Porous CaP/silk composite scaffolds to repair femur defects in an osteoporotic model.

The most common complication for patients with postmenopausal osteoporosis is bone-related defects and fractures. While routine medication has a high probability of undesirable side effects, new approaches have aimed to develop regeneration procedures that stimulate new bone formation while reversing bone loss. Recently, we have synthesized a new hybrid CaP/silk scaffold with a CaP-phase distribution and pore architecture better suited to facilitate cell differentiation and bone formation.

Effects of enamel matrix proteins in combination with a bovine-derived natural bone mineral for the repair of bone defects.

Objectives: Previously, the use of enamel matrix derivative (EMD) in combination with a natural bone mineral (NBM) was able to stimulate periodontal ligament cell and osteoblast proliferation and differentiation. Despite widespread use of EMD for periodontal applications, the effects of EMD on bone regeneration are not well understood. The aim of the present study was to test the ability of EMD on bone regeneration in a rat femur defect model in combination with NBM.

In vitro characterization of a synthetic calcium phosphate bone graft on periodontal ligament cell and osteoblast behavior and its combination with an enamel matrix derivative.

Objectives: Recent studies suggest that a combination of enamel matrix derivative (EMD) with grafting material may improve periodontal wound healing/regeneration. Newly developed calcium phosphate (CaP) ceramics have been demonstrated a viable synthetic replacement option for bone grafting filler materials.

Aims: This study aims to test the ability for EMD to adsorb to the surface of CaP particles and to determine the effect of EMD on downstream cellular pathways such as adhesion, proliferation, and differentiation of primary human osteoblasts and periodontal ligament (PDL) cells.

Effect of decreased implant healing time on bone (re)modeling adjacent to plateaued implants under functional loading in a dog model.

Objectives: The purpose of this study was to evaluate the effect of early functional loading to plateaued implants on bone formation and implant stability in a dog model.

Materials And Methods: Early loading (EL), nonloading control, and delayed loading (DL) groups were compared using six beagle dogs under functional loading. The Periotest® values were measured dynamically for 6 weeks.

In vitro evaluation of demineralized freeze-dried bone allograft in combination with enamel matrix derivative.

Background: Preclinical and clinical studies suggest that a combination of enamel matrix derivative (EMD) with demineralized freeze-dried bone allograft (DFDBA) may improve periodontal wound healing and regeneration. To date, no single study has characterized the effects of this combination on in vitro cell behavior. The aim of this study is to test the ability of EMD to adsorb to the surface of DFDBA particles and determine the effect of EMD coating on downstream cellular pathways such as adhesion, proliferation, and differentiation of primary human osteoblasts and periodontal ligament (PDL) cells.

Five-year results evaluating the effects of platelet-rich plasma on the healing of intrabony defects treated with enamel matrix derivative and natural bone mineral.

Background: Regenerative periodontal surgery using the combination of enamel matrix derivative (EMD) and natural bone mineral (NBM) with and without addition of platelet-rich plasma (PRP) has been shown to result in substantial clinical improvements, but the long-term effects of this combination are unknown.

Methods: The goal of this study was to evaluate the long-term (5-year) outcomes after regenerative surgery of deep intrabony defects with either EMD + NBM + PRP or EMD + NBM. Twenty-four patients were included.

Synthesis and inflammatory response of a novel silk fibroin scaffold containing BMP7 adenovirus for bone regeneration.

Gene therapy has garnished tremendous awareness for the repair of osseous defects. It exhibits high efficiency gene transfer and osteogenic differentiation potential making it well suitable for the sustained delivery of growth factors to local tissues. In the present study a simplified solution-based in situ biomimetic synthesis method is demonstrated for bone morphogenetic protein 7 (BMP7) adenovirus combined with silk fibroin scaffolds.

Delivery of PDGF-B and BMP-7 by mesoporous bioglass/silk fibrin scaffolds for the repair of osteoporotic defects.

Osteoporosis is a chronic disease affecting millions of people worldwide caused by an imbalance between bone-forming osteoblasts and bone-resorbing osteoclasts. Despite recent developments in pharmacological agents to prevent osteoporotic-related fractures, much less attention has been placed on the repair of bone defects following fracture. Critical to this process is the recruitment of mesenchymal stem cells (MSCs) to defect sites by growth factors.

Osteoblast proliferation and differentiation on a barrier membrane in combination with BMP2 and TGFβ1.

Objectives: Bioresorbable collagen membranes are routinely utilized in guided bone regeneration to selectively direct the growth and repopulation of bone cells in areas of insufficient volume. However, the exact nature by which alveolar osteoblasts react to barrier membranes as well as the effects following the addition of growth factors to the membranes are still poorly understood. The objective of the present study was therefore to investigate the effect of a bioresorbable collagen membrane soak-loaded in growth factors bone morphogenetic protein 2 (BMP2) or transforming growth factor β1 (TGFβ1) on osteoblast adhesion, proliferation, and differentiation.

Gene array of primary human osteoblasts exposed to enamel matrix derivative in combination with a natural bone mineral.

Objectives: The application of an enamel matrix derivative (EMD) for regenerative periodontal surgery has been shown to promote formation of new cementum, periodontal ligament, and alveolar bone. In intrabony defects with a complicated anatomy, the combination of EMD with various bone grafting materials has resulted in additional clinical improvements, but the initial cellular response of osteoblasts coming in contact with these particles have not yet been fully elucidated. The objective of the present study was to evaluate the in vitro effects of EMD combined with a natural bone mineral (NBM) on a wide variety of genes, cytokines, and transcription factors and extracellular matrix proteins on primary human osteoblasts.

Impact of bone harvesting techniques on cell viability and the release of growth factors of autografts.

Background: Autogenous bone grafts obtained by different harvesting techniques behave differently during the process of graft consolidation; the underlying reasons are however not fully understood. One theory is that harvesting techniques have an impact on the number and activity of the transplanted cells which contribute to the process of graft consolidation.

Materials And Methods: To test this assumption, porcine bone grafts were harvested with four different surgical procedures: bone mill, piezosurgery, bone drilling (bone slurry), and bone scraper.

Osteoinduction: a review of old concepts with new standards.

Since the discovery of osteoinduction in the early 20th century, innovative biomaterials with osteoinductive potential have emerged. Over the last 50 years, however, our ability to describe biological phenomena accurately has been improved dramatically by advancements in cell and molecular biology. The aim of this review is to divide the osteoinduction phenomenon into 3 principles: (1) mesenchymal cell recruitment, (2) mesenchymal differentiation to bone-forming osteoblasts, and (3) ectopic bone formation in vivo.

Adsorption of enamel matrix proteins to a bovine-derived bone grafting material and its regulation of cell adhesion, proliferation, and differentiation.

Background: The use of various combinations of enamel matrix derivative (EMD) and grafting materials has been shown to promote periodontal wound healing/regeneration. However, the downstream cellular behavior of periodontal ligament (PDL) cells and osteoblasts has not yet been studied. Furthermore, it is unknown to what extent the bleeding during regenerative surgery may influence the adsorption of exogenous proteins to the surface of bone grafting materials and the subsequent cellular behavior.

Enamel matrix protein adsorption to root surfaces in the presence or absence of human blood.

Background: The clinical use of an enamel matrix derivative (EMD) has been shown to promote formation of new cementum, periodontal ligament (PDL), and bone and to significantly enhance the clinical outcomes after regenerative periodontal surgery. It is currently unknown to what extent the bleeding during periodontal surgery may compete with EMD adsorption to root surfaces. The aim of this study is to evaluate the effect of blood interactions on EMD adsorption to root surfaces mimicking various clinical settings and to test their ability to influence human PDL cell attachment and proliferation.

Osteogenic potential of autogenous bone grafts harvested with four different surgical techniques.

The osteogenic potential of autogenous bone grafts is superior to that of allografts and xenografts because of their ability to release osteoinductive growth factors and provide a natural osteoconductive surface for cell attachment and growth. In this in vitro study, autogenous bone particles were harvested by four commonly used techniques and compared for their ability to promote an osteogenic response. Primary osteoblasts were isolated and seeded on autogenous bone grafts prepared from the mandibles of miniature pigs with a bone mill, piezo-surgery, bone scraper, and bone drill (bone slurry).

Premature osteoblast clustering by enamel matrix proteins induces osteoblast differentiation through up-regulation of connexin 43 and N-cadherin.

In recent years, enamel matrix derivative (EMD) has garnered much interest in the dental field for its apparent bioactivity that stimulates regeneration of periodontal tissues including periodontal ligament, cementum and alveolar bone. Despite its widespread use, the underlying cellular mechanisms remain unclear and an understanding of its biological interactions could identify new strategies for tissue engineering. Previous in vitro research has demonstrated that EMD promotes premature osteoblast clustering at early time points.

Enamel Matrix Proteins and Periodontal Wound Healing and Regeneration.

Introduction: The goal of regenerative periodontal therapy is the reconstitution of lost periodontal structures (i.e., the new formation of root cementum, periodontal ligament, and alveolar bone).

Proliferation, differentiation and gene expression of osteoblasts in boron-containing associated with dexamethasone deliver from mesoporous bioactive glass scaffolds.

Boron is one of the trace elements in the human body which plays an important role in bone growth. Porous mesopore bioactive glass (MBG) scaffolds are proposed as potential bone regeneration materials due to their excellent bioactivity and drug-delivery ability. The aims of the present study were to develop boron-containing MBG (B-MBG) scaffolds by sol-gel method and to evaluate the effect of boron on the physiochemistry of B-MBG scaffolds and the response of osteoblasts to these scaffolds.

Smoking during pregnancy--a challenge to practitioners.

Smoking during pregnancy is a common finding among women whose parents have been smokers, among those whose husbands are smokers, among women who smoked more than 10 cigarettes per day before they became pregnant, and women who started to smoke at an early age. Smoking while pregnant is dangerous to both mother and child. Smoking exposure risks such as infertility (both primary and secondary), bleeding during pregnancy, abruptio placentae, placenta praevia, premature rupture of membranes, premature birth, low birth weight newborns, sudden infant death syndrome are taken into consideration.

Modelling imperfect adherence to HIV induction therapy.

Background: Induction-maintenance therapy is a treatment regime where patients are prescribed an intense course of treatment for a short period of time (the induction phase), followed by a simplified long-term regimen (maintenance). Since induction therapy has a significantly higher chance of pill fatigue than maintenance therapy, patients might take drug holidays during this period. Without guidance, patients who choose to stop therapy will each be making individual decisions, with no scientific basis.

Reinforcement of resin based cement with titania nanotubes.

Objective: One of the limitations of resin cements and flowable dental composites is their poor mechanical properties such as low flexural strength and fracture resistance under body conditions. The present study was performed to enhance the mechanical properties of commercial acrylic cement (CMW1) by introducing novel nanostructured titania tubes (n-TiO(2) tubes) into the cement matrix, with the tubes acting as a reinforcing phase. The long term objective is to add these fillers as reinforcement to dental resin cements and flowable composites in combination with existing fillers.

The effect of enamel matrix proteins on the spreading, proliferation and differentiation of osteoblasts cultured on titanium surfaces.

Modifications of implant surface topography and chemistry have proven a means to enhance osseointegration, a process that ensures the stability of bone-contacting devices, including titanium dental implants. The commercial product Emdogain is an enamel matrix derivative (EMD) extracted from porcine teeth commonly used in periodontal surgery, where it has been shown to potentiate regeneration of bone. The aim of the present study was to evaluate the effect of EMD on the attachment, proliferation and differentiation of osteoblasts on titanium surfaces in vitro.

Accelerated molecular dynamics simulation of thin-film growth with the bond-boost method.

We review the bond-boost method for accelerated molecular dynamics (MD) simulation and we demonstrate its application to kinetic phenomena relevant to thin-film growth. To illustrate various aspects of the method, three case studies are presented. We first illustrate aspects of the bond-boost method in studies of the diffusion of Cu atoms on Cu(001).

Multiple-time scale accelerated molecular dynamics: addressing the small-barrier problem.

We present a method for accelerated molecular-dynamics simulation in systems with rare-event dynamics that span a wide range of time scales. Using a variant of hyperdynamics, we detect, on the fly, groups of recurrent states connected by small energy barriers and we modify the potential-energy surface locally to consolidate them into large, coarse states. In this way, fast motion between recurrent states is treated within an equilibrium formalism and dynamics can be simulated over the longer time scale of the slow events.

Thermal desorption of large molecules from solid surfaces.

We use molecular-dynamics simulations and importance sampling to obtain transition-state-theory rate constants for thermal desorption of an n-alkane series from Au(111). We find that the binding of a large molecule to a solid surface involves different types of local minima. The preexponential factors increase with increasing chain length and can be substantially larger than typical estimates for small molecules.