Pilot clinical study to evaluate the efficacy of a professionally delivered high fluoride varnish on erosive tooth wear in an in-situ model.

Objectives: The aim for this pilot study was to investigate the effect of a sodium fluoride varnish on step height measured by a profilometer from human enamel worn by healthy volunteers with a novel in situ/ex vivo erosion design.

Method: Healthy volunteers aged 18-70 years wore a palatal splint containing 8 human enamel samples and underwent two 3-day treatment periods for 6 h a day with a varnish containing sodium fluoride at 22,600 ppm and the control with the same ingredients but without fluoride. Each splint contained 4 polished and 4 unpolished samples.

Temperature Rise Associated with Adiabatic Shear Band: Causality Clarified.

One of the most important issues related to adiabatic shear failure is the correlation among temperature elevation, adiabatic shear band (ASB) formation and the loss of load capacity of the material. Our experimental results show direct evidence that ASB forms several microseconds after stress collapse and temperature rise reaches its maximum about 30  μs after ASB formation. This observation indicates that temperature rise cannot be the cause of ASB.

Peptide-Mediated Biomimetic Regrowth of Human Enamel In Situ.

Mimicking the dynamics of mineral loss and gain involved in dental caries formation can help us evaluate and compare the mineralization efficacy of different treatment agents used in enamel remineralization. Here, we offer an abridged study design outlining the preparation of tooth samples, creation of artificial dental lesions, application of a peptide, and characterization of the regrown enamel-like mineral layer.

Peptide-Based Bioinspired Approach to Regrowing Multilayered Aprismatic Enamel.

The gradual discovery of functional domains in native enamel matrix proteins has enabled the design of smart bioinspired peptides for tooth enamel mimetics and repair. In this study, we expanded upon the concept of biomineralization to design smaller amelogenin-inspired peptides with conserved functional domains for clinical translation. The synthetic peptides displayed a characteristic nanostructured scaffold reminiscent of 'nanospheres' seen in the enamel matrix and effectively controlled apatite nucleation in vitro resulting in the formation of smaller crystallites.

Amelogenin Affects Brushite Crystal Morphology and Promotes Its Phase Transformation to Monetite.

Amelogenin protein is involved in organized apatite crystallization during enamel formation. Brushite (CaHPO·2HO), one of the precursors of hydroxyapatite mineralization , has been used for fabrication of biomaterials for hard tissue repair. In order to explore its potential application in biomimetic material synthesis, we studied the influence of the enamel protein amelogenin on brushite morphology and phase transformation to monetite.

Efficacy of amelogenin-chitosan hydrogel in biomimetic repair of human enamel in pH-cycling systems.

Amelogenin-chitosan (CS-AMEL) hydrogel has shown great potential for the prevention, restoration, and treatment of defective enamel. As a step prior to clinical trials, this study aimed to examine the efficacy of CS-AMEL hydrogel in biomimetic repair of human enamel with erosive or caries-like lesions in pH-cycling systems. Two models for enamel defects, erosion and early caries, were addressed in this study.

Assembly of Layered Monetite-Chitosan Nanocomposite and Its Transition to Organized Hydroxyapatite.

Bioinspired synthesis of hierarchically structured calcium phosphate (CaP) material is a highly promising strategy for developing improved bone substitute materials. However, synthesis of CaP materials with outstanding mechanical properties still remains an ongoing challenge. Inspired by the formation of lamellar structure in nacre, we designed an organic matrix composed of chitosan and cis-butenediolic acid (maleic acid, MAc) that could assemble into a layered complex and further guide the mineralization of monetite crystals, resulting in the formation of organized and parallel arrays of monetite platelets with a brick-and-mortar structure.

Matrix metalloproteinase-20 mediates dental enamel biomineralization by preventing protein occlusion inside apatite crystals.

Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin.

Amelogenin and Enamel Biomimetics.

Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization , and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics.

Amelogenin-chitosan matrix for human enamel regrowth: effects of viscosity and supersaturation degree.

We recently reported an amelogenin-chitosan (CS-AMEL) hydrogel as a promising biomimetic material for future in situ human enamel regrowth. To further optimize the necessary conditions for clinical applicability of CS-AMEL hydrogel, herein we studied the effects of viscosity and supersaturation degree on the size and orientation of synthetic crystals by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Raising the hydrogel viscosity by increasing chitosan concentration from 1% to 2% (w/v) improved the orientation of the crystals, while a higher supersaturation (σ(HAp) >10.

Development of amelogenin-chitosan hydrogel for in vitro enamel regrowth with a dense interface.

Biomimetic enamel reconstruction is a significant topic in material science and dentistry as a novel approach for the treatment of dental caries or erosion. Amelogenin has been proven to be a critical protein for controlling the organized growth of apatite crystals. In this paper, we present a detailed protocol for superficial enamel reconstruction by using a novel amelogenin-chitosan hydrogel.

An amelogenin-chitosan matrix promotes assembly of an enamel-like layer with a dense interface.

Biomimetic reconstruction of tooth enamel is a significant topic of study in materials science and dentistry as a novel approach to the prevention, restoration, and treatment of defective enamel. We have developed a new amelogenin-containing chitosan hydrogel for enamel reconstruction that works through amelogenin supramolecular assembly, stabilizing Ca-P clusters and guiding their arrangement into linear chains. These amelogenin Ca-P composite chains further fuse with enamel crystals and eventually evolve into enamel-like co-aligned crystals, anchored to the natural enamel substrate through a cluster growth process.

Macromolecules on nano-outlets responding to electric field and pH for dual-mode drug delivery.

Macromolecules responsive to both electric field and pH are modified on the outlets of mesoporous silica nanospheres to form a novel dual-mode drug delivery system. Dual drug delivery modes are indicated by the release patterns obtained by simulating the body's gastric and intestinal fluid ex vivo. In a pH 1.

An effective gold nanotubes electrode for amperometric biosensor.

A sensitive and effective amperometric glucose biosensor based on gold nanotubes electrode (GNTE) was investigated. Gold nanotubes (GNTs), which were prepared by electroless plating of the metal within the pores of nanoporous polycarbonate (PC) track-etched membranes, were filled into a hollow teflon cylinder to construct a GNTE. Glucose oxidase (GOD) was immobilized on the electrode via glutaraldehyde cross-linkage method.

Synthesis of h-AIN nanowires via carbothermal reduction and nitridation method using acetylene black.

Using acetylene black as an assistant reagent in the ammonia atmosphere, one dimensional (1D) hexagonal single crystalline aluminum nitride (AIN) nanowires were successfully synthesized via carbothermal reduction and nitridation method. With smooth surface and uniform diameter, the wool-like product of AIN nanowires grow along [001] direction and are 80-120 nm in diameter and several tens micrometers in length. According to thermodynamic and kinetic analysis, AI2O3 initially was reduced to a volatile suboxide gas Al2O at 1800 degrees C.

Dipolar molecules as impellers achieving electric-field-stimulated release.

Here we report the design of a new external electric field-controlled release system using functional dipolar molecules as nanoimpellers. The dipolar molecule 4-(3-cyanophenyl)butylene, which can reorient in response to external electric fields with different frequencies because of its strong inherent dipole moment, was synthesized and grafted onto the inner surfaces of mesopores. Under an alternating electric field, the swinging flexible molecular chains consequently push guest molecules out of the pore voids.

Investigation of layer-by-layer assembled heparin and chitosan multilayer films via electrochemical spectroscopy.

The layer-by-layer (LbL) assembly as a simple and effective method has been extensively used to prepare polyelectrolyte films but the buildup mechanism is expected to be further clarified. In this work, the structure and formation mechanism of LbL-assembled heparin/chitosan multilayer composite films were characterized by electrochemical system, scanning electron microscope and atom force microscope. The results revealed that the film grew linearly in the first 10 bilayers based on measured linear increase of film resistance with number of layers, while the film grew exponentially in the later 10 bilayers based on measured nonlinear increase of film resistance.

Ultrasonic-irradiation-assisted oriented assembly of ordered monetite nanosheets stacking.

Bioactive monetite (anhydrous calcium hydrogen phosphate, CaHPO(4)) with orderly layered structure assembled by nanosheets has been successfully synthesized by a sonochemical-assisted method in the presence of cetyltrimethylammonium bromide (CTAB). The thicknesses of the nanosheets are 100-200 nm, and the lateral sizes are about 2 microm. Because of the strong affinity with the phosphate ions as well as the (200) faces of the crystals, CTAB molecules can make the formation and stabilization of monetite nanosheets with (200) exposed face.