The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.

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EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals

Bisphenol A: An endocrine disruptor with widespread exposure and multiple effects

Nanoparticles are normally considered to be of a size no greater than 100 nm, and the exploitation of their unique attributes to combat infection has increased markedly over the past decade. The potential of nanoparticles to control the formation of biofilms within the oral cavity, as a function of their biocidal, anti-adhesive, and delivery capabilities, is now coming under close scrutiny. Possible uses as constituents of prosthetic device coatings, as topically applied agents, and within dental materials are being explored. The latest insights into the application of nanoparticles in the control of oral infections, including their use in photodynamic therapy, will be discussed in this review. In particular, the use of nanoparticulate silver, copper, zinc, silicon, and their oxides will be considered in relation to their effects on bacterial populations. The recent interest in the applications of nanoparticulate polymers and calcium phosphates will also be assessed. Particular attention will be paid to the toxicity issues surrounding the potential impact of nanoparticles on oral and other tissues.

The Use of Nanoparticles to Control Oral Biofilm Formation

Objectives
The aim of our study was to measure and compare degree of conversion (DC) as well as micro- (indentation modulus, E; Vickers hardness, HV) and macromechanical properties (flexural strength, σ; flexural modulus, Eflexural) of two recently launched bulk fill resin-based composites (RBCs): Surefil® SDR™ flow (SF) and Venus® bulk fill (VB).

In vitro comparison of mechanical properties and degree of cure of bulk fill composites

The prevention of tooth decay and the treatment of lesions and cavities are ongoing challenges in dentistry. In recent years, biomimetic approaches have been used to develop nanomaterials for inclusion in a variety of oral health-care products. Examples include liquids and pastes that contain nano-apatites for biofilm management at the tooth surface, and products that contain nanomaterials for the remineralization of early submicrometre-sized enamel lesions. However, the treatment of larger visible cavities with nanomaterials is still at the research stage. Here, we review progress in the development of nanomaterials for different applications in preventive dentistry and research, including clinical trials.

Nanomaterials in preventive dentistry

The aim of this in vitro investigation was to compare various roughness and topography measurement methods to characterize the surface quality in several types of resin composites. The initial surface quality of several resin composites was compared. The materials evaluated were of three categories: i) hybrid: TPH Spectrum; ii) reinforced microfill: Micronew and iii) microhybrid: Synergy Duo, Esthet-X, Point.4 and Palfique Estelite. Three Groups of identical disk-shaped specimens (10 × 1.5 mm) were prepared from each material (n = 6) and polished with Soflex discs. Macro-roughness (Ra) was measured with Group 1 by 2-D profilometry. Atomic Force Microscopy (AFM) gave 3-D images and micro-roughness (Ra) of Group 2. Surface optical gloss at 60∘ was determined for Group 3. Specimens of each material were also studied by scanning electron microscopy. Macro-Ra values (μm) ranged from 0.30 to 0.56. Micro-Ra values ranged from 0.03 to 0.14 and they differed from macro-Ra values in ranking order. Percentage Gloss values ranged from 30.6 to 70.1%. The results revealed that micro-roughness showed a high correlation with gloss values (r = 0.93), whilst macro-roughness did not (r = 0.62). Moreover, the AFM method showed higher capability to distinguish surface roughness compared with the 2-D profilometry and to reveal more detailed definition of surface texture than the examination under SEM.

Evaluation of surface characteristics of dental composites using profilometry, scanning electron, atomic force microscopy and gloss-meter

Effect of a CPP-ACP agent on the demineralization and remineralization of dentine in vitro

Corticosterone-regulated actions in the rat brain are affected by perinatal exposure to low dose of bisphenol A.

The reparative mechanisms that operate following carious and traumatic dental injury are critical for pulp survival and involve a series of highly conserved processes. It appears that these processes share genetic programs-linked to cytoskeletal organization, cell movement, and differentiation-that occur throughout embryogenesis. Reactionary dentin is secreted by surviving odontoblasts in response to moderate stimuli, leading to an increase in metabolic activity. In severe injury, necrotic odontoblasts are replaced by other pulp cells, which are able to differentiate into odontoblast-like cells and produce a reparative dentin. This complex process requires the collaborative efforts of cells of different lineage. The behavior of each of the contributing cell types during the phases of proliferation, migration, and matrix synthesis as well as details of how growth factors control wound cell activities are beginning to emerge. In this review, we discuss what is known about the molecular mechanisms involved in dental repair.

Christos Rahiotis

Papers

Evaluation of surface characteristics of dental composites using profilometry, scanning electron, atomic force microscopy and gloss-meter

Effect of a CPP-ACP agent on the demineralization and remineralization of dentine in vitro

Corticosterone-regulated actions in the rat brain are affected by perinatal exposure to low dose of bisphenol A.

Parallels between Tooth Development and Repair: Conserved Molecular Mechanisms following Carious and Dental Injury

The effect of different light-curing units on fatigue behavior and degree of conversion of a resin composite.