Assessment of Enamel Color Stability of Resins Infiltration Treatment in Human Teeth: A Systematic Review.

(1) The evolution of techniques and materials used in dentistry has led to the introduction of a technique known as micro-infiltration, using ICON infiltrating resin. The purpose of this study was to evaluate whether the resin infiltrant can remain stable in the enamel color of human teeth over time or if it causes discoloration and review current knowledge on color stability based on the literature selected solely on studies performed on human teeth and to provide a perspective on the methods proposed by clinicians in the infiltration procedure; (2) Methods: This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement; (3) Results: Twelve studies were selected for this review. The study results suggest that the device content is sufficiently comprehensive.

Probiotics Function in Preventing Atopic Dermatitis in Children.

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by relapsing eczematous injuries and severe pruritus. In the last few years, the AD prevalence has been increasing, reaching 20% in children and 10% in adults in high-income countries. Recently, the potential role of probiotics in AD prevention has generated considerable interest.

Understanding nanocalcification: a role suggested for crystal ghosts.

The present survey deals with the initial stage of the calcification process in bone and other hard tissues, with special reference to the organic-inorganic relationship and the transformation that the early inorganic particles undergo as the process moves towards completion. Electron microscope studies clearly exclude the possibility that these particles might be crystalline structures, as often believed, by showing that they are, instead, organic-inorganic hybrids, each comprising a filamentous organic component (the crystal ghost) made up of acidic proteins. The hypothesis is suggested that the crystal ghosts bind and stabilize amorphous calcium phosphate and that their subsequent degradation allows the calcium phosphate, once released, to acquire a hydroxyapatite, crystal-like organization.

Osteoporosis-bone remodeling and animal models.

Osteoporosis is a very common skeletal disorder characterized by reduced bone mass and altered trabecular microarchitecture that leads to bone fragility and fractures. Such disease is due to alterations of the remodeling process that occurs in the basic multicellular units that are transitory cellular complexes including an osteoclastic phase (osteoclast activation and resorption of microscopic portions of bone), a reversion phase (osteoclast replacement by so-called postosteoclastic cells), and an osteoblastic phase (osteoblastic reconstruction of the resorbed bone matrix till the initial volume is regained). Bone remodeling is regulated by a number of systemic and local factors; among the former, besides physical activity and mechanical stresses, a primary role is played by hormones such as parathyroid hormone, vitamin D metabolites, estrogens, calcitonin, and glucocorticoids; among the latter, several growth factors (macrophage colony-stimulating factor, transforming growth factor β, platelet-derived growth factor, fibroblast growth factor 1, bone morphogenetic protein, and insulin-like growth factor 1), as well as the osteoprotegerin-receptor activator of nuclear factor-κ B ligand system and the sclerostin, play a primary function.

A review of phosphate mineral nucleation in biology and geobiology.

Relationships between geological phosphorite deposition and biological apatite nucleation have often been overlooked. However, similarities in biological apatite and phosphorite mineralogy suggest that their chemical formation mechanisms may be similar. This review serves to draw parallels between two newly described phosphorite mineralization processes, and proposes a similar novel mechanism for biologically controlled apatite mineral nucleation.

Bone mineralization.

This review attempts to summarize the findings made available by the literature on the mineralization of bone. The types of bone, their structures and compositions, the nature and organization of organic and inorganic matter, the organic-inorganic relationships, and the mineralization mechanism itself, are the main topics of the present review. As in other hard tissues, bone mineralization occurs in, and is conditioned by, the components of the organic matrix.

Medial artery calcification of uremic patients: a histological, histochemical and ultrastructural study.

Recent findings suggest that vascular calcification (VC) is an active process similar to bone mineralization, the vascular smooth muscle cells (VSMCs) undergoing phenotypic differentiation into osteoblastic cells and synthesizing calcification-regulating proteins found in bone. This study has investigated the VC process of uremic patients, with a morphologic approach. Epigastric artery samples from 49 uremic, non-diabetic patients were taken during kidney transplantation.

Osteopetrosis complicated by osteomyelitis of the maxilla and mandible: light and electron microscopic findings.

This report presents a case of osteopetrosis in a 25-year-old male, which was complicated by the development of osteomyelitis in the maxilla and mandible following traumatic injury and tooth extractions. The osteomyelitis in the mandible was refractory to marginal resection and antibiotic therapy. Partial resection with mandible reconstruction was then carried out.

Calcification and silicification: a comparative survey of the early stages of biomineralization.

Most of the studies on biomineralization have focused on calcification and silicification, the two systems that predominate in nature in the construction of skeletal or integumental hard tissues. They have, however, been studied separately, as if they were completely distinct processes, in spite of their several points of contact, especially as far as the organic-inorganic relationships during the early mineralization stages are concerned. A very tight association of the inorganic substance with organic macromolecules, in fact, initially characterizes both systems.

Immunohistochemical localization and mRNA expression of matrix Gla protein and fetuin-A in bone biopsies of hemodialysis patients.

Matrix Gla protein (MGP) and fetuin-A are inhibitors of arterial calcifications. In blood of rats, calcium-phosphate-fetuin-MGP complexes, produced in bone, have been identified. Indeed, an association between bone resorption, release of such complexes, and arterial calcifications has been reported.

OPG and RANKL mRNA and protein expressions in the primary and secondary metaphyseal trabecular bone of PTH-treated rats are independent of that of SOST.

Sclerostin, encoded by the SOST gene, is a recently identified protein which seems to affect bone remodeling by inhibiting bone formation via Wnt pathways. A previous study on OPG and RANKL, two cytokines involved in the control of osteoclastogenesis, showed that the anabolic effect produced by intermittent treatment with parathyroid hormone was characterized by an increase in OPG/RANKL mRNA ratio in the primary spongiosa of metaphyseal bone of rat femur, and by its falling in the secondary spongiosa, in comparison to controls (Silvestrini et al. (2007a)).

Effects of intermittent parathyroid hormone (PTH) administration on SOST mRNA and protein in rat bone.

Sclerostin, the secreted protein product of the SOST gene, which is mainly expressed by osteocytes, has recently been proposed as a negative regulator of bone osteoblastogenesis. Chronic elevation of PTH reduces SOST expression by osteocytes, while controversial results have been obtained by intermittent PTH administration. We have investigated the effects of intermittently administered PTH on SOST expression and sclerostin localization, comparing them with those of controls, as they appeared in three different bone segments of rat tibia: secondary trabecular metaphyseal and epiphyseal bone, and cortical diaphyseal bone.

Effects of the administration of corticosterone, parathyroid hormone, or both, and of their withdrawal, on rat bone and cartilage histomorphometric parameters, and on osteoprotegerin and RANKL mRNA expression and proteins.

We have studied the effects of the treatment with corticosterone (CORT), parathyroid hormone (PTH), or both (CORT + PTH), and of their withdrawal (CORT-rec and CORT + PTH-rec), on the osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) localization and expression and on histomorphometric parameters in primary and secondary spongiosa of rat femur and tibia metaphyses. In the secondary spongiosa of the CORT group, the bone remodeling and the OPG/RANKL mRNA ratio decreased. In the PTH group, the bone turnover and the structural and connectivity indices increased, and the OPG/RANKL mRNA ratio fell; this ratio rose, however, in the primary spongiosa.

Renal osteodystrophy: alpha-Heremans Schmid glycoprotein/fetuin-A, matrix GLA protein serum levels, and bone histomorphometry.

Background: Fetuin-A of hepatic origin circulates in large amounts in serum, but also is expressed in bone, where it is an inhibitor of transforming growth factor beta (TGF-beta)/bone morphogenetic protein (BMP) proteins. Together with matrix GLA protein (MGP), fetuin-A is able to make up a complex with calcium and phosphate that is more soluble than calcium and phosphate alone, preventing its deposition in extraskeletal tissues. Experimental results suggested that this complex is made at bone tissue level.

25-hydroxyvitamin D levels and bone histomorphometry in hemodialysis renal osteodystrophy.

Background: The importance of 25-hydroxyvitamin D (25-OHD) serum levels in hemodialysis chronic renal failure has not been so far histologically evaluated. Information still lacking relate to the effect of 25-OHD deficiency on serum parathyroid hormone (PTH) levels and on bone and its relationship with calcitriol levels.

Methods: This retrospective study has been performed on a cohort of 104 patients on hemodialysis from more than 12 months, subjected to transiliac bone biopsy for histologic, histomorphometric, and histodynamic evaluation.

Osteoprotegerin (OPG) and RANKL expression and distribution in developing human craniomandibular joint.

During embryogenesis the bone tissue of craniomandibular joint (CMJ) is formed through two pathways: intramembranous ossification and endochondral ossification. The development process is under the control of regulatory factors. The osteoprotegerin (OPG) and the receptor activator of nuclear factor (NF)-kappaB ligand are key regulators of osteoclastogenesis.

Calcified tissue histochemistry: from microstructures to nanoparticles.

It has long been recognized that histochemistry and cytochemistry offer the only ways of gathering information about the biochemical composition of tissues and cells without disrupting their microscopic architecture. A variety of methods have been put forward for studying nuclei acids, proteins, carbohydrates, lipids, enzymes and other components of intact tissues and cells. By now, many of these have only a historical interest.

Detection of osteoprotegerin (OPG) and its ligand (RANKL) mRNA and protein in femur and tibia of the rat.

Osteoprotegerin (OPG) and the receptor activator of nuclear factor (NF)-kB ligand (RANKL) are key regulators of osteoclastogenesis. The present study had the main aim of showing the localization of OPG and RANKL mRNA and protein in serial sections of the rat femurs and tibiae by immunohistochemistry (IHC) and in situ hybridization (ISH). The main results were: (1) OPG and RANKL mRNA and protein were co-localized in the same cell types, (2) maturative/hypertrophic chondrocytes, osteoblasts, lining cells, periosteal cells and early osteocytes were stained by both IHC and ISH, (3) OPG and RANKL proteins were mainly located in Golgi areas, and the ISH reaction was especially visible in active osteoblasts, (4) immunolabeling was often concentrated into cytoplasmic vacuoles of otherwise negative proliferative chondrocytes; IHC and ISH labeling increased from proliferative to maturative/hypertrophic chondrocytes, (5) the newly laid down bone matrix, cartilage-bone interfaces, cement lines, and trabecular borders showed light OPG and RANKL immunolabeling, (6) about 70% of secondary metaphyseal bone osteocytes showed OPG and RANKL protein expression; most of them were ISH-negative, (7) osteoclasts were mostly unstained by IHC and variably labeled by ISH.

Serum leptin in dialysis renal osteodystrophy.

Background: The hormone leptin is considered to have a role in the prevention of osteoporosis and probably acts on bone tissue through inhibition of osteoclasia. Its action has been attributed to interference in osteoprotegerin (OPG)/OPG-ligand equilibrium. Contradictory data also have been reported, casting doubts on the positive effect on bone mass of the hormone, at least in males.

Localization of the glucocorticoid receptor mRNA in cartilage and bone cells of the rat. An in situ hybridization study.

The in vivo localization of glucocorticoid receptor (GR) mRNA expression was studied in the cartilage and bone cells of the femur of young adult rats to compare its distribution with that of the GR protein, which had previously been shown histochemically in the same areas. To achieve this, we used a synthetic oligodeoxynucleotide as a probe, in line with the published human GR (hGR) cDNA sequence. The probe was coupled to fluorescein (FL), applying a rapid Fast-Tag TM FL nucleic acid labeling method.

PTH 1-84 and PTH "7-84" in the noninvasive diagnosis of renal bone disease.

Background: The intact parathyroid hormone (PTH) assay evaluates levels of serum 1-84 PTH and other N-terminally truncated PTH fragments, mainly PTH "7-84." This PTH molecule has been found experimentally to interfere with biological activity of PTH 1-84, perhaps through its binding to the PTH receptor complex. Therefore, assuming that high levels of PTH 7-84 are a cause of bone resistance to PTH, it has been hypothesized that a decreased 1-84 to 7-84 PTH ratio caused by a relative increase in PTH 7-84 level might help in the noninvasive diagnosis of low-turnover osteodystrophy (LTO).

Renal osteodystrophy in predialysis and hemodialysis patients: comparison of histologic patterns and diagnostic predictivity of intact PTH.

Background: Comparison of renal osteodystrophy in predialysis and hemodialysis has been rarely reported. Distinct patterns of renal osteodystrophy could be found in these conditions. In addition the use of parathyroid hormone (PTH) and other markers for noninvasive diagnosis may result in different predictive values in predialysis and hemodialysis patients.

Serum osteoprotegerin and renal osteodystrophy.

Background: Numerous growth factors and cytokines are known to modulate bone turnover. An important, recently discovered complex involved in osteoclastogenesis is the osteoprotegerin/osteoprotegerin-ligand (OPG/OPGL) cytokine complex, which is produced by osteoblasts. Many factors, including parathyroid hormone (PTH), appear to affect bone turnover through this pathway.

Alkaline phosphatase and tartrate-resistant acid phosphatase in osteoblasts of normal and pathologic bone.

A review of histochemical and immunohistochemical studies on alkaline phosphatase (AP) and tartrate-resistant acid phosphatase (TRAP) in osteoblasts leads to the following conclusions: 1) AP is a typical (non-specific) marker of osteoblasts, and TRAP is a typical (non-specific) marker of osteoclasts; 2) both enzymes may be used to identify the precursors of these cells and are found in young osteocytes; 3) both are released into the extracellular space; 4) both are expressed by metaphyseal osteoblast-like cells whose ultrastructural characteristics are similar to those of post-osteoclastic cells of the basic multicellular unit (BMU) and are also exhibited by osteoblasts and macrophages; 5) the increased numbers of these cells in hypocalcemic animals suggests that the local calcium ion concentration may trigger the transition of the reversal into the formation phase of the BMU.