POLYMER CHEMISTRY OF DENTAL ADHESIVES

Dental adhesives are water soluble, non-toxic materials that bind composite resins to dentin and enamel. Adhesive systems are dependent on a polymerization process at the interface and require different moieties to prepare the substrate to effectively interact with the tooth surface. Due to their critical role in restorative procedures, many chemists are interested in strengthening the adhesive bond strength at the interface. This review paper covers the evolution of dental adhesive systems over time and provides an extensive overview of what components make up a dental adhesive system. Additionally, this article explores the common issues found in adhesive systems, and how current researchers are working to approach these complications to increase the success rate of dental restorations

Shear Bond Strength of Nine Dual Cured Build-Up Materials and a Light-Curing Adhesive System on Dentin

The purpose of this study was to measure the shear bond strength of nine different commercially available dual cured core build-up materials on human dentin in conjunction with a light curing adhesive system. The null hypothesis was that there is no statistical significant difference among the core build-up systems

Shear Bond Strength Evaluation of Composite versus Glass Ionomer Cement Over One Year

Role and Significance of Restorative Dental Materials1 Composite resin is a widely used restorative material, because of its esthetic properties, biocompatibility, and more importantly its low environmental impact. The properties of a restorative material require significant durability, strength and withstand degradation of the restoration when subjected to different factors in the oral cavity. The oral environment is a complex environment where a restorative material must be able to sustain against bacteria, changing pH, temperature, masticatory forces and saliva etc. The oral cavity is considered to be the harshest environment for a dental material in the body. Glass ionomer cements (GIC) are the only direct restorative material to bond chemically to dental hard tissues due to the formation of ionic bonds between carboxylate groups and calcium. The propertities of GIC include adhesion to moist tooth structures, anticariogenic properties due to release of fluoride, thermal compatibility with tooth enamel, biocompatibility and low toxicity. The use of GICs in a mechanically loaded situation, however, has been hampered by their low mechanical performance. Poor mechanical properties, such as low fracture strength, toughness and wear, limit their extensive use in dentistry as a filling material in stress-bearing applications. In the posterior dental region, glass ionomer cements are mostly used as a temporary filling material. The requirement to strengthen those cements has led to an ever-increasing research effort into reinforcement or strengthening concepts. Shear Bond Testing is an established method to evaluate the bond strength between dental hard tissue and restorative materials.2,

Shear Bond Strength Evaluation of an Experimental Dentin Adhesive In Comparison With 5 Commercial Adhesives in a Dental School Setting

The aim of the in-vitro study was to evaluate the shear bond strength of a newly developed experimental dentin adhesive and compare it with the shear bond strength of different commercially available dentin adhesives in a dental school setting

Применение полномостового резонансного инвертора для ремонта специальной техники в полевых условиях

Определено, что при проведении ремонтов автотранспортной и специальной техники вдали от стационарных баз наиболее энергоемкими и трудозатратными являются сварочные работы. На основании проведенного исследования была предложена инновационная конструкция сварочного инвертора, использующего эффект резонанса, обладающая повышенной надежностью, недорогого конструктивного исполнения (в условиях серийного производства). С целью повышения надежности и удешевления предлагаемой конструкции инвертора предложен целый ряд новых подходов. Исследуется инверторный полномостовой источник сварочного тока с реализацией резонансного эффекта, обладающий стабильностью и плавностью работы, высокой надежностью, потому что схема данного преобразователя не чувствительна к перепадам питающего напряжения

Assessment of Potential Tooth Movement and Bite Changes With a Hard-Acrylic Sleep Appliance: A 2-Year Clinical Study

Oral appliance therapy (OAT) has been shown to successfully treat patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). However, OAT is often associated with the occurrence of side effects such as unwanted tooth movement. Positive airway pressure therapy is more commonly used to treat OSAHS, because of the reluctance to prescribe OAT as a result of these side effects. Even so, Pliska does report on tooth movement due to tongue thrusting as a result of the use of positive airway pressure. Although OAT is an effective treatment for OSAHS along with its greater compliance, long-term use of some oral appliances has been shown to result in several side effects, including tooth movement. Past studies have shown this to result in significant effects, such as craniofacial changes, anteroposterior positioning of the molars, inclination of the upper and lower incisors, and irregularity of the lower incisors. According to the American Academy of Dental Sleep Medicine’s published article on management of side effects, tooth movement (specifically occlusal changes represented by incisor changes, position of canines, decreased overjet/overbite, and altered occlusal contacts/bite changes) is one of the five significant concerns during the treatment of obstructive sleep apnea using an oral appliance. It was reported that there is a significant difference in anterior crowding using a flexible oral appliance without incisor coverage versus a rigid OA. The rigid OA demonstrated less tooth movement. Recently, new devices with proprietary computer-aided design/computer-aided manufacturing (CAD/CAM) technology have been introduced and made available to clinicians. This study aims to investigate the changes in tooth movement with a hard-acrylic rigid oral appliance, the ProSomnus® Sleep Appliance, over a 2-year period. This research project was based on an approved Internal Review Board (IRB) protocol

Novel Insights Into N-Glycan Fucosylation and Core Xylosylation in C. reinhardtii

Chlamydomonas reinhardtii (C. reinhardtii) N-glycans carry plant typical beta 1,2-core xylose, alpha 1,3-fucose residues, as well as plant atypical terminal beta 1,4-xylose and methylated mannoses. In a recent study, XylT1A was shown to act as core xylosyltransferase, whereby its action was of importance for an inhibition of excessive Man1A dependent trimming. N-Glycans found in a XylT1A/Man1A double mutant carried core xylose residues, suggesting the existence of a second core xylosyltransferase in C. reinhardtii. To further elucidate enzymes important for N-glycosylation, novel single knockdown mutants of candidate genes involved in the N-glycosylation pathway were characterized. In addition, double, triple, and quadruple mutants affecting already known N-glycosylation pathway genes were generated. By characterizing N-glycan compositions of intact N-glycopeptides from these mutant strains by mass spectrometry, a candidate gene encoding for a second putative core xylosyltransferase (XylT1B) was identified. Additionally, the role of a putative fucosyltransferase was revealed. Mutant strains with knockdown of both xylosyltransferases and the fucosyltransferase resulted in the formation of N-glycans with strongly diminished core modifications. Thus, the mutant strains generated will pave the way for further investigations on how single N-glycan core epitopes modulate protein function in C. reinhardtii

The Effect of COVID-19 On Antibiotic Resistance

Over three years have passed since the beginning of the COVID-19 pandemic. During these times we have experienced significant changes in all areas of our life. In healthcare, more attention was focused on COVID-19 than other concerns. An unexpected consequence of the pandemic was a silent progression of an increased spread of multi-resistant pathogens. While antibiotic use during the pandemic varied across healthcare settings, antibiotics were prescribed for COVID-19 patients, even though antibiotics are known not to be effective against viruses.1 In dentistry, antibiotics were prescribed to prevent potential dental infections, since many dental offices were not open. Antimicrobial resistance was one of our greatest public health concerns prior to the COVID-19 pandemic, and it remains so