Porosity and sealing ability of root fillings with gutta-percha and BioRoot RCS or AH Plus sealers. Evaluation by three ex vivo methods.

AIM: To investigate the ability of BioRoot RCS, a tricalcium silicate-based root canal sealer and AH Plus to effectively fill the root canals of contralateral teeth using three evaluation methods, and to investigate also the correlation between the methods. METHODOLOGY: The prepared root canals of ten pairs of contralateral mandibular premolar teeth were filled with gutta-percha and sealer using lateral compaction. The percentage of voids within the root canal was assessed by micro-computed tomography, whilst sealing ability was investigated by fluid transport and leakage of fluorescent microspheres. The interaction of sealer with dentine, and sealer penetration were assessed by confocal microscopy. The void volume, fluid flow, microsphere leakage and sealer interaction with dentine for both materials were compared. Nonparametric (Mann-Whitney) tests were used to compare the % void and fluid transport of the two sealers. Spearman correlation was used to assess the pairwise relationships between the techniques. The level of significance was set to 0.05. RESULTS: BioRoot RCS exhibited significantly more percentage of voids than AH Plus. There was no difference in fluid flow and microsphere penetration. BioRoot RCS exhibited a different pattern of sealer penetration and interaction with the dentine walls compared to AH Plus. For both materials, the pairwise correlations between the three techniques were close to zero, indicating weak relationships. CONCLUSIONS: MicroCT analysis revealed a higher void volume for BioRoot RCS. The other techniques did not show a difference between the sealing ability of the sealers. The correlation between the three ex vivo methods of assessment was weak demonstrating their complementarity rather than their concordance.

Investigation of chemical changes in sealers during application of the warm vertical compaction technique.

AIM: To assess (i) heat generated by pluggers during warm vertical compaction of gutta-percha and investigation of temperature changes on the external root surface during canal filling, and (ii) the chemical changes of root canal sealers induced by heat. METHODOLOGY: Four sealers, namely AH Plus, MTA Plus and two other experimental sealers based on tricalcium silicate, were characterised. External temperatures generated on the root surface during warm vertical compaction of gutta-percha with different sealers inside the root canal were monitored using an infrared thermography camera. Chemical changes induced by heating the sealers were assessed by Fourier transform infrared (FT-IR) spectroscopy. RESULTS: MTA Plus and the experimental sealers were composed of a cement and radiopacifier, with epoxy resin or a water-soluble polymer as dispersant, whilst AH Plus was epoxy resin-based. The heat generated at the tips of the continuous wave pluggers was found to be lower than the temperature set and indicated on the device LCD display. The sealers reduced the heat generated on the external root surfaces during the heating phase. AH Plus sustained changes to its chemical structure after exposure to heat, whilst the other sealers were unaffected. CONCLUSIONS: The temperatures recorded at the tips of continuous wave pluggers varied with their taper and were lower than the temperature set on the System B LCD display. Root canal sealers reduced the dissipation of heat generated during warm vertical compaction, with the temperature at the external root surface maintained at 37-41 °C, a temperature below that is necessary to cause irreversible damage to bone and periodontium. The use of AH Plus sealer during warm vertical compaction techniques results in chemical changes in the sealer. The effect on sealer properties needs to be further investigated.

Physicochemical and mechanical properties of zirconium oxide and niobium oxide modified Portland cement-based experimental endodontic sealers.

AIM: To evaluate the physicochemical and mechanical properties of Portland cement-based experimental sealers (ES) with different radiopacifying agents (zirconium oxide and niobium oxide micro- and nanoparticles) in comparison with the following conventional sealers: AH Plus, MTA Fillapex and Sealapex. METHODOLOGY: The materials were tested for setting time, compressive strength, flow, film thickness, radiopacity, solubility, dimensional stability and formaldehyde release. Data were subjected to anova and Tukey tests (P < 0.05). RESULTS: MTA Fillapex had the shortest setting time and lowest compressive strength values (P < 0.05) compared with the other materials. The ES had flow values similar to the conventional materials, but higher film thickness (P < 0.05) and lower radiopacity (P < 0.05). Similarly to AH Plus, the ES were associated with dimensional expansion (P > 0.05) and lower solubility when compared with MTA Fillapex and Sealapex (P < 0.05). None of the endodontic sealers evaluated released formaldehyde after mixing. CONCLUSION: With the exception of radiopacity, the Portland cement-based experimental endodontic sealers presented physicochemical properties according to the specifications no 57 ANSI/ADA (ADA Professional Product Review, 2008) and ISO 6876 (Dentistry - Root Canal Sealing Materials, 2012, British Standards Institution, London, UK). The sealers had setting times and flow ability that was adequate for clinical use, satisfactory compressive strength and low solubility. Additional studies should be carried out with the purpose of decreasing the film thickness and to determine the ideal ratio of radiopacifying agents in Portland cement-based root canal sealers.

Comparison of the apple vinegar with other chelating solutions on smear layer and calcium ions removal from the root canal.

BACKGROUND: The action of endodontic instruments during biomechanical preparation results in smear layer formation. Removing the smear layer enhances disinfection into dentinal tubules in addition to allowing tridimensional sealing of the root canal system. AIM: This study was designed to evaluate the smear layer removal and quantify the calcium ion release resulting from final irrigation with different chelating solutions. MATERIALS AND METHODS: Fifty human canines were instrumented and the final irrigation was performed with apple vinegar, 5% malic acid, 5% acetic acid, 17% ethylenediamine tetra-acetic acid (EDTA), and distilled water (control), which were collected and analyzed by atomic absorption spectrometry to quantify the concentration of calcium ions released. Smear layer removal was assessed in the cervical, middle, and apical thirds by SEM. RESULTS: There was statistically significant difference (P < 0.001) between 17% EDTA and the other solutions with regard to smear layer removal. Apple vinegar, 5% malic acid, and 5% acetic acid promoted similar root canal cleaning. There was no statistical difference among the root canal thirds. The highest concentrations of calcium ions were obtained with 17% EDTA (P<0.001) followed by malic acid, apple vinegar, and acetic acid. Apple vinegar and acetic acid removed the smallest quantity of calcium ions. CONCLUSION: It was concluded that 17% EDTA enabled greater smear layer removal and promoted release of the highest concentrations of calcium ions than the other solutions tested.