicate network: The strong absorption bands at 1001.71/cm and 812.71/cm confirm that the primary component of the bioglass is a silicate network. Additional evidence for this is provided by peaks in the 500–800/cm range, which correspond to various Si–O and Si–O–Si vibrational modes, indicating the presence of silicate linkages

• Structural complexity: The multiple peaks observed in the 500–800/cm region suggest that the bioglass has a complex and possibly heterogeneous structure with diverse silicate linkages. This indicates that the material is not uniformly composed but instead contains a variety of structural motifs within the silicate network [Figure 2].

Figure 2.

Fourier transform infrared peaks of novel bioactive glass-based bioceramic sealer

X-ray diffraction analysis of BioRoot RCS

The XRD analysis for BioRoot RCS provided the following key results based on the peak positions and intensities:

• Major peaks: Significant diffraction peaks are observed at 21.41°, 24.28°, 28.37°, 31.62°, and 45.08°. These peaks correspond to specific crystal planes and indicate the crystalline phases present in the sample

• Strongest peak: The most intense diffraction peak occurs at 28.37°, with a relative intensity of 100%. This suggests that the corresponding phase or crystallographic plane dominates the crystalline structure of the material

• Additional peaks: There are multiple additional peaks ranging between 21.41° and 71.55°, which represent different crystallographic orientations and phases within the BioRoot RCS material [Figure 3].

Figure 3.

X-ray diffraction analysis of BioRoot RCS

Fourier transformed infrared spectroscopy analysis – BioRoot RCS

The FTIR analysis of BioRoot RCS revealed the following peaks:

1. 3400.62/cm: This peak corresponds to O-H stretching vibrations, typically seen in hydroxyl groups (water or alcohols). In endodontic materials, this can indicate the presence of hydrated phases or water content

2. 2888.29/cm: This peak likely corresponds to C-H stretching, indicating the presence of organic components or aliphatic chains

3. 1658.27/cm: This peak is usually attributed to the bending vibration of water molecules (H-O-H), also suggesting water or hydroxyl group presence in the material

4. 1443.90/cm: This may indicate C-H bending vibrations, often found in organic compounds or carbonate groups (CO₃²^–)

5. 1351.83/cm: The peak around this range can be associated with the symmetric stretching of carbonate groups, suggesting the presence of carbonates (e.g., calcium carbonate)

6. 1086.15/cm: A prominent peak here could indicate Si-O stretching vibrations, likely due to silicate-based materials present in bioactive cements or sealers

7. 942.16/cm and 874.90/cm: These may be attributed to phosphate or silicate compounds, often seen in materials like bioactive glasses or cementitious materials

8. 732.16/cm: This peak could correspond to bending vibrations of silicate or aluminosilicate groups

9. 576.66/cm: Typically assigned to Si-O bending or deformation vibrations, reinforcing the presence of silicate phases

10. 515.81/cm: This can also indicate bending vibrations from silicate or phosphate structures [Figure 4].

Figure 4.

Fourier transform infrared analysis of BioRoot RCS

The FTIR spectrum of the sample appears to show characteristic peaks of hydroxyl groups, carbonates, silicates, and possibly phosphate-containing materials. This suggests that the material analyzed could be a bioactive sealer or cement, containing components like calcium silicate, hydroxyl groups, and carbonates, commonly found in root canal sealers or bioactive materials.

DISCUSSION

The characterization and elemental analysis of novel biomaterials for endodontic applications are essential to ensure compliance with rigorous safety standards, bioactivity, and clinical efficacy.[16] The increasing demand for materials that not only meet these criteria but also improve clinical outcomes necessitates innovative approaches in material science. Bioactive glasses have gained prominence in orthopedic applications due to their unique ability to promote osseointegration, which facilitates a direct and stable interface with bone through strong chemical bonds.[17] This inherent property positions bioactive glass as a promising candidate for various dental applications, particularly in bioceramic sealers utilized for root canal treatments

Despite the potential of bioactive glasses, commercially available bioceramic sealers such as BioRoot RCS exhibit significant limitations.[18] Notably, these materials are often hindered by short setting times, which can complicate clinical procedures, and low antimicrobial activity, which is essential for preventing postoperative infections and ensuring the long-term success of endodontic treatments.[19] The study presented here addresses these critical shortcomings by developing a novel bioactive glass-based bioceramic sealer designed to enhance bioactivity, osteogenic capacity, and working time. These improvements are expected to better accommodate clinical requirements, ultimately improving patient outcomes. Research indicates that while initial inflammatory responses are common with endodontic sealers, the progressive reduction observed with materials like calcium hydroxide and by the 28^th day highlights the importance of developing bioactive glass-based bioceramic sealers that prioritize long-term biocompatibility and sustained anti-inflammatory effects.[20]

The application of advanced analytical techniques, such as XRD and FTIR spectroscopy, has yielded valuable insights into the structural and compositional characteristics of the novel sealer. The XRD analysis revealed a high degree of nanoscale crystallinity within the sealer. This feature is advantageous as increased nanoscale crystallinity enhances the surface area-to-volume ratio, thereby improving the material’s interaction with biological tissues.[21] This interaction is pivotal for promoting bioactivity, as effective bonding between the sealer and surrounding tissues is directly linked to the clinical success of root canal treatments.[21,22] The dominant peak observed at 28.337° further suggests the potential for hydroxyapatite formation by the sealer, a crucial event in bone regeneration that underscores the material’s therapeutic capabilities.

In comparison, BioRoot RCS also demonstrated a well-crystallized nature with significant peaks at 21.41°, 28.37°, and 45.08°, indicative of its bioactive properties. However, the novel sealer exhibits superior crystallite distribution, which may result in enhanced clinical performance, including improved integration with bone and stability over time. The intricate relationship between the sealer’s crystallinity and its mechanical properties underscores the importance of optimizing material design to achieve desired clinical outcomes.

The FTIR analysis further complemented the XRD findings by revealing the presence of functional groups such as hydroxyls, carbonates, and silicates in both materials.[23] The novel sealer’s reactive silicate network is integral to its bioactivity, facilitating the formation of hydroxyapatite layers essential for effective bonding with dental tissues.[24] The presence of carbonate species in the new sealer closely resembles that of natural bone mineral, suggesting a greater potential for tissue bonding and regeneration. This similarity not only promotes initial cell attachment but also supports the long-term formation of bone-like tissue, which is critical for the stability and functionality of dental restorations.

The structural integrity of the silicate network is further evidenced by the Si-O and Si-O-Si vibrational modes observed in the FTIR spectrum, which imply substantial mechanical strength capable of withstanding the dynamic forces encountered in the oral cavity. This characteristic is vital for ensuring the durability of the sealer in clinical applications, where mechanical stress can compromise the integrity of the restoration.

One of the most promising aspects of bioactive glass-based bioceramic sealers is their ability to release therapeutic ions, which not only enhance bioactivity but also provide antimicrobial benefits. The ionic dissolution process releases calcium and phosphate ions, which play a critical role in maintaining a favorable pH environment that inhibits bacterial growth and neutralizes acidic by-products of bacterial metabolism.[24,25] This property is particularly significant for endodontic applications, as the root canal environment often serves as a reservoir for persistent microbial activity, contributing to posttreatment failures. In addition, recent studies have shown that the incorporation of trace elements such as zinc and magnesium into bioactive glass compositions further enhances their antimicrobial efficacy and osteogenic potential by stimulating cellular activity and promoting mineralization. These advancements underscore the potential of tailoring the composition of bioactive glass-based sealers to optimize clinical performance for diverse patient populations.

Furthermore, the interaction between bioactive glass-based sealers and surrounding tissues highlights their potential for fostering regenerative endodontics. Unlike conventional sealers that act as passive barriers, bioactive sealers actively participate in the healing process by stimulating cellular responses and promoting tissue repair. Their ability to form a hydroxyapatite layer not only ensures a strong seal but also facilitates the regeneration of periapical tissues, a feature particularly beneficial in cases involving extensive bone loss or periapical pathology. This regenerative capacity positions bioactive glass sealers as potential candidates for more advanced applications in minimally invasive endodontics, offering both functional and esthetic benefits.

An additional significant finding from the study is the in vitro generation of a hydroxycarbonate apatite (HCA) layer within the silicate network of the novel sealer. The formation of this layer indicates not only effective integration with bone but also the promotion of bone regeneration a particularly valuable trait in dental applications where long-term stability and functionality are paramount for treatment success. Similar to the bioactive properties observed in gold nanoparticle-based dental varnishes, the novel bioactive glass-based bioceramic sealer shows promising potential in enhancing mineralization and improving biocompatibility, which could contribute to more effective tissue regeneration in endodontic treatments.[25,26,27]

A key difference between the novel bioactive glass-based sealer and BioRoot RCS is their viscosity and setting time. BioRoot RCS is characterized by its relatively low viscosity, which facilitates ease of handling but may limit its ability to maintain dimensional stability within the root canal.[28] In contrast, the novel sealer has a higher viscosity, improving its adaptability to the canal walls and enhancing its sealing capability. Furthermore, BioRoot RCS sets more quickly, which, while advantageous in clinical settings, may reduce working time and complicate obturation procedures. The novel sealer, however, features a moderately extended setting time, allowing for better manipulation during placement while still achieving optimal final hardness. This controlled setting time may offer an advantage in complex cases requiring precise application and adaptation of the sealer.

In conclusion, the novel bioactive glass-based bioceramic sealer offers significant benefits over traditional sealers like BioRoot RCS, including enhanced bioactivity, superior crystallinity, and improved mechanical properties. These improvements could result in better clinical outcomes when used as a sealer in endodontic treatments, supporting more effective biological integration and tissue regeneration. However, further in vitro and in vivo research is necessary to fully confirm these findings and assess the broader clinical implications of this innovative biomaterial. Exploring the potential applications of the novel sealer in various dental and orthopedic fields could lead to important advancements in patient care and treatment success.

CONCLUSION

The objective of this study was to assess the characterization of a novel bioactive glass-based bioceramic sealer in comparison to BioRoot RCS using XRD and FTIR spectroscopy. XRD analysis exhibited the novel sealer exhibited a high degree of crystallinity with nanoscale crystallites, with a prominent diffraction peak observed at 28.337°. This indicates a multiphase composition and a well-ordered crystalline structure, which is a critical factor for hydroxyapatite formation, thereby suggesting enhanced bioactivity. Likewise, BioRoot RCS displayed significant crystalline peaks at 21.41°, 28.37°, and 45.08°, confirming its well-crystallized nature. FTIR Observations inferred the novel sealer revealed functional groups corresponding to hydroxyl (OH) groups, carbonates, and silicate linkages, indicating the presence of a reactive silicate network, which is crucial for bioactivity. BioRoot RCS similarly exhibited peaks corresponding to OH groups, carbonates, and silicates, confirming its bioactive composition. Both sealers contain key bioactive components, with the novel sealer showing potential enhancements in crystalline arrangement and chemical composition, which may improve its clinical efficacy compared to BioRoot RCS. The findings suggest that the novel sealer possesses greater bioactive and osteogenic potential, making it a promising candidate for commercialization in endodontic therapy.

Limitations and future scope

Despite the promising results, several limitations exist in the study of this novel bioactive glass-based bioceramic sealer. These limitations include the small sample size, reliance on in vitro testing, lack of long-term data, and the potential presence of impurities in the material.

To address these limitations, future research should focus on several key areas. Firstly, conducting extensive in vivo studies will provide a more accurate assessment of the novel sealer’s performance under physiological conditions. Secondly, investigating the long-term stability and bioactivity of the novel sealer is essential to evaluate its durability and sustained effectiveness over time. In addition, refining the formulation and processing methods to minimize contaminants will enhance the quality and reliability of the sealer.

Overall, these steps will ensure a comprehensive evaluation of the bioactive glass-based bioceramic sealer, supporting its potential for clinical use and contributing to improved outcomes in both dental and orthopedic treatments.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Self Funded.