Evaluating the advancements in a recently introduced universal adhesive compared to its predecessor.

Background/purpose: The dental adhesive market is constantly evolving to meet the demands of dentists and patients, but new products and upgrades should be rigorously evaluated before being used in clinical practice. This study investigated the physicomechanical properties and dentin bonding efficacy of a newly upgraded universal adhesive compared to its predecessor. Materials and methods: Twenty-four molars were divided into four groups (n = 6/group) based on adhesive (new vs. predecessor) and application mode [self-etch (SE) vs. etch-and-rinse (ER)] for evaluating their dentin microtensile bond strength (µTBS), failure pattern, and bonding interface. Additional thirty-six molars' crowns were perpendicularly sectioned to obtain flat mid-coronal dentin discs. The opposing dentin surfaces of each disc received contrasting treatments (new/predecessor adhesive applied in SE/ER mode), resulting in six interventions. The bonded discs (n = 6/intervention) were used to assess the adhesives' survival probability employing a double-sided µTBS test. The other physicomechanical properties examined were adhesives' oxygen inhibition layer (OIL), viscosity, hardness, elastic modulus, degree of conversion (DC), and in-situ DC. Results: Both adhesive versions showed similar µTBS (P > 0.05), failure pattern (P > 0.05), and survival probability (P > 0.008). ER mode promoted resin tag formation and exhibited a slender adhesive layer for both adhesives. The newer adhesive version showed a thinner adhesive layer in general with narrower OIL (P < 0.001), less viscosity (P < 0.001), higher hardness (P < 0.05), elastic modulus (P < 0.05), DC (P < 0.001), and in-situ DC (P < 0.001). Conclusion: While the newly updated adhesive had superior physicomechanical properties with more fluidity, its dentin bonding efficacy and survival probability were comparable to its predecessor.

Enhancement of bacterial cellulose production by ethanol and lactic acid by using Gluconacetobacter kombuchae.

The current study intended to analyze the impact of ethanol and lactic acid on the bacterial cellulose yield as well as physicochemical and mechanical properties, by using Gluconacetobacter kombuchae. The optimization of ethanol and lactic acid concentration has been done by using one-way ANOVA. Both the supplements significantly enhance the yield of bacterial cellulose (BC) as compared to the standard Hestrin-Schramm medium (control). Optimization leads to significant increase in BC yield as compared to the control, i.e., the addition, of optimized concentration of lactic acid (0.6%) increases the yield from (0.78 ± 0.026) g to (4.89 ± 0.020) g dry weight, and optimized concentration of ethanol (1%) increases the yield from (0.73 ± 0.057) g to (3.7 ± 0.01) g dry weight. Various physicochemical and mechanical properties of BC films produced in different media (i.e., HS, HS + Ethanol, and HS + Lactic acid), such as the crystallinity, structure, tensile strength, strain at break, Young's modulus, and water holding capacity, were also examined, by employing various techniques such as SEM, FTIR, XRD, etc. BC produced in medium supplemented with the optimum concentration of both the additives were found to possesses higher porosity. Though, slight decline in crystallinity was observed. But the tensile strength and strain at break, were upgraded 1.5-2.5 times, 2-2.5 times, respectively. This article attempted to present a method for enhancing BC yields and characteristics that may lead to more widespread and cost-effective use of this biopolymer.

Dataset on the performance characteristics of briquettes from selected agricultural wastes using a piston-type briquetting machine.

Densification of agricultural wastes for briquette production has considerable potential to meet the growing energy demand and contribute towards a safe environment worldwide. The datasets contained in this paper are the performance characteristics of raw and torrefied briquettes produced from sawdust (SD), cassava peels (CP), cornhusk (CH), and their blends using a developed piston-type briquetting machine. The physicomechanical, chemical, structural, and combustion indices including the kinetic parameters, were determined using standard methods. The result obtained show that each briquettes sample has the infrared transmittance of C-H, OH, C-O, and C=C with the SD sample having the highest and CP, the lowest. The feedstock mixture and increase in torrefaction temperature enhance the physicomechanical properties of the briquettes through water preconditioning. The combustion characteristics show that the torrefied briquettes and their blends could be co-fired with coal, and are well suited for heating applications and reduce environmental pollution. The activation energy, pre-exponential factor, and R2 values of the briquettes ranged between 39.70-60.76 kJ/mol, 5.52-9.17 min-1, and 0.95-0.98, respectively. The data provided in this paper will therefore be useful for energy enthusiasts and coal engine design, and assist in choosing the appropriate briquette blends with increased calorific value for heating applications.

Synthesis of chemically-crosslinked multi-arm star-shaped polyurethane with triple-shape memory effect.

In this study, chemically-crosslinked multi-arm star-shaped polyurethanes (SPUs) were prepared using three, four, and six-arm polycaprolactone, hexamethylene diisocyanate, and 1, 4-butanediol. The hydrogen bonding indices of soft and hard segments were calculated using Fourier transform infrared spectra. The results indicated that the phase separation among hard and soft segments increased with the increment of PCL arm numbers. Moreover, the results of X-ray diffraction and differential scanning calorimetry showed that the crystallization ability of the three and four-arm SPUs were lower than that for six-arm SPU (6SPU), which is due to their higher crosslinking densities. In addition, the results of the mechanical studies showed that the crosslinking density and degree of crystallinity are the main effective parameters controlling the mechanical properties, by which 6SPU showed higher Young's modulus and lower elongation at break compared to other SPUs. Cyclic shape memory studies showed that 6SPU could fix approximately all the temporary shapes during three cycles and recover 100% of its original shape. Moreover, 6SPU could show triple-shape memory effect (TSME) by which it could fix two different temporary shapes. These results show that 6SPU has a high potential for practical applications due to its good mechanical properties, shape memory fatigue resistance, and TSME.

Structurally stable and surface-textured polylactic acid/copolymer/poly (ε-caprolactone) blend-based electrospun constructs with tunable hydroxyapatite responsiveness.

Functionally-designed nanotextured and copolymer (COP) mediated PLA/PCL (70:30 w/w) blend-based interface-engineered electrospun mats (EMs) based constructs, with phase-specific interactions, have been successfully developed. The thermal stability of constructs remained up to ∼300-350 °C, while the crystallinity reduced to ∼12-23 %, indicating enhanced pliability. The tensile strength increased by ∼75 % without much compromise in the tensile modulus whereas the dynamic relaxation response of the constructs shifted to lower temperatures upon the incorporation of ≥ 2.5 phr (parts per hundred parts of resin) of COP. The zeta potential evaluated from radial surface exposure intensity could be manipulated by controlling the extent of COP content (-60 mV for ∼5 phr COP) which in turn led to the dynamics of site-specific charge neutralization driven attachment of Ca2+ ions (∼13 % for ∼5 phr COP) of the nano-hydroxyapatite (n-HA). Such uniformly dispersed, n-HA attached, and surface-decorated (COP ≤ 5 phr) EMs enabled the selective L929 fibroblast cell attachment (∼200 % cell viability for ∼2.5 phr COP). Thus, the approach may prove to augment the biomineralization of Ca and apatite-driven healing kinetics amongst implant-seeking and inflammation-prone sites and thereby, paving a new pathway for controlled and targeted healing of bone, cartilage, dental gums, and other sites demanding n-HA and/or calcium-phosphorus assisted healing mechanism.

Designing suture-proof cell-attachable copolymer-mediated and curcumin- ß-cyclodextrin inclusion complex loaded aliphatic polyester-based electrospun antibacterial constructs.

The paper demonstrates curcumin/ß-cyclodextrin-based inclusion complex (IC) loaded polyvinyl alcohol (PVA) dip-coated and copolymer-compatibilized polylactic acid (PLA)/poly(ε-caprolactone) (PCL) blend-based electrospun mats (EMs) as antibacterial, and suture-resistant constructs, to overcome the present challenges in developing structurally-stable, biocompatible, pliable, and stand-alone multifunctional-biomedical-devices. The thermal, microstructural, and viscoelastic characterization confirmed the presence of H-bonding interactions between IC and PVA moieties and between IC incorporated PVA matrix with the copolymer-mediated nanotextured PLA/PCL blend-based EMs. IC release and surface PVA erosion induced a decrease in modulus (>4-fold) and strength (>2-fold) of constructs (post-release). Mechanistically new and architectural-framework-defined PVA-gelation induced bi-axially diverted suture-failure (post-release) and resulted in a significant enhancement in suture-retention-strength (>3-fold), energy (>5-fold), and displacement (>2-fold) for ~20 wt% IC-loaded-PVA-coated EM-constructs. The fabricated EM-constructs exhibited improvement in surface-hydrophilicity (contact angle ~45°), surface nano-roughness (~ 600 nm), surface area (~34 m2/g), pore volume (~3.6 × 10-2 cc/g), IC release efficacy (~20 % burst release), antibacterial activity (adherent bacteria <10 %) against E. coli and S. aureus, and L929 fibroblast-cell-viability (~135 %), which varied as a function of IC-content in the PVA matrix. Our study conceptually establishes a novel and efficient technique for designing antibacterial, suture-resistant engineered-EM-constructs with tunable properties for their potential use in wound-dressings, periodontal-membranes, drug-delivery, and regenerative-systems.

Comparative Evaluation of Physicomechanical Properties and Antimicrobial Activity of White Portland Micro- and Nanoparticulate Peruvian Cement, Mineral Trioxide Aggregate, and Neomineral Trioxide Aggregate.

AIM: To compare the surface microhardness, compressive strength, and antimicrobial activity of white Portland nanoparticle and microparticle Peruvian cement, mineral trioxide aggregate (MTA), and neomineral trioxide aggregate (NeoMTA) at 24 hours and 28 days. MATERIALS AND METHODS: Twenty specimens were prepared for each group of cement microparticulated powder (PCm), nanoparticulated cement (PCn), MTA, and NeoMTA to be evaluated at two different times, 24 hours and 28 days for the surface microhardness test and compressive strength. For the antimicrobial activity tests, another 20 specimens were prepared for each group of cement where they were subdivided into two subgroups according to the different periods at 24 hours and 48 hours. For the surface microhardness and compressive strength, the specimens, and the cement groups were mixed according to the manufacturer's instructions and transferred to a cylindrical polyethylene mold of 6-mm diameter and 4-mm height. The compressive strength test was conducted using a universal testing machine. Moreover, the agar diffusion technique was to evaluate the antibacterial and antifungal activity of the American Type Culture Collection (ATCC) Enterococcus faecalis and Candida albicans. Finally, the data were statistically analyzed. RESULTS: The highest microhardness values for the 24-hour subgroup were recorded for NeoMTA cement (16.99 ± 2.02), followed by MTA, PCn, and PCm, respectively. As for the 28-day subgroup, PCn cement (41.64 ± 3.20) presented the highest microhardness, followed by NeoMTA, PCm, and MTA, respectively, with statistically significant differences among them. The compressive strength of both subgroups 24 hours and 28 days exhibited the highest mean for PCn (41.3 ± 4.29, 65.74 ± 3.06), followed by PCm, NeoMTA, and the lowest value for MTA cement. Finally, for the antimicrobial activity, the highest mean for the 24-hours and 48-hours subgroup was recorded for NeoMTA cement (17.6 ± 1.26, 17.8 ± 1.44), followed by PCn, PCm, and the lowest value for MTA, with significant differences between them. CLINICAL SIGNIFICANCE: It is highly recommended, Portland cement (PC) as a viable substitute since it has very similar components and properties, but at a lower cost. CONCLUSION: Regardless of the evaluation time, PCn produced higher surface microhardness and compressive strength; however, NeoMTA showed higher antimicrobial activity.

Fabrication and characterization of remineralizing dental composites containing calcium type pre-reacted glass-ionomer (PRG-Ca) fillers.

OBJECTIVE: To fabricate and characterize dental composites with calcium type pre-reacted glass-ionomer (PRG-Ca) fillers. METHODS: PRG-Ca fillers were prepared by the reaction of calcium fluoroaluminosilicate glass with polyacrylic acid. Seven dental composites were produced from the same organic matrix (70/30wt% Bis-GMA/TEGDMA), with partial replacement of barium borosilicate (BaBSi) fillers (60wt%) by PRG-Ca fillers (wt%): E0 (0) - control, E1 (10), E2 (20), E3 (30), E4 (40), E5 (50) and E6 (60). Enamel remineralization was evaluated in caries-like enamel lesions induced by S. mutans biofilm using micro-CT. The following properties were characterized: degree of conversion (DC%), roughness (Ra), Knoop hardness (KHN), flexural strength (FS), flexural modulus (FM), water sorption (Wsp), water solubility (Wsl), and translucency (TP). Data were analyzed to one-way ANOVA and Tukey's HSD test (α=0.05). RESULTS: All composites with PRG-Ca induced enamel remineralization. E0 and E1 presented similar and highest DC% than E2=E3=E4=E5=E6. Ra and KHN were not influenced by PRG-Ca fillers (p<0.05). The higher the content of PRG-Ca, the lower FS, FM and TP (p<0.05). Wsp increased linearly with the content of PRG-Ca fillers (p<0.05). E6 presented the highest Wsl (p<0.05), while the Wsl of the other composites were not different from each other (p>0.05). SIGNIFICANCE: Incorporation of 10-40wt.% of PRG-Ca fillers endowed remineralizing potential to dental composites without jeopardizing the overall behavior of their physicochemical properties. Dental composites with PRG-Ca fillers seems to be a good alternative for reinforcing the enamel against caries development.

Fabrication and characterization of remineralizing dental composites containing hydroxyapatite nanoparticles.

The aim of this study was to fabricate and characterize dental composites containing hydroxyapatite nanoparticles (HApNPs). Four dental composites were produced from the same organic matrix (70 wt% Bis-GMA and 30 wt% TEGDMA), with partial replacement of BaBSi particles (65 wt%) by HApNPs in the following concentrations (wt%): E0 (0) - control, E10 (10), E20 (20) and E30 (30). Ca2+ and PO43- release was evaluated in solutions with different pHs (4, 5.5, and 7) using atomic emission spectroscopy with microwave-induced nitrogen plasma while the enamel remineralization potential was evaluated in caries-like enamel lesions induced by S. mutans biofilm using micro-CT. The following properties were characterized: degree of conversion (DC%), microhardness (KHN), flexural strength (FS), elastic modulus (EM) and translucency (TP). The higher the HApNPs content, the higher the Ca2+ and PO43- release. The ions release was influenced by pH (4 > 5.5 > 7) (p < 0.05). All composites loaded with HApNPs were able to remineralize the enamel (E30 = E20 > E10) (p < 0.05). Contrarily, E0 was not able of recovering the enamel mineral loss. E0 and E10 presented highest DC%, while E20 and E30 showed similar and lowest DC%. KHN and FS were decreased with the addition of HApNPs, while EM was not influenced by the incorporation of HApNPs. E10 presented statistically similar TP to E0, while this property decreased for E20 and E30 (p < 0.05). Incorporation of HApNPs into dental composites promoted enamel remineralization, mainly at potentially cariogenic pH (= 4), while maintained their overall performance in terms of physicomechanical properties.

Characterization of low-shrinkage dental composites containing methacrylethyl-polyhedral oligomeric silsesquioxane (ME-POSS).

The aim of this study was to characterize low-shrinkage dental composites containing methacrylethyl-polyhedral oligomeric silsesquioxane (ME-POSS). Four experimental composites were manufactured, two of which contained organic matrixes of BisGMA-TEGDMA (70/30 wt% - BGC) and BisEMA-TEGDMA (80/20 wt% - BEC). The two other experimental composites replaced BisGMA and BisEMA with 25 wt% of ME-POSS (BGP and BEP). The composites also contained 70 wt% of 0.7 µm silanized BaBSi particles. The following properties were evaluated: Degree of conversion (DC%), volumetric polymerization shrinkage (VS%), polymerization shrinkage stress (Pss), flexural strength (FS), Flexural modulus (FM), hardness (KHN), water sorption (Wsp), water solubility (Wsl), diffusion coefficient (D), and wear. The DC% was not influenced by the presence of ME-POSS, with BEC (75.6%) and BEP (74.8%) presenting higher DC% than BGC (60.6%) and BGP (55.6%). The ME-POSS-containing composites (BGP and BEP) presented significantly lower VS% and Pss. The FS ranged from 92.7 to 142.0 MPa and the FM from 3.6 to 10.3 GPa. ME-POSS did not influence the KHN. BEC and BEP presented lower Wsp and Wsl when compared to BGC and BGP. D ranged from 1.0 × 10-6 to 7.4 × 10-6 cm2 m-1. Incorporation of ME-POSS significantly decreased the wear for both binary matrices (p < 0.05). With the exception of FS and FM for BGP, the incorporation of ME-POSS decreased the VS% and Pss without jeopardizing the other properties of the experimental dental composites.

Promoted Osteoconduction of Polyurethane-Urea Based 3D Nanohybrid Scaffold through Nanohydroxyapatite Adorned Hierarchical Titanium Phosphate.

The lack of optimal physiological properties, bacterial colonization, and auto-osteoinduction, are the foremost issues of orthopedic implantations. In terms of bone healing, many researchers have reported the release of additional growth factors of the implanted biomaterials to accelerate the bone regeneration process. However, the additional growth factor may cause side effects such as contagion, nerve pain, and the formation of ectopic bone. Thus, the design of an osteoconductive scaffold having excellent biocompatibility, appropriate physicomechanical properties, and promoted auto osteoinductivity with antibacterial activity is greatly desired. In this study, 2D rodlike nanohydroxyapatite (nHA) adorned titanium phosphate (TP) with a flowerlike morphology was synthesized by a hydrothermal precipitation reaction. The nanohybrid material (nHA-TP) was incorporated into the synthesized polycaprolactone diol and spermine based thermoplastic polyurethane-urea (PUU) via in situ technique followed by salt leaching to fabricate the macroporous 3D polymer nanohybrid scaffold (PUU/nHA-TP). Structure explication of PUU was performed by NMR spectroscopy. The synthesized nanohybrid scaffold with 1% nHA-TP showed 67% increase of tensile strength and 18% improved modulus compared to the pristine PUU via formation of H-bonding or dative bonds between the metal and the amide linkage of the polyurethane or polyurea. In vitro study showing improved cell viability and proliferation of the seeded cell revealed the superior osteoconductivity of the nanohybrid scaffold. Most importantly, the in vivo experiments revealed a significant amount of bone regeneration in the nanohybrid scaffold implanted tibial site compared to the pristine scaffold without any toxic effect. Introduction of the minute amount of titanium phosphate within the adorned nHA promotes the osteoconductivity significantly by the capability of forming coordinate bonds of the titanium ion. Depending on the mechanical, physicochemical, in vitro characteristics, and in vivo osteoconductivity, the PUU/nHA-TP nanohybrid scaffold has great potential as an alternative biomaterial in bone tissue regeneration application.