Significant Differences In Roughness Research Articles

Effect of polymerization methods on surface roughness and hardness of commercially available self-curing acrylic resins: a comparative study

Purpose This paper aims to compare the surface roughness and hardness of three commercially available self-curing acrylic resins for dental use, under different polymerization conditions. Design/methodology/approach A comparative in vitro study was conducted using a convenience sample of 12 × 5 × 2 mm blocks with n = 40 for each material (Nic Tone, Arias Plus and Orthocryl®), with subgroups according to the polymerization method: conventional (C) and polymerization under ambient conditions (A). The surface roughness of the materials was measured using a profilometer; hardness was measured with a portable hardness tester. Additionally, surface morphology as well as particles size and morphology were evaluated with scanning electron microscopy. Findings There were significant differences in roughness and hardness values between the three self-curing acrylic resins (p < 0.05), as well as within each self-curing acrylic resin according to the polymerization method used (p < 0.05). The samples polymerized with the conventional method presented lower surface roughness and hardness values. Originality/value This study provides scientific evidence of values not provided by manufacturers in relation to the surface roughness and hardness of these materials, and all of them met the ideal minimum values of surface roughness, regardless of the polymerization technique used.

Re-recognition of the role of roughness in keloid assessment

BackgroundUnder visual observation, keloids are more rough than normal skin. This roughness may be used to assess the activity and severity of keloids but lacks the support of objective and accurate evidence. The purpose of this study was to verify the role of roughness in the development of keloids and to clarify the advantage of roughness in the comprehensive assessment of keloids. MethodsPatients with keloids who attended Peking Union Medical College Hospital were recruited. Keloids were classified into progressive, stable, and atrophic stages based on the change in size over the past year and blood perfusion. The keloids were evaluated using the Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS). The roughnesses of the keloid and normal skin were measured using the Phaseshift Rapid In vivo Measurement Of the Skin (PRIMOS), and blood perfusion was measured using laser speckle contrast imaging (LSCI). ResultsThirty-three patients with a total of 81 keloids were included. The surface roughness values Sa, Sq, and Sz of the keloid region were 243.70 (143.85–328.05), 316.20 (179.85–475.20), and 1708.20 (1098.30–4087.20), respectively, which were 4.87, 4.80, and 3.08 times higher than those of normal skin. There were significant differences in roughness among the different keloid stages. A significantly strong correlation between roughness and other assessed indices was found. ConclusionsRoughness as a morphological characteristic is of great value in the evaluation of keloids. It is recommended as an important examination for keloids.

Role of CO2 Laser on SBS between Dental Porcelain and Composite Resin Repair Process

Background. The surface modification of porcelain material can be conducted by mechanical, chemical, or laser means. This study investigated the CO2 laser effect on porcelain to enhance bonding with composite resin. Materials and methods. A total of 33 blocks of feldspathic porcelain were randomly divided into 3 groups of 10. Additionally, three specimens were used in scanning electronic microscopy and energy-dispersive spectroscopy tests. Group I was treated with 9.5% hydrofluoric acid (HF), Group II with a 5 W CO2 laser, and Group III with CO2 followed by etching with 9.5% HF. Then, a Bisco intraoral repair kit was used, followed by the application of repair composite resin (Tetric N Ceram) on the porcelain surface using a Teflon mold and light-curing source. Shear bond strength (SBS) was assessed by using a digital universal testing machine, and failure modes were evaluated. Data were analyzed by analysis of variance (ANOVA) and least significant difference test. Results. A high significant difference in roughness and SBS was found amongst the tested groups P < 0.001 . SBS and roughness for Group III were significant at P < 0.05 , and the lowest value was observed in Group II. The cohesive mode of failure was dominant in Groups I and III, whereas adhesive failure was dominant in Group II. Conclusion. The surface treatment of porcelain with CO2 laser followed by HF application can enhance roughness and SBS, and can be recommended when extra retention during repair indication.

Effect of buffer layer and substrate growth temperature on the microstructural evolution of hexagonal boron nitride thin films

Hexagonal boron nitride (hBN) thin films have excellent optical, electrical, and corrosion resistance properties that can enable a wide range of applications. The current study explores pulsed laser deposition technique for synthesizing hBN thin films. The microstructure, mechanical, and wetting properties of hBN thin films were analyzed as a function of substrate growth temperature (25 °C, 300 °C, 500 °C, and 800 °C) and buffer layer addition (Cu or Ti). The microstructure of hBN thin films was found to be influenced by the deposition temperature. This study revealed that the layered growth (for samples deposited at 25 °C) and layer plus island growth (for samples deposited at ≥300 °C) to be the primary growth modes of the thin films regardless of the buffer layer. The roughness of hBN thin films with the Cu buffer layer, in general, increased with the increase in deposition temperature, whereas no significant differences in roughness were observed for films deposited on Si and Ti buffer layer. Grazing Incidence X-ray diffraction results showed the presence of hexagonal close packed crystal structure for all the deposited thin films. These results were corroborated with Raman spectroscopy. The hBN thin films exhibited the hardness and modulus values of ~10–14 GPa and ~120–180 GPa, respectively. No considerable differences in mechanical properties were observed for hBN thin films deposited at various temperatures except for the films deposited with the Cu buffer layer, which showed lower mechanical properties. The wettability of hBN thin films was analyzed using contact angle measurements. The wettability was found to be directly influenced by the surface roughness of hBN thin films. Characterization of hBN thin films indicates that the deposition temperature and buffer layer addition had an influence on the growth and microstructural evolution of hBN thin films.

Effects of food-simulating solutions on the surface properties of two CAD/CAM resin composites

During clinical service, dental materials could experience chemical degradation due to exposure to different diet components which could affect their functions and longevity. So, the objective of this study was to investigate the effect of food simulating solutions on surface properties of two CAD/CAM dental resin composites. Two CAD/CAM composites; a nano-hybrid and a resin nano-ceramic were machined into 2 mm plates then assessed at baseline for their surface roughness and microhardness. Each group was immersed into distilled water, ethanol and methyl ethyl ketone (MEK) for 15 days at 37oC. The surface properties were evaluated after one day, 10 and 15 days of immersion by a surface profilometer and Vickers microhardness tester, and finally the surface morphology was studied using scanning electron microscopy. At baseline, there was no significant difference in roughness between Teric CAD and Lava Ultimate, however, Lava Ultimate was significantly harder than Tetric CAD. Aging in ethanol had no significant effect on roughness and hardness of both the materials. Yet, Lava Ultimate showed significantly higher roughness and hardness compared to Tetric CAD. Immersion in MEK resulted in a significant increase in roughness of Lava Ultimate at 10 and 15 days. Neverthless, it caused a significant decrease in hardness of Tetric CAD at 10 and 15 days and Lava Ultimate at 10 days. Finally, water immersion caused a significant increase of roughness Tetric CAD. Exposure to different storage media variably affected the surface properties of CAD/CAM machinable composites. Both materials showed greater stability in surface properties when being immersed in ethanol than MEK. Hence, the surface deterioration suggests the advisability of more research involving increased immersion periods and involvement of thermocycling changes. Key words:Food simulating solutions, chemical degradation, nano-hybrid CAD/CAM composite, resin nano-ceramic CAD/CAM material, surface roughness, micro-hardness, surface morphology.

ANALYSIS OF THE INFLUENCE OF TURNING PARAMETERS OF CUZN39PB3 AND AW 6060 MATERIALS ON SURFACE ROUGHNESS

The article presents an analysis of the turning parameters of two non-ferrous materials. The tested materials were: brass CuZn39Pb3 and aluminum alloy AW 6060. A Kyocera turning knife and a WNMG 080404 AH plate were used to make the samples. Three parameters were tested: rotational speed, feed and depth of cut at three levels of variability. The roughness parameters Ra and Rz were selected for the analysis. On the basis of the obtained results, it was shown that the feed used during machining has the greatest influence on roughness, while the change of depth or cutting speed does not cause significant differences in roughness.

Fracture surface formation of notched 2017A-T4 aluminium alloy under bending fatigue

The effect of cyclic loading on facture surface topology in notched components made by aluminium alloys is not completely clear. Fractography and fracture mechanics can help to understand this interdependency. This paper aims to study the distribution of the fracture surface roughness of notched 2017A-T4 aluminium alloy after bending fatigue using an optical focus-variation surface measurement technique by applying the fracture zone concept. The effects of stress level at the notch root and the load ratio on fatigue crack growth and fracture surfaces are analysed. Profile and areal surface parameters of four fracture surface regions were investigated at incremental crack lengths of the specimens. Studies have confirmed that the surface areas associated with the main stages of fatigue phenomenon (i.e. crack initiation, crack propagation, and final rupture) have significant differences in roughness which can be explained by the different loading scenarios. Overall, fatigue fracture surfaces have smallest roughness values at the crack initiation stage and a gradual increase during the fatigue crack growth stage.

Surface Roughness on the Slots and Wings of Various Ceramic Self-Ligating Brackets and their Potential Concern on Biofilm Formation.

The surface roughness of various orthodontic materials could affect biofilm formation and friction. The purpose of this study was to examine the surface roughness and chemical composition of the slots and wings of several ceramic self-ligating brackets. Four types of ceramic self-ligating brackets were separated into experimental groups (DC, EC, IC, and QK) while a metal self-ligating bracket (EM) was used as the control group. Atomic force microscopy and energy-dispersive x-ray spectroscope were used to examine the surface roughness and chemical composition of each bracket slot and wing. The control group was made of ferrum and chrome while all the experimental groups were comprised of aluminum and oxide. There was a statistically significant difference in the roughness average (Sa) among the various self-ligating brackets (p< 0.001 in slots and p<0.01 in the wing). The slots in the EC group had the lowest Sa, followed by the DC, IC, control, and QK groups. The wings in the IC group had the lowest Sa, followed by the EC, DC, control, and QK groups. There is a significant difference in the surface roughness of the slots and wings among several types of ceramic self-ligating brackets.

Influence of Milling Tool and Prosthetic Materials on Roughness of the Dental CAD CAM Prostheses in End Milling Mode

Dental prostheses are machined by computer-aided design and manufacturing (CAD/CAM) tools. The integrity of the surface obtained, which must be suitable to meet expected clinical requirements is influenced by the milling parameters programmed. The integrity of the occlusal prosthesis surface obtained by the end milling mode, that is milling with a diamond rotary cutting tip, plays a major role in the clinical requirements desired. This study aims to investigate the impact of the tool-biomaterial couple in the CAD/CAM end milling mode on surface integrity (through roughness). Two CAD/CAM tools and four CAD/CAM biomaterials, both combined to four feed rates are tested. The surface roughness (Ra, Rt, Rz, Sa, Sq, and Sz) is observed for each couple. Finally, pairwise comparisons (Kruskal-Wallis test) of tool-biomaterial couples are performed. The results indicate that all the machined surfaces reveal isotropic surface topology. The roughness depends on the hardness of the biomaterial and not on the feed rate. The statistical tests reveal a significant difference in roughness depending on the tool used. To conclude, when milling the functional occlusal shape, biomaterial hardness and the tool used are key factors for achieving a given roughness consistent with clinical requirements.

Estimating Nanoscale Surface Roughness of Polyethylene Terephthalate Fibers.

Quantitation of surface roughness is difficult, if subtle, but significant differences cause an uncommon variance. We used atomic force microscopy to measure the surface roughness of polyethylene terephthalate (PET) fibers before and after a 30 s plasma treatment of 300 W. Samples were measured multiple times at different locations, in four scan sizes. The surface roughness was expressed in terms of nine roughness parameters. Despite the large number of data, simple statistics was not able to detect significant differences in roughness before and after plasma treatment. A factorial analysis of variance (ANOVA) of the normalized data and a sum of ranking differences analysis using four types of data preprocessing and their factorial ANOVA confirmed that (i) the plasma treatment had roughened the PET fiber surface; (ii) the roughness increases with the scanned area in the measured range; and (iii) what the best roughness parameters are in discriminating between surfaces before and after treatment. Although the compared roughness estimators were on different scales, a roughness estimation of the nanoscale surfaces was feasible, where other methods fail. The presented methodology can be applied widely and unambiguously for highly different method comparison tasks.

Experimental Comparison of Micromilling Pure Titanium and Ti–6Al–4V

Pure titanium is the ideal metallic material to be used for producing dental implants due to its good corrosion resistance and biocompatibility. However, pure titanium does not present high mechanical resistance, which can be a limiting factor. Recently, the pure titanium is being replaced by titanium alloy with aluminum and vanadium (Ti–6Al–4V). This study deals with micromilling machinability of pure titanium and Ti–6Al–4V considering mechanical properties, the forces measured during the process, surface roughness, top burr height, and chips morphology. The cutting tests are performed for the constant depth of cut and cutting speed, and a range of feed per tooth from 0.5 to 4.0 μm/tooth. Results show no significant differences in roughness and burr formation, whereas higher forces are found for the titanium alloy compared to pure metal. Both materials produce long chips for smaller feeds.

Perceptual and Acoustic Outcomes of Early-Stage Glottic Cancer After Laser Surgery or Radiotherapy: A Meta-Analysis.

Laser surgery (LS) or radiotherapy (RT) is normally recommended in early glottic cancer. The objective of this study was to perform a comprehensive meta-analysis of acoustic and perceptual outcomes to compare voice quality of LS or RT in early-stage glottic cancer. Data sources were obtained after searching PubMed, Google Scholar, EBSCO, and RISS using the following search terms: glottic cancer, glottic carcinoma, endoscopic surgery, laser surgery, radiotherapy, radiation, voice, voice quality, and grade, roughness, breathiness, asthenia, and strain (GRBAS) scale. Articles that compared voice outcomes between LS and RT were identified. This meta-analysis included 15 articles with 744 patients, including 400 in the LS group and 344 in the RT group. Random effects models were selected. Forest plots included standardized mean differences, standard errors, variance, 95% confidence intervals (lower limit to upper limit), z-values, and P-values. In perceptual analysis, grade (G) and asthenia (A) of RT were significantly better than LS. There was no statistically significant difference in roughness (R), breath (B), or strain (S) between LS and RT groups. Jitter, shimmer, and noise to harmonic ratio measurements showed significant differences, resulting in enhanced posttreatment effect of RT compared to LS. Results of our meta-analysis suggested that RT might lead to superior voice quality than LS in early glottic cancer.

Evaluation of colour change and surface roughness of two resin-based composites when exposed to beverages commonly used by children: an in-vitro study

AimTo evaluate and compare the surface roughness and colour change of microhybrid and nanocomposite after exposure to beverages commonly used by children.MethodsThirty discs were prepared using Filtek Z250 and Filtek Supreme composites. Discs were immersed in distilled water, orange juice and Coca-Cola. Colour and surface roughness were measured at baseline and on days 15 and 30.ResultsFiltek Z250 and Filtek Supreme showed no significant difference in surface roughness and colour change at all measurement times. Immersion solution had a significant effect on surface roughness as well as colour change. Specimens immersed in Coca-Cola demonstrated the highest effect, followed by those immersed in orange juice, while specimens immersed in distilled water had the least effect. There was a significant increase in surface roughness and colour change over time. The change in colour was more evident in the period between baseline measurements and after 15 days. There was a significant interaction between media type and time.ConclusionsBoth composites showed no significant difference in roughness and colour change at all measurement times. There was a significant increase in surface roughness and colour change in all immersion solutions tested over time. Coca-Cola caused unacceptable colour change.

Rolling contact fatigue behavior of TiN based coatings deposited on ADI by cathodic arc deposition and plasma based ion implantation and deposition

This work studies the surface characteristics and, particularly, the rolling contact fatigue (RCF) behavior of austempered ductile iron (ADI) samples coated with TiN based coatings of about 1 μm in thickness. Films synthesized by cathodic arc deposition (CAD) at a fixed nitrogen flow, compositional gradient films synthesized by CAD at a variable nitrogen flow and plasma based ion implanted and deposited (PBIID) films were comparatively analyzed.The results indicated that CAD films showed a strong TiN (111) preferred orientation while PBIID films a more randomly orientation. The crystallite size of CAD films was more than the double of PBIID films. Residual stresses of the PBIID films were lower than those of CAD films, the lowest hardness and elastic modulus were obtained for CAD films grown at variable nitrogen flow, while no significant differences in roughness, H/E ratio and adhesion were observed among the different films. Regarding RCF tests, failures in samples coated with TiN at constant flow were characterized by a progressive coating delamination followed by the formation of fatigue spalls inside the delaminated areas. Failures in samples coated with PBIID and gradient TiN were characterized by the formation of fatigue spalls with slight coating delamination. There were no significant differences between the RCF resistance of uncoated ADI and the samples with CAD films while the samples with PBIID films had a noticeably higher resistance. The better performance could be associated with the low compressive residual stresses and the fine grained microstructure induced by the PBIID process.

In vitro evaluation of the polishing effect and optical properties of monolithic zirconia

Statement of problemThe relationship between surface roughness and the optical characteristics of zirconia prostheses may be affected by the type of shaded block. PurposeThe purpose of this in vitro study was to investigate changes in surface roughness and brightness of monolithic zirconia blocks of different shades after polishing. Material and methodsThe surface roughness averages of 3 different kinds of shaded zirconia blocks (Zenostarof T0 [T0], Zenostar sun [Ts], and Zenostar sun chroma [Tsc]) were compared after surface polishing. Fifteen specimens of differing thicknesses were produced per block. (1 mm and 3 mm). Surface morphology and compositions were analyzed by using filed emission scanning electron microscopy (FE-SEM) and energy dispersive spectrometry. A 1-way ANOVA and the post hoc Scheffé test were performed (α=.05). The correlations between surface roughness and brightness were determined using the Pearson correlation analysis (α=.01). ResultsAfter phased polishing, Ts had the highest average roughness, followed by T0 and then Tsc. A statistically significant difference in roughness was observed between Ts and Tsc (P<.05). Ts exhibited multiple distinct layers in the FE-SEM image. Carbon was detected in the Ts specimens only. Brightness was highest in T0, followed by Ts and then Tsc. A positive correlation was observed between brightness and surface roughness for all specimens (P<.01). This correlation was stronger in the thicker specimens. ConclusionsThe results of this study suggest that polishing affects monolithic zirconia differently depending on shade. The polishing of monolithic zirconia reduces both surface roughness and brightness. The optical properties of monolithic zirconia vary by thickness and can be opaque or translucent.

Effect of Lowering Laser Energy on the Surface Roughness of Human Corneal Lenticules in SMILE.

To determine the effect of lowering femtosecond laser energy on the surface quality of the intrastromal interface during small incision lenticule extraction (SMILE). Forty age- and diopter-matched female patients (40 eyes) with moderate myopia received SMILE with different energy levels (100 to 150 nJ) and fixed spot separation (4.5 μm). Five human corneal lenticules from each energy group were evaluated by atomic force microscopy and scanning electron microscopy (SEM). Both anterior and posterior surface characteristics of the lenticules were assessed. All measurements of surface roughness were approximately three times higher and in the anterior and posterior surface of the lenticules with the energy level of 150 nJ than with 100 nJ (P < .001). Furthermore, atomic force microscopy analysis found that energy differences of 15 nJ or more made a significant difference in surface roughness at energy levels of 115 nJ or higher. Interestingly, there was no significant difference in all roughness values of both surfaces among the 100, 105, and 110 nJ groups. In addition, all values of surface roughness were significantly positively correlated with laser energy for both anterior and posterior surfaces of the lenticule (P < .001). Consistent with atomic force microscopy results, SEM also showed that the SMILE lenticules in the higher laser energy group had more irregular surfaces. Lowering laser energy levels can improve surface quality of the lenticule of SMILE. To achieve better visual outcomes with faster recovery after the procedure, it is recommended to reduce the laser energy to less than 115 nJ at a spot separation of 4.5 μm. [J Refract Surg. 2017;33(9):617-624.].

Surface properties of multilayered, acrylic resin artificial teeth after immersion in staining beverages.

Objective To evaluate the effect of staining beverages (coffee, orange juice, and red wine) on the Vickers hardness and surface roughness of the base (BL) and enamel (EL) layers of improved artificial teeth (Vivodent and Trilux).Material and Methods Specimens (n=8) were stored in distilled water at 37°C for 24 h and then submitted to the tests. Afterwards, specimens were immersed in one of the staining solutions or distilled water (control) at 37°C, and the tests were also performed after 15 and 30 days of immersion. Data were analyzed using 3-way ANOVA and Tukey’s test (α=0.05).Results Vivodent teeth exhibited a continuous decrease (p<0.0005) in hardness of both layers for up to 30 days of immersion in all solutions. For Trilux teeth, similar results were found for the EL (p<0.004), and the BL showed a decrease in hardness after 15 days of immersion (p<0.01). At the end of 30 days, this reduction was not observed for coffee and water (p>0.15), but red wine and orange juice continuously reduced hardness values (p<0.0004). Red wine caused the most significant hardness changes, followed by orange juice, coffee, and water (p<0.006). No significant differences in roughness were observed for both layers of the teeth during the immersion period, despite the beverage (p>0.06).Conclusions Hardness of the two brands of acrylic teeth was reduced by all staining beverages, mainly for red wine. Roughness of both layers of the teeth was not affected by long-term immersion in the beverages.

Electrochemical Anisotropy of Nanostructured Titanium for Biomedical Implants

The effect of surface pre-treatment on electrochemical anisotropy of nanostructured Ti rods with a strong fiber texture produced for dental implants by a complex severe plastic deformation route was studied in Hank’s solution using DC and AC electrochemical tests. Ti ion release has been quantified by inductively coupled plasma optical emission spectroscopy. The HF/HNO3-pickling produces a similar electrochemical behaviour in both transverse and circumferential surfaces of nanostructured Ti rod. The electrochemical anisotropy of HF-pickled nanostructured Ti is considerable due to a significant difference in roughness of the prismatic and basal planes, resulting in increased release of Ti4+ ions from basal planes. Electrochemical anisotropy is further enhanced in the presence of D-glucose in Hank’s solution. It is recommended to avoid HF-pickling of nanostructured Ti implants in favour of HF/HNO3-mixtures.

Quasi-Spherical Cell Clusters Induced by a Polyelectrolyte Multilayer.

Fibroblasts cultured on polyelectrolyte multilayers, PEMUs, made from poly(diallyldimethylammonium), PDADMA, and poly(styrene sulfonate), PSS, showed a variety of attachment modes, depending on the charge of the last layer and deposition conditions. PEMUs terminated with PDADMA (cationic) were cytotoxic when built in 1.0 M NaCl but cytophilic when built in 0.15 M NaCl. Cells adhered poorly to all PSS-capped (anionic) films. PEMUs built in 0.15 M NaCl but terminated with a layer of PSS in 1.0 M NaCl induced most cells to form spherical clusters after about 48 h of culture. These clusters still interrogated the surface, and when they were replated on control tissue culture plastic, cells emerged with close to 100% viability. Differences between the various surfaces were probed in an effort to identify the mechanism responsible for this unusual behavior, which did not follow accepted correlations between substrate stiffness and cell adhesion. No significant differences in roughness or wetting were observed between cluster-inducing PSS-capped multilayers and those that did not produce clusters. When the surface charge was assayed with radiolabeled ions a strong increase in negative surface charge was revealed. Viewing the multilayer as a zwitterionic solid and comparing its surface charge density to that of a cell membrane yields similarities that suggest a mechanism for preventing protein adhesion to the surface, a necessary step in the integrin-mediated mechanotransduction properties of a cell.

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.