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.

From hazardous asbestos containing wastes (ACW) to new secondary raw material through a new sustainable inertization process: A multimethodological mineralogical study.

Nowadays, asbestos-containing wastes (ACW) still represent an important environmental problem and a severe health hazard due to the well known pulmonary diseases derived from asbestos fibers inhalation. Except for a very few cases, ACW are currently confined in controlled landfills, giving rise to increasingly high amounts of still hazardous wastes. A promising alternative to landfill confinement is represented by ACW inertization, but the high cost of the inertization processes so far proposed by the scientific community have hampered the creation of actually operative plants. In this paper, we explore the possibility to use an innovative process that ensures the obtainment of asbestos-free inert material in an exceptionally short processing time, thus greatly reducing cost-related problems. The efficacy of the inertization process has been verified through accurate mineralogical investigations on both chrysotile and crocidolite de-activated fibers, through X-ray diffraction, scanning and transmission electron microscopy. Overall mineralogical, microstructural and granulometric characteristics of the inert bulk material suggest that it could be successfully re-used as a secondary raw material in ceramic industries. This innovative inertization procedure could therefore provide an effective and economically sustainable solution for ACW management.

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.

Vital root resection in severely furcation-involved maxillary molars: Outcomes after up to 7 years.

AIMS: To introduce a novel therapeutic approach for the treatment of furcation-involved maxillary molars by vital root resection and report longer-term outcomes of a case series. METHODS: Eleven patients with 15 maxillary molars affected by double/triple class II (n = 10) or single/double class III (n = 5) furcation defects and advanced vertical bone loss around one root participated. Teeth were treated with deep pulpotomy using a calcium silicate-based cement. After 4 weeks, the affected roots were removed by periodontal microsurgery and processed for histological evaluation of the pulp. All patients were enrolled into a supportive periodontal care programme. During the follow-up period, assessments of tooth sensitivity, response to percussion, mobility, pocket probing depth (PPD) and bleeding on probing (BOP) were made, periapical radiographs obtained and patient-reported outcomes collected. RESULTS: All teeth remained sensitive to pulp testing. After 1 year and 3-7 years of follow-up, PD was ≤5 mm at all resected teeth. Furcation status was much improved. Neither increasing mobility nor clinical or radiographic signs of periapical pathology were observed throughout the individual observation period. All patients were pleased with the result of therapy. Histologic sections revealed a functional dentin-pulp complex. CONCLUSIONS: This case series demonstrates the possibility of maintaining severely furcation-involved molars by vital root resection for up to 7 years. Root canal therapy and its associated costs and complications can thus be avoided.

Analysis of the Activity and Expression of Cyclooxygenases COX1 and COX2 in THP-1 Monocytes and Macrophages Cultured with BiodentineTM Silicate Cement.

BiodentineTM is a material based on hydrated calcium silicate with odontotropic properties. However, from the clinician's perspective, every material used to fill a tooth-even those showing the optimal biochemical parameters-is in fact a foreign body introduced to the organism of the host. Therefore, apart from the chemical parameters of such materials, equally important is the so-called biocompatibility of such materials. The aim of the study was to investigate whether BiodentineTM, used in the regeneration of the pulp-dentine complex, may affect the expression of the enzymes cyclooxygenase 1 (COX1) and cyclooxygenase 2 (COX2) in THP-1 monocytes/macrophages and the amount of prostanoids synthesized by these enzymes-precursors of biologically active prostanoids such as prostaglandin E2 (PGE2) and thromboxane (TXB2) which are mediators of inflammation. An original aspect of this research is the use of the THP-1 monocyte/macrophage cell model and the use of biomaterial in direct contact with cells. In this way we tried to reflect the clinical conditions of regenerative pulp and periodontal tissue treatment using BiodentineTM. The results of our study showed a lack of macrophage activation (measured by flow cytometry) and a lack of stimulation of the expression of the studied cyclooxygenase enzymes (measured by Western blotting and fluorescent microscopy), as well as a lack of increase in the concentration (measured by ELISA method) of their inflammatory mediators (PGE2 and TXB2) in vitro incubated with BiodentineTM.

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.

The Influence of New Silicate Cement Mineral Trioxide Aggregate (MTA Repair HP) on Metalloproteinase MMP-2 and MMP-9 Expression in Cultured THP-1 Macrophages.

The aim of the present study was to investigate the new silicate cement mineral trioxide aggregate (MTA Repair HP) with respect to its effect on the inflammation process involving the tooth and periodontal tissues. The composition of MTA Repair HP was supplemented with plasticizer agents which can have a negative effect on the modulation of tooth inflammation. The silicate-based material in question is widely used in regeneration of the pulp-dentin complex, treatment of perforations of various locations in the tooth, as well as in surgical treatment of the complications of periapical tissue. The improved bioceramic restorative cement can affect the expression of metalloproteinases MMP-2 and MMP-9 in monocytes/macrophages involved in modulation of inflammation and regenerative processes of the tooth and periodontal tissues. The novel aspect of the present study lies in the application of the model of THP-1 monocyte/macrophage and applying the biomaterial in direct contact with the cells. Hence, it provides a representation of clinical conditions with respect to regenerative pulp and periodontal treatment with the use of MTA Repair HP. A lack of macrophage activation (as measured with flow cytometry) was found. Moreover, the study identified a lack of expression stimulation of the studied metalloproteinases (with the use of Western blotting and fluorescent microscopy). Similarly, no increase in MMP-2 and MMP-9 concentration was found (measured by ELISA method) in vitro when incubated with MTA Repair HP. Based on the results it can be concluded that new MTA Repair HP does not increase the inflammatory response in monocytes/macrophages associated with the activity of the described enzymes. It can also be speculated that they do not affect the process of dentin regeneration in which MMP-2 and MMP-9 play significant roles.

The use of Bioceramics as root-end filling materials in periradicular surgery: A literature review.

INTRODUCTION: Periradicular surgery involves the placement of a root-end filling following root-end resection, to provide an apical seal to the root canal system. Historically several materials have been used in order to achieve this seal. Recently a class of materials known as Bioceramics have been adopted. The aim of this article is to provide a review of the outcomes of periradicular surgery when Bioceramic root-end filling materials are used on human permanent teeth in comparison to "traditional" materials. METHODS & RESULTS: An electronic literature search was performed in the databases of Web of Science, PubMed and Google Scholar, between 2006 and 2017, to collect clinical studies where Bioceramic materials were utilised as retrograde filling materials, and to compare such materials with traditional materials. In this search, 1 systematic review and 14 clinical studies were identified. Of these, 8 reported the success rates of retrograde Bioceramics, and 6 compared treatment outcomes of mineral trioxide aggregate (MTA) and traditional cements when used as root-end filling materials. CONCLUSION: Bioceramic root-end filling materials are shown to have success rates of 86.4-95.6% (over 1-5 years). Bioceramics has significantly higher success rates than amalgam, but they were statistically similar to intermediate restorative material (IRM) and Super ethoxybenzoic acid (Super EBA) when used as retrograde filling materials in apical surgery. However, it seems that the high success rates were not solely attributable to the type of the root-end filling materials. The surgical/microsurgical techniques and tooth prognostic factors may significantly affect treatment outcome.

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.

Effects of two fast-setting calcium-silicate cements on cell viability and angiogenic factor release in human pulp-derived cells.

Mineral trioxide aggregate (MTA) is considered a pulp-capping agent of choice, but has the drawback of a long setting time. This study aimed to assess two different types of calcium-silicate cements as pulp-capping agents, by investigating their in vitro cytotoxicity and angiogenic effects in human pulp cells. ProRoot MTA, Endocem Zr, and Retro MTA were prepared as set or freshly mixed pellets. Human pulp-derived cells were grown in direct contact with these three cements, Dycal, or no cement, for 7 days. Initial cell attachment, viability, calcium release, and the levels of vascular endothelial growth factor (VEGF), angiogenin, and basic fibroblast growth factor (FGF-2) were evaluated statistically using a linear mixed model (P < 0.05). The biocompatibility of Retro MTA was similar to those of the control and ProRoot MTA. Endocem Zr groups showed fewer and more rounded cells after a 3-day culture; however, the initial cytotoxicity appeared transient. All test materials showed significant increases in calcium concentration compared with the control group (P < 0.05). VEGF and angiogenin levels in ProRoot MTA and Retro MTA groups were significantly higher than those in the Endocem Zr group (P < 0.05). FGF-2 levels were not significantly different between groups (P > 0.05). We demonstrate that Retro MTA, which has a short setting time, has similar biocompatibility and angiogenic effects on human pulp cells, and can therefore potentially be as effective in pulp capping as ProRoot MTA. Endocem Zr showed intermittent cytotoxicity and elicited lower levels of VEGF and angiogenin expression.

Effects of two calcium silicate cements on cell viability, angiogenic growth factor release and related gene expression in stem cells from the apical papilla.

AIM: To evaluate the effects of two types of calcium silicate cements on viability, angiogenic growth factor release, and angiogenic and inflammation-related gene expression in human stem cells from the apical papilla (SCAP). METHODOLOGY: SCAPs were grown for 7 days with either ProRoot mineral trioxide aggregate (MTA) or Biodentine (BD). Cell viability and media concentrations of vascular endothelial growth factor (VEGF/VEGFA) and angiopoietin 1 (ANGPT1) were measured. The expression of genes related to angiogenic potential and inflammatory response was measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). One-way and two-way analyses of variance with multiple comparisons Tukey's test were performed (P < 0.05). RESULTS: Cells in contact with either cement were associated with increased cell viability compared with the no-treatment group at day 1 but there were no differences amongst groups at days 3 and 7. Exposure to either cement significantly increased VEGF concentrations at day 3; however, ANGPT-1 levels decreased significantly compared with the no-treatment group at day 3. Exposure to MTA and BD stimulated expression of VEGFA and FIGF/VEGFD. Furthermore, exposure to both cements significantly decreased the mRNA levels of ANGPT1 and FGF2 relative to the no-treatment group. CONCLUSIONS: Both MTA and BD stimulated the expression of angiogenic genes and release of VEGF, inducing similar expression patterns; however, they appeared to inhibit the expression of specific genes, including ANGPT1 and FGF2.

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.

Odontoblastic Differentiation, Inflammatory Response, and Angiogenic Potential of 4 Calcium Silicate-based Cements: Micromega MTA, ProRoot MTA, RetroMTA, and Experimental Calcium Silicate Cement.

INTRODUCTION: The aim of this study was to analyze the effects of different calcium silicate-based cements (CSCs) for pulp capping materials including MicroMega MTA (MMTA; MicroMega, Besanchon, France), RetroMTA (RMTA; BioMTA, Seoul, Korea), ProRoot MTA (PMTA; Dentsply, Tulsa, OK), and experimental CSC (ECSC) on odontoblastic differentiation, in vitro angiogenesis, and the inflammatory response in human dental pulp cells. METHODS: Differentiation was evaluated by alkaline phosphatase activity, alizarin red staining, and reverse-transcriptase polymerase chain reaction (RT-PCR) for the marker genes. The levels of inflammatory mediators and cytokines were measured by RT-PCR and an enzyme-linked immunosorbent assay. In vitro angiogenesis was assessed by RT-PCR for angiogenic genes and an endothelial tube formation assay. RESULTS: PMTA, MMTA, and ECSC increased the alkaline phosphatase activity and mineralization nodule formation and up-regulated messenger RNA (mRNA) expression of odontoblastic markers compared with RMTA. In addition, PMTA, MMTA, and ECSC up-regulated the mRNA of angiogenic genes in human dental pulp cells and increased the capillary tube formation of endothelial cells compared with RMTA. However, all CSCs showed similar expression levels of inducible nitric oxide synthase and cyclooxygenase-2 protein as well as proinflammatory mediators such as nitric oxide, prostaglandin E2, tumor necrosis factor alpha, interleukin (IL)-1ß, IL-6, and IL-8 mRNA. CONCLUSIONS: Taken together, our experimental results suggest that all CSCs are favorable materials for pulp capping, but PMTA, MMTA, and ECSC may be recommended over RMTA.

Role of the P38 pathway in calcium silicate cement-induced cell viability and angiogenesis-related proteins of human dental pulp cell in vitro.

INTRODUCTION: This study investigated that calcium silicate (CS) cement may influence the behavior of human dental pulp cells (hDPCs) via mitogen-activated protein kinase pathway, in particular p38. We have addressed that Si ion released from CS cement can influence osmolarity in the medium, which may stimulate hDPC viability and induce angiogenesis-related proteins through stimulation of the nitric oxide synthase and nitric oxide secretion. METHODS: The hDPCs was cultured with CS cement to angiogenesis. Then, cell viability, ion concentration, osmolality, nitric oxide secretion, the von Willebrand factor, and angiopoietin-1 protein expression were examined. RESULTS: CS cement elicited a significant (P < .05) increase of 15%, 20%, and 19% in viability compared with control on days 1, 3, and 5 of cell seeding, respectively. The CS cement consumed calcium and phosphate ions and released more Si ions in medium. The CS significantly (P < .05) increased the osmolality to 303.52 ± 3.07, 315.03 ± 5.80, and 319.95 ± 4.68 mOsm/kg for 1, 3, and 5 days, respectively. P38 was activated through phosphorylation; the phosphorylation kinase was investigated in our cell system after culture with CS cement. Moreover, expression levels for angiopoietin-1 and von Willebrand factor in hDPCs on CS cement were higher than those of the CS + p38 inhibitor (SB203580) group (P < .05) at all of the analyzed time points. CONCLUSIONS: This study showed that CS cement was able to activate the p38 pathway in hDPCs cultured in vitro. Moreover, Si was shown to increase osmolality required to facilitate the angiogenic differentiation of hDPCs via the p38 signaling pathway. When the p38 pathway was blocked by SB203580, the angiogenic-dependent protein secretion was decreased. These findings verified that the p38 pathway plays a key role in regulating the angiogenic behavior of hDPCs cultured on CS cement.

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.

Antiosteoclastogenic activity of silicate-based materials antagonizing receptor activator for nuclear factor kappaB ligand-induced osteoclast differentiation of murine marcophages.

INTRODUCTION: This study investigated whether calcium silicate cement extract exerted antiosteoclastogenic actions in murine RAW 264.7 macrophages cultured with receptor activator for nuclear factor kappaB (RANKL). METHODS: The RAW 264.7 macrophage cell was treated with RANKL to osteoclastogenesis. Then, cell viability, cell death, and cathepsin K expression were examined. RESULTS: The silicon (Si)-inhibited RANKL-induced formation of osteoclasts during the osteoclast differentiation process. It was also found that ≥4 mmol/L Si reduced RANKL-enhanced tartrate-resistant acid phosphatase (TRAP) activity in a dose-dependent manner. Furthermore, Si diminished the expression and secretion of cathepsin K elevated by RANKL and was concurrent with the inhibition of TRAF6 induction and nuclear factor kappaB activation. CONCLUSIONS: The current report shows that silicate abrogated RANKL-induced osteoclastogenesis by retarding osteoclast differentiation. The Si can modulate every cell through dose-dependent in vitro RANKL-mediated osteoclastogenesis, such as the proliferation and fusion of preosteoclasts, and the function of osteoclasts. Therefore, silicate-based materials may be a potential therapeutic agent targeting osteoclast differentiation in bone defects.

Chemical-physical properties of experimental root canal sealers based on butyl ethylene glycol disalicylate and MTA.

OBJECTIVE: The aim of this study was to evaluate the calcium release, pH, flow, solubility, water absorption, setting and working time of three experimental root canal sealers based on mineral trioxide aggregate (MTA) and two forms of calcium phosphates (CaP). METHODS: The materials were composed of a base and a catalyst pastes mixed in a 1:1. The base paste was made by 60% bismuth oxide and 40% butyl ethylene glycol disalicylate. Three different catalyst pastes were formulated containing 60% MTA or 40% MTA+20% CaP (hydroxyapatite HA or dibasic calcium phosphate dehydrate DCPD), 39% Resimpol 8% and 1% titanium dioxide. MTA Fillapex was used as control. The release of calcium and hydroxyl ions, solubility and water absorption were measured on regular intervals for 28 days. The working time and flow were tested according to ISO 6876:2001 and the setting time according to ASTM C266. The data were analyzed using 1-way ANOVA with Tukey's test (p<.01). RESULTS: All the cements showed basifying activity and released calcium ions. MTA Fillapex showed the highest values of flow (p<.01) and working/setting times (p<.01) and the smallest values of solubility (p<.01) and water absorption (p<.01). SIGNIFICANCE: All experimental materials showed satisfactory physical-chemical properties to be used as endodontic sealers in clinical practice.