Significant Differences In Roughness Research Articles

Atomic scale surface structure and morphology of InAs nanowire crystal superlattices: the effect of epitaxial overgrowth.

While shell growth engineering to the atomic scale is important for tailoring semiconductor nanowires with superior properties, a precise knowledge of the surface structure and morphology at different stages of this type of overgrowth has been lacking. We present a systematic scanning tunneling microscopy (STM) study of homoepitaxial shell growth of twinned superlattices in zinc blende InAs nanowires that transforms {111}A/B-type facets to the nonpolar {110}-type. STM imaging along the nanowires provides information on different stages of the shell growth revealing distinct differences in growth dynamics of the crystal facets and surface structures not found in the bulk. While growth of a new surface layer is initiated simultaneously (at the twin plane interface) on the {111}A and {111}B nanofacets, the step flow growth proceeds much faster on {111}A compared to {111}B leading to significant differences in roughness. Further, we observe that the atomic scale structures on the {111}B facet is different from its bulk counterpart and that shell growth on this facet occurs via steps perpendicular to the ⟨112⟩B-type directions.

Cold plasma-induced surface modification of heat-polymerized acrylic resin and prevention of early adherence of Candida albicans.

Atmospheric-pressure cold plasma was applied to process the surface of heat-polymerized acrylic resin. Changes to the physical properties and early adherence of Candida albicans were investigated. Alternating current cold plasma with Ar/O2 as working gas was used. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to study the possible mechanism. Experimental results showed that after plasma treatment, the contact angle of acrylic resin significantly decreased. There were no significant differences in roughness, flexural strength and elasticity modulus, but microhardness was significant improved in the treated group. More importantly, the early adherence of Candida albicans on the surface was reduced after plasma treatment. Cold plasma seemed to be a promising and convenient strategy of preventing the early adherence of Candida albicans on acrylic resins, which would greatly benefit potential dental applications.

Effect of tooth brush abrasion and thermo-mechanical loading on direct and indirect veneer restorations

This study investigated toothbrush abrasion and in vitro aging on ceramic (indirect technique) and composite veneers (direct technique). Identical composite and individual human incisors were restored with industrially preformed composite veneers, indirectly produced ceramic veneers, and direct composite restorations. Surface roughness was determined before and after tooth brushing. A 5-year period of oral service was simulated by thermal cycling and mechanical loading (TCML). After TCML, all specimens were examined with microscopy and scanning electron microscopy. Specimens without failures during TCML were loaded until failure. analysis of variance; Bonferroni's post hoc analysis, Kaplan-Meier-Log Rank test (α = 0.05). Tooth brushing yielded a non-significant increase (p = 0.560) in roughness in all materials (industrial veneer, 0.12+/-0.07 μm, direct restoration, 0.18+/-0.14 μm, ceramic, 0.35+/-0.16 μm). No significant differences in roughness could be determined between the materials, neither before nor after testing (p < 0.001). After TCML of artificial teeth, direct and preformed composite veneers on composite teeth showed no failures or damages. Two ceramic veneers showed cracking in the labial area. After TCML of human teeth, transmission microscopy indicated a facial crack in a ceramic veneer and chipping in the cervical area of a preformed veneer. Two direct composite veneers lost retention. No significantly different survival rates were found between the three veneer groups. Fracture force on human teeth varied between 527.8+/-132.4 N (ceramic), 478.3+/-165.4 N (preformed composite), and 605.0+/-263.5 N (direct composite). All materials revealed comparable wear resistance. Indirect ceramic, direct restorative composite, and preformed composite veneers showed comparable failure rates and satisfying longevity. The results indicate similar longevity of the chosen materials for veneer restorations.

Comparative evaluation of dental resin composites based on micron- and submicron-sized monomodal glass filler particles

ObjectivesA model resin composite containing a novel monomodal inorganic filler system based on submicron-sized Ba–Si–Al glass particles (NanoFine NF180; Schott) was formulated and compared with an experimental composite containing micron-sized particles (UltraFine UF1.0; Schott). MethodsThe filler particles were characterized using X-ray microanalysis and granulometry, while the composites were characterized in terms of filler–resin morphology, radiopacity, degree of CC conversion, hardness, flexural strength/modulus, work-of-fracture, surface roughness and gloss (before and after simulated toothbrushing abrasion), and bulk compressive creep. The composites were formulated from the same photoactivated dimethacrylate co-monomer, incorporating mass fractions of 75% micron- and 78% submicron-sized particles. Quantitative data were analyzed at a significance level of p<0.05. ResultsBoth filler systems exhibited a narrow grain size range (175±30 and 1000±200nm), with differences restricted to the size and specific area of the particles. The composites were similar in radiopacity, flexural strength, work-of-fracture, and creep. The submicron composite was harder but had lower flexural modulus and CC conversion. No significant differences in roughness were observed before brushing, although the submicron composite had higher gloss. Brushing increased roughness and decreased gloss on both materials, but the submicron composite retained higher gloss after brushing. SignificanceThe monomodal submicron glass filler system demonstrated potential for use in restorative dental composites, particularly due to improved esthetic properties.

Voice Quality of Life after Type II Thyroplasty for Spasmodic Dysphonia

Objective: 1) Determine the effectiveness of type II thyroplasty for adductor spasmodic dysphonia (AdSD), through perceptual and accoustic analysis. 2) Assess the pre- and postoperative quality of life of AdSD patients using the Voice Handicap Index-10 (VHI-10). Method: Retrospective study. Twelve patients with AdSD underwent type II thyroplasty between March 2007 and December 2010. Measured outcomes included perceptual assessment, acoustic analyses (DVB, SDF0, jitter, shimmer, and HNR), and VHI-10 and were performed prior to and six months or more after surgery. VHI-10 and acoustic evaluation scores were compared. Results: Average follow-up interval was 12.6 months. In perceptual analysis (GRBAS), overall grade and strain significantly improved after surgery ( P = .0017, P = .0002). There were no significant difference in roughness, breathiness, and asthenia. In acoustic analysis, DVB, SDF0, jitter, shimmer, and HNR ( P = .039, P = .0003, P = .0016, P = .0011, P = .0003) improved significantly after surgery. Mean VHI-10 scores significantly improved from a mean of 26.5 to 3.75. Conclusion: Treatment of AdSD with type II thyroplasty significantly improved voice-related quality of life and acoustic findings. The study revealed a significant relationship between the acoustic parameters and the VHI-10. The results confirmed that VHI-10 can be a valuable tool for assessing type II thyroplasty for AdSD.

30-Month randomised clinical trial to evaluate the clinical performance of a nanofill and a nanohybrid composite

Objective To evaluate the clinical performance of a nanofill and a nanohybrid composite in restorations in occlusal cavities of posterior teeth in a randomised trial over 30 months. Methods Forty-one adolescents participated in the study. The teeth were restored with a nanofill (Filtek Z350, 3M ESPE), a nanohybrid (Esthet-X, Dentsply); Filtek Z250 (3M ESPE) was used as a control. After 30 months, the restorations were evaluated in accordance with the US Public Health Service (USPHS) modified criteria. The McNemar and Friedman tests were used for statistical analysis, at a level of significance of 5%. Results There were significant differences in the roughness of Filtek Z250 ( p = 0.008) and Filtek Z350 ( p < 0.001) when the four time periods (baseline, 6 months, 12 months and 30 months) were compared. There were significant differences in the marginal adaptation of Filtek Z250 ( p = 0.001), Filtek Z350 ( p < 0.001) and Esthet-X ( p = 0.011). Except for one of each composite restoration, all the modifications ranged from Alpha to Bravo. There were significant differences in the surface roughness ( p = 0.005) when the three composites were compared after 30 months. Conclusions The materials investigated showed acceptable clinical performance after 30 months. Long-term re-evaluations are necessary for a more detailed analysis of these composites (CEP: #1252).

Effects on titanium implant surfaces of chemical agents used for the treatment of peri‐implantitis

The treatment of peri-implantitis, which causes tissue deterioration surrounding osseointegrated implants, involves surface decontamination and cleaning. However, chemical cleaning agents may alter the structure of implant surfaces. We investigated three such cleaning solutions. Commercially pure (grade 4) machined titanium discs (CAMLOG Biotechnologies AG, Switzerland) were treated with 3% H(2)O(2) (5 min), saturated citric acid (pH = 1) (1 min) or chlorhexidine gel (5 min), and their surface properties were examined by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Human epithelial cell attachment (24-h observation) and proliferation (72-h observation) were investigated via dimethylthiazolyl-diphenyltetrazolium bromide (MTT) and bicinchoninic acid (BCA) protein content assays. AFM revealed no significant difference in roughness of the three treated surfaces. XPS confirmed the constant presence of typical surface elements and an intact TiO(2) layer on each surface. The XPS peaks after chlorhexidine gel treatment demonstrated C-O and/or C=O bond formation, due to chlorhexidine digluconate infiltrating the surface. MTT and BCA assays indicated similar epithelial cell attachments in the three groups; epithelial cell proliferation being significantly higher after H(2)O(2) than after chlorhexidine gel treatment (not shown by BCA assays). These agents do not harm the Ti surface. Cleaning with H(2)O(2) slightly enhances human epithelial cell growth, in contrast to chlorhexidine gel.

Topography of epitaxial GaAs surfaces for growth

The topography and surface roughness of (100) GaAs substrates and buffers after different preparation procedures were determined from atomic force microscopy (AFM) measurements. In order to characterize the topography over a wide range of length scales, multiple large 5×5 μm2 AFM scans were acquired for each sample. These scans were analyzed both by histogramming the distribution of pixel heights and by finding the rms roughness at length scales from 10 nm to 5 μm using a tiling analysis. The influence of substrate aging and chemical etching on buffers grown by molecular beam epitaxy was studied, as was the effect of different buffer growth procedures. Immediately after thermal desorption of the surface oxide, all wafers were extremely rough, as expected, with wafers etched in HCl:H20 (1:1) somewhat smoother than untreated epiready wafers, while wafers etched in H2O2:NH4OH:H2O (3:1:10) were rougher. After as little as 100 nm of buffer growth, however, there was no significant difference in roughness of etched or as-received substrates, and all samples were quite smooth with a rms roughness around 0.27 nm. The buffer growth conditions were found to significantly affect surface roughness. Interrupting the supply of Ga at the start of the growth enhanced mounding on the wafer surface, while postgrowth annealing at the growth temperature reduced the surface roughness and changed the characteristic topography of the surface.

Finishing Systems on the Final Surface Roughness of Composites

This study evaluated differences in surface roughness of a microhybrid (Gradia Direct, GC America) and a nanofil (Filtek Supreme, 3M ESPE) composite using four polishing systems: PoGo/Enhance (DENTSPLY/Caulk), Sof-Lex (3M ESPE), Astropol (Ivoclar Vivadent), and Optidisc (KerrHawe). An aluminum mold was used to prepare 2 X 60 composite disks (10 mm X 2 mm). Composite was packed into the mold, placed between two glass slabs, and polymerized for 40 seconds from the top and bottom surfaces. Specimens were finished to a standard rough surface using Moore's disks with six brushing strokes. Specimens were rinsed and stored in artificial saliva in individual plastic bags at 36 degrees C for 24 hours prior to testing. Specimens were randomly assigned to one of the four polishing systems and were polished for 30 seconds (10 seconds per grit) with brushing strokes according to the manufacturer's instructions. Mean surface roughness (Ra) was recorded with a surface-analyzer 24 hours after storage in artificial saliva, both before and after polishing. Means were analyzed using two-way and one-way analysis of variance (ANOVA) and Tukey multiple comparison tests at p < 0.05. There was a statistically significant difference for baseline measures between Filtek and Gradia (p=0.0338). For Filtek, Sof-Lex provided a significantly smoother surface (Ra=0.80 +/- 0.21) than Optidisc (Ra=0.93 +/- 0.28), Astropol (Ra=1.15 +/- 0.24), and Pogo/Enhance (Ra=1.39 +/- 0.39). For Gradia, Sof-Lex provided a significantly smoother surface (Ra=0.47 +/- 0.09) and Astropol provided a significantly rougher surface (Ra=1.39 +/- 0.19) than Pogo/Enhance (Ra=1.11 +/- 0.20) and Optidisc (Ra=1.15 +/- 0.18). There was no significant difference in roughness between composites for individual polishing systems (p=0.3991). Filtek specimens were smoother than Gradia specimens after baseline roughening. Sof-Lex provided the smoothest final surface when used with either composite. Astropol provided a rough surface for Gradia specimens.

Preparation and characterisation of controlled release co-spray dried drug–polymer microparticles for inhalation 1: Influence of polymer concentration on physical and in vitro characteristics

A series of co-spray dried microparticles containing di-sodium cromoglycate (DSCG) and polyvinyl alcohol (PVA – 0%, 30%, 50%, 70% and 90% w/w, respectively), were prepared as potential controlled release (CR) viscous/gelling vehicles for drug delivery to the respiratory tract. The microparticles were characterised in terms of particle size, crystal structure, density, surface morphology, moisture sorption, surface energy and in vitro aerosolisation efficiency. The co-spray dried particles were amorphous in nature and had spherical geometry. High-resolution atomic force microscopy analysis of the surfaces of the DSCG/PVA suggested no significant differences in roughness between microparticles containing 30–90% w/w PVA (ANOVA, p < 0.05), while no specific trend in either size or density was observed with respect to PVA concentration. In comparison, a linear decrease in the relative moisture sorption ( R 2 = 0.997) and concurrent increase in total surface free energy ( R 2 = 0.870) were observed as PVA concentration was increased. Furthermore a linear increase in the aerosolisation efficiency, measured by inertial impaction, was observed as PVA concentration was increased ( R 2 = 0.993). In addition, the increase in aerosolisation efficiency showed good correlation with equilibrium moisture content ( R 2 = 0.974) and surface energy measurement ( R 2 = 0.905). These relationships can be attributed to the complex interplay of particle forces at the contiguous interfaces in this particulate system.

Aesthetic Diode Laser Welding of Stainless Steel

In the present study the use of diode laser for stainless steel aesthetic welding is considered. In fact the surface smoothness of the weld bead, attributed to the mode stability of the laser system, suggests its application for aesthetic weld joint. The aims of this work were to: define a process map, based on an aesthetic criterion; mechanically characterize the weld joints (by Vickers micro-hardness and tensile test); analyse the surface of the specimens in terms of roughness. Moreover, gas tungsten-arc (TIG) weld joints were carried out and analogously tested to make a comparison with the diode laser results. Good aesthetic butt joints were obtained with diode laser welding. The same results were found working with constant power speed ratio (i.e. constant fluence). Comparison between TIG and Laser Beam Welding (LBW), showed no significant difference in roughness, while ultimate tensile load was higher for TIG welding. The differences in joint strength depend on the different cross-sectional area and on the extension and microstructure of the base metal, heat-affected zone and melted zone. However, diode laser technology allows to obtain smaller bead size.

Replication of a holographic ion-etched spherical blazed grating for use at extreme-ultraviolet wavelengths: topography

We have measured the topography of a holographic ion-etched spherical blazed grating and three of its replicas using an atomic force microscope. The master grating had a roughness of less than 5 angstroms rms, a blaze angle of 2.5 degrees, and an antiblaze angle of 3.3 degrees. Thus the groove profile was more triangular than sawtooth. We find that the replication process did not significantly change the master grating. Moreover, we find no significant difference in roughness, blaze angle, or antiblaze angle between the master and its replicas before or after multilayer coating. However, bumps were observed on the gratings after coating, the cause of which is not understood. Although widespread, they occupy a relatively small fraction of the total area.

Brushing Effect of Abrasive Dentifrices during At-home Bleaching with 10% Carbamide Peroxide on Enamel Surface Roughness

During tooth bleaching abrasive dentifrices might change the outer superficial enamel. The aim of this in vitro study was to evaluate the roughness of human enamel exposed to a 10% carbamide peroxide bleaching agent at different times and submitted to different superficial cleaning treatments. The study consisted of 60 sound human enamel slabs, randomly assigned to different treatment groups: G1--not brushed; G2--brushed with a fluoride abrasive dentifrice; G3--brushed with a non-fluoride abrasive dentifrice; and G4--brushed without a dentifrice. There were 15 enamel slabs per group. Slabs of molar teeth were obtained and sequentially polished with sandpaper and abrasive pastes. A perfilometer was used to obtain the mean of Ra value on the surface of each specimen to initial and experimental times. Bleaching was performed on the enamel surface for six hours daily. After that, each slab received a cleaning surface treatment and was stored in artificial saliva. Analysis of variance (ANOVA) and Tukey's HSD hoc analysis (alpha =0.05) revealed significant differences in roughness values over time for enamel bleached and treated with different superficial cleaning methods. G1 and G4 showed no significant differences in roughness over time, G2 and G3 showed a significant increase in the surface roughness values. This in vitro investigation showed the sole use of 10% carbamide peroxide did not alter the enamel surface roughness, but the cleaning treatments that employed the use of brushing with abrasive dentifrices resulted in a significant increase of enamel surface roughness.

Effects of a 10% Carbamide Peroxide Bleaching Agent on Roughness and Microhardness of Packable Composite Resins

Bleaching agents containing 10% carbamide peroxide may be applied to the surface of preexisting packable resin-based composite restorations. The aim of this in vitro study was to evaluate the effect of a 10% carbamide peroxide bleaching agent (Review, SS White, Rio de Janeiro, Brazil) on surface roughness and microhardness of three packable resin-based composites (Fill Magic condensable, Vigodent, Rio de Janeiro, Brazil; Alert, Jeneric Pentron, Wallingford, CT, USA; Definite, Degussa, Hanau, Germany). For the control (no bleaching) and experimental (bleaching treatment) groups, 12 specimens of each material were prepared in cylindrical acrylic molds. The experimental specimens were exposed to the bleaching agent for 6 hours a day for 3 weeks. During the remaining time (18 h), they were stored in artificial saliva. The control specimens remained immersed in artificial saliva throughout the experiment. Surface roughness and microhardness measurements were performed on the top surface of each specimen. Analysis of variance and the Tukey test showed no significant differences in roughness among the packable composites evaluated (p = .18), but those submitted to the treatment with a 10% carbamide peroxide bleaching agent displayed significantly higher mean surface roughness than did the corresponding control group for each material. For the microhardness tests, there were significant differences among materials (p < .0001). Alert showed the highest microhardness values followed by Definite and Fill Magic condensable. Ten percent carbamide peroxide bleaching agents may change the surface roughness of packable composites, but they do not alter their microhardness. Under the conditions of this study, a 3-week bleaching regimen with 10% carbamide peroxide agents affected the roughness of packable composites. Nevertheless, the surface microhardness was not affected, although there were differences among the materials evaluated inherent to their composition.

Influence of Age, Anatomic Site and Race on Skin Roughness and Scaliness

Background: Variations in skin roughness and scaliness between age groups, anatomic sites and race have been assumed but minimally quantified. Objective: We quantitatively investigated skin roughness, scaliness and stratum corneum hydration as a function of age, anatomic site and race (white and black). Methods: Skin roughness, scaliness and stratum corneum hydration were determined in vivo by noninvasive bioengineering and image analysis techniques in 22 female subjects grouped according to age (young and aged) and race (white and black). Results: Skin roughness, scaliness and stratum corneum hydration varied significantly in different anatomic areas and age groups. There was no racial variation in skin hydration between any anatomic site, nor significant differences in roughness and scaliness between races, except for the preauricular area. Skin roughness was significantly increased in the aged, compared to the young at the preauricle, volar forearm, lower back, thigh and lower leg. Older women demonstrated significantly more scaling at the preauricle than younger women. Stratum corneum hydration correlated with scaliness. No significant correlation between stratum corneum hydration and skin roughness was observed. Conclusion: Age and anatomic site but not race demonstrated a significant influence on skin roughness and scaliness. The desquamation index appears a good indicator of the status of stratum corneum hydration.

In vitro effect of topical fluoride on dental porcelain

Fifty-seven porcelain samples were randomly subjected to a variety of topical fluorides for time intervals of 4 to 64 minutes. Half of each porcelain surface was masked to prevent contact with the fluoride. Measurements of roughness were made for the fluoride-treated and the untreated porcelain surfaces to evaluate the effect of the different fluoride preparations over time. The resulting surfaces were also examined using an SEM. Conclusions from this study include the following. Statistically significant differences in roughness were found among surfaces exposed to 1.23% acidulated phosphate fluoride gel, 8% stannous fluoride, and the control surfaces. There were no significant differences in roughness between the test and control surfaces with 0.05%, 0.2%, and 2% sodium fluoride solutions or 0.4% stannous fluoride gel. The dentist should be aware of the potentially deleterious effects of prescribing or administering a topical fluoride for patients with porcelain/metal restorations.