Changxiang Wang

University of Birmingham · School of Dentistry

Toothbrushing with toothpaste is used for daily maintenance of oral hygiene, and aims to remove food debris, the dental plaque biofilm and dental stains from tooth surfaces. However, toothpastes can also cause tooth abrasion as different particle morphologies are known to exert differential cleaning and abrasivity. Consequently, silica and alumina...

Regulatory testing of hydraulic cements used in dentistry and standard test methods for root-end filling materials do not exist. The aim of this study was to identify a simple, reproducible method for testing the solubility of materials that set with water (hydraulic) used as root-end filling materials in dentistry. Commercial and prototype hydraul...

Four calcined alumina abrasive particles [ultrafine (0.05 μm), 3 μm, 9 μm and 20 μm] with defined sizes were investigated for their effects on toothbrush abrasion, surface polishing and stain removal in vitro. The existence of a critical particle size (CPS) was shown for the first time in a tooth model system and in the present study a CPS of ~2.3...

Background The present study aimed to develop an in vitro model for stain removal from natural enamel for the assessment and comparison of oral hygiene products. Methods Bovine teeth (n = 8 per group) were ground/polished to provide flat enamel specimens and ferric-tannate deposits were precipitated onto the enamel surfaces. The ferric-tannate sta...

Objectives: Abrasive wear of sound dental hard tissues results from the abrasive particles in toothpastes. We hypothesize that the wear is proportional to the number of filament tufts in contact with the brushed enamel surfaces. Methods: Eight highly polished bovine enamel specimens per treatment group were prepared to 1200-grit SiC and 3 µm diam...

Objectives: Recently reported data demonstrated that abrasive particle size has significant influence on enamel surface finish in terms of gloss, wear depth and surface roughness (J Dent Res (Spec Iss A): 727, 2011). Since most abrasive systems used in toothpastes will display a distribution of particle size, the objective of this study was to exam...

A finite element model was developed to simulate compression experiments on single tomato cells from suspension cultures. The cell was modelled as a thin-walled liquid-filled sphere with a permeable wall allowing flow of fluid out in response to internal turgor increases due to the compression. The permeability of the cell wall/plasma lemma was con...

Objectives: The majority of modern toothpastes use abrasive grades of silica to clean and polish the tooth surface. The objective of this study was to investigate the effect of using micronised calcined alumina on tissue wear and surface finish of roughened enamel. Methods: Eight bovine enamel specimens per treatment group were prepared to grit 400...

Objectives: The extent of cleaning achieved by a toothpaste is generally regarded to be dependent upon its dentine abrasivity. This study aimed to investigate cleaning and abrasivity characteristics of novel toothpaste formulations containing a low concentration of micronised calcined alumina as the sole abrasive compared to two commercial whitenin...

Objectives: Inclusion of abrasive particles in toothpastes can impact on both dental tissue wear and surface finish of the tissue, although generally use of abrasives with broad particle ranges precludes an understanding of the influence of particle size. The objective of this study was to investigate the effect of abrasive particle size on the wea...

The intrinsic cell wall mechanical properties of Baker's yeast (Saccharomyces cerevisiae) cells were determined. Force-deformation data from compression of individual cells up to failure were recorded, and these data were fitted by an analytical model to extract the elastic modulus of the cell wall and the initial stretch ratio of the cell. The cel...

Objectives: Sodium Tripolyphosphate (STP) is commonly incorporated in toothpastes for stain removal, where its mild chelating properties interfere with stained pellicle integrity. However, these chelating properties may negatively impact on enamel surface finish. This study aimed to investigate the effects of STP treatment on the surface finish of...

Objectives: Abrasive wear of sound dental hard tissues depends on the toothpaste abrasive particles and also the characteristics of the toothbrush delivering them. The relative effects of soft versus hard brush filament are controversial. The aim of this in vitro study was to compare the abrasion of bovine enamel and dentin after brushing with thre...

Calcium alginate microspheres have been studied extensively as carriers in drug delivery systems, for encapsulation of biological materials such as biocatalysts, and as matrices in tissue engineering. Understanding the mechanical properties of such microspheres is essential because they may be exposed to mechanical forces during processing and in e...

The aim of this study was to measure key material properties of the cell walls of single suspension-cultured plant cells and relate these to cell-wall biochemistry. To this end, micromanipulation was used to compress single tomato cells between two flat surfaces until they ruptured, and force-deformation data were obtained. In addition to measuring...

In the present study, nanoclay was introduced to PMMA bone cement to obtain a new formulation of bioactive PMMA cement (PMMA/HA/nanoclay). To evaluate the interfacial property of the new bioactive cement for use as a fixation agent, Brazilian disk specimens were used to study the interfacial strength of synthetic bone-cement interface. The results...

The aim of the present study is to evaluate the biomineralization behavior of silk fibroin. The biomimetic mineralization was carried out in an alternative calcium/phosphate soaking solution (ACPS). The formation of calcium phosphate deposits was identified by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD...

The mechanical behavior of single tomato fruit cells has been characterized using high strain-rate microcompression testing. Single cells isolated by gentle washing from inner pericarp tissue were compressed to a wide range of deformations at a speed of 1500 µm/s, and then released. The cells were larger than any tested previously by microcompressi...

A recently developed high strain-rate micro-compression tester was used for the mechanical characterization of alginate microspheres produced by emulsification/internal gelation. Single microparticles with diameters of 80– were compressed to a wide range of deformations at different speeds (10–), and then released, or held at constant deformation t...

Nanoindentation experiments on tricalcium phosphate (TCP) bioceramic sintered at different temperatures were performed with a Berkovich indenter for determining hardness and elastic modulus from load and displacement data. The hardness and Young's modulus increased with the increase of sintering temperature up to 1300 °C, but the Young's modulus de...

The relationship between composition and structure of plant primary cell walls, and cell mechanical properties is not fully understood, partly because intrinsic properties of walls such as Young's modulus cannot be obtained readily. The aim of this work is to show that Young's modulus of walls of single suspension-cultured tomato cells can be deter...

The mechanism of bone-like apatite formation on the surface of pure titanium pretreated with NaOH solution is still being investigated. The apatite formation may depend on the solution that is used. In the present study, several types of solutions such as simulated body fluid (SBF), calcium aqueous solution (CAS), and phosphate aqueous solution (PA...

Bone-like apatite formed on the surface of Ti6Al4V pretreated with NaOH solution after having been immersed in simulated body fluid (SBF), while no apatite formed on the surface of untreated Ti6Al4V. In the present study, electrochemical impedance spectroscopy (EIS) measurement was used to investigate the nucleation and growth of apatite on chemica...

Bone-like apatite was found to form on some pretreated metals after their immersion in simulated body fluid (SBF). In the current investigation, pure Ti, Ti-6Al-4V and 316L stainless steel were pretreated with an alkaline solution and subsequently immersed in SBF. To study the formation and growth of bone-like apatite on the pretreated metals, elec...

Thermokinetics method was used to study the self-setting kinetics of a new kind of calcium phosphate cement (CPC) in the present study. A calcium-deficient hydroxyapatite CPC was developed by using alpha-TCP and other calcium phosphate bioceramics. The mixing liquids used were deionized water and 0.25 M NaH2PO4/Na2HPO4, respectively. The calorimetr...

Bone-like apatite formed on the surface of pure titanium pretreated with NaOH solution after having been immersed in simulated body fluid (SBF). In the present study, electrochemical impedance spectroscopy (EIS) measurement was used to investigate the nucleation and growth of apatite on chemically treated pure titanium immersed in the SBF solution....

Ion beam sputtering and ion beam sputtering/mixing deposition techniques were used to produce thin bioactive glass coatings on titanium substrate. It was found that as-deposited coatings were amorphous. Scanning electron microscopical examination showed that the coatings had a uniform and dense structure and that fabrication parameters affected the...

Ion beam sputtering/mixing deposition was used to produce thin calcium phosphate coatings on titanium substrate from the hydroxyapatite target. It was found that as-deposited coatings were amorphous. No distinct absorption band of the hydroxyl group was observed in FTIR spectra of the coatings but new absorption bands were present for CO32-, which...

Ar+ ion beam sputtering/mixing deposition was used to produce thin calcium phosphate coatings on titanium substrate from hydroxyl-poly-calcium sodium phosphate (HPPA) and HPPA + Ti targets. Three types of coatings (one type of monolayer coating and two types of functionally graded coating) were manufactured. It was found that as-sputtered coatings...

Ion-beam-sputtering/mixing deposition was used to produce thin calcium phosphate coatings on titanium substrate from the hydroxyapatite target. The mixing beam could be either Ar+ or N+ ions. It was found that as-deposited coatings were amorphous. No distinct peak of the hydroxyl group was observed in FTIR spectra of the coatings, but new spectral...

X-ray photoelectron spectroscopy was used to analyze the ion beam sputter deposited calcium phosphate coating. Pure titanium plates of the size 20mm × 20mm × 1mm were used as the substrtate. They were polished and ultrasonically cleaned with acetone. Hydroxyapatite (HA) powder was synthesized using the wet method. HA powder disks used to analyze th...

Calcium phosphate coatings produced by means of ion beam sputter deposition are amorphous and therefore exhibit high dissolution rate. Heat treatments can provide the energy needed to form crystalline hydroxyapatite-like coatings. In this investigation, to produce crystalline coatings, conventional heat treatment using an electric furnace was condu...

Ion beam sputtering/mixing deposition was used to produce dense and homogeneous calcium phosphate (Ca-P) coatings on titanium substrate. The mixing beam was either Ar+ or N+ ions. Scanning electron microscopy revealed that the deposited coatings had a uniform and dense structure. The calcium to phosphorous ratio of these coatings varied between 2.0...

Two biodegradable materials, namely, tricalcium phosphate (TCP) and polyhydroxybutyrate (PHB), were used to produce a new composite material for tissue replacement/regeneration. Commercially available TCP and PHB were used, with both materials being in the form of fine powders. They were characterised prior to composite production. TCP/PHB composit...

Ar+ ion beam sputter deposition was used to produce thin calcium phosphate (hydroxyl poly calcium sodium phosphate, HPPA) coating on polished titanium substrate. In this study, HPPA ceramic target was sputtered by an argon-ion beam with energy of 0.9 keV, 1.2 keV and 1.5 keV, respectively. X-Ray diffraction (XRD), scanning electron microscopy (SEM)...

Ion beam sputtering/mixing deposition was used to produce dense and homogeneous calcium phosphate (Ca-P) coatings on titanium substrate. The mixing beam was either Ar+ or N+ ions. Scanning electron microscopy revealed that the deposited coatings had a uniform and dense structure. The calcium to phosphorous ratio of these coatings varied between 2.0...

Hydroxy-apatite (Ca10(PO4)6(OH)2,HA) is a potential material for coating on metal implants owing to its bioaffinity and osteo-integration to body. At present, in addition to bulk HA directly used in restoration and reconstruction surgery, hydroxy-apatite is also coated on metal implants by plasma-spraying method, adhesion and sintering. However, th...

The friction and wear properties of UHMWPE rubbing against SiC ceramics under dry sliding and lubrication of fresh plasma or water were evaluated with Falex machine at 37 °C. The surfaces of specimens were observed with scanning electron microscope and surface profilometer. It was found that the friction coefficient is highest at dry sliding and lo...

Hydroxy-apatite (Ca₁₀(PO₄)₆(OH) ₂, HA), owing to its bioaffinity and osteo-integration to the body, is a potential material for coating metal implants. At present, in addition to bulk HA directly used in restoration and reconstructive surgery, hydroxy-apatite is also coated on metal implants by the plasma...