Calcium Silicate Cements Application in Lateral Root Perforation Repair: A Case Report with 16-Month Follow-Up

Lateral root perforations are unfortunate procedures during endodontic treatment and often lead to tooth extraction. Conditioning factors such as time, size, location, inappropriate disinfection and sealing, are indispensable to achieve acceptable long-term outcomes. Calcium silicate cements are bioactive materials used for perforation repair. They can be set in moist environments such as blood, saliva and dentinal fluid making them a reliable material for clinical applications. This case report describes the treatment and repair after a 16-month follow-up of a lateral root perforation of the maxillary lateral incisor.

An evaluation of the inflammatory response of lipopolysaccharide-treated primary dental pulp cells with regard to calcium silicate-based cements

This study compared the biological changes of lipopolysaccharide （LPS）-treated dental pulp （DP） cells directly cultured on mineral trioxide aggregate （MTA） and calcium silicate （CS） cements. DP cells were treated with LPS for 24 h. Then, the LPS-treated DP cells were cultured on MTA or CS cements. Cell viability, cell death mechanism and interleukin （IL）-1β expressions were analysed. A one-way analysis of variance was used to evaluate the significance of the differences between the means. A significantly higher IL-1β expression （2.9-fold） was found for LPS-treated cells （P〈0.05） compared with DP cells without LPS treatment at 24 h. Absorbance values of LPS-treated cells cultured on CS cement were higher than a tissue culture plate. A significant difference （P〈0.05） in cell viability was observed between cells on CS and MTA cements 24 h after seeding. At 48 h, a high concentration of Si （5 mM） was released from MTA, which induced LPS-treated DP cell apoptosis. The present study demonstrates that CS cement is biocompatible with cultured LPS-treated DP cells. MTA stimulates inflammation in LPS-treated DP cells, which leads to greater IL-1β expression and apoptosis.

Optimization of the Content of Tricalcium Silicate of High Cementing Clinker

Optimization of the content of tricalcium silicate（C 3 S）of high cementing clinker was investigated.The content of free-CaO（f-CaO）,mineral composite,the content of C 3 S in the clinker and the hydration product were analyzed by chemical analysis and X-ray diffraction（XRD）.＂K Value＂method of QXRD was selected as a quantitative analysis way to measure the content of C 3 S,and the strength of cement paste was determined.The results show that at a water cement ratio of 0.29,the strength of cement paste with 73%C 3 S can be up to 97.5 MPa at 28 days age.The strength at 28 d of cement with 73%C 3 S is 16%higher than that with 78%C 3 S at water requirement for normal consistency.The relationship between the strength of high cementing Portland cement and the content of C 3 S in the clinker is nonlinear.According to the strength of cement paste,the optimal content of C 3 S in cement clinker is around 73%in this paper.

Siliceous Cementation of Chlorite-Coated Grains in the Permian Sandstone Gas Reservoirs,Ordos Basin

Objective It has long been controversial that whether authigenic chlorite coatings in sandstone reservoirs can prevent precipitation of siliceous cements. It is commonly believed that chlorite coatings （also called chlorite films, chlorite linings, or chlorite rims） may prevent quartz overgrowth, and thus help the preservation of original pores in sandstone reservoirs. Recently, however, this assumption has been challenged by reservoir geologists. This dispute cannot be solved by mere analysis of thin sections, nor by chemical equations and diagenesis analysis. The main objective of the present contribution is to shed light on this problem on the basis of sandstone samples from the Permian Shanxi and Shihezi Formations in the eastern part of the Sulige gas field, Ordos Basin in central China.

Evaluation of the effect of sodium silicate addition to mine backfill,GelfillLPart 1

In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investigated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill（CHF）. The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The mechanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical（uniaxial compressive strength） and physical（water retention） properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry（MIP） revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

Study on the Adsorption Characteristics of Inorganic Activated Charcoal Gel on Formaldehyde

In this paper, the powdered activated carbon is taken as the main raw material to develop a new material of inorganic activated charcoal gel by using silicate cement as the gelling agent. The micro-structure of this material is characterized by XRD, BET, SEM, EDS and so on; and the adsorption and cyclic regeneration characteristics of formaldehyde on the material are primarily studied. The experimental results show that this material is an adsorbent on the basis of micropores distributed between 0.60-1.12 nm, with specific surface area of 452.86 m2/g, average pore size of 2.62 nm and total pore space of 0.30 m3/g. The samples have excellent formaldehyde adsorption ability with saturation adsorption of 268.00 mg/g; after 20 times of cyclic adsorption and desorption, the formaldehyde adsorption rate of the samples can remain 49% of the original value, showing good cyclic regeneration of the samples.

Diagenetic mineralogy and its effect on the reservoir properties of the sandstones of the Permian of S120 block(Sulige gas field),Ordos Basin,NW China

The characteristics of diagenetic minerals and their effects on reservoir quality of the tight sandstones of the Permian in Sulige gas field of the Ordos Basin were studied through observations on thin sections,scanning electron microscopy,energy dispersive spectroscopy analysis and electron microprobe analysis.Diagenetic minerals in the Permian sandstones consist of illite,kaolinite,chlorite,siliceous and calcite cements.Large amounts of intercrystalline pores between kaolinite and illite provide channels for acidic fluids flow and thereby were conducive to the formation of clastic solution pores,intergranular solution pores and composite pores.Authigenic chlorite occurs in the form of three morphotypes as grain-coating,pore-lining and pore-filling.Grain-coating and pore-lining chlorite with different crystal shapes occur as coatings on the framework grains.Pore-filling chlorite precipitated as discrete flaky plates in pore spaces.Quartz microcrystals developed but quartz overgrowth did not develop because of the occurrence of porelining chlorite.This,in turn,led to the preservation of primary pores by occupying potential nucleation sites for quartz overgrowth and thereby preventing quartz microcrystals from merging into quartz overgrowth.This process is regarded as the most important for influencing the quality of the lithophysical properties.Calcite cement was mainly precipitated during a late diagenetic stage and has a negative effect on the reservoir quality.This study provides important insights into analyzing the relationship between diagenetic minerals and reservoir quality and the results are directly applicable to the exploration and development of tight sandstone reservoirs all over the world.