Mechanism of action of Bioactive Endodontic Materials

Abstract A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.

Resumo Uma busca contínua de materiais bioativos com capacidade de substituir o tecido pulpar danificado, com efetiva capacidade de selamento e biocompatibilidade, tem representado a atenção e foco de muitos estudos ao longo das últimas décadas. Este estudo envolve uma revisão narrativa da literatura desenvolvida por meio de pesquisas representativas encontradas no PUBMED/MEDLINE e pesquisas em livros didáticos associadas ao mecanismo de ação de materiais bioativos (hidróxido de cálcio, agregado de trióxido mineral (MTA) e cimentos de silicato de cálcio). A presente análise reflexiva das particularidades dos elementos químicos destes materiais bioativos, considerando o mecanismo de ação tecidual e antibacteriano, possibilita um melhor entendimento das características e similaridades no comportamento tecidual. A pasta de hidróxido de cálcio continua sendo a substância antibacteriana de escolha como medicação intracanal para o tratamento das infecções do sistema de canais radiculares. Este fato se deve a disponibilidade química de íons cálcio e hidroxila do hidróxido de cálcio aos tecidos, e a inibição enzimática bacteriana. Os cimentos de silicato de cálcio, dentre os quais inclui o MTA, apresentam uma resposta biológica favorável ao estímulo à deposição de tecido mineralizado nas áreas seladas e em contato com tecido conjuntivo. Este fato é decorrente da similaridade entre os elementos químicos, em especial devido a dissociação iônica, ao potencial estímulo de enzimas teciduais, e a contribuição com um meio alcalino decorrente do pH destes materiais. O comportamento dos materiais bioativos, em especial o MTA e os novos cimentos de silicato de cálcio na atividade de selamento biológico mostraram efetivos. A endodontia contemporânea atualmente conta com o potencial de materiais bioativos com propriedades análogas capaz de estimular o selamento biológico em perfurações radiculares laterais e de furca, em obturações radiculares, capeamento pulpar, pulpotomia, apicificação e procedimentos endodônticos regenerativos, além de outras condições clínicas.

Comparative analysis of bond strength to root dentin and compression of bioceramic cements used in regenerative endodontic procedures.

OBJECTIVES: This study compared the Biodentine, MTA Repair HP, and Bio-C Repair bioceramics in terms of bond strength to dentin, failure mode, and compression. MATERIALS AND METHODS: Fifty-four slices obtained from the cervical third of 18 single-rooted human mandibular premolars were randomly distributed (n = 18). After insertion of the bioceramic materials, the push-out test was performed. The failure mode was analyzed using stereomicroscopy. Another set of cylindrically-shaped bioceramic samples (n = 10) was prepared for compressive strength testing. The normality of data distribution was analyzed using the Shapiro-Wilk test. The Kruskal-Wallis and Friedman tests were used for the push-out test data, while compressive strength was analyzed with analysis of variance and the Tukey test, considering a significance level of 0.05. RESULTS: Biodentine presented a higher median bond strength value (14.79 MPa) than MTA Repair HP (8.84 MPa) and Bio-C Repair (3.48 MPa), with a significant difference only between Biodentine and Bio-C Repair. In the Biodentine group, the most frequent failure mode was mixed (61%), while in the MTA Repair HP and Bio-C Repair groups, it was adhesive (94% and 72%, respectively). Biodentine showed greater resistance to compression (29.59 ± 8.47 MPa) than MTA Repair HP (18.68 ± 7.40 MPa) and Bio-C Repair (19.96 ± 3.96 MPa) (p < 0.05). CONCLUSIONS: Biodentine showed greater compressive strength than MTA Repair HP and Bio-C Repair, and greater bond strength than Bio-C Repair. The most frequent failure mode of Biodentine was mixed, while that of MTA Repair HP and Bio-C Repair was adhesive.

Physicochemical, antimicrobial, and biological properties of White-MTAFlow.

OBJECTIVES: To evaluate a new material containing tantalum oxide as an alternative radiopacifier, and a water-based gel for hydration, in comparison with two calcium silicate-based cement: ProRoot MTA and Biodentine. MATERIALS AND METHODS: ProRoot MTA (Dentsply), Biodentine (Septodont), and a new hydraulic calcium silicate cement White-MTAFlow (Ultradent) (in 'thin' consistency) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The interaction with dentin was also assessed using SEM and EDS. Physical and chemical properties radiopacity, setting time, linear flow, volumetric central filling, and lateral flow, pH, and volume change were investigated together with the color luminosity (L) and color change (ΔE). The agar diffusion and direct contact antimicrobial activity, and methylthiazolyldiphenyl-tetrazolium-bromide (MTT) cytotoxicity using human fibroblast cells were also evaluated. Data were statistically analyzed at a 5% significance level. RESULTS: All materials were composed of tricalcium and dicalcium silicate but had different radiopacifiers, and calcium hydroxide (portlandite) deposition was detected in XRD analysis. White-MTAFlow exhibited radiopacity values in accordance with ISO standard, and the longest setting time. The water-based gel provided the highest linear flow, a comparable cavity central filling, and the highest groove-lateral flow in the volumetric flow analysis. White-MTAFlow exhibited an alkalinity reduction, and Biodentine, a progressive increase of pH values after 28 days. However, similar volume loss for White-MTAFlow was assessed in comparison to Biodentine after the 28-day immersion. White-MTAFlow showed the highest L value (91.5), and ProRoot MTA the lowest (78.1) due to dentin staining caused by bismuth migration. None of the materials exhibited inhibition halos against the tested bacteria, and similar turbidity values were obtained after 48 h in direct contact with E. faecalis, indicating an upregulation to bacterial growth. White-MTAFlow showed MTT cytocompatibility similarly to the control group. CONCLUSIONS: White-MTAFlow in 'thin' consistency presents comparable physicochemical, biological, and antimicrobial properties to ProRoot MTA and Biodentine, and does not cause color alteration in dentin. CLINICAL RELEVANCE: White-MTAFlow is a suitable material for use as reparative endodontic cement. Further studies considering its biocompatibility are necessary.

Physical-mechanical properties of a resin-modified calcium silicate material for pulp capping

Abstract The purpose of this study was to investigate and to compare the physical-mechanical properties of a resin-modified calcium silicate material (TheraCal LC), used for pulp-capping, to MTA (Angelus) and a calcium hydroxide cement (Dycal). Specimens of each material (n=12) were prepared in Teflon molds (3.58 mm x 3 mm) and measured before and after immersion in distilled water for 24 h and 30 days to evaluate the dimensional change. The same specimens were submitted to compressive strength test on a Universal Testing Machine (Instron) (1 mm/min). Root canals were filled with the cements (n=8), and after 24 h, the bond strength (push-out test) to dentin was also assessed on a Universal Testing Machine (1 mm/min). Eight additional specimens of TheraCal LC were prepared to evaluate the bond strength immediately after light curing. Data were analyzed using One-Way ANOVA, and Tukey or Bonferroni post hoc tests (p<0.05). Percentage expansion of TheraCal LC was above the Specification No. 57 of ANSI/ADA, in both periods. The dimensional change for TheraCal LC was higher than MTA in 24 h and 30 days; and Dycal in 30 days (p<0.05). TheraCal LC had higher compressive and bond strength to dentin in comparison with MTA and Dycal (p<0.05). Although TheraCal LC expanded more than the ANSI/ADA recommendation, its compressive and push-out bond strength to dentin were satisfactory and superior to MTA and Dycal.

Resumo O objetivo deste estudo foi investigar e comparar as propriedades físico-mecânicas de um material à base de silicato de cálcio modificado por resina (TheraCal LC) ao MTA (Angelus) e um cimento de hidróxido de cálcio (Dycal). Espécimes de cada material (n=12) foram fabricados em moldes de Teflon (3,58 mm x 3 mm) e medidos antes e após imersão em água destilada por 24 h e 30 dias para avaliar a alteração dimensional. Os mesmos espécimes foram submetidos ao teste de resistência à compressão em uma Máquina Universal de Testes (Instron) (1 mm/min). Canais radiculares foram preenchidos com os cimentos (n=8), e após 24 h, a resistência de união (teste de push-out) também foi avaliada em uma Máquina Universal de Testes (1 mm/min). Oito amostras adicionais de TheraCal LC foram preparadas para avaliar a resistência de união imediatamente após a fotoativação. Os dados foram analisados utilizando os testes ANOVA de 1-fator e Tukey; ou Bonferroni (p<0,05). A expansão percentual do TheraCal LC ficou acima da Especificação No. 57 do ANSI/ADA, em ambos os períodos. Os valores de alteração dimensional para TheraCal LC foram maiores que MTA em 24 h e 30 dias; e Dycal em 30 dias (p<0,05). TheraCal LC apresentou maior resistência à compressão e união à dentina em comparação ao MTA e Dycal (p<0,05). Embora TheraCal LC tenha expandido mais que a recomendação da ANSI/ADA, sua resistência à compressão e de união à dentina foram satisfatórias e superiores ao MTA e Dycal.

Effect of Using Biomimetic Analogs on Dentin Remineralization with Bioactive Cements

Abstract This study evaluated the impact of using biomimetic analogs (poly-acrylic acid and sodium tri-meta-phosphate) on dentin remineralization using two cement materials, the first is calcium silicate based and the second is calcium hydroxide based materials. Two standardized occlusal cavities (mesial and distal) were prepared within dentin after removal of occlusal enamel. Artificial demineralized dentin was induced through pH cycling (8 h in demineralizing and 16 h in remineralizing solutions). Demineralized cavities were divided into four groups; two groups received cement materials. The other groups were first treated with biomimetic analogs then restored with pulp cement materials. Teeth were sectioned buccolingually into two halves. Treated cavities with analogs were stored in simulated body fluid containing poly-acrylic acid. Untreated cavities were stored in simulated body fluid only. Ground unstained sections of demineralized dentin were examined using light microscope. Specimens were examined after 1, 6 and 12 weeks of storage using energy dispersive X-ray Spectroscopy (EDX) and Vickers microhardness was evaluated. Two-way ANOVA was used to analyze data statistically. Calcium silicate-based cement group with biomimetic analogs showed the highest statistically significant calcium and phosphorous wt% in addition to highest surface hardness values after 12 weeks of storage. Demineralized dentin ground sections showed increase in light zones after total period of storage. Calcium silicate-based cement showed the best ability to enrich the artificial carious dentin with ions for remineralization. Using biomimetic analogs had a significant impact on demineralized dentin surface hardness improvement.

Resumo Este estudo avaliou o impacto do uso de análogos biomiméticos (ácido poli-acrílico e tri-meta-fosfato de sódio) na remineralização da dentina usando dois materiais de cimento, o primeiro à base de silicato de cálcio e o segundo à base de hidróxido de cálcio. Duas cavidades oclusais padronizadas (mesial e distal) foram preparadas na dentina após a remoção do esmalte oclusal. A dentina desmineralizada artificial foi induzida por ciclagem de pH (8 h em soluções desmineralizantes e 16 h em soluções remineralizantes). Cavidades desmineralizadas foram divididas em quatro grupos; dois grupos receberam materiais de cimento. Os outros grupos foram tratados primeiro com análogos biomiméticos e depois restaurados com materiais de cimento de celulose. Os dentes foram seccionados bucolingualmente em duas metades. As cavidades tratadas com análogos foram armazenadas em fluido corporal simulado contendo ácido poli-acrílico. As cavidades não tratadas foram armazenadas apenas em fluido corporal simulado. Secções não coradas de dentina desmineralizada foram examinadas usando microscópio óptico. As amostras foram examinadas após 1, 6 e 12 semanas de armazenamento usando Espectroscopia de Raios-X dispersiva por energia (EDX) e microdureza Vickers. ANOVA a dois fatores foi usada para analisar os dados estatisticamente. O grupo de cimento à base de silicato de cálcio com análogos biomiméticos apresentou os maiores percentagens em peso estatisticamente significantes de cálcio e fósforo, além dos maiores valores de dureza superficial após 12 semanas de armazenamento. Seções desmineralizadas de dentina mostraram aumento nas zonas de luz após o período total de armazenamento. O cimento à base de silicato de cálcio mostrou a melhor capacidade de enriquecer a dentina cariada artificial com íons para remineralização. O uso de análogos biomiméticos teve um impacto significativo na melhoria da dureza superficial da dentina desmineralizada.

Influence of ultrasonic agitation on bond strength, marginal adaptation, and tooth discoloration provided by three coronary barrier endodontic materials.

OBJECTIVES: The effect of ultrasonic agitation (UA) on bond strength and adaptation of cervical plugs prepared with MTA Angelus (MTA), MTA Repair HP (MTAHP), and Biodentine (BIO) was evaluated. Dentin discoloration caused by the materials/treatment was also assessed. MATERIALS AND METHODS: Seventy-two single rooted teeth were divided into six groups depending on the materials/treatment. After cervical plug preparation, dentin discs were excised for the push-out test; additional discs were analyzed under the confocal microscope to determine adaptation (gaps occurrence). For dentin discoloration analysis (ΔE), blocks of bovine incisors had cavities prepared and filled with the materials/treatment (from 7 to 180 days). RESULTS: Both bond strength and adaptation were positively influenced by UA (P < 0.05). Comparison between materials showed an advantage for BIO when compared to MTAHP (P < 0.05). The best and worst results were provided by BIO/UA (12.66 MPa and 1.87%) and MTAHP (2.54 MPa and 28.58%), respectively. For ΔE, significant differences were observed throughout the periods. Just the MTA without UA exhibited noticeable discoloration at 180 days (P < 0.05). CONCLUSIONS: UA favored a better adaptation of the materials to the dentin root, resulting in higher bond strength and adaptation of the materials to the root canal walls. Moreover, UA reduced MTA discoloration, keeping it imperceptible over the period evaluated. CLINICAL RELEVANCE: The better adaptation and higher bond strength provided by UA can be considered clinically relevant due to the importance of maintaining blood clot integrity and the possible esthetic compromise provided by reparative materials when used as coronary barrier in regenerative procedures.

Biodentine and MTA modulate immunoinflammatory response favoring bone formation in sealing of furcation perforations in rat molars.

OBJECTIVES: Evaluate the tissue reaction of periodontium subjacent to furcation perforations in rat molars sealed with Biodentine or mineral trioxide aggregate (MTA). MATERIALS AND METHODS: The pulp chamber floor of right upper first molars of 60 rats was perforated and filled with Biodentine, MTA, or cotton pellet (sham); the left first molars were used as control. After 7, 15, 30, and 60 days, maxillary fragments were processed for paraffin-embedding. The periodontal space (PS), volume density of inflammatory cells (VvIC) and fibroblasts (VvFb), number of osteoclasts, and collagen content were obtained. Interleukin-6 (IL-6) and osterix (osteoblast marker) were detected by immunohistochemistry. The data were submitted to ANOVA and Tukey's test (p ≤ 0.05). RESULTS: At 7 days, high values in VvIC, IL-6-immunolabeled cells, and osteoclasts were accompanied by reduced collagen content in enlarged PS of experimental groups. At all periods, VvIC, number of osteoclasts and IL-6, and PS were higher in sham than in Biodentine and MTA (p < 0.0001). From 7 to 60 days, significant reduction in VvIC, IL-6 immunoexpression, and osteoclasts was accompanied by significant increase in VvFb, osteoblasts, and collagen in Biodentine and MTA groups. At 60 days, significant differences in VvIC, PS, IL-6, osteoclasts, and osteoblasts were not found between Biodentine and MTA. Significant differences in the osteoclast number were not observed among Biodentine, MTA, and control groups while osteoblasts number was higher in Biodentine and MTA groups. CONCLUSIONS: Despite the initial inflammatory reaction and bone resorption, the sealing of furcation perforations with Biodentine and MTA favors the repair of periodontal tissues. CLINICAL RELEVANCE: Biodentine and MTA exhibit potential as repair material in the treatment of furcation perforations.

Zirconium oxide and niobium oxide used as radiopacifiers in a calcium silicate-based material stimulate fibroblast proliferation and collagen formation.

AIM: To evaluate the influence of the addition of microparticulate (micro) and nanoparticulate (nano) zirconium oxide (ZrO2 ) and niobium pentoxide (Nb2 O5 ) to a calcium silicate-based cement (CS) on the subcutaneous healing process in rats compared with MTA Angelus™. METHODOLOGY: In each rat, two polyethylene tubes filled with the following materials: (i) MTA; (ii) CS + ZrO2 micro; (iii) CS + ZrO2 nano; (iv) CS + Nb2 O5 micro or (v) CS + Nb2 O5 nano were implanted subcutaneously; empty polyethylene tubes were used in the Control group. After 7, 15, 30 and 60 days, the specimens (n = 5 per group in each period) were fixed and embedded in paraffin. Masson's trichrome sections were used to obtain the volume density of the inflammatory cells (VvIC) and fibroblasts (VvFb). The sections were also stained with Picrosirius-red to calculate the birefringent collagen content. Fibroblast growth factor-1 (FGF-1) was detected by immunohistochemistry, and the number of immunolabelled cells was obtained. The data were subjected to two-way anova followed by Tukey's test (P ≤ 0.05). RESULTS: At all periods, the VvIC was significantly lower (P < 0.001) in all the CS and Control groups than in the MTA group. At all periods, the VvFb was reduced significantly (P = 0.023) in the MTA group in comparison with the other groups. In addition, the number of immunolabelled cells in the capsules of the CS groups was significantly higher (P < 0.001) than in the MTA group at all time-points. CONCLUSIONS: The experimental materials (CS + ZrO2 and CS + Nb2 O5 ) induced fibroblast proliferation and accelerated the regression of the inflammatory reaction. However, the addition of nanoparticulate radiopacifiers did not improve the biological properties of a calcium silicate-based cement when compared to microparticulate agents.

Effect of Silver Nanoparticles on Physicochemical and Antibacterial Properties of Calcium Silicate Cements

Abstract Mineral trioxide aggregate (MTA) and Portland cement (PC) are calcium silicate cements. They have similar physicochemical, mechanical and biological properties. The addition of zirconium oxide (ZrO2) to PC provides radiopacity. Silver nanoparticles (AgNPs) may improve some properties of cements. The aim of this study was to evaluate the effect of AgNPs on physicochemical/mechanical properties and antibacterial activity of white MTA (WMTA) and PC associated with ZrO2. The following materials were evaluated: WMTA; PC 70% + ZrO2 30%; WMTA+ AgNPs; and PC 70% + ZrO2 30% + AgNPs. The study evaluated radiopacity, setting time, pH, compressive strength and solubility. For radiopacity analysis, radiographs were made alongside an aluminum (Al) step wedge. To evaluate the antibacterial activity, direct contact test was performed on planktonic cells and Enterococcus faecalis biofilm induced on bovine root dentin for 14 days. The experimental periods were 5 and 15 h. Data were obtained as CFU mL-1. The obtained data were submitted to ANOVA and Tukey tests (p<0.05). The addition of AgNPs to WMTA increased the pH, lowered the solubility and the initial and final setting times. The addition of AgNPs to PC/ZrO2 maintained the pH, lowered the solubility, and increased the setting time and compressive strength. The radiopacity of all materials was higher than 4 mmAl. The addition of AgNPs promoted an increase in antibacterial activity for calcium silicate cements and favored the physicochemical and mechanical properties of the materials.

Resumo Mineral trióxido agregado (MTA) e cimento Portland (CP) são cimentos à base de silicato de cálcio. Eles apresentam propriedades físico-químicas, mecânica e biológicas semelhantes. A adição de óxido de zircônio (ZrO2) ao CP confere radiopacidade. Nanopartículas de prata (NPsAg) podem melhorar propriedades dos cimentos. O objetivo deste estudo foi avaliar o efeito da NPsAg nas propriedades físico-químicas, mecânicas e na atividade antibacteriana do MTA branco (WMTA) e CP associado ao ZrO2. Os seguintes materiais foram avaliados: WMTA; CP 70% + ZrO2 30%; ; WMTA + NPsAg; CP 70% + ZrO2 30% + NPsAg. Foram avaliados a radiopacidade, tempo de presa, pH, resistência à compressão e solubilidade. Para análise da radiopacidade foram tiradas radiografias ao lado de uma escala de alumínio (Al). Para avaliar a atividade antibacteriana, foi realizado o teste de contato direto sobre células planctônicas e biofilme de Enterococcus faecalis formado em dentina radicular bovina durante 14 dias. Os períodos experimentais foram 5 e 15 h. Os dados foram obtidos como UFC mL-1 e submetidos aos testes de ANOVA e Tukey (p<0,05). A adição de NPsAg ao WMTA elevou o pH, diminuiu a solubilidade e os tempos de presa inicial e final. A adição de NPsAg ao CP/ZrO2 manteve o pH, diminuiu a solubilidade, aumentou o tempo de presa e a resistência à compressão. A radiopacidade de todos os materiais foi maior do que 4 mmAl. A adição de NPsAg promoveu um aumento da atividade antibacteriana dos cimentos à base de silicato de cálcio e favoreceu as propriedades físico-químicas e mecânicas dos materiais.

Sealing ability of two root-end filling materials in a bacterial nutrient leakage model.

AIM: To compare in vitro the sealing ability of root-end fillings with mineral trioxide aggregate (MTA) and EndoSequence BioCeramic Root Repair Material-Fast Set (BC-RRM) Putty using a novel bacterial nutrient leakage model, which provides information on whether or not intracanal bacteria are receiving nutrients from serum via leakage channels. METHODOLOGY: Sixty single-rooted decoronated mandibular incisors with instrumented root canals were subjected to root-end resection and ultrasonic preparation. The root specimens were mounted in the experimental apparatus, and the root-end cavities filled with the test materials. The positive control group used warm Gutta-percha and no sealer. In the negative controls, the entire resected surface was covered with varnish. After sterilization in ethylene oxide, the root canal was inoculated with 1.5 × 10(5) washed cells of Enterococcus faecalis. The apparatus was filled with foetal bovine serum, leaving only the apical root immersed. After 30-day incubation, samples were taken from the canal, cultured and the colony-forming units (CFUs) counted. Statistical analysis was performed using the Mann-Whitney test for quantitative and the Fisher exact test for qualitative data. RESULTS: In the MTA group, 10 of 20 (50%) specimens still had detectable viable bacteria in the canals (mean, 8.97 × 10(3)  CFUs). In the BC-RRM Putty group, 5 of 18 (28%) specimens were positive for bacterial growth (mean, 2.88 × 10(4)  CFUs). There was no significant difference when comparing the quantitative or presence/absence data from the MTA and BC-RRM Putty groups. Positive and negative controls yielded the expected results. CONCLUSIONS: MTA and BC-RRM Putty had similar sealing ability. The experimental model was effective in determining whether or not residual intracanal bacteria could survive by receiving nutrients from outside.

Physicochemical properties of calcium silicate cements associated with microparticulate and nanoparticulate radiopacifiers.

OBJECTIVES: The objective of this paper was to evaluate the physicochemical properties of calcium silicate cements with different chemical compositions, associated with radiopacifying agents. MATERIALS AND METHODS: Mineral trioxide aggregate (MTA) Angelus, calcium silicate cement with additives (CSC), and resinous calcium silicate cement (CSCR) were evaluated, with the addition of the following radiopacifiers: microparticles (micro) or nanoparticles (nano) of zirconium oxide (ZrO(2)), niobium oxide (Nb(2)O(5)), bismuth oxide (Bi(2)O(3)), or calcium tungstate (CaWO(4)). Setting time was evaluated using Gilmore needles. Solubility was determined after immersion in water. The pH and calcium ion release were analyzed after 3, 12, and 24 h and 7, 14, and 21 days. The data obtained were submitted to analysis of variance and Tukey's test, at a level of significance of 5 %. RESULTS: CSC + CaWO(4) and CSCR + ZrO(2) micro, Nb(2)O(5) and CaWO(4) presented results similar to MTA, with a shorter final setting time than the other associations. CSC and CSCR+ ZrO(2) micro presented a higher degree of flow. All the cements evaluated presented low solubility. The materials presented alkaline pH and released calcium ions. CONCLUSIONS: ZrO(2) micro radiopacifier may be considered a potential substitute for Bi(2)O(3) when associated with CSC or CSCR. CLINICAL RELEVANCE: The proposed materials, especially when associated with ZrO(2), are potential materials for use as alternatives to MTA.

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

OBJECTIVES: The physicochemical properties and the tissue reaction promoted by microparticulated or nanoparticulated niobium pentoxide (Nb2O5) added to calcium silicate-based cement (CS), compared to MTA-Angelus™, were evaluated. MATERIALS AND METHODS: Materials were submitted to the tests of radiopacity, setting time, pH, and calcium ion release. Polyethylene tubes filled with the materials were implanted into rats subcutaneously. After 7, 15, 30, and 60 days, the specimens were fixed and embedded in paraffin. Hematoxylin & eosin (H&E)-stained sections were used to compute the number of inflammatory cells (IC). Interleukin-6 (IL-6) detection was performed, and the number of immunolabeled cells was obtained; von Kossa method was also carried out. Data were subjected to ANOVA and Tukey test (p ≤ 0.05). RESULTS: Nb2O5micro and Nb2O5nano provided to the CS radiopacity values (3.52 and 3.75 mm Al, respectively) superior to the minimum recommended. Groups containing Nb2O5 presented initial setting time significantly superior than mineral trioxide aggregate (MTA). All materials presented an alkaline pH and released calcium ions. The number of IC and IL-6 immunolabeled cells in the CS + Nb2O5 groups was significantly reduced in comparison to MTA in all periods. von Kossa-positive structures were observed adjacent to implanted materials in all periods. CONCLUSIONS: The addition of Nb2O5 to the CS resulted in a material biocompatible and with adequate characteristics regarding radiopacity and final setting time and provides an alkaline pH to the environment. Furthermore, the particle size did not significantly affect the physicochemical and biological properties of the calcium silicate-based cement. CLINICAL RELEVANCE: Niobium pentoxide can be used as radiopacifier for the development of calcium silicate-based materials.

Microparticulated and nanoparticulated zirconium oxide added to calcium silicate cement: Evaluation of physicochemical and biological properties.

The physicochemical and biological properties of calcium silicate-based cement (CS) associated to microparticulated (micro) or nanoparticulated (nano) zirconium oxide (ZrO2 ) were compared with CS and bismuth oxide (BO) with CS. The pH, release of calcium ions, radiopacity, setting time, and compression strength of the materials were evaluated. The tissue reaction promoted by these materials in the subcutaneous was also investigated by morphological, immunohistochemical, and quantitative analyses. For this purpose, polyethylene tubes filled with materials were implanted into rat subcutaneous. After 7, 15, 30, and 60 days, the tubes surrounded by capsules were fixed and embedded in paraffin. In the H&E-stained sections, the number of inflammatory cells (ICs) in the capsule was obtained. Moreover, detection of interleukin-6 (IL-6) by immunohistochemistry and number of IL-6 immunolabeled cells were carried out. von Kossa method was also performed. The differences among the groups were subjected to Tukey test (p ≤ 0.05). The solutions containing the materials presented an alkaline pH and released calcium ions. The addition of radiopacifiers increased setting time and radiopacity of CS. A higher compressive strength in the CS + ZrO2 (micro and nano) was found compared with CS + BO. The number of IC and IL-6 positive cells in the materials with ZrO2 was significantly reduced in comparison with CS + BO. von Kossa-positive structures were observed adjacent to implanted materials. The ZrO2 associated to the CS provides satisfactory physicochemical properties and better biological response than BO. Thus, ZrO2 may be a good alternative for use as radiopacifying agent in substitution to BO.

Tridimensional quantitative porosity characterization of three set calcium silicate-based repair cements for endodontic use.

The aim of the this study was to quantitatively evaluate in three-dimensional (3D), the porosity degree of three improved silicate-based endodontic repair cements (iRoot BP Plus®, Biodentine®, and Ceramicrete) compared to a gold-standard calcium silicate bioactive cement (Pro Root® MTA). From each tested cement, four samples were prepared by a single operator following the manufacturer's instructions in terms of proportion, time, and mixing method, using cylindrical plastic split-ring moulds. The moulds were lubricated and the mixed cements were inserted with the aid of a cement spatula. The samples were scanned using a compact micro-CT device (Skyscan 1174, Bruker micro-CT, Kontich, Belgium) and the projection images were reconstructed into cross-sectional slices (NRecon v.1.6.9, Bruker micro-CT). From the stack of images, 3D models were rendered and the porosity parameters of each tested material were obtained after threshold definition by comparison with standard porosity values of Biodentine®. No statistically significant differences in the porosity parameters among the different materials were seen. Regarding total porosity, iRoot BP Plus® showed a higher percentage of total porosity (9.58%), followed by Biodentine® (7.09%), Pro Root® MTA (6.63%), and Ceramicrete (5.91%). Regarding closed porosity, Biodentine® presented a slight increase in these numbers compared to the other sealers. No significant difference in porosity between iRoot BP Plus®, Biodentine®, and Ceramicrete were seen. In addition, no significant difference in porosity between the new calcium silicate-containing repair cements and the gold-standard MTA were found.