3D Printed Microfluidic Devices

3D printing has revolutionized the microfabrication prototyping workflow over the past few years. With the recent improvements in 3D printing technologies, highly complex microfluidic devices can be fabricated via single-step, rapid, and cost-effective protocols as a promising alternative to the time consuming, costly and sophisticated traditional cleanroom fabrication. Microfluidic devices have enabled a wide range of biochemical and clinical applications, such as cancer screening, micro-physiological system engineering, high-throughput drug testing, and point-of-care diagnostics. Using 3D printing fabrication technologies, alteration of the design features is significantly easier than traditional fabrication, enabling agile iterative design and facilitating rapid prototyping. This can make microfluidic technology more accessible to researchers in various fields and accelerates innovation in the field of microfluidics. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel methodological developments in 3D printing and its use for various biochemical and biomedical applications

Threats to adhesive/dentin interfacial integrity and next generation bio-enabled multifunctional adhesives

Nearly 100 million of the 170 million composite and amalgam restorations placed annually in the United States are replacements for failed restorations. The primary reason both composite and amalgam restorations fail is recurrent decay, for which composite restorations experience a 2.0–3.5-fold increase compared to amalgam. Recurrent decay is a pernicious problem—the standard treatment is replacement of defective composites with larger restorations that will also fail, initiating a cycle of ever-larger restorations that can lead to root canals, and eventually, to tooth loss. Unlike amalgam, composite lacks the inherent capability to seal discrepancies at the restorative material/tooth interface. The low-viscosity adhesive that bonds the composite to the tooth is intended to seal the interface, but the adhesive degrades, which can breach the composite/tooth margin. Bacteria and bacterial by-products such as acids and enzymes infiltrate the marginal gaps and the composite\u27s inability to increase the interfacial pH facilitates cariogenic and aciduric bacterial outgrowth. Together, these characteristics encourage recurrent decay, pulpal damage, and composite failure. This review article examines key biological and physicochemical interactions involved in the failure of composite restorations and discusses innovative strategies to mitigate the negative effects of pathogens at the adhesive/dentin interface

An experimental fibre-reinforced dental resin composite

PhD ThesisFibre-reinforced dental resin composites (FRCs) have shown increased fracture resistance and tensile strength compared with particulate filled composites (PFC). However, clinically successful restorative materials require adequate bond strength and wear resistance along with high strength. An experimental FRC (ST) was developed and tested as a dentine replacement. It has randomly distributed E-glass fibres above their critical length of 0.5-1.6 mm. This work aimed to evaluate the possibility of using ST as a single restorative material by assessing its three-body wear resistance and surface contact fatigue. The polymerisation shrinkage, water sorption, and bond strength of ST were also assessed. Two commercially available materials; an FRC (Build It FR) and PFC (Z250) were used as comparators. ST showed significantly lower wear resistance and higher contact fatigue. No significant difference was found regarding polymerisation shrinkage but ST had significantly higher water sorption, lower shear bond strength (SBS) to human dentine. SBS of the interfacial layers within and between the dental resin composites was evaluated after 24 hours and 1 year of water storage in the absence of an oxygen inhibition layer. Build It/Z250 showed a significantly higher SBS at both time intervals. The presence of an oxygen inhibited layer increased the interfacial strength in all groups except ST/Z250. ST formulations were varied in resin/diluent (Bis-GMA/TEGDMA) ratios, filler loading and fibre lengths for development. Wear testing found changing the Bis-GMA/TEGDMA ratio from 60/40 to 70/30 decreased the wear resistance regardless of filler loading and fibre length. In summary, wear resistance of ST and its variants was insufficient to recommend its use as a single restorative material without a surface veneer of PFC. As a dentine replacement, ST was only comparable with Z250 and Build It in polymerisation shrinkage and SBS between composites in the absence of an oxygen inhibition layer

Bacterial Interactions with Dental and Medical Materials

The interaction of bacteria with biomaterials’ surfaces has critical clinical implications on the development and progression of biofilm-related diseases. In this book "Bacterial Interactions with Dental and Medical Materials", encouraging findings on tissue-contacting biomaterials to control biofilms, enhanced understanding of key mechanisms, and clinical perspectives are discussed toward improving healthcare

Evaluation of Shear Bond Strength of Four Commercially Available Resin Cements: In Vitro Study

INTRODUCTION: Dentists have searched for ideal restorative material for many years, although direct restorative materials such as amalgam, cements and composites have been used with reasonable good success during past several decades, but they are not ideal for large restorations or for fixed partial dentures. When a restoration is placed in aesthetic zone, the surface quality and aesthetic potential over a period of time becomes very crucial to provide a life like restoration to the patients. The end of twentieth century saw vast development in all-ceramic dental restorations because of increased popularity of all-ceramic materials. Dental ceramics are attractive dental restorations, because of their biocompatibility, long term color stability, wear-resistance, and their ability to be formed into desired shapes. Dental restorations using all-ceramic materials in association with adhesive cements have become popular in the last decade, primarily because of esthetic properties such as translucence, fluorescence, and opalescence that better simulate the appearance of natural dentition. The cementation process is vital for the clinical success of all-ceramic restorations. It has been purported that some all-ceramic restorations may be cemented with zinc phosphate, glass ionomer, or resin composite cements. Therefore, the success of the cementation process may depend on the composition of the ceramic material. When zinc phosphate or glass- ionomer cements are used, adequate retention form of the preparation is necessary. When this is compromised, adhesive luting systems are recommended. The bond of the resin luting agent to the tooth structure is enhanced by acid etching the tooth structure and by the use of a dental adhesive. The applications of dual-polymerizing resin cements for all-ceramic restorations have considerably increased due to the ability of these cements to polymerize completely and their greater resistance to occlusal loading. Since the use of all ceramic restorations requires considerable support from the underlying composite resin cement and dentin for a successful clinical outcome, the luting agent should have high bond strength, not only to the ceramic surface, but also to the tooth surface. The long-term success of resin bonded all-ceramic restorations depends in part on a durable bond being created between the hard tissues of the tooth and the adhesive cement4. A durable bond between the adhesive cement and the restoration is also critical, throughout the lifetime of a restoration. There is agreement that a stable bond increases both the retention and the fracture resistance of the abutment and the restoration and that it reduces the incidence of micro leakage. AIM AND OBJECTIVES: The aim of this study was to compare the shear bond strength of four commercially available resin cements with their respective bonding system to human teeth. The objectives of this in vitro study are: 1. To compare the shear bond strength of four commercially available resin cements with their respective bonding system to human teeth. 2. To conduct failure mode analysis of resin cements using microscopy. METHODOLOGY: I. Tooth Preparation, II. Laminate Fabrication, III. Cementation of Veneers to the tooth, IV. Experimental design- Randomized four groups of twelve teeth comprising Six Anterior and Six Posterior teeth. a. Group I Rely X. b. Group II Variolink N. c. Group III Calibra. d. Group IV SeT PP. V. Measurement of Shear Bond Strength by Universal Testing Machine (UTM). VI. Statistical Evaluation. STATISTICAL EVALUATION: Statistical analysis of the Maximum load recorded was done with the use of a Software (SPSS Software). Mean of all the cement group were analyzed using One way ANOVA test with maximum load as the dependent variable and the type of Resin cements as independent variable. Unpaired T-Test was also done with <0.05 to indicate significance. SUMMARY AND CONCLUSION: This study was done to Compare and Evaluate the Shear bond strength of four commercially available resins cements namely Rely X, Variolink N, Calibra and SeT PP to human dental hard tissue and ceramic. The number of teeth sample for each group was six in number (three anterior and three posterior teeth). Ceramic Laminates was fabricated and luted to the respective human teeth samples according to manufactures instructions. The samples were stored for 24hrs in distilled water followed by thermo cycling. The sample was tested for maximum load failure using Universal Testing Machine. The data obtained was analyzed statistically by One Way ANOVA and Unpaired T-test. For Anterior teeth sample Calibra shows the highest mean load value of 464.33 and SeT PP shows the lowest value of 288.00. For Posterior teeth sample, Rely X shows the highest value of 272.97 while SeT PP shows the lowest load value of 154.33. Among all the cements SeT PP shows the lowest load values. One Way ANOVA Test for teeth sample shows insignificance of load value among all the cements at 5% of confidence level (p<0.05). Within the limitation of this study following conclusions was made: (1) There is no significance differences exist in long-term durability to human dentin between the cementing agents with their respective bonding system. (2) Simplifying the application procedures of the corresponding adhesives following three step total-etch, two step total-etch, one-step self-etch, or no use of adhesives, affect the effectiveness of the bond to human dentin

Natural Polymers and Biopolymers II

BioPolymers could be either natural polymers – polymer naturally occurring in Nature, such as cellulose or starch…, or biobased polymers that are artificially synthesized from natural resources. Since the late 1990s, the polymer industry has faced two serious problems: global warming and anticipation of limitation to the access to fossil resources. One solution consists in the use of sustainable resources instead of fossil-based resources. Hence, biomass feedstocks are a promising resource and biopolymers are one of the most dynamic polymer area. Additionally, biodegradability is a special functionality conferred to a material, bio-based or not. Very recently, facing the awareness of the volumes of plastic wastes, biodegradable polymers are gaining increasing attention from the market and industrial community. This special issue of Molecules deals with the current scientific and industrial challenges of Natural and Biobased Polymers, through the access of new biobased monomers, improved thermo-mechanical properties, and by substitution of harmful substances. This themed issue can be considered as collection of highlights within the field of Natural Polymers and Biobased Polymers which clearly demonstrate the increased interest in this field. We hope that this will inspire researchers to further develop this area and thus contribute to futures more sustainable society.

Novel biological and technological platforms for dental clinical use

none4siopenOrsini, Giovanna; Pagella, Pierfrancesco; Putignano, Angelo; Mitsiadis, Thimios A.*Orsini, Giovanna; Pagella, Pierfrancesco; Putignano, Angelo; Mitsiadis, Thimios A