Radiopacity, pH and antimicrobial activity of Portland cement associated with micro- and nanoparticles of zirconium oxide and niobium oxide

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of zirconium oxide and zinc oxide nanoparticles on physicochemical properties and antibiofilm activity of a calcium silicate-based material

The aim of the present study was to evaluate the antibiofilm activity against Enterococcus faecalis, compressive strength. and radiopacity of Portland cement (PC) added to zirconium oxide (ZrO2), as radiopacifier, with or without nanoparticulated zinc oxide (ZnO).The following experimental materials were evaluated: PC, PC + ZrO2, PC + ZrO2 + ZnO (5%), and PC + ZrO2 + ZnO (10%). Antibiofilm activity was analyzed by using direct contact test (DCT) on Enterococcus faecalis biofilm, for 5 h or 15 h. The analysis was conducted by using the number of colony-forming units (CFU/mL). The compressive strength was performed in a mechanical testing machine. For the radiopacity tests, the specimens were radiographed together with an aluminium stepwedge. The results were submitted to ANOVA and Tukey tests, with level of significance at 5%. The results showed that all materials presented similar antibiofilm activity (

Interference of the assessment method in pH values of an epoxy-based cement

Introduction: Alkalinization potential is a fundamental property of endodontic epoxy-based cements containing calcium hydroxide. Studies have shown discrepant pH results for same materials at different evaluation periods. A possible reason accounting for these differences may be the assessment procedures. Objective: To evaluate the pH value of an epoxy-based cement (Sealer 26) in different periods of analysis, using two assessment methods. Material and methods: Sealer 26 was manipulated and immediately placed into polyethylene tubes (n=10, each group) and immersed in distilled water. In G1, the tubes were kept in the same water during all experiment; and in G2, the tubes were removed and placed into another flask with an equal amount of water after the pH evaluation. The pH of these solutions was measured at 24 hours, 7, 14 and 28 days. Analysis were made within the same group according to the experimental periods and between groups in each experimental period. Data were submitted to ANOVA (α = 5%) and t test, respectively. Results: For G1 and G2, all periods showed different pH values (p < 0.05), except between 14 and 28 days (p > 0.05) and between 7 and 14 days (p > 0.05), respectively. In each period, no significant differences were observed between the groups. Conclusion: The method to obtain the pH values in different experimental periods no interfered in the final results. However, difference was observed when the results were analyzed at same group.

Evaluation of the physicochemical properties and push-out bond strength of mta-based root canal cement

Aim: This study investigated the flowability, setting time, pH, calcium release and bond strength of a MTA-based cement (MTA Fillapex®) compared to AH Plus and Sealapex. Materials and methods: For the flowability test, the ISO 6876:2001 specification was utilized and for the setting time test, the ASTM C266-03 specification was utilized. For the pH and calcium release measurements, 10 samples were prepared for each group and analyzed for several different periods. For the push-out test, dentin disks were distributed into three groups, according to the cement utilized and into three subgroups, according to the root third (n = 10). After obturation, the specimens underwent push-out testing. The data were compared statistically using a significance level of 5%. Results: The flowability of all materials was found to be similar (p > 0.05). The setting times were different among the groups tested (MTA Fillapex < Sealapex < AH Plus) (p < 0.05). At days 7 and 28, the MTA Fillapex presented the higher pH values (p < 0.05). At 24 hours and at 14 days, the calcium release of the MTA Fillapex was similar to that of Sealapex (p > 0.05). AH Plus presented the lowest pH and calcium release values (p < 0.05). In all root thirds, the adhesion to the dentin of the MTA Fillapex and Sealapex were significantly lower than that of AH Plus (p < 0.05). Conclusion: MTA Fillapex and Sealapex presented several similar properties and both were found to be different than AH Plus. Clinical significance: This study evaluated the physicochemical and mechanical properties of new MTA-based root canal cement, in order to use this scaler in root canal fillings. MTA Fillapex showed satisfactory properties for clinical use.

A new calcium silicate-based material (Biodentine) for filling radicular perforation in an endodontic-periodontal lesion: a case report

This case report presents an apical radicular perforation management using new calcium silicate-based cement (Biodentine) in a combined endodontic-periodontal lesion. The presence of apical radicular perforation may interfere in the endodontic treatment prognosis. Radicular perforation filling with bioactive cement through endodontic surgery is a possible treatment. This study presents an apical radicular perforation with periodontal involvement, due to alveolar bone loss on the buccal radicular surface from an incorrect intracanal preparation for the fiber post placing. The chosen alternative was a periapical surgery, the perforation was filled with a silicate and calcium chloride bioactive cement (Biodentine; Septodont, Saint-Maur-des-Fosses Cedex, France), and the radicular surface was etched with citric acid, because the access from root canal was impossible. The follow-up was for 8 months, through clinical and radiographic analysis. At the end of the follow-up, radiographic analyses showed the bone healing, and no clinical changes in periodontal probing depth, gingival recession, and the height of the interproximal mesial and distal papillae were observed. The root perforation treatment has a difficult management, especially when the dental root has a simultaneous periodontal commitment. The Biodentine proves to be a promising material for use in these situations.

Compressive strength and setting time of MTA and portland cement associated with different radiopacifying agents

The aim of this study was to evaluate the compressive strength and setting time of MTA and Portland cement (PC) associated with bismuth oxide (BO), zirconium oxide (ZO), calcium tungstate (CT), and strontium carbonate (SC). Methods. For the compressive strength test, specimens were evaluated in an EMIC DL 2000 apparatus at 0.5 mm/min speed. For evaluation of setting time, each material was analyzed using Gilmore-type needles. The statistical analysis was performed with ANOVA and the Tukey tests, at 5% significance. Results. After 24 hours, the highest values were found for PC and PC + ZO. At 21 days, PC + BO showed the lowest compressive strength among all the groups. The initial setting time was greater for PC. The final setting time was greater for PC and PC + CT, and MTA had the lowest among the evaluated materials (< 0.05). Conclusion. The results showed that all radiopacifying agents tested may potentially be used in association with PC to replace BO.

Ph and antimicrobial activity of portland cement associated with different radiopacifying agents

The aim of this study was to evaluate the antimicrobial activity and pH changes induced by Portland cement (PC) alone and in association with radiopacifiers. Methods. The materials tested were pure PC, PC + bismuth oxide, PC + zirconium oxide, PC + calcium tungstate, and zinc oxide and eugenol cement (ZOE). Antimicrobial activity was evaluated by agar diffusion test using the following strains: Micrococcus luteus, Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans. After 24 hours of incubation at 37°C, inhibition of bacterial growth was observed and measured. For pH analysis, material samples (n=10) were placed in polyethylene tubes and immersed in 10 mL of distilled water. After 12, 24, 48, and 72 hours, the pH of the solutions was determined using a pH meter. Results. All microbial species were inhibited by the cements evaluated. All materials composed of PC with radiopacifying agents promoted pH increase similar to pure Portland cement. ZOE had the lowest pH values throughout all experimental periods. Conclusions. All Portland cement-based materials with the addition of different radiopacifiers (bismuth oxide, calcium tungstate, and zirconium oxide) presented antimicrobial activity and pH similar to pure Portland cement.

Portland cement use in dental root perforations: a long term followup

Root canal and furcal perforations are causes of endodontic therapy failure and different materials that stimulate tissue mineralization have been proposed for perforation treatment. In the first case, a patient presented tooth 46 with unsatisfactory endodontic treatment and a periapical radiographic lesion. A radiolucent area compatible with a perforating internal resorption cavity was found in the mesial root. The granulation tissue was removed, and root canals were prepared. The intracanal medication was composed of calcium hydroxide and the perforation cavity was filled with Portland cement. The 11-year followup showed radiographic repair of the tissue adjacent to the perforation and absence of clinical signs and symptoms or periapical lesion. In the second case, a patient presented with edema on the buccal surface of tooth 46. The examination showed a radiolucent area in the furcation region compatible with an iatrogenic perforation cavity. The mesial root canals were calcified, and only the distal root canal was prepared. The cavity was filled with a calcium hydroxide-based paste and the distal root canal was obturated. In sequence, the perforation cavity was filled with Portland cement. The 9-year followup showed the tooth in masticatory function with radiographic and clinical aspects compatible with normality.

Niobium pentoxide as radiopacifying agent of calcium silicate-based material: evaluation of physicochemical and biological properties

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chemical characterization and bioactivity of epoxy resin and Portland cement-based sealers with niobium and zirconium oxide radiopacifiers

The purpose of this study was to characterize and to evaluate the bioactivity potential of experimental root canal sealers (ES) based on Portland cement, epoxy resin with nano- and micro-particles of niobium or zirconium oxide used as radiopacifiers in comparison to AH Plus and MTA Fillapex. Methods Specimens of the sealers (10 mm in diameter × 1 mm thick) were prepared and the radiopacity was evaluated according to ISO 6876 (2012) specifications. Characterization of the sealers was performed under the scanning electron microscope (SEM) immediately after setting and after immersion for 28 days in Hank's balanced salt solution (HBSS). In addition X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were also performed. The pH and calcium ion release were measured after 1, 7, 14, 21 and 28 days after completion of seating using a digital pH meter and an atomic absorption spectrophotometer, respectively. Results The experimental sealers exhibited an average radiopacity of 2.5 mm thickness of aluminum, which was similar to MTA Fillapex (P > 0.05) and inferior to AH Plus (P < 0.05). AH Plus did not show bioactivity. Although the experimental sealers did not exhibit the formation of hydration product, they encouraged the deposition of crystalline spherical structures of calcium deficient phosphate. The highest pH and calcium release values were observed with the experimental sealers (P < 0.01). ES-Nb-micro was the only sealer to present hexagonal shaped crystal deposition. Significance Novel root canal sealers based on a mixture of Portland cement, epoxy resin and radiopacifier exhibited a degree of bioactivity although no evidence of cement hydration was demonstrated on material characterization. The radiopacifier particle size had limited effect on the sealer microstructure and chemical properties.

Supercritical carbonation treatment on extruded fibre-cement reinforced with vegetable fibres

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Use of high-resolution thermogravimetric analysis (HRTG) technique in spent FCC catalyst/Portland cement pastes

Thermogravimetric analysis is one of the most common instrumental techniques used for the characterization of pastes, mortars and concretes based on both calcium hydroxide and Portland cement. Important information about pozzolanic materials can be assessed concerning calcium hydroxide consumption and the formation of new hydrated products. Nevertheless, in some cases, problems associated with the overlapped decomposition processes for hydrates make the analysis of obtained data difficult. In this paper, the use of high-resolution thermogravimetric analysis, a powerful technique that allows separating decomposition processes in analysis of hydrated binders, was performed for spent FCC catalyst-Portland cement pastes. These pastes were monitored for 1, 4, 8 h and 1, 2, 3, 7 and 28 curing days. In order to study the influence of the pozzolanic material (spent FCC catalyst), Portland cement replacements of 5, 15 and 30 % by mass were carried out. The presence of spent FCC catalyst in blended pastes modified the amount and the nature of the formed hydrates, mainly ettringite and stratlingite.