Evaluation of the Impact of Irradiance Lamps and Storage Media on Elution of TEGDMA from Dental Composites.

OBJECTIVES: The aim of this study was to evaluate and compare the effect of irradiance light and storage media on the elution of triethylene glycol dimethacrylate (TEGDMA) from conventional Filtek Z350XT 3M ESPE and two bulk-fill composites Shofu Beautifil-Bulk and Filtek Bulk fill flowable 3M ESPE using high-performance liquid chromatography (HPLC). MATERIALS AND METHODS: Shofu Beautifil-Bulk, Filtek Bulk fill flowable 3M ESPE, and Filtek Z350XT 3M ESPE were the three types of composites used in this study. Disk shaped samples of 4-mm thickness and 10-mm diameter were fabricated using a stainless steel mold and were polymerized using light emitting diode (LED) and quartz tungsten halogen (QTH) lamps. After polymerization, the samples were immersed in ethanol, artificial saliva with betel quid extract, and distilled water for 1, 7, and 30 days, respectively. The elution of monomer TEGDMA was evaluated using HPLC. STATISTICAL ANALYSIS: To evaluate the mean concentration difference, mixed way analysis of variance (ANOVA) was applied. Between different light, materials, and within the time duration, Tukey's post hoc test was used. A p value of 0.05 was considered significant. RESULTS: During the first day of storage, a significant amount of monomer TEGDMA elution was seen in all the materials. The highest values observed to be in the disks cured with QTH lamp. However, the highest elution was seen when the disks were immersed in ethanol/water solution. While the most stable medium was distilled water, artificial saliva with betel nut extract also had a significant effect on the elution of TEGDMA. The highest value obtained was of Filtek Bulk fill flowable 3M ESPE after 30 days of immersion in both LED and QTH cured disks. CONCLUSION: Filtek Bulk fill flowable 3M ESPE shows better properties in relation to the release of monomer TEGDMA as it releases less amount of monomer in the storage media. The release of monomer was highest in ethanol as compared to artificial saliva and distilled water with the passage of time.

Chitosan-based materials for dental implantology: A comprehensive review.

Chitosan, a versatile biopolymer, has gained recognition in the discipline of dental implantology due to possessing salient properties. This comprehensive review explores the potential of chitosan in dental implants, focusing on its biocompatibility, bioactivity, and the various chitosan-based materials that have been utilized for dental implant therapy. The review also highlights the importance of surface treatment in dental implants to enhance osseointegration and inhibit bacterial biofilm formation. Additionally, the chemical structure, properties, and sources of chitosan are described, along with its different structural forms. The characteristics of chitosan particularly color, molecular weight, viscosity, and degree of deacetylation are discussed about their influence on its applications. This review provides valuable insights into the promising utilization of polymeric chitosan in enhancing the success and functionality of dental implants. This study highlights the potential applications of chitosan in oral implantology. Chitosan possesses various advantageous properties, including muco-adhesiveness, hemostatic action, biocompatibility, biodegradability, bioactivity, and antibacterial and antifungal activities, which enhance its uses in dental implantology. However, it has limited aqueous solubility at the physiological pH, which sometimes restricts its biological application, but this problem can be overcome by using modified chitosan or chitosan derivatives, which have also shown encouraging results. Recent research suggests that chitosan may act as a promising material for coating titanium-based implants, improving osteointegration together with antibacterial properties.

Exploring the Effect of Cetylpyridinium Chloride Addition on the Antibacterial Activity and Surface Hardness of Resin-Based Dental Composites.

The aim of this study was to evaluate the effect of cetylpyridinium chloride (CPC) addition on the antibacterial and surface hardness characteristics of two commercial resin-based dental composites (RBDCs). A total of two hundred and seventy (n = 270) specimens from Filtek Z250 Universal and Filtek Z350 XT flowable RBDCs were fabricated with the addition of CPC at 2 %wt and 4 %wt concentrations to assess their antibacterial activity using the agar diffusion test and direct contact inhibition test, and their surface hardness using the Vickers microhardness test after 1 day, 30 days, and 90 days of aging. A surface morphology analysis of the specimens was performed using a scanning electron microscope (SEM). The RBDCs that contained 2 %wt and 4 %wt CPC demonstrated significant antibacterial activity against Streptococcus mutans up to 90 days, with the highest activity observed for the 4 %wt concentration. Nevertheless, there was a reduction in antibacterial effectiveness over time. Moreover, compared to the control (0 %wt) and 2 %wt CPC groups, the universal RBDCs containing 4 %wt CPC exhibited a notable decrease in surface hardness, while all groups showed a decline in hardness over time. In conclusion, the satisfactory combination of the antibacterial effect and surface hardness property of RBDCs was revealed with the addition of a 2 %wt CPC concentration.

Biocatalytic potential of Brassica oleracea L. var. botrytis leaves peroxidase for efficient degradation of textile dyes in aqueous medium.

Dye-contaminated wastewater discharge from textile and dye manufacturing industries is reported as a world worse water polluter due to the toxic and mutagenic behavior of dyes. Peroxidase, one of the key enzymes of oxidoreductases, is widely distributed in nature and has been currently exploited in industries for various applications. Widespread applications of peroxidases are associated with their nonspecific nature towards a wide spectrum of substrates such as phenols, aromatic amines, pesticides, antibiotics, and synthetic dyes. The present study explored the potential of ammonium sulfate precipitated partially purified Brassica oleracea L. var. botrytis leaves peroxidase for degradation of reactive textile dyes Remazol Turquoise Blue 133 G and Drim Red CL4BN. Various physico-chemical parameters such as pH (2-9), temperature (20-70 â„ƒ), enzyme activity (3-24 U/mL), concentrations of H2O2 (0.4-1.4 Mm) and dye (10-100 mg/L) were optimized for enzymatic decolorization of both dyes' solution. Studies revealed that maximum degradation (95%) of Remazol Turquoise Blue 133 G with peroxidase was achieved with 25 mg/L of initial dye concentration, in the presence of 0.8 mM hydrogen peroxide with 45 min of incubation time, at pH 3, 4, and 5, and 70 °C. Maximal decolorization (97%) of Drim Red CL4BN was obtained at pH 2.0, in 10 min of incubation time at 45 â„ƒ using o-dianisidine hydrochloride as a redox mediator. In conclusion, the findings illustrate the prospect of Brassica oleracea peroxidase to remediate dye pollutants and dye-based industrial effluents in a green technology theme.

Biomimetic Approaches in Clinical Endodontics.

In the last few decades, biomimetic concepts have been widely adopted in various biomedical fields, including clinical dentistry. Endodontics is an important sub-branch of dentistry which deals with the different conditions of pulp to prevent tooth loss. Traditionally, common procedures, namely pulp capping, root canal treatment, apexification, and apexigonesis, have been considered for the treatment of different pulp conditions using selected materials. However, clinically to regenerate dental pulp, tissue engineering has been advocated as a feasible approach. Currently, new trends are emerging in terms of regenerative endodontics which have led to the replacement of diseased and non-vital teeth into the functional and healthy dentine-pulp complex. Root- canal therapy is the standard management option when dental pulp is damaged irreversibly. This treatment modality involves soft-tissue removal and then filling that gap through the obturation technique with a synthetic material. The formation of tubular dentine and pulp-like tissue formation occurs when stem cells are transplanted into the root canal with an appropriate scaffold material. To sum up tissue engineering approach includes three components: (1) scaffold, (2) differentiation, growth, and factors, and (3) the recruitment of stem cells within the pulp or from the periapical region. The aim of this paper is to thoroughly review and discuss various pulp-regenerative approaches and materials used in regenerative endodontics which may highlight the current trends and future research prospects in this particular area.

Evaluating the pH of Various Commercially Available Beverages in Pakistan: Impact of Highly Acidic Beverages on the Surface Hardness and Weight Loss of Human Teeth.

The objectives of this study were to investigate the pH of common beverages and to evaluate the effects of common acidic beverages on the surface hardness and weight loss of human tooth specimens. A total of 106 beverages were conveniently purchased from supermarkets in Karachi, Pakistan. Prior to evaluation, beverages were refrigerated or stored at room temperature in accordance with the manufacturers' recommendations. Beverages were categorized into six groups: 'Sports and Energy drinks', 'Water', 'Fruit Juices and Drinks', 'Sodas', 'Milk and Flavored Milk' and 'Teas and Coffee'. Using a pH meter, the pH of each beverage was measured in triplicate at room temperature. In addition, the influence of five highly acidic beverages on the weight loss and surface hardness of human tooth specimens was evaluated using gravimetric analysis and the Vickers hardness tester, respectively. 'Sports and Energy drinks', 'Fruits Juices and Drinks' and 'Sodas' were the most acidic beverage categories, with a pH range of 3.00−5.00. A total of 33% of beverages tested in this study were highly acidic (pH less than 4.00), 29% of beverages were moderately acidic (pH 4.00−4.99) and 31% were mildly acidic (pH 5.00−6.99). Significant weight loss was observed in all immersed specimens compared to control counterparts (p < 0.05). Similarly, for surface hardness, five highly acidic beverages (Red Bull, Pepsi, Apple Cidra, Tang Mosambi and Tang Orange) significantly decreased the surface hardness of specimens (p < 0.05). The pH levels of commonly available beverages in Pakistan are highly acidic, which may encourage loss of minerals from teeth; hence, affecting their surface hardness.

Effect of Nanostructures on the Properties of Glass Ionomer Dental Restoratives/Cements: A Comprehensive Narrative Review.

Overall perspective of nanotechnology and reinforcement of dental biomaterials by nanoparticles has been reported in the literature. However, the literature regarding the reinforcement of dental biomaterials after incorporating various nanostructures is sparse. The present review addresses current developments of glass ionomer cements (GICs) after incorporating various metallic, polymeric, inorganic and carbon-based nanostructures. In addition, types, applications, and implications of various nanostructures incorporated in GICs are discussed. Most of the attempts by researchers are based on the laboratory-based studies; hence, it warrants long-term clinical trials to aid the development of suitable materials for the load bearing posterior dentition. Nevertheless, a few meaningful conclusions are drawn from this substantial piece of work; they are as follows: (1) most of the nanostructures are likely to enhance the mechanical strength of GICs; (2) certain nanostructures improve the antibacterial activity of GICs against the cariogenic bacteria; (3) clinical translation of these promising outcomes are completely missing, and (4) the nanostructured modified GICs could perform better than their conventional counterparts in the load bearing posterior dentition.

Biomimetic Aspects of Restorative Dentistry Biomaterials.

Biomimetic has emerged as a multi-disciplinary science in several biomedical subjects in recent decades, including biomaterials and dentistry. In restorative dentistry, biomimetic approaches have been applied for a range of applications, such as restoring tooth defects using bioinspired peptides to achieve remineralization, bioactive and biomimetic biomaterials, and tissue engineering for regeneration. Advancements in the modern adhesive restorative materials, understanding of biomaterial-tissue interaction at the nano and microscale further enhanced the restorative materials' properties (such as color, morphology, and strength) to mimic natural teeth. In addition, the tissue-engineering approaches resulted in regeneration of lost or damaged dental tissues mimicking their natural counterpart. The aim of the present article is to review various biomimetic approaches used to replace lost or damaged dental tissues using restorative biomaterials and tissue-engineering techniques. In addition, tooth structure, and various biomimetic properties of dental restorative materials and tissue-engineering scaffold materials, are discussed.

Production, thermodynamic characterization, and fruit juice quality improvement characteristics of an Exo-polygalacturonase from Penicillium janczewskii.

Exo-polygalacturonase (Exo-PG), an extracellular pectinolytic enzyme with great potential in the food industry, was produced from Penicillium janczewskii under solid-state fermentation using wheat bran as a lignocellulosic substrate. Optimization of various fermentation process variables revealed that a moisture level of 70%, d-mannitol (carbon source), yeast extract (nitrogen source) and ZnSO4/NiCl2 as metal salt inducers generated the maximum yield of Exo-PG. After ammonium sulfate precipitation (70% saturation level), the enzyme was characterized in terms of various kinetic (i.e., temperature, pH, inhibitors, Michaelis-Menten constants) and thermodynamic parameters (i.e., Ea, ΔH*, ΔS* and ΔG*). The temperature and pH optima were 45 °C and 6.0, respectively, and the Exo-PG presented stability at a wider range of temperature and pH values. Metal ions Mn+2 markedly improved the enzyme activity, while exposure to urea and ethylenediaminetetraacetic acid drastically inhibited the biocatalytic performance. The kinetic parameters i.e., km and Vmax were computed to be 10 mM and 41.67 U/mL, respectively. A profound increase in clarity, yield, and reduction in viscosity was achieved for different fruit juices (apple, mango, and peach) after treatment with Exo-PG. Total antioxidant and total phenolic contents were also ameliorated. In conclusion, the catalytic activity, thermal steadiness, and fruit juices clarification performance of Exo-PG manifests a great prospect for bio-industrial exploitation.

Flexural strength of modified and unmodified acrylic denture base material after different processing techniques.

BACKGROUND: Conventional heat cure polymerized acrylic resin(unmodified) is most acceptable denture base material in dentistry since decades. It has been modified with reinforcement of fillers and different processing techniques were introduced to enhance its mechanical and physical properties. The objective of this research is to determine and compare the effect of different processing techniques on flexural strength of modified and unmodified denture base acrylic resin. Air circulating oven is introduced for the first time in this study and its efficacy is also compared with other conventional processing techniques. METHODS: In this study total number of 114 rectangular specimens were fabricated by conventional heat cured acrylic (Stellon QC 20, Dentsply) for Group A (n=57), and rubber reinforced acrylic resin (High impact, Meadway) for Group B (n=57). Three equipment including water bath, dry oven and air circulating oven were utilized for processing specimens individually. Each sub-group of processing techniques (n=19) were tested for flexural strength through a three-point bending test by a universal testing machine. The statistical analysis initiated with descriptive analysis followed by independent t test for mean comparison of flexural strength of all three processing techniques among both testing group. One-way ANOVA and 2-way ANOVA followed by Scheffe post hoc test were also applied. p-value of 0.05 or less was considered as significant. RESULTS: Statically significant p-value <0.001 was found in response of flexural strength in all processing techniques (water bath, dry oven, air circulating oven) of both testing groups. Water bath processing demonstrated highest flexural strength values in both denture base material used in this study. The unit used for flexural strength was MPa. CONCLUSION: This study manifested highest flexural strength in conventional and rubber reinforced heat cure samples when processed through water bath. Air circulating oven also presented acceptable flexural strength in conventional heat cure acrylic resin specimens when compared with other techniques.

Recent advances in the production strategies of microbial pectinases-A review.

Pectinases, member of the hydrolases family of enzymes, are one of the important enzymes of the biotechnological sector with 25% share in the global food and beverage enzyme market. They hold a leading position among the commercially produced industrial enzymes. These enzymes are sustainable and environmentally-friendly tool of nature with wide application perspective in many industrial processes, such as, retting and degumming of plant fibers, fermentation of tea and coffee, oil extraction, clarification of fruit juices and wine, valorization of industrial wastes, debasement of cellulosic biomass for biofuel production, wastewater remediation, desizing, scouring and bleaching of fabric, animal feed production, and protoplast fusion technology etc. However, like many other industrial enzymes, pectinases also face the constraint of low yield and productivity in its economized production. Therefore, pectinases have been the target of studies aiming to achieve the expression levels on a commercial scale. Among the natural sources of pectinases, microbial pectinases are employed frequently owing to its ease of production and unique physicochemical properties. This review mainly focuses on the production of pectinase enzymes along with different types of recent strategies used for their production optimization to get overexpression/production. The promise of genetic engineering approaches applied so far to get the higher production of these enzymes using simpler molecular devices and simple fermentation media is also covered in this review.

Purification, Kinetic, and Thermodynamic Characteristics of an Exo-polygalacturonase from Penicillium notatum with Industrial Perspective.

An extracellular exo-polygalacturonase (exo-PG) produced by Penicillium notatum was purified (3.07-folds) by ammonium sulfate fractionation, ion exchange, and gel filtration chromatography. Two distinct isoforms of the enzyme, namely exo-PGI and exo-PGII, were identified during column purification with molecular weights of 85 and 20 kDa, respectively, on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme displayed its optimum activity at pH 6.0 and 50 °C and was found to be stable in the slightly acidic pH (ranging from 4.5 to 6.0). Michaelis-Menten parameters, i.e., K m (app) and V max for pectin hydrolysis, were calculated to be 16.6 mg/mL and 20 µmol/mL/min, respectively. The enzyme followed biphasic deactivation kinetics. Phase I of the exo-PGI showed half-lives of 6.83 and 2.39 min at 55 and 80 °C, respectively, whereas phase II of the enzyme exhibited a half-life of 63.57 and 22.72 min at 55 and 80 °C, respectively. The activation energy for denaturation was 51.66 and 44.06 kJ/mol for phase I and phase II of the exo-PGI, respectively. The enzyme activity was considerably enhanced by Mn2+, whereas exposure to a hydrophobic environment (urea and sodium azide solution) drastically suppressed the enzyme activity. Results suggest that exo-PGI might be considered as a potential candidate for various applications, particularly in the food and textile industries.

Improvement of activity, thermo-stability and fruit juice clarification characteristics of fungal exo-polygalacturonase.

An extracellular exo-polygalacturonase (exo-PG) from Penicillium notatum was immobilized in sodium-alginate matrix through two different protocols, viz. covalent bonding and adsorption to enhance its catalytic activity, thermal stability and life-time properties for industrial applications. Covalent immobilization was more efficient in terms of high relative activity (45.89%) and immobilization yield (71.6%) as compared to adsorption. Immobilized exo-PG derivatives displayed maximum activities at pH 5.5 and 55°C as compared to free enzyme which showed its optimum activity at pH 6.0 and 50°C. The affinity of enzyme towards its substrate (Km(app)) was reduced after immobilization and Vmax of covalently immobilized exo-PG decreased to 66.7% while the Vmax value of adsorbed enzyme increased up to 150% as compared to free counterpart. Both immobilization techniques greatly enhanced the thermal stability profile of the enzyme. At 60°C, immobilized exo-PGs retained more than 90% of their residual activities after 60min of heating, while free enzyme did not show any activity at the same temperature. Thermodynamic properties (i.e., Ea, ΔH*, ΔS*and ΔG*) of the free and immobilized enzymes were also investigated. Sodium-alginate covalently immobilized and adsorbed enzymes showed excellent recycling efficiencies and retained 50.0% and 41.0% of original activities, respectively after seven consecutive batch reactions. Moreover, the immobilized enzymes treatment achieved promising results in turbidity and viscosity reduction as well as clarity amelioration in various fruit juices. Altogether catalytic, thermo-stability and fruit juices clarification characteristics of the immobilized ex-PGs suggest a high potential for biotechnological exploitability.

Microhardness of heat cure acrylic resin after treatment with disinfectants.

OBJECTIVE: To evaluate the effect of disinfectants and distilled water on the micro-hardness of heat cure acrylic resins. METHODS: The case-control study was conducted at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, and Nadirshaw Edulji Dinshaw University of Engineering and Technology, Karachi, from April to October 2011. Specimens were fabricated from heat cure acrylic resin material and they were divided into four equal groups. Group 1 was evaluated at baseline and was taken as the control group. Group 2 was immersed in distilled water for 20 minutes, Group 3 in1% sodium hypochlorite for 20 minutes, and Group 4 in 2% alkaline gluteraldehyde for 10 minutes. All specimens were polished, stored in distilled water for 24 hours prior to experiment. All the specimens were immersed twice daily for a total of 60 days after which they were tested for Vickers micro-hardness test. Statistical analysis was conducted with one-way analysis of variance and Tukey post hoc test (a=0.05). RESULTS: There were 72 specimens divided into four groups of 18(25%) each. Statistically significant differences were found among all groups (p<0.0001). The storage medium had an effect on the micro-hardness of heat cure acrylic resins. Group 4 showed the most reduction in the hardness value which was followed by Group 3. CONCLUSIONS: The hardness of heat cure acrylic resin was affected by disinfectants.

Effect of denture cleansers on the color stability of heat cure acrylic resin.

OBJECTIVE: To compare the color stability of heat cure acrylic resin after immersion in distilled water and denture cleansers. STUDY DESIGN: In-vitro experimental study. PLACE AND DURATION OF STUDY: Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Al-Karam Textiles, Karachi, from January to April 2012. METHODOLOGY: Seventy two rectangular shaped specimens; 18 specimens were measured at baseline (control group) of the study (0 day), 18 specimens were immersed in distilled water. Eighteen (18) in Fittydent denture cleanser tablets for 10 minutes and eighteen (18) in Dentipur denture cleanser tablets for 10 minutes. Specimens were polished and stored in istilled water for 24 hours prior to experiment. After 60 days of immersion, the specimens were tested for color changes with spectrophotometer. SPSS 16 was used for statistical analysis. RESULTS: There was statistically significant difference in the color change (ΔE) among all groups (p < 0.001) after 60 days of immersion. At baseline (0 day), trace amount of color change was observed whereas when specimens were immersed in Fittydent denture cleansers tablets for 60 days noticeable change in color was observed. Very slight change in color was bserved when specimens were immersed in distilled water and dentipur denture cleanser solution. CONCLUSION: The color stability of denture base acrylic resin was influenced by the type of denture cleansers used.

Effect of disinfectants on the colour stability of heat cure acrylic resin.

BACKGROUND: Contaminated dentures need to be disinfected as a part of denture hygiene regimen. This study was conducted to determine the colour stability of heat cure acrylic resin after treatment with two disinfectants. METHODS: This in-vitro experimental study was conducted at Dr Ishrat-ul- Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Al Karam Textiles Karachi, from January to April 2012. Total 72 rectangular shaped specimens; 18 specimens were measured at baseline (control group) of the study (0 day), 18 specimens were immersed in distilled water. Eighteen (18) specimens were placed in 1% Sodium Hypochlorite solution for 20 minutes and eighteen (18) specimens were placed in Alkaline Gluteraldehyde for 10 minutes. All specimens were polished, stored in distilled water for 24 hours prior to experiment. All the specimens were immersed twice daily for total of 60 days. After 60 days of immersion the specimens were tested for colour changes with spectrophotometer. SPSS-16 was used for statistical analysis. RESULTS: There was statistically significant difference in the colour change (AE) between all groups (p<0.001) after 60 days of immersion. At baseline (0 day), trace amount of colour change was observed whereas when specimens immersed in distilled water undergo slight change in colour after 60 days of immersion. Furthermore, specimens immersed in 1% Sodium hypochlorite for 20 minutes and 2%AlklcalineGluteraldehyde for 10 minutes for 60 days twice a day showed noticeable changes in colour. CONCLUSION: There results of the study advocated that the colour stability of denture base acrylic resin is affected by the disinfectants used.

Diametral tensile strength of two dental composites when immersed in ethanol, distilled water and artificial saliva.

OBJECTIVE: To examine the effect of distilled water, artificial saliva and ethanol on the tensile strength of direct tooth-coloured restorative material. METHODS: The study was conducted at Dr. Ishrat ul Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences (DUHS), Karachi, from April 2011 to September 2012. The testing was performed at the Pakistan Council of Scientific and Industrial Research (PCSIR) laboratories. Two composite resins Filtek Z250 and Spectrum TPH were tested. Specimens (13 mm x 3 mm x 2 mm) of each material were prepared in the stainless steel mould according to the manufacturers' instructions and distributed into 3 equal groups: one immersed in distilled water, the other in artificial saliva, and the last one in ethanol for 24 hours. Tensile strength was determined after 24 hours in universal Instron Testing Machine. RESULTS: There were 72 specimens in all; 36 (50%) each for Filtek Z250 and Spectrum TPH. The three sub-groups in each case had 12 (33.3%) specimens. For the Filtek Z250, there was no statistically significant difference between immersion in distilled water and artificial saliva, but the ethanol group presented lower tensile strength (p<0.05). For the Spectrum TPH, samples immersed in ethanol and artificial saliva presented lower tensile strength compared to distilled water (p<0.05). CONCLUSION: The tested composite resins were affected by the immersion media and adversely affected the mechanical properties of composite resins.