scholarly journals Tuning Nano-Amorphous Calcium Phosphate Content in Novel Rechargeable Antibacterial Dental Sealant

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1544 ◽  
Author(s):  
Maria Ibrahim ◽  
Faisal AlQarni ◽  
Yousif Al-Dulaijan ◽  
Michael Weir ◽  
Thomas Oates ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Flexural Strength ◽  
Amorphous Calcium Phosphate ◽  
Mechanical Performance ◽  
Flexural Modulus ◽  
Dental Materials ◽  
Ion Release ◽  
Dental Sealants ◽  
Mass Fractions ◽  
The Impact

Dental sealants with antibacterial and remineralizing properties are promising for caries prevention among children and adolescents. The application of nanotechnology and polymer development have enabled nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) to emerge as anti-caries strategies via resin-based dental materials. Our objectives in this study were to (1) incorporate different mass fractions of NACP into a parental rechargeable and antibacterial sealant; (2) investigate the effects on mechanical performance, and (3) assess how the variations in NACP concentration would affect the calcium (Ca) and phosphate (PO4) ion release and re-chargeability over time. NACP were synthesized using a spray-drying technique and incorporated at mass fractions of 0, 10, 20 and 30%. Flexural strength, flexural modulus, and flowability were assessed for mechanical and physical performance. Ca and PO4 ion release were measured over 70 days, and three ion recharging cycles were performed for re-chargeability. The impact of the loading percentage of NACP upon the sealant’s performance was evaluated, and the optimized formulation was eventually selected. The experimental sealant at 20% NACP had flexural strength and flexural modulus of 79.5 ± 8.4 MPa and 4.2 ± 0.4 GPa, respectively, while the flexural strength and flexural modulus of a commercial sealant control were 70.7 ± 5.5 MPa (p > 0.05) and 3.3 ± 0.5 GPa (p < 0.05), respectively. A significant reduction in flow was observed in the experimental sealant at 30% NACP (p < 0.05). Increasing the NACP mass fraction increased the ion release. The sealant formulation with NACP at 20% displayed desirable mechanical performance and ideal flow and handling properties, and also showed high levels of long-term Ca and PO4 ion release and excellent recharge capabilities. The findings provide fundamental data for the development of a new generation of antibacterial and rechargeable Ca and PO4 dental sealants to promote remineralization and inhibit caries.

Effect of low nanoclay content on the physico-mechanical properties of poly(lactic acid) nanocomposites

2018 ◽  
Vol 27 (2) ◽  
pp. 43-54 ◽  
Author(s):  
JR Robledo-Ortíz ◽  
AS Martín del Campo ◽  
EJ López-Naranjo ◽  
M Arellano ◽  
CF Jasso-Gastinel ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Impact Strength ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Flexural Modulus ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Degradation Temperature ◽  
Nanoclay Content ◽  
The Impact

In this work, three different nanoclays (1.44P, 1.34MN, and Cloisite 15A) were used to reinforce an injection grade poly(lactic acid) (PLA). The nanocomposites (NCs) were prepared using three different nanoclay concentration levels (1, 3, and 5 wt%) in a twin-screw extruder. To evaluate their mechanical performance (static and dynamic tests) and thermal properties, the respective samples were obtained by injection molding. Results showed that the three nanoclays significantly increased the tensile and flexural modulus of the injection grade PLA. The 1.34MN NCs also showed improvement in the tensile strength. An increment in flexural strength was obtained with 1.34MN and 1.44P nanoclays, while with nanoclay 15A, the flexural strength decreased. Additionally, the use of 5 wt% of 1.44P nanoclay allowed an increase in impact strength while using 1.34MN and 15A nanoclays, the impact strength was similar to the one observed for pure PLA. In general, mechanodynamic analysis results showed that storage modulus increased with nanoclay content; while thermogravimetric analysis indicated that none of the nanoclays has a significant effect over the degradation temperature of pure PLA. Differential scanning calorimetry results showed that the crystallinity of PLA is enhanced with nanoclay inclusion. For 1.34MN NCs, X-ray diffraction observations exposed that the mineral clay relative intensity peaks disappeared indicating nanoclay exfoliation, which contributes to the increase in tensile and flexural strength in the NCs. Nevertheless for 1.44P and 15A nanoclays, an increase in the interlayer distance (intercalation) was detected.

scholarly journals Is Micro X-ray Computer Tomography a Suitable Non-Destructive Method for the Characterisation of Dental Materials?

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1271
Author(s):  
Andreas Koenig ◽  
Leonie Schmohl ◽  
Johannes Scheffler ◽  
Florian Fuchs ◽  
Michaela Schulz-Siegmund ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Computer Tomography ◽  
Mechanical Performance ◽  
Dental Materials ◽  
Three Dimensional ◽  
X Rays ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Multiple Measurements ◽  
High Doses

The aim of the study was to investigate the effect of X-rays used in micro X-ray computer tomography (µXCT) on the mechanical performance and microstructure of a variety of dental materials. Standardised bending beams (2 × 2 × 25 mm3) were forwarded to irradiation with an industrial tomograph. Using three-dimensional datasets, the porosity of the materials was quantified and flexural strength was investigated prior to and after irradiation. The thermal properties of irradiated and unirradiated materials were analysed and compared by means of differential scanning calorimetry (DSC). Single µXCT measurements led to a significant decrease in flexural strength of polycarbonate with acrylnitril-butadien-styrol (PC-ABS). No significant influence in flexural strength was identified for resin-based composites (RBCs), poly(methyl methacrylate) (PMMA), and zinc phosphate cement (HAR) after a single irradiation by measurement. However, DSC results suggest that changes in the microstructure of PMMA are possible with increasing radiation doses (multiple measurements, longer measurements, higher output power from the X-ray tube). In summary, it must be assumed that X-ray radiation during µXCT measurement at high doses can lead to changes in the structure and properties of certain polymers.

scholarly journals Mechanical Performance of Unstitched and Silk Fiber-Stitched Woven Kenaf Fiber-Reinforced Epoxy Composites

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4801
Author(s):  
Yasir Khaleel Kirmasha ◽  
Mohaiman J. Sharba ◽  
Zulkiflle Leman ◽  
Mohamed Thariq Hameed Sultan
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Mechanical Test ◽  
Natural Fibers ◽  
Silk Fiber ◽  
Epoxy Composites ◽  
Test Results ◽  
The Impact ◽  
Woven Kenaf

Fiber composites are known to have poor through-thickness mechanical properties due to the absence of a Z-direction binder. This issue is more critical with the use of natural fibers due to their low strength compared to synthetic fibers. Stitching is a through-thickness toughening method that is used to introduce fibers in the Z-direction, which will result in better through-thickness mechanical properties. This research was carried out to determine the mechanical properties of unstitched and silk fiber-stitched woven kenaf-reinforced epoxy composites. The woven kenaf mat was stitched with silk fiber using a commercial sewing machine. The specimens were fabricated using a hand lay-up method. Three specimens were fabricated, one unstitched and two silk-stitched with deferent stitching orientations. The results show that the stitched specimens have comparable in-plane mechanical properties to the unstitched specimens. For the tensile mechanical test, stitched specimens show similar and 17.1% higher tensile strength compared to the unstitched specimens. The flexural mechanical test results show around a 9% decrease in the flexural strength for the stitched specimens. On the other hand, the Izod impact mechanical test results show a significant improvement of 33% for the stitched specimens, which means that stitching has successfully improved the out-of-plane mechanical properties. The outcome of this research indicates that the stitched specimens have better mechanical performance compared to the unstitched specimens and that the decrease in the flexural strength is insignificant in contrast with the remarkable enhancement in the impact strength.

Effect of CPP-ACP Application on Flexural Strength of Bleached Enamel and Dentin Complex

2011 ◽  
Vol 36 (4) ◽  
pp. 372-379 ◽  
Author(s):  
M Khoroushi ◽  
H Mazaheri ◽  
AE Manoochehri
Keyword(s):  
Calcium Phosphate ◽  
Flexural Strength ◽  
Amorphous Calcium Phosphate ◽  
Clinical Relevance ◽  
In Vitro Simulation ◽  
Casein Phosphopeptide ◽  
Bovine Enamel ◽  
At Home

Clinical Relevance In the absence of saliva, flexural strength of the bovine enamel-dentin complex decreases after in vitro simulation of both at-home and in-office bleaching procedures. Application of Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) subsequent to both bleaching regimens could compensate for this decrease.

Natural durability of organomodified layered silicate filled wood flour reinforced polypropylene nanocomposites

2013 ◽  
Vol 20 (3) ◽  
pp. 227-232 ◽  
Author(s):  
Behzad Kord
Keyword(s):  
Weight Loss ◽  
Flexural Strength ◽  
Water Absorption ◽  
Wood Flour ◽  
Flexural Modulus ◽  
Layered Silicate ◽  
Natural Durability ◽  
Thickness Swelling ◽  
Melt Mixing ◽  
The Impact

AbstractThe effect of organomodified montmorillonite (OMMT) loading on the natural durability properties of polypropylene/wood flour composites exposed to brown-rot fungi (Coniophora puteana) was studied. To meet this objective, the blend composites were prepared through the melt mixing of polypropylene/wood flour at 50% weight ratios, with various amounts of OMMT (0, 3 and 6 per hundred compounds [phc]) in a hake internal mixer. The samples were then made by injection molding. The amount of coupling agent was fixed at 2 phc for all formulations. After specimen and culture medium preparation, the specimens were exposed to the purified fungus at 25°C and 75% relative humidity for 14 weeks. Identical specimens of the same composite, without being exposed to the fungus, were provided as the control specimens. After the discussed periods; weight loss, flexural strength, flexural modulus, hardness, water absorption, and thickness swelling of specimens were measured. Results indicated that OMMT had significant effects on the natural durability of the studied composite formulations. All mechanical properties were affected by the fungus, to a greater extent in the case of specimens without OMMT than the specimens with OMMT. Furthermore, the flexural strength and modulus increased with an increase of OMMT up to 3 phc and then decreased. However, the impact strength, water absorption and thickness swelling was decreased with increase of OMMT loading. Also, the lowest weight loss and the highest hardness were observed in the composite containing 6 phc organoclay. The morphology of the nanocomposites was examined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Morphological findings revealed that intercalation came from the sample with 3 phc concentration of OMMT, which implies the formation of intercalation morphology and better dispersion than 6 phc.

Amorphous Calcium Phosphate Based Polymeric Composites: Effects of Polymer Composition and Filler's Particle Size on Composite Properties

2005 ◽  
Vol 284-286 ◽  
pp. 737-740 ◽  
Author(s):  
Drago Skrtic ◽  
S.Y. Lee ◽  
Joseph M. Antonucci ◽  
D.W. Liu
Keyword(s):  
Particle Size ◽  
Calcium Phosphate ◽  
Physicochemical Properties ◽  
Amorphous Calcium Phosphate ◽  
Fine Tuning ◽  
Polymer Composition ◽  
Ion Release ◽  
The Matrix ◽  
Carboxylic Groups ◽  
Composite Properties

This study explores how a) the resin grafting potential for amorphous calcium phosphate (ACP) and b) particle size of ACP affects physicochemical properties of composites. Copolymers and composites were evaluated for biaxial flexure strength (BFS), degree of vinyl conversion (DC), mineral ion release and water sorption (WS). Milled ACP composites were superior to unmilled ACP composites and exhibited 62 % and 77 % higher BFS values (dry and wet state, respectively). The average DC of copolymers 24 h after curing was 80 %. DC of composites decreased 10.3 % for unmilled Zr-ACP and 4.6 % for milled Zr-ACP when compared to the corresponding copolymers. The WS increased as follows: copolymers < milled Zr-ACP composites < unmilled Zr-ACP composites. The levels of Ca and PO4 released from both types of composites increased with the increasing EBPADMA/TEGDMA ratio in the matrix. They were significantly above the minimum necessary for the redeposition of HAP to occur. No significant consumption of released calcium by the carboxylic groups of methacryloxyethyl phtahalate (MEP) occurred at a mass fraction of 2.6 % of MEP in the resin. Improvements in ACP composite’s physicochemical properties are achieved by fine tuning of the resin and improved ACP’s dispersion within the polymer matrix after ball-milling.

Effect of Chitosan-Grafted-Poly (Methyl Methacrylate) Content on Mechanical Properties and Thermal Degradation of Poly (Vinyl Chloride) Composites

2015 ◽  
Vol 735 ◽  
pp. 3-7
Author(s):  
Aznizam Abu Bakar ◽  
Nur Azmyra Abdul Aziz ◽  
Azman Hassan ◽  
Nurhusna Azmi
Keyword(s):  
Flexural Strength ◽  
Filler Content ◽  
Flexural Modulus ◽  
Nitrogen Atmosphere ◽  
Mechanical And Thermal Properties ◽  
Radical Initiation ◽  
Roll Mill ◽  
Free Radical Initiation ◽  
The Impact ◽  
Thermal Stability Of

The graft copolymerization was carried out under nitrogen atmosphere using the free radical initiation technique. The blend formulations were first dry blended using a mixer before being milled into sheets on a two-roll mill at 170°C, and then hot pressed into composites specimens at 175°C for 10 min. The objective of this study to investigate the mechanical and thermal properties of PVC blends. The flexural strength and modulus of ungrafted composites increased with increasing filler content from 2 to 10 part per hundred resin (phr) while the grafted composites also increased only from 2 to 6 phr filler content. The flexural modulus of ungrafted was higher compared to the grafted composites whereas the grafted showed good flexural strength than ungrafted composites. The impact strength of both composites decreased with increasing filler content but the ungrafted composites showed good toughness than grafted composites. The thermal stability of both composites increased compared to unfilled PVC.

Mechanical performance of hybrid woven jute–roselle-reinforced polyester composites

2019 ◽  
Vol 27 (7) ◽  
pp. 407-418 ◽  
Author(s):  
Mohammad Hazim Mohamad Hamdan ◽  
Januar Parlaungan Siregar ◽  
Sabu Thomas ◽  
Maya John Jacob ◽  
Jamiluddin Jaafar ◽  
...  
Keyword(s):  
Composite Plate ◽  
Synthetic Fibre ◽  
Mechanical Performance ◽  
Flexural Modulus ◽  
Natural Fibre ◽  
Impact Testing ◽  
Void Content ◽  
Fibre Reinforcement ◽  
Pull Out ◽  
The Impact

Natural fibre acts as a significant replacement for the known synthetic fibre that tends to cause critical environmental issues. Hence, the hybridization of natural fibre reinforcement has been considered as one of the strategies in reducing synthetic fibre applications. The current research was conducted to determine the effect of layering sequence on the mechanical performance of hybrid woven jute–roselle. In addition, eight different types of composite plate that consisted of single and hybrid were fabricated through the implementation of hand lay-up method. In this case, each composite plate had to undergo the tensile, flexural and impact testing in order to acquire the effect of varying layering sequences. The results of the present study showed that the hybridization of jute–roselle provided was significant, especially on the flexural and impact performance. Furthermore, the tensile strength and modulus were higher on the JRRJ sample and maximum flexural strength also managed to be recorded by the same sample. However, the maximum flexural modulus only managed to be recorded in sample RRJJ. Meanwhile, the impact testing revealed that the composite plate of sample JJRR had the highest impact strength. The void content for all the samples was acceptable because all of them were less than 7%. Finally, scanning electron microscopic image illustrated that the fractured surfaced of composite sample was typically smooth with less formation of void and fibre pull-out.

Stability of Ultrathin Amorphous Calcium Phosphate Artificial Enamel Sheets under Simulated Intraoral Environment Condition

2019 ◽  
Vol 829 ◽  
pp. 16-20
Author(s):  
Nobuhiro Kato ◽  
Mizuki Hirai ◽  
Ei Yamamoto ◽  
Shigeki Hontsu
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Dental Materials ◽  
Cross Sectional ◽  
Sem Image ◽  
Long Term Stability ◽  
Optical Images ◽  
Surface Morphologies ◽  
Environment Condition

Dental materials purely composed of calcium phosphate are ideal for the dental medicine. We have been developing ultrathin amorphous calcium phosphate (ACP) sheets for enamel repair. In this study, long term stability of the ultrathin ACP sheets applied on enamel surfaces which kept in a simulated intraoral condition for 21 days was evaluated. Surface morphologies of the ACP sheets were observed by optical images. A boundary condition between the ACP sheet and the enamel was evaluated by cross-sectional SEM image. A durability of the ACP sheet was evaluated by a brushing test conducted after 21 days incubation. As the result of these evaluations, it was confirmed that the ACP sheets were stable even after long-term incubation under the simulated intraoral environment condition.

Sign in / Sign up

Export Citation Format

Share Document