Impact of Immersion Media on Physical Properties and Bioactivity of Epoxy Resin-Based and Bioceramic Endodontic Sealers

Calcium Silicate-Based Sealers: Apatite Deposition on Root Canal Dentin and pH Variation Analysis

OBJECTIVE

 This study analyzes the biomineralization potential of calcium silicate-based sealers Ceraseal (Meta Biomed Co., Cheongju, Korea) and AH Plus Bioceramic (Dentsply Sirona, United States), focusing on evaluating apatite deposition in root canal dentin and pH increases.

MATERIALS AND METHODS

 Calcium silicate-based sealers Ceraseal (Meta Biomed Co.) and AH Plus Bioceramic (Dentsply Sirona) were applied to the root canal dentin of premolars that had undergone root canal preparation procedures. This was followed by a 14-day immersion in phosphate-buffered saline (PBS). Biomineralization analysis was performed by analyzing the formation of the apatite layer after the 14-day immersion. The thickness of the apatite layer deposits was observed using a scanning electron microscope (SEM). Additionally, the sealers were placed in molds and submerged in PBS solution with pH measurements taken on days 0, 7, and 14 using a digital pH meter.

STATISTICAL ANALYSIS

 The average thickness of apatite deposition in the interfacial layer was analyzed using the Mann-Whitney's test. The pH value differences among the groups were analyzed using a one-way analysis of variance test, followed by a post hoc least significant difference.

RESULTS

 There were differences in the apatite deposition in the interfacial layer between Ceraseal and AH Plus Bioceramic within 14 days of observation. There was a significant difference (p < 0.05) between the pH values of Ceraseal and AH Plus Bioceramic at 7 and 14 days of observation. Ceraseal showed greater alkalizing activity compared with AH Plus Bioceramic.

CONCLUSION

 Calcium silicate-based sealer Ceraseal showed better biomineralization potential than AH Plus Bioceramic.

Interfacial adaptation of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer

Background

The sealer's interfacial adaptability is one of the critical factors for successful root canal therapy. This study evaluated and compared the interfacial adaptability of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer (C3 S-BG-P) to root dentin with two bioactive sealers Nishika Canal Sealer BG and BioRootTM RCS.

Methods

Thirty newly extracted single-rooted lower premolars were decoronated and instrumented. The roots were assigned to three groups: C3 S-BG-P, Nishika Canal Sealer BG, and BioRootTM RCS (n=10) and obturated with the single-cone method. Each root was sectioned horizontally to obtain three slices at 2, 5, and 10 mm from the apex. The width of the gaps at the sealer‒dentin interface from each section's mesial and distal sides was measured under a field emission scanning electron microscope (FESEM) at×1.0 using the Digimizer software program. One-way ANOVA and post hoc Tukey tests for multiple comparisons were used to interpret and analyze the collected data.

Results

The mean gap width at the sealer‒dentin interface of C3 S-BG-P and Nishika Canal Sealer BG was significantly less than that of BioRootTM RCS at all root sections (P≤0.05). However, the mean gap width at the sealer‒dentin interface of C3 S-BG-P was not significantly different from Nishika Canal Sealer BG (P>0.05). Moreover, there were greater interfacial gaps at the apical level than at the coronal level for all the tested sealers.

Conclusion

C3 S-BG-P exhibited interfacial adaptation that was nearly comparable to Nishika Canal Sealer BG and superior to BioRootTM RCS.

Nanoleakage of apical sealing using a calcium silicate-based sealer according to canal drying methods

Objectives

This study investigated the nanoleakage of root canal obturations using calcium silicate-based sealer according to different drying methods.

Materials and Methods

Fifty-two extracted mandibular premolars with a single root canal and straight root were selected for this study. After canal preparation with a nickel-titanium rotary file system, the specimens were randomly divided into 4 groups according to canal drying methods (1: complete drying, 2: blot drying/distilled water, 3: blot drying/NaOCl, 4: aspiration only). The root canals were obturated using a single-cone filling technique with a calcium silicate-based sealer. Nanoleakage was evaluated using a nanoflow device after 24 hours, 1 week, and 1 month. Data were collected twice per second at the nanoscale and measured in nanoliters per second. Data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U-tests (p < 0.05).

Results

The mean flow rate measured after 24 hours showed the highest value among the time periods in all groups. However, the difference in the flow rate between 1 week and 1 month was not significant. The mean flow rate of the complete drying group was the highest at all time points. After 1 month, the mean flow rate in the blot drying group and the aspiration group was not significantly different.

Conclusions

Within the limitations of this study, the canal drying method had a significant effect on leakage and sealing ability in root canal obturations using a calcium silicate-based sealer. Thus, a proper drying procedure is critical in endodontic treatment.

Physical-chemical properties and acellular bioactivity of newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer

OBJECTIVES

To evaluate the physiochemical properties and apatite-forming ability of a newly prepared nano-tricalcium silicate-58s bioactive glass-based endodontic sealer (C3S-BG-P) and compare its results with the Nishika BG canal sealer and BioRoot™ RCS.

METHODS

The physicochemical properties (setting time, flow, solubility, film thickness, and radiopacity) of C3S-BG-P, Nishika BG canal sealer, and BioRoot™ RCS were evaluated in accordance with ANSI/ADA 57/2000 (reaffirmed 2012) and ISO 6876:2012 for root canal sealing materials. The in vitro apatite-forming ability was evaluated after 28 days of immersion of disc-shaped specimens in phosphate-buffered saline (PBS) using field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy.

RESULTS

The results of physiochemical tests indicated that all the tested sealers complied with the ADA and ISO standards; however, the solubility of the BioRoot did not meet the two standards. C3S-BG-P revealed significantly superior properties in all physicochemical tests compared to Nishika and BioRoot; however, the solubility of Nishika was significantly lower than that of C3S-BG-P. Furthermore, all tested sealers exhibited apatite precipitation on their surfaces after 28 days of immersion in PBS.

CONCLUSIONS

C3S-BG-P had superior physicochemical properties, which mitigated the disadvantages of calcium silicate-based sealers. Moreover, it exhibited apatite precipitation after immersion in PBS. Further in vivo studies utilizing animal models or clinical studies are necessary to support the rationale of the newly developed sealer for clinical application.

Characterisation of the Bioactivity and the Solubility of a New Root Canal Sealer

OBJECTIVES

This study aimed to analyse the effect of using phosphate buffer solution (PBS) on the solubility, pH changes, surface structure, and elemental composition of a new bioceramic Cerafill sealer compared with Endosequence sealer and AH26 resin-based sealer.

METHODS

A fresh mixture of each sealer moistened with either deionised water or PBS was subjected to a setting time test. Set discs (n = 10) were submerged in either deionised water or PBS to evaluate pH changes and solubility at 1, 7, 14, 21, and 28 days. Surface characterisation of the sealers was done before and after solubility tests using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy analyses.

RESULTS

An analysis of variance revealed a significant delay in setting of BC-Endosequence (P < .001) with no significant difference when each sealer was moistened with deionised water or PBS (P > .05). Both bioceramic sealers exhibited highly alkaline pH (range, 9.47-10.72). When the sealer was submerged in deionised water, Endosequence exhibited significantly greater solubility, whilst Cerafill and AH26 gained weight. When the sealers were submerged in PBS, both bioceramic sealers gained more weight, with significantly greater values for Endosequence (P < .001). Hydroxyapatite formation was revealed by SEM/EDX and FTIR.

CONCLUSIONS

PBS promoted the formation of hydroxyapatite crystals that protect the bioceramic sealers from dissolving.

Gafchromic™ EBT3 Film Measurements of Dose Enhancement Effects by Metallic Nanoparticles for 192Ir Brachytherapy, Proton, Photon and Electron Radiotherapy

Interest in combining metallic nanoparticles, such as iron (SPIONs), gold (AuNPs) and bismuth oxide (BiONPs), with radiotherapy has increased due to the promising therapeutic advantages. While the underlying physical mechanisms of NP-enhanced radiotherapy have been extensively explored, only a few research works were motivated to quantify its contribution in an experimental dosimetry setting. This work aims to explore the feasibility of radiochromic films to measure the physical dose enhancement (DE) caused by the release of secondary electrons and photons during NP–radiotherapy interactions. A 10 mM each of SPIONs, AuNPs or BiONPs was loaded into zipper bags packed with GAFCHROMIC™ EBT3 films. The samples were exposed to a single radiation dose of 4.0 Gy with clinically relevant beams. Scanning was conducted using a flatbed scanner in red-component analysis for optimum sensitivity. Experimental dose enhancement factors (DEFExperimental) were then calculated using the ratio of absorbed doses (with/without NPs) converted from the films’ calibration curves. DEFExperimental for all NPs showed no significant physical DE beyond the uncertainty limits (p > 0.05). These results suggest that SPIONs, AuNPs and BiONPs might potentially enhance the dose in these clinical beams. However, changes in NPs concentration, as well as dosimeter sensitivity, are important to produce observable impact.