Rapid formation of bioaggregates and morphology transition to biofilm streamers induced by pore-throat flows.

Bioaggregates are condensed porous materials comprising microbes, organic and inorganic matters, and water. They are commonly found in natural and engineered porous media and often cause clogging. Despite their importance, the formation mechanism of bioaggregates in porous media systems is largely unknown. Through microfluidic experiments and direct numerical simulations of fluid flow, we show that the rapid bioaggregation is driven by the interplay of the viscoelastic nature of biomass and hydrodynamic conditions at pore throats. At an early stage, unique flow structures around a pore throat promote the biomass attachment at the throat. Then, the attached biomass fluidizes when the shear stress at the partially clogged pore throat reaches a critical value. After the fluidization, the biomass is displaced and accumulated in the expansion region of throats forming bioaggregates. We further find that such criticality in shear stress triggers morphological changes in bioaggregates from rounded- to streamer-like shapes. This knowledge was used to control the clogging of throats by tuning the flow conditions: When the shear stress at the throat exceeded the critical value, clogging was prevented. The bioaggregation process did not depend on the detailed pore-throat geometry, as we reproduced the same dynamics in various pore-throat geometries. This study demonstrates that pore-throat structures, which are ubiquitous in porous media systems, induce bioaggregation and can lead to abrupt disruptions in flow.

Bio-active cements-Mineral Trioxide Aggregate based calcium silicate materials: a narrative review.

Recent advances in the field of endodontics have greatly improved the outcome and success rate of dental materials. For last three decades, there has been great interest in the development of bioactive dental material with the ability to interact and induce surrounding dental tissues to promote regeneration of pulpal and periradicular tissues. As these bioactive materials are mainly based on calcium silicates, they are also referred to as Calcium Silicate materials. The first material introduced was Mineral Tri-oxide Aggregate, which, due to its favourable biological properties, gained importance initially. However, later, due to its drawbacks, liked is colouration, long setting time and difficult manipulation, several modifications were done and newer bioactive materials, such as Biodentine, BioAggregate, Endosequence, Calcium-Enriched Mixture etc., were developed. The main applications of these materials are for pulp capping (direc t/indirec t), pulpotomy, perforation repair, resorption defects, apexogenesis and as retrograde filling materials, apexification and endodontic sealers. This review discusses the various types of bioactive materials, their composition, setting mechanism, and literature evidence for current applications.

Are Bioceramics the Dernier Cri in the Management of Stage 4 Developed Root? A Finite Element Analysis.

AIM: To compare the stress distribution of four modalities of reinforcing the radicular space of a pulpless central incisor exhibiting stage 4 root development. MATERIALS AND METHODS: The model of a pulpless immature central incisor with a stage 4 of root development supporting periodontium was generated based on the properties. The longitudinal growth of the root was completed. Four such models were developed. Then, the radicular space was rehabilitated as follows: Model 1: Ceramicrete; Model 2: Biomimetic Mineralization; Model 3: Biodentine; Model 4: Bioaggregate. They were subjected to three different loading conditions. One was to mimic the mastication by applying a load of 70 N applied at 45° angle. Second loading condition was a vertical load of 100 N to mimic bruxism. The third loading condition was to mirror the impact of a frontal trauma. A load of 100 N was applied labially. RESULTS: It was observed that during mastication, Model 2 has exhibited the lowest concentration of von Mises stresses, followed by Model 3 and then Model 4 followed by Model 1; this could be because the modulus of elasticity of Model 2 is comparable to that of Dentin. During bruxism and horizontal impact, the maximal stress concentration was found in Model 4, Model 3, Model 2, followed by Model 1. CONCLUSION: The closer the elasticity of modulus of the primary endodontic replacement monoblock was to that of dentin, the lower were the stresses generated. However, as the increase in stress values was minimal between groups, these obturating materials can be viable reinforcement materials for the rehabilitation of cases of stage 4 developing root. Biomimetic mineralization strategies can be a viable treatment option for managing cases of the open apex. CLINICAL RELEVANCE: Biomimetic mineralization strategies and bioceramics can be used for obturation of root canals with open apex, instead of utilizing these bioceramics as apical plugs.

Portland cement induces human periodontal ligament cells to differentiate by upregulating miR-146a.

BACKGROUND/PURPOSE: Bioaggregates such as Portland cement (PC) can be an economical alternative for mineral trioxide aggregate (MTA) with additional benefit of less discoloration. MTA has been known to induce differentiations of several dental cells. MicroRNAs are important regulators of biological processes, including differentiation, physiologic homeostasis, and disease progression. This study is to explore how PC enhances the differentiation of periodontal ligament (PDL) cells in microRNAs level. METHODS: PDL cells were cultured in a regular PC- or MTA-conditioned medium or an osteoinduction medium (OIM). Alizarin red staining was used to evaluate the extent of mineralization. Transfection of microRNA mimics induced exogenous miR-31 and miR-146a expression. The expression of microRNAs and differentiation markers was assayed using reverse-transcriptase polymerase chain reaction. RESULTS: PC enhanced the mineralization of PDL cells in a dose-dependent manner in the OIM. Exogenous miR-31 and miR-146a expression upregulated alkaline phosphatase (ALP), bone morphogenic protein (BMP), and dentin matrix protein 1 (DMP1) expression. However, miR-31 and miR-146a modulates cementum protein 1 (CEMP1) expression in different ways. PC also enhanced ALP and BMP but attenuated CEMP1 in the OIM. Although the OIM or PC treatment upregulated miR-21, miR-29b, and miR-146a, only miR-146a was able to be induced by PC in combination with OIM. CONCLUSION: This study demonstrated that PC enhances the differentiation of PDL cells, especially osteogenic through miR-146a upregulation. In order to control the ankylosis after regenerative endodontics with the usage of bioaggregates, further investigations to explore these differentiation mechanisms in the miRNA level may be needed.

The influence of the casting process on the internal structure and physical properties of hemp-lime.

Bio-aggregate composites such as hemp-lime offer a more sustainable alternative to traditional walling infill material. Hemp-lime, whether in situ or prefabricated, is generally either cast or sprayed, which results in a directionally dependent, typically layered, physical structure. This paper considers the impact of compaction and layering on the directional thermal conductivity, compressive strength and internal structure of the material through use of a novel image analysis method. The results presented indicate that production variables have a significant, and crucially, directionally dependent impact on the thermal and mechanical properties of cast hemp-lime.

Partial Pulpotomy with BioAggregate in Complicated Crown Fractures: Three Case Reports.

This report describes three cases of complicated crown fractures treated with partial pulpotomy using BioAggregate. Three maxillary permanent central incisors with complicated crown fracture were treated by partial pulpotomy using BioAggregate and reviewed clinically and radiographically for 24 months. Throughout this period, there was no spontaneous pain, periapical radiolucency, and coronal discoloration; the pulp was observed to be vital. Based on these findings, it was concluded that BioAggregate can be used in partial pulpotomy treatment of complicated crown fracture.

Effect of Biodentine and Bioaggregate on odontoblastic differentiation via mitogen-activated protein kinase pathway in human dental pulp cells.

AIM: To compare the mineralization inductive capacity of Biodentine and Bioaggregate with Mineral trioxide aggregate (MTA) and to investigate possible signaling pathways of mineralization in human dental pulp cells (HDPCs). METHODOLOGY: Viability of HDPCs in response to Biodentine, Bioaggregate, and MTA was measured using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide. To investigate their potential to induce odontoblast differentiation, expression of dentine sialophosphoprotein (DSPP) and dentine matrix protein1 (DMP1) mRNA level was evaluated by RT-PCR. For the mineralized nodule assay, Alizarin red staining was performed. To determine the role of MAPK signaling in the odontoblastic differentiation of HDPCs, activated MAPKs were investigated by Western blot and the effect of MAPK inhibitor was examined by Alizarin red S staining. The results were statistically analysed using one-way anova and the Bonferroni test. RESULTS: The effects of MTA, Biodentine, and Bioaggregate on cell viability were similar. Biodentine and Bioaggregate enhanced DSPP and DMP1 mRNA expression compared to the control group, but to the same extent as MTA (P < 0.05). MTA, Biodentine, and Bioaggregate increased the area of calcified nodules compared to the control (P < 0.01). MTA, Biodentine, and Bioaggregate increased phosphorylation of extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). MAPK inhibitors attenuated mineralized nodule formation, which was increased by MTA, Biodentine, and Bioaggregate, respectively (P < 0.01). CONCLUSION: Biodentine and Bioaggregate stimulated odontoblastic differentiation and mineralization nodule formation by activating the MAPK pathway as did MTA. This suggests that the new materials could be useful for regenerative endodontic procedures.

Effect of BioAggregate on osteoclast differentiation and inflammatory bone resorption in vivo.

AIM: To investigate the effect of BioAggregate (Innovative Bioceramix, Vancouver, BC, Canada) on lipopolysaccharide (LPS)-induced bone destruction in vivo and to compare its performance with that of mineral trioxide aggregate (MTA; Dentsply Tulsa Dental, Tulsa, OK, USA). METHODOLOGY: Mouse bone marrow macrophages (BMMs) were primary cultured and treated with several concentrations of BioAggregate and MTA extracts. Cell viability was measured with a Cell Counting Kit-8 assay, whilst in vitro osteoclast differentiation was evaluated with tartrate-resistant acid phosphatase (TRAP) staining. LPS-induced mouse calvarial bone destruction model was established to assess the effect of BioAggregate and MTA extracts in vivo. Mice were killed on day 7, and calvarial bones were prepared for microcomputed tomography scanning, histologic analysis and double-immunofluorescence staining. Statistical tests used were one-way anova followed by Student-Newman-Keuls test. RESULTS: BioAggregate extracts displayed no obvious cytotoxicity to BMMs and significantly inhibited (P < 0.01) the differentiation of RANKL-stimulated BMMs. Comparable effects were induced by MTA. BioAggregate and MTA extracts markedly reduced (P < 0.01) osteoclast numbers and attenuated (P < 0.05) bone resorption in LPS-challenged mouse calvaria. The expression levels of osteoclastogenic cathepsin K and its upstream regulator nuclear factor of activated T-cell cytoplasmic 1 and c-Fos were also decreased by BioAggregate and MTA extracts. CONCLUSIONS: BioAggregate and MTA showed comparable inhibitory effect on osteoclast differentiation and inflammatory bone resorption in vivo.

Resistance to leakage of various thicknesses of apical plugs of Bioaggregate using liquid filtration model.

AIM: The aim of this study was to compare the resistance to leakage of different thicknesses of Bioaggregate (BA) and 4-mm-thick white mineral trioxide aggregate (WMTA) in an apexification model using liquid filtration. METHODS: 32 extracted mandibular premolar teeth were sectioned at the cemento-enamel junction and 3-4 mm from the tooth apex to obtain 12-mm-long root segments. The apical and coronal thirds were prepared with size two through six Gates Glidden burs. The teeth were divided into four groups according to material and thickness, as follows: Group 1: 2-mm BA; Group 2: 4-mm BA; Group 3: 12-mm (total length) BA; Group 4: 4-mm WMTA (control). The empty parts of the roots in Groups 1, 2, and 4 were filled with gutta-percha and root canal sealer, and leakage was measured using fluid filtration. The data were analyzed using the Kruskal-Wallis H-test. RESULTS: No statistical differences in microleakage were observed between Groups 1, 2, and 4 (P > 0.05). Group 3 (roots filled completely with BA) showed significantly less leakage than the other groups tested (P < 0.01). CONCLUSIONS: The findings of this study showed that 12 mm of BA exhibited the best resistance to leakage. At the same time, 2-4 mm of BA showed similar results when compared to 4-mm MTA. In light of these results, this study suggests that BA may be a good candidate for further clinical studies when used as an apical barrier for apexification.

Trace metal contents of three tricalcium silicate materials: MTA Angelus, Micro Mega MTA and Bioaggregate.

AIM: To investigate the levels of nine metals [aluminium (Al), antimony (Sb), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), iron (Fe), lead (Pb) and molybdenum (Mo)] in MTA Angelus, Micro Mega MTA and Bioaggregate using inductively coupled plasma-optical emission spectrometry (ICP-OES). METHODOLOGY: Each material (0.2 g) was digested using a mixture of hydrochloric and nitric acids and then filtered. The levels of nine metals in the resulting filtrates were measured by ICP-OES. The results were statistically analysed using one-way anova and the Bonferroni test. RESULTS: MTA Angelus contained more aluminium, beryllium and chromium than Micro Mega MTA (P < 0.05), whilst their levels of arsenic, cadmium and iron were similar. Antimony, lead and molybdenum were not detected in any of the three tested cements. Bioaggregate contained trace amounts of aluminium. CONCLUSIONS: MTA Angelus and Micro Mega MTA contained small amounts of seven tested metal oxides. Bioaggregate only contained trace amounts of aluminium.

Bioactivity of Calcium Silicate-Based Endodontic Materials: A Comparative in vitro Evaluation.

Background: Bioactivity refers to the ability of a material to interact with living organisms or biological systems in a way that elicits a specific response. In the context of materials science and medicine, bioactivity is particularly important because it can determine the suitability of material for various applications. Objective: To evaluate and compare different commercially available calcium silicate-based materials regarding: 1. Morphological and elemental analysis at the dentin/material interface. 2. Calcium and silicon release and uptake by adjacent root canal dentine by evaluating the calcium and silicon incorporation depth in adjacent root canal dentin. Materials and Methods: This study examined four calcium silicate-based cements: Biodentine, MTA Angelus, BioAggregate, and MTA Plus. One hundred extracted human teeth with intact apices and no cavities were selected. Root sections measuring 3 mm in length were created at the mid-root level using low-speed diamond discs. Bioactivity was evaluated at 1, 7, 30, and 90 days, respectively. Results: The principal composition of the interfacial dentine layer and incorporation of calcium and silicon into dentine was measured at 1, 7, 30, and 90 days. Statistical analysis was performed by multiple comparisons using post hoc Tukey HSD. Conclusion: All the materials have shown bioactivity, i.e. release of calcium, silicon, and their uptake in the adjacent dentin in the presence of phosphate-buffered saline.

Biocompatibility of BioAggregate and mineral trioxide aggregate on the liver and kidney.

AIM: To investigate and compare the systemic toxic effect of DiaRoot BioAggregate and grey ProRoot Mineral trioxide aggregate (MTA) on the liver and kidney after 7 and 30 days. METHODOLOGY: Forty-two white albino rats were divided into two main groups. Group (1), considered the control group (n = 18), was further divided into two subgroups. The negative control subgroup (n = 6) received no treatment. The empty tube subgroup (n = 12) received empty sterile Teflon tubes. In Group (2), considered the experimental group (n = 24), the rats were divided equally into two subgroups. One subgroup received MTA, whilst the other received BioAggregate. The materials in the Teflon tubes were implanted subcutaneously in the dorsal side of the rats. Blood samples were taken to investigate the change of kidney and liver functions on day 7 and day 30. The liver and kidney organs were subjected to histopathological examination and calculation of the number of inflammatory cells. Data analysis was performed using one-way anova with post hoc multiple comparisons with the Tukey's test. Student's t-test was used to compare the changes in liver and kidney functions amongst the groups. RESULTS: On day 7, a significantly more severe inflammatory reaction was observed in both experimental subgroups compared with the control (P < 0.05); the severity decreased after 30 days. The kidney functions were not affected after 7 days but had subsequently increased after 30 days (P < 0.001). Liver functions increased after 7 days and had decreased in the BioAggregate subgroup after 30 days, whilst in the MTA subgroup, a continuous increase in the level of liver function was observed. CONCLUSIONS: Mineral trioxide aggregate had adverse effects on the liver and kidney that were significantly more severe than BioAggregate but with no permanent damage.

BioAggregate and iRoot BP Plus optimize the proliferation and mineralization ability of human dental pulp cells.

AIM: To investigate the cytotoxicity of BioAggregate and iRoot BP Plus root canal sealer (iRoot BP Plus) to human dental pulp cells (hDPCs) and their effect on proliferation and mineralization of hDPCs and to compare their performance with that of mineral trioxide aggregate (MTA). METHODOLOGY: Human dental pulp cells were seeded onto the prepared BioAggregate, iRoot BP Plus and MTA, respectively. Cell proliferation was assessed by CCK-8 cell proliferation kit on days 1, 3, 5 and 7. ALP activity was measured to evaluate the cell differentiation potential on days 1, 3, 5 and 7. The expression of odontoblastic differentiation-related genes (dentine phosphoprotein, dentine matrix protein-1 and osteocalcin) was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Statistical tests used were one-way anova and post hoc Tukey's test. RESULTS: The proliferation of hDPCs in the MTA group was suppressed throughout the culture period, whereas the BioAggregate group and the iRoot BP Plus group first significantly increased cell numbers on day 1 (P < 0.01) and then decreased on day 3 to day 7. ALP activity was enhanced in all the three groups from day 3, whilst iRoot BP Plus showed significantly higher ALP activity than MTA (P < 0.01). qRT-PCR indicated that both BioAggregate and iRoot BP Plus groups were associated with a higher upregulation of mineralization and odontoblastic differentiation-associated gene expressions as compared to MTA group (P < 0.05). CONCLUSIONS: BioAggregate and iRoot BP Plus were nontoxic and able to induce mineralization and odontoblastic differentiation-associated gene expression in hDPCs.

Push-out bond strength of a nano-modified mineral trioxide aggregate.

INTRODUCTION: To analyze the push-out bond strength of Angelus WMTA (Angelus Dental Products), a nano-modification of WMTA (Kamal Asgar Research Center) and Bioaggregate (Innovative Bioceramix). METHODS: Sixty 2-mm-thick root sections were prepared from 60 single-rooted human teeth. The dentin disks were randomly divided into three groups (n = 20) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate, respectively. Push-out bond strength values of the specimens were measured by a universal testing machine and examined under scanning electron microscope at × 40 magnification to determine the nature of the bond failure. The data were analyzed with a Kruskal-Wallis test. RESULTS: The greatest mean for push-out bond strength (138.48 ± 11.43 MPa) was observed for the nano-modification of WMTA. The values decreased to 110.73 ± 11.19 and 25.64 ± 5.27 MPa for Angelus WMTA and Bioaggregate, respectively. There were significant differences between the groups (P < 0.001). Inspection of the samples revealed the bond failure to be predominantly adhesive type except for the nano-modification group, as some samples also exhibited cohesive failures. CONCLUSIONS: It is concluded that the force needed for the displacement of the nano-modification of WMTA (NWMTA) was significantly higher than for Angelus WMTA and Bioaggregate.

Stresses in Teeth with External Cervical Resorption Defects Restored with Different Biomimetic Cements: A Finite Element Analysis.

INTRODUCTION: This study compared the stress distributions in teeth with simulated external cervical resorption defects restored with different restorative materials and identified areas of high stress concentration. METHODS: A maxillary central incisor created in a scanned model using HyperWorks software (Altair Engineering Inc, Troy, MI) served as the control. External cervical resorption defects based on Shanon Patel's classification were created (1Bd/2Bd/3Bd) in the scanned model. The defects were restored using mineral trioxide aggregate, Biodentine, glass ionomer cement, and Bioaggregate. On all the models, a force of 100 N was applied on the palatal aspect 2 mm incisal to the cingulum directed at 45° along the long axis of the tooth. RESULTS: The stresses generated in dentin and cementum are less, with a restorative material having a high Young's modulus. For the 1Bd defect, MTA and Bioaggregate showed least stresses in dentin and cementum, respectively, whereas Biodentine had consistently lower stresses in dentin and cementum. Larger defects like 2Bd and 3Bd restored with Bioaggregate exhibited minimum stresses in dentin and cementum. CONCLUSIONS: Bioaggregate and Biodentine replace dentin with maximum stress and maximum strain. Elastic moduli similar to or higher than dentin are preferred for restoring cervical third resorptive lesions of the tooth.

Retarding Effect of Hemp Hurd Lixiviates on the Hydration of Hydraulic and CSA Cements.

Wood wool panels are widely used in the construction industry as sustainable cementitious composites, but there is a growing need to replace traditional Portland cement with a binder that has a lower embodied carbon footprint. In addition, the sustainability of these panels may face serious impediments if the required amount of wood for their production needs a harvest rate higher than the rate at which the tree sources reach maturity. One solution is to use the wooden part of fast-growing plants such as hemp. However, the compounds extracted from the mixture of plants and water are the main cause of the delay observed during the hydration process of hydraulic binders in these cementitious composites. The objective of this study is to evaluate the effect of bio-aggregate lixiviates (hemp hurd) on the hydration kinetics of calcium sulfoaluminate (CSA) cement as a low-embodied-carbon alternative to ordinary Portland cement (OPC). The isothermal calorimeter showed that the hemp hurd lixiviate caused a greater delay in GU's hydration process than CSA's. At a 5% concentration, the main hydration peak for GU cement emerged after 91 h, whereas for CSA cement, it appeared much earlier, at 2.5 h. XRD and TGA analysis showed that after 12 h of hydration, hydration products such as calcium silicate hydrates (C-S-H) and portlandite (CH) were not able to form on GU cement, indicating low hydration of silicate products. Moreover, at 5% concentration, the carbonation of ettringite was observed in CSA cement. The compressive strength values obtained from the mixes containing hemp hurd lixiviate consistently showed lower values compared to the reference samples prepared with distilled water. Furthermore, the CSA samples demonstrated superior compressive strength when compared to the GU samples. After 28 days of hydration, the compressive strength values for CSA cement were 36.7%, 63.5% and 71% higher than GU cement at a concentration of 0.5%, 2% and 5% hemp hurd lixiviate, respectively.

Roles of high/low nucleic acid bacteria in flocs and probing their dynamic migrations with respirogram.

Bacterial migration is crucial for the stability of activated sludge but rarely reported. The static distribution was explored by changes in bacteria concentration with extracellular polymeric substances (EPS) extractions. Next, denitrification and aeration were conducted as normal running conditions for examining the bacterial migration between floc-attached and dispersed growth. Above observations were further explored by conducting copper ion (Cu2+) shock as an extreme running condition. After extracting EPS, low nucleic acid (LNA) bacteria migrated from the sludge to the supernatant primarily, and high nucleic acid (HNA) bacteria remained in the residual sludge, suggesting that HNA bacteria mainly distributed inside the sludge while LNA bacteria outside the sludge. During the denitrification process, LNA bacteria migrated out of flocs, which increased by 6.94 × 106 events/mL in the supernatant. During the feast phase of aeration, LNA bacteria grew attached to flocs, causing the increased flocs diameter from 45.60 to 47.40 µm. During the following aerobic famine phase, LNA bacteria grew dispersedly, but HNA bacteria remained unchanged. However, a further severe famine phase drove HNA bacteria to be dispersed, breaking flocs with the decreased diameter from 48.10 to 46.50 µm. When the Cu2+ shock was employed, LNA and HNA bacteria increased but the LNA/HNA ratio decreased in the supernatant, indicating more HNA bacteria migrating to the dispersed phase. From a structural perspective, HNA bacteria distributed inside the sludge and functioned as the backbone of flocs, undertaking the maintenance of flocs stability primarily; while LNA bacteria distributed outside the sludge and functioned as filling materials, having a secondary influence on flocs stability. These processes were also probed by respirogram exactly, correlating the system-scale measurement and microscale migrations and providing an early warning signal under abnormal circumstances. The processed HNA-backbone theory is promising for regulating the stability of activated sludge based on bacterial migrations.

Micro-CT comparative evaluation of porosity and dentin adaptation of root end filling materials applied with incremental, bulk, and ultrasonic activation techniques.

The purpose of this study is to investigate the effect of different application methods on the adaptation to dentin and porosity properties of calcium silicate based materials. This study included 72 maxillary canine teeth that had been extracted for various reasons. Following the root canal treatment, root, end resections were performed on the specimens. After the apicectomy, 3 mm deep cavities were created. All materials were mixed according to the manufacturer's instructions. Retrograde cavities were filled with RetroMTA [Group 1a-1c], Biodentine [Group 2a-2c] and BioAggregate [Group 3a-3c]. Placement techniques were applied for each material by using incremental, bulk technique and ultrasonic activation, respectively. The samples were scanned with the SkyScan 1272 µCT system. Porosity values were higher in bulk fill and incremental placement techniques than ultrasonic technique when using MTA and BioAggregate (p < 0.05), but Biodentine showed no statistically significant difference (p > 0.05) on using different placement techniques. The ultrasonic activation technique is beneficial to improve the condensation quality of MTA and BioAggregate. Biodentine showed better results regardless of different application techniques.

Bond Behavior of a Bio-Aggregate Embedded in Cement-Based Matrix.

This paper investigates the bond behavior between a bio-aggregate and a cement-based matrix. The experimental evaluation comprised physical, chemical, image, and mechanical characterization of the bio-aggregate. The image analyses about the bio-aggregate's outer structure provided first insights to understand the particularities of this newly proposed bio-aggregate for use in cementitious materials. A mineral aggregate (granitic rock), largely used as coarse aggregate in the Brazilian civil construction industry, was used as reference. The bond behavior of both aggregates was evaluated via pull-out tests. The results indicated that both aggregates presented a similar linear elastic branch up to each respective peak loads. The peak load magnitude of the mineral aggregate indicated a better chemical adhesion when compared to the bio-aggregate's. The post-peak behavior, however, indicated a smoother softening branch for the bio-aggregate, corroborated by the microscopy image analyses. Although further investigation is required, the macaúba crushed endocarp was found to be a thriving bio-material to be used as bio-aggregate.

Evaluation of a collagen-bioaggregate composite scaffold in the repair of sheep pulp tissue.

PURPOSE: This study aimed to compare the effects of the collagen-BioAggregate mixture (CBA-M) and collagen-BioAggregate composite (CBA-C) sponge as a scaffolding material on the reparative dentin formation. MATERIALS AND METHODS: CBA-C sponge (10:1 w/w) was obtained and characterized by Scanning Electron Microscopy (SEM) and Mercury Porosimetry. Cytotoxicity of the CBA-C sponge was tested by using the L929 mouse fibroblast cell line. Dental pulp stem cells (DPSCs) were isolated from the pulp tissue of sheep teeth and characterized by flow cytometry for the presence of mesenchymal stem cell marker, CD44. The osteogenic differentiation capability of isolated DPSCs was studied by Alizarin Red staining. The cells were then used to study for the compatibility of CBA-C sponge with cell proliferation and calcium phosphate deposition. The effect of CBA-C sponge and CBA-M on the induction of dentin regeneration was studied in the perforated teeth of sheep for the eight-week period. All the analyses were performed with appropriate statistical hypothesis tests. RESULTS: CBA-C sponge was found to be biocompatible for DPSCs. The DPSCs seeded on the CBA-C sponge were able to differentiate into the osteoblastic lineage and deposit calcium phosphate crystals in vitro. Reparative dentin formation was observed after the second week in the CBA-C sponge applied group. At the end of eight weeks, a complete reparative dentin structure was formed in the CBA-C sponge applied group, whereas necrotic tissue residues were observed in groups treated with the CBA-M. CONCLUSION: CBA-C sponge represents a better microenvironment for reparative dentin formation probably due to maintaining DPSCs and allowing their osteogenic differentiation and thus calcium phosphate deposition.