Degree of conversion and physicomechanical properties of newly developed flowable composite derived from rice husk using urethane dimethacrylate monomer.

This study evaluated the use of urethane dimethacrylate (UDMA) as a base monomer to prepare the newly developed flowable composite (FC) using nanohybrid silica derived from rice husk in comparison to bisphenol A-glycidyl methacrylate (Bis-GMA) on the degree of conversion and physicomechanical properties. The different loadings of base monomer to diluent monomer were used at the ratio of 40:60, 50:50, and 60:40. The bonding analysis confirmed the presence of nanohybrid silica in the newly developed FC. Independent t-test revealed a statistically significant increase in the degree of conversion, depth of cure and Vickers hardness of the UDMA-based FC, while surface roughness showed comparable results between the two base monomers. In conclusion, UDMA-based FC demonstrated superior performance with 60%-65% conversions, a significantly higher depth of cure exceeding 1 mm which complies with the Internal Standard of Organization 4049 (ISO 4049), and a substantial increase in Vickers hardness numbers compared to Bis-GMA-based FC, making UDMA a suitable alternative to Bis-GMA as a base monomer in the formulation of this newly developed FC derived from rice husk.

Evaluation of bacterial leakage and marginal adaptation of the bioceramics pulp dressing materials: an invitro study.

OBJECTIVE: To compare the sealing ability and marginal adaptation of three calcium silicate-based cement (Biodentine, Pro root MTA, MTA Angelus) using a bacterial leakage model and scanning electron microscope (SEM). METHODS: Recently extracted lower first premolars were randomly categorized into three experimental groups (n = 15 samples), positive control (n = 5 samples), and negative control group (n = 5 sample). Samples from the experimental groups and positive control group were subject to cavity Class I occlusal preparation followed by modified coronal pulpotomy. Different types of bioceramic dressing material were placed in 3 mm thickness accordingly, group 1 (Biodentine), group 2 (MTA Angelus), and group 3 (ProRoot MTA). No dressing material was placed in the positive control group (group 4). All samples were placed in the incubator for 24 h at 37℃, 100% humidity, for the materials to be completely set. The final restoration was placed using the Z350 resin composite. A double layer of nail varnish was applied over all the sample surfaces except the occlusal site. Whereas the samples' surfaces in the negative control, were completely covered. A 3 mm length was measured from the root apex of the samples from each group, before proceeding with the resection. The bacterial leakage test was performed using Enterococcus faecalis TCC 23,125, and a sample from each experimental group was randomly chosen for SEM. Data analysis was conducted under the One-way ANOVA test, completed by Tukey's post hoc test. RESULTS: There is a significant difference in sealing ability and marginal adaptation between the groups. (p < 0.05). The study showed that Pro Root MTA had the superior sealing ability and marginal adaptation compared to Biodentine and MTA Angelus. CONCLUSION: The ProRoot MTA as a coronal pulpotomy pulp dressing material, was found to have a better marginal adaptation and sealing ability compared to three other bioceramics materials. The material would be the better choice during clinical settings and procedures.

Phytochemical Compounds of Raw Versus Methanol-Extracted Kelulut, Tualang, and Manuka Honeys.

Honey has been widely used for medicinal purposes since ancient times. It is produced by stinging bees or stingless bees by processing the collected nectar or plant sap in their bodies into raw honey. Extraction of honey will result in the pooling of crude volatile bioactive materials that could enhance its benefits. This work aims to compare the phytochemical characteristics of raw and methanol-extracted honeys in the Kelulut, Tualang and Manuka honeys. All types of raw honey samples were extracted by using the methanol extraction method and both groups were analysed using gas chromatography/mass spectrometry (GC/MS) at the National Poison Centre, Universiti Sains Malaysia, Malaysia. The findings showed that 23 compounds were identified in raw Kelulut honey and 18 compounds in methanol-extracted Kelulut honey; 28 compounds were identified in raw Tualang honey and 29 compounds in methanol-extracted Tualang honey; 19 compounds in raw Manuka honey and 22 compounds in methanol-extracted Manuka honey. There were differences in the phytochemical substances detected in raw and methanol-extracted honeys. The major compounds in raw honeys were mostly from the ketone, alcohol, and ester groups, whereas the ketone group was dominant in methanol-extracted honeys. Most bioactive substances identified in the methanol-extracted variant of honeys were more concentrated than the raw variant. A majority of these substances have antimicrobial characteristics.

A Review on the Role of Earthworms in Plastics Degradation: Issues and Challenges.

Recently, the contribution of earthworms to plastic degradation and their capability to swallow smaller plastic fragments, known as microplastics, has been emphasized. The worm physically changes the size of microplastics and enhances microbial activities to increase the possibility of degradation. However, no research has shown that earthworms can chemically degrade microplastics to an element form, CO2 or H2O. In this review, previous research has been thoroughly explored to analyse the role that earthworms could play in plastic degradation in the soil. Earthworms can significantly affect the physical characteristics of plastics. However, earthworms' abilities to chemically degrade or change the chemical structure of plastics and microplastics have not been observed. Additionally, earthworms exhibit selective feeding behaviour, avoiding areas containing a high plastics concentration and rejecting plastics. Consequently, earthworms' abilities to adapt to the microplastics in soil in the environment can cause a problem. Based on this review, the challenges faced in earthworm application for plastic degradation are mostly expected to be associated with the toxicity and complexity of the plastic material and environmental factors, such as the moisture content of the soil and its temperature, microbial population, and feeding method.

The Influence of Filler Particles on the Mechanical Properties of Maxillofacial Prosthetic Silicone Elastomers: A Systematic Review and Meta-Analysis.

Although numerous studies have demonstrated the benefits of incorporating filler particles into maxillofacial silicone elastomer (MFPSE), a review of the types, concentrations and effectiveness of the particles themselves was lacking. The purpose of this systematic review and meta-analysis was to review the effect of different types of filler particles on the mechanical properties of MFPSE. The properties in question were (1) tensile strength, (2) tear strength, (3) hardness, and (4) elongation at break. The findings of this study can assist operators, technicians and clinicians in making relevant decisions regarding which type of fillers to incorporate based on their needs. The systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 26 original articles from 1970 to 2019 were selected from the databases, based on predefined eligibility criteria by two reviewers. The meta-analyses of nine papers were carried out by extracting data from the systematic review based on scoring criteria and processed using Cochrane Review Manager 5.3. Overall, there were significant differences favoring filler particles when incorporated into MFPSE. Nano fillers (69.23% of all studies) demonstrated superior comparative outcomes for tensile strength (P < 0.0001), tear strength (P < 0.00001), hardness (P < 0.00001) and elongation at break (P < 0.00001) when compared to micro fillers (30.76% of all studies). Micro fillers demonstrated inconsistent outcomes in mechanical properties, and meta-analysis of elongation at break argued against (P < 0.01) their use. Current findings suggest that 1.5% ZrSiO4, 3% SiO2, 1.5% Y2O3, 2-6% TiO2, 2-2.5% ZnO, 2-2.5% CeO2, 0.5% TiSiO4 and 1% Ag-Zn Zeolite can be used to reinforce MFPSE, and help the materials better withstand mechanical degradation.

Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review.

This paper critically reviews the impacts of supplementing trace elements on the anaerobic digestion performance. The in-depth knowledge of trace elements as micronutrients and metalloenzyme components justifies trace element supplementation into the anaerobic digestion system. Most of the earlier studies reported that trace elements addition at (sub)optimum dosages had positive impacts mainly longer term on digester stability with greater organic matter degradation, low volatile fatty acids (VFA) concentration and higher biogas production. However, these positive impacts and element requirements are not fully understood, they are explained on a case to case basis because of the great variance of the anaerobic digestion operation. Iron (Fe), nickel (Ni) and cobalt (Co) are the most studied and desirable elements. The right combination of multi-elements supplementation can have greater positive impact. This measure is highly recommended, especially for the mono-digestion of micronutrient-deficient substrates. The future research should consider the aspect of trace element bioavailability.