Pit and fissure sealants — A review

Caries on the occlusal surface of dentition is a significant dental health problem. Among all of the teeth particularly molars and premolars have greater susceptibility to caries. Their susceptibility to caries is probably related to its occlusal morphology. Use of fissure sealant and fluoride have been shown to play an important role in reducing caries. This can be possible through converting the caries susceptible areas like pits and fissures into glazed surface which prevent bacterial colonization and makes the tooth easy to clean. Pit and fissure areas of enamel do not receive sufficient protection from topical or systemic fluorides, the reason for ineffectiveness of fluorides in the pit and fissure caries may be due to inaccessibility to these areas and due to the differences in enamel thickness. The most efficient way to prevent pit and fissure caries is by effectively sealing the fissures using resins called pit and fissure sealants.

Micro-structural and compositional study: ε-Fe2O3 crystals in the Hare’s Fur Jian Ware

The Jian kilns in the present-day Jianyang county of Fujian province are well-known as their thick and lustrous black-glazed porcelain production. The hare’s fur (HF) glazed Jian wares characterized by radial fur-like strips, as one of the most typical representatives of black-glazed tea bowls, are originated from phase separation of glaze melt and crystallization of iron oxides. In this work, various techniques were performed on the yellowish-brown HF samples, including portable energy-dispersive X-ray fluorescence (PXRF), synchrotron X-ray absorption near-edge spectroscopy (XANES), optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy (RS). The objective of this study was to well understand the microstructure characteristics and chemical compositions of glaze patterns. Results showed that the main constituents of the ceramic glaze were alumina (10.61-16.43 wt.%), silica (62.20-77.07 wt.%), calcium (3.85-6.97 wt.%) and iron oxide (4.10-8.35 wt.%). The studies evidenced that the presence of metastable epsilon-hematite crystals (ε-Fe2O3) formed on the brownish yellow glazed surface. Microstructural analysis revealed that there were three types of crystal structures in the glaze surface, one consisted of well-grown leaf-like or dendritic-like structure with highly ordered branches at micrometers scales, one was comprised of flower-like clusters accompanied by branches radiating from the center, petals growing along the branches and needles on both sides of the petals, and the last embraced a honeycomb structure tightly packed with plentiful spherical or irregular-shaped particles. In addition, ε-Fe2O3 crystals in the cross-section of glaze showed a gradient distribution.

Failure Analysis of a High Voltage Feedthrough of Indus-2 Synchrotron Radiation Source

In this paper, a failure analysis of a high voltage feedthrough of the Indus 2 synchrotron radiation source which brought about venting of the vacuum chamber is discussed. A detailed failure analysis demonstrated that the main cause responsible for the failure of the feedthrough was high humidity in the atmosphere surrounding the feedthrough assembly, which resulted in the corrosion of CuSil braze filler alloy at the ground terminal and also caused flashover between positive (+) and ground terminals. Thermal cycling of the insulator due to flashover resulted in spalling of glazed surface layer and assisted crack propagation from the flashover-generated surface defects. The remedial measures recommended to avoid similar failure include: thorough cleaning of feedthrough and its connectors before installation, use gasket-type sealing in the protective cover of the connector on the air side, use of metallic tubes in place of polyurethane cooling water tubes and design change of feedthrough to shift brazed joint to vacuum side.

Sintered Glass-Ceramics, Self-Glazed Materials and Foams from Metallurgical Waste Slag

The materials used for the synthesis of parent glass are 70% wt. metallurgical slag and 30% wt. industrial quartz sand. The initial batch is melted at and then quenched in water. The resulting glass frit is milled bellow 75 microns and pressed 1400 °C into “green” samples. In a next stage, they are heat treated at different temperatures with various heating rates and holding times. As a result, it is demonstrated the possibility for production variations, allowing the manufacture of three types of new materials by using the same pressed glass powders. We highlight the flexibility of the synthesis obtaining namely well densified glass-ceramics at about 950 °C, self-glazed glass-ceramics at about 1000 °C or glass-ceramic foams at approximately 1100 °C. The first set of materials is characterized by very well sintered structure combined with reasonable crystallinity; the second one—by smooth self-glazed surface with an attractive appearance and good properties and the third one—by 80–90% closed porosity and very good thermal stability above 1000 °C.

Spatial Day Light Autonomy and Energy Analysis of a Residential Building for Different Climatic Conditions and Window-to-Wall Ratios

Building envelope of the structures plays a crucial role in the energy consumption. To decrease the amount of Energy Consumption in Building, Energy saving materials and Optimal sizing of Openings to be selected. In this aspect a model is simulated by using the Design Builder Software to Analyse the Spatial Daylight Autonomy, Thermal Comfort and Annual Energy Consumption. Windows impact the heat exchanges between indoor environment and outdoor environment. This possibly permit a proper utilization of solar energy. The research aims to investigate the influence of window-to-wall ratio in different of different climate conditions in India which has been introduced as hot dry, hot humid and moderate climates. The research has studied the most possible window-to-wall ration in the region based on previous work 5%, 10%,15% and 20% out of the faced surface area of the building. This paper sketch out the modus operandi and the alike results of an analysis which targets to find out the ideal size of the glazed surface, which permits the minimum amount of overall energy consumption and determining the efficient building materials .The analyses and simulation procedures were performed using Design Builder software and the window dimensions are calculated in terms of the ratio between the glazed surface to the gross facade area, defined as window to wall ratio (WWR).

A CAD/CAM Zirconium Bar as a Bonded Mandibular Fixed Retainer: A Novel Approach with Two-Year Follow-Up

Stainless steel alloys containing 8% to 12% nickel and 17% to 22% chromium are generally used in orthodontic appliances. A major concern has been the performance of alloys in the environment in which they are intended to function in the oral cavity. Biodegradation and metal release increase the risk of hypersensitivity and cytotoxicity. This case report describes for the first time a CAD/CAM zirconium bar as a bonded mandibular fixed retainer with 2-year follow-up in a patient who is subjected to long-term treatment with fixed orthodontic appliance and suspected to have metal hypersensitivity as shown by the considerable increase of nickel and chromium concentrations in a sample of patient’s unstimulated saliva. The CAD/CAM design included a 1.8 mm thickness bar on the lingual surface of lower teeth from canine to canine with occlusal rests on mesial side of first premolars. For better retention, a thin layer of feldspathic ceramic was added to the inner surface of the bar and cemented with two dual-cured cement types. The patient’s complaint subsided 6 weeks after cementation. Clinical evaluation appeared to give good functional value where the marginal fit of digitized CAD/CAM design and glazed surface offered an enhanced approach of fixed retention.

Indoor Climate of Residential Interiors and Asymmetry of Radiation

The paper is oriented on the indoor climate of residential interiors. Questionnaire survey in new residential building has showed problems with securing quality of indoor climate. In smaller residential interiors with large glazed surface was this problem bigger. Cause of problems was formation of local thermal discomfort. One of the most serious area of local thermal discomfort is asymmetry of radiation. To clarify asymmetry of radiation, there were carried out experimental measurements in a special microclimatic laboratory for convective heating. In this paper, there is presented the scientific analysis and the outputs from measurements. In the conclusion of this paper are introduced principals for designing the residential interiors without local thermal discomfort.

Electrospinning Preparation and Properties of Tb(phen)L3/PMMA Rare Earth Luminescent Fibers

nanomicron fiber of Tb (phen)L3/poly (methyl methacrylate) (PMMA) was successfully prepared by electrospinning using ethyl acetate (EA) and N,N-dimethyl-formamide (DMF) as the solvent. The influence of collector distance, feed rate, applied voltage and the proportion of EA/DMF on the morphology of the as-prepared fibers were discussed. Based on the researched results, the nanomicron fibers with glazed surface and uniform distribution were prepared. The fluorescent spectra indicate that the nanomicron fibers have good fluorescent properties.