Average Surface Roughness Values Research Articles

Comparative Evaluation of Enamel Surface Abrasion Produced by Three Different Types of Toothbrush Bristle Designs: An In-vitro Study

Introduction: The toothbrush is one of the most commonly used mechanical aids for plaque control, capable of removing plaque efficiently. However, improper toothbrushing habits can lead to tissue trauma, such as abrasion or gingival recession. The design of toothbrush bristles is one of the most common etiological factors for abrasion. Aim: To evaluate and compare the enamel surface abrasion produced by three different toothbrush bristle designs in conjunction with a standard dentifrice. Materials and Methods: In this in-vitro study conducted in the Department of Periodontics, Bharati Vidyapeeth Dental College and Hospital, Pune, Maharashtra, India, from June 2023 to January 2024, a total of 21 extracted human premolars were collected. After thorough cleaning, the teeth were stored in normal saline. The crown portions of the teeth were mounted on an acrylic resin base and profilometric analysis was performed to record the average enamel surface roughness (Ra) value. The teeth were randomly divided into three groups based on the toothbrush bristle design used for toothbrushing: Group A: Tapered bristle, Group B: End-rounded bristle, Group C: Flattrim bristle. Toothbrushing was carried out using a customised toothbrushing device and a standard dentifrice twice daily for six weeks. After six weeks, profilometric analysis was conducted again. Descriptive statistics were expressed as means and standard deviations. The comparison of enamel surface abrasion among the three different toothbrush bristle designs was performed using the One-Way Analysis of Variance (ANOVA) test, followed by the post-hoc Bonferroni test for pairwise comparison. In this test, a p-value less than or equal to 0.05 was considered statistically significant. All analyses were conducted using Statistical Package for the Social Sciences (SPSS) version 25.0. Results: The results showed significantly greater Ra values for Group C (flat-trim bristle: 0.13±0.06) compared to Group A (tapered bristle: 0.09±0.03) and Group B (end-rounded bristle: 0.04±0.02). Group B exhibited the lowest Ra value, indicating the least enamel surface roughness (p-value: 0.038*). Conclusion: Within the limitations of the study, stylus profilometer analysis demonstrated that the flat-trim toothbrush bristle design is more prone to causing enamel surface abrasion than the endrounded and tapered bristle designs. The end-rounded toothbrush bristle design causes minimal enamel surface abrasion and is safer to use as an effective mechanical plaque control aid.

Evaluation of Ni-Co/TiO2-CeO2 nanocomposite coatings fabricated by electro-co-deposition

Multiarticulate metal matrix composites have recently attracted the attention of many researchers. In this study, the efficacy of two reinforcement particles, TiO2 and CeO2, on the Ni-Co alloy coating was investigated. This coating is formed via the electro-co-deposition method on the copper substrate. The coated copper was examined and identified using field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) system, an electrochemical workstation, surface roughness measuring instruments, and a microhardness machine. Findings showed that adding TiO2 and CeO2 nanoparticles into Ni-Co makes better the morphology of the surface, decreases the crystalline size, and improves the corrosion resistance, wear resistance and microhardness of the Ni-Co alloy coating. For Ni-Co /TiO2-CeO2 coating, the average surface roughness value was estimated at 85 nm, which is almost twice the roughness of Ni-Co alloy coating.

Studies on surface roughness and axial thrust force of drilled holes in Mg-Zn-Ca bio-medical alloy

Mg-Zn-Ca alloy is a promising candidate for orthopaedic implants such as bone plates and screws, as it has a similar mechanical strength and elastic modulus to bone, and it degrades in the body without causing toxicity or inflammation. Drilling studies are necessary to optimize the drilling process parameters, to evaluate the machinability and surface integrity of Mg-Zn-Ca alloy, and to ensure the effective and efficient drilling for various applications in the medical and engineering fields. The present experimental study emphasizes the influence of Ca content, biofriendly coolants and their combined effect with standard drill bits on the surface quality and axial thrust force in the drilling operation of Mg-Zn-Ca alloy. The drilling parameters such as cutting speed, feed rate, standard tools, bio-compatible coolants were optimized with respect to the amount of Ca in the Mg-Zn alloy. The axial thrust force and average surface roughness of drilled holes were considered as response of the experiments. The drilled surfaces were measured for average surface roughness in the transverse direction along the centre path of the drilled hole and a qualitative analysis was also carried out using advanced confocal microscope. The results revealed that the cutting speed among continuous factors significantly influenced the axial thrust force and average surface roughness. The effect of categorical factors was assessed using a regression based ranking method. The results of statistical analysis revealed that high speed steel, and vegetable oil offered improved surface quality, whereas the coconut oil showed low axial thrust force. The liquid nitrogen showed high value of axial thrust force and average surface roughness due to the brittleness induced by cryogenic coolant before drilling operation.

Effects of thermomechanical parameters on surface texture in filament materials extrusion: outlook and trends

The material extrusion process has been widely used to manufacture custom products. However, the surface texture varies due to the additive mechanism of the process, which depends on the layer height and surface orientation, resulting in varying average surface roughness values for inclined, flat and vertical surfaces. Different strand welding conditions result in non-uniform internal stresses, surface distortions, layer traces, weak bonding, non-uniform pores and material overflow. This paper comprehensively examines material extrusion process achievements in surface texture quality and studies and summarises the most influential processing parameters. Parameter effects are critically discussed for each topic; flat, inclined, and vertical surfaces. The results of this research help reduce post-processing.

Fabrication and growth mechanism of Al-Si coatings deposited on Mo substrate by hot dip plating technology

The Al-Si coatings with a low surface roughness were deposited on Mo substrate via the hot-dip plating technology, and the effects of deposition parameters on the microstructure, phase composition and surface roughness were systematically investigated. The results show that the hot-dip Al-Si coating is consist of a Mo(Si, Al)2 inner layer and an Al(Si)-Mo(Si, Al)2 outer layer. The coating surface is composed of Si(70.21–92.66 at%)-Al alloy phase containing Mo (Si, Al)2 grains and Al(73.83–92.32 at%)-Si alloy phase. With the increase of deposition temperature and the extension of time, the average grain area of Mo (Si, Al)2 increases from 0.264 μm2 to 0.623 μm2. The coating surface becomes smoother with the increase of deposition temperature, while rougher with the time. The maximum and minimum average surface roughness(RSa) values of the coating are 0.847 and 0.431μm, respectively. The coating thickness increased with the increase of deposition temperature and times. When the deposition temperature is 1000 ℃, the thickness value of the Mo (Si, Al)2 layer of the coating increases in a parabolic law with deposition time, and the Kp(reaction rate constant) is 4.5 ×10−13 m2/s. The growth of coatings is essentially a process of depositing Al, Si elements in the form of Mo (Si, Al)2 intermetallic compounds on Mo substrate.

An In Vitro Analysis of the Effects of Mouthwashes on the Surface Properties of Composite Resin Restorative Material.

Restorative composite resins have clinical prime importance in modern dental practice, but numerous factors influence their prognosis in the oral environment. Their interaction with oral care products, like mouthwashes, is one such factor. This study aimed to evaluate the quantifiable effects of different mouthwashes on the surface properties of the composite resin restorative material. The method involved formulating 90 samples of nanohybrid composite resins (Medicept Dental India Private Limited, Mumbai, India). The samples were treated with 1% alcohol, without alcohol, and with a saline solution (control). Surface roughness (Ra values) and microhardness had been checked before and after an exposure period of 24 hours. Data were thus tabulated, and from that, average values of surface roughness and microhardness were derived. This data was analyzed using the IBM SPSS Statistics for Windows, V. 26.0 (IBM Corp., Armonk, NY). Analysis of variance (ANOVA) and a t-test were used to compare the means of the variables. The level of significance was fixed at p < 0.05. The surface roughness value was significantly highest in the ethanol-containing mouthwash-treated samples after 24 hours of exposure (p < 0.05). The microhardness was statistically lower in these samples (p < 0.05). These research data give quantitative information, however, about the mass effect of mouthwashes on the composite resin restorative material. The presented changes, which were illustrated by the values of surface roughness and microhardness, are drawing attention to the fact that a cautious approach must be taken in the recommendations for oral care in the provision of intensive treatments with restorative composite resins.

Powder Bed Fusion-Laser Beam of IN939: The Effect of Process Parameters on the Relative Density, Defect Formation, Surface Roughness and Microstructure.

This study investigates the effects of process parameters in the powder bed fusion-laser beam (PBF-LB) process on IN939 samples. The parameters examined include laser power (160, 180, and 200 W), laser scanning speed (400, 800, and 1200 mm/s), and hatch distance (50, 80, and 110 μm). The study focuses on how these parameters affect surface roughness, relative density, defect formation, and the microstructure of the samples. Surface roughness analysis revealed that the average surface roughness (Sa) values of the sample ranged from 4.6 μm to 9.5 μm, while the average height difference (Sz) varied from 78.7 μm to 176.7 μm. Furthermore, increasing the hatch distance from 50 μm to 110 μm while maintaining constant laser power and scanning speed led to a decrease in surface roughness. Relative density analysis indicated that the highest relative density was 99.35%, and the lowest was 93.56%. Additionally, the average porosity values were calculated, with the lowest being 0.06% and the highest reaching 9.18%. Although some samples had identical average porosity values, they differed in porosity/mm2 and average Feret size. Variations in relative density and average porosity were noted in samples with the same volumetric energy density (VED) due to different process parameters. High VED led to large, irregular pores in several samples. Microcracks, less than 50 μm in length, were present, indicating solidification cracks. The microstructural analysis of the XZ planes revealed arc-shaped melt pools, columnar elongated grains aligned with the build direction, and cellular structures with columnar dendrites. This study provides insights for optimizing PBF-LB process parameters to enhance the quality of IN939 components.

Effects of thermal treatment on air-dried density, color change, average surface roughness, and sound absorption capacity of Scots pine

This study was conducted to investigate some characteristics of thermally treated Scots pine (Pinus sylvestris L.) wood specimens such as air-dried density, color change, average surface roughness, and sound absorption capacity. Heat treatment of Scots pine wood was performed at atmospheric pressure at 140, 160, 180, and 200 °C for 2 h. As a result, the air-dried density values of the thermally treated wood decreased as the temperature of the thermal treatment increased. With the increase of thermal treatment temperature, an increase in total color change values was detected on the surfaces of the samples and the color of the samples became darker. The average surface roughness (Ra) value of samples improved due to thermal treatment conditions and the highest value was determined in thermally treated samples at 200 °C as 3.59 μm. At 140 °C the value of maximum sound absorption coefficient was observed to be 0.48 at 2500 Hz and the highest sound transmission loss value, which was 36.7 dB, was measured at 6300 Hz and at 200 °C.

METAL DEBRIS RELEASE MAY BE UNDER-RECOGNIZED IN TOTAL ANKLE ARTHROPLASTY

Despite advancements, revision rates following total ankle replacement (TAR) are high in comparison to other total joint replacements. This explant analysis study aimed to investigate whether there was appreciable metal particulate debris release from various contemporary TARs by describing patterns of material loss. Twenty-eight explanted TARs (9 designs: 3 fixed and 6 mobile bearing), revised for any reason, were studied. The articulating surfaces of the metal tibial and talar components as well as the polyethylene insert were assessed for damage features using light microscopy. Based on the results of the microscopic analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy was performed to determine the composition of embedded debris identified, as well as non-contacting 3D profilometry. Pitting, indicative of material loss, was identified on the articulating surfaces of 54% of tibial components and 96% of talar components. Bearing constraint was not found to be a factor, with similar proportions of fixed and mobile bearing metal components showing pitting. More cobalt-chromium than titanium alloy tibial components exhibited pitting (63% versus 20%). Significantly higher average surface roughness (Sa) values were measured for pitted areas in comparison to unpitted areas of these metal components (p&lt;0.05). Additionally, metallic embedded debris (cobalt-chromium likely due to pitting of the tibial and talar components or titanium likely from loss of their porous coatings) was identified in 18% of polyethylene inserts. The presence of hard 3rd body particles was also indicated by macroscopically visible sliding plane scratching, identified on 79% of talar components. This explant analysis study demonstrates that metal debris is released from the articulating surfaces and the coatings of various contemporary TARs, both fixed and mobile bearing. These findings suggest that metal debris release in TARs may be an under-recognised issue that should be considered in the study of painful or failed TAR moving forwards.

Effect of Process Parameters on the Roughness and Wetting Characteristics of SS304 Surfaces Using Electrolytic and Plasma Electrolytic Polishing Techniques

Metallic parts manufactured by conventional machining and additive manufacturing techniques possess poor surface quality and require post-processing operations before their end-use. Many methods exist for the post-processing of parts with free-form surfaces. In this study, two of the most used polishing techniques, electrolytic polishing (EP) and plasma electrolytic polishing (PeP), were investigated to understand the morphology of the resultant surface after both techniques. Pilot experiments suggested that an aqueous solution of ammonium sulphate is the most effective electrolyte for both the polishing techniques in terms of the lowest achievable value of average surface roughness ( Ra ). A systematic investigation of the electrolyte concentration, applied voltage, and polishing time revealed an identical dependence on all these process parameters: First, a decrease and then an increase in Ra. A minimum Ra of 0.63 μm and 0.49 μm were achieved with EP and PeP, respectively. Samples polished by PeP possess high gloss with negligible changes to the shape and form of the samples. Furthermore, static contact angle measurements with water revealed that surfaces treated with PeP showed higher hydrophilicity compared to those polished with EP. This can be attributed to the lower Ra value achieved with PeP.

Enhancement of bone mineral formation on Ti6Al4V surface by PM-EDCLT combined with acid etching

For Bone-anchored limb prostheses, osseointegration plays a significant role in the mechanically stable interface between bone and implants. Titanium alloy is the most usable alloy for hard tissue replacement. The drawbacks of the titanium implant are corrosion, leaching and poor osseointegration. In this research, powder mixed (hydroxyapatite) - electric discharge-assisted centreless turning (PM-EDCLT) (Impulse current- 5amp, duty factor- 57%, hydroxyapatite concentration 18 g/l, and rpm-360) and acid etching (solution – HF: HNO3: H2O = 1:2:50) were used for the surface modification of screw-fit implants. Average surface roughness value maximum in PM-EDCLT machined surface (1.249 µm) followed by PM-EDCLT machined + 5 min. Acid etching (1.055 µm), PM-EDCLT machined + 10 min. Acid etching (0.9829 µm), PM-EDCLT machined + 15 min. acid etching (0.8223 µm), bare surface with 10 min. Acid etching (0.2866 µm), 15 min. acid etching (0.2714 µm) and 5 min. Acid etching (0.1896 µm). Investigations using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) proved that the deposited layer on the powder-mixed EDCLT machined sample was hydroxyapatite. After sinking samples in the Simulated Body Fluid (SBF) solution, it was concluded that the percentage of bone minerals like oxide, Ca, and P deposition increases after increasing the acid etching time on the PM-EDCLT machined surfaces. Little effect was found on the deposition of bone minerals on the surface of acid etching only by increasing the etching time. There is a clear trend of decreasing the contact angle with increasing the acid etching time on the PM-EDCLT surfaces.

Effect of Minimum Quantity of Lubricant on Carbide Tools and Surface Integrity in the Machining of Titanium Aluminides

Titanium aluminides are being explored as potential materials for the aeronautical sector. However, their application is limited by the high costs of processing and their difficulties in machining. This research evaluates the effectiveness of the minimum quantity lubrication technique (MQL) on the turning process of Ti48Al2Cr2Nb aluminide in terms of tool wear, tool life, cutting forces, surface integrity, and temperature. It was found that MQL conditions can improve the process efficiency, reducing the thermally induced wear mechanisms and enlarging the tool life compared to dry machining. Furthermore, it allows the cutting speed to be incremented, leading to lower processing times. However, MQL seems to not be effective in the reduction of the strain-hardening effect near the machined surface and, although the number of microcracks is reduced, defect-free surfaces cannot be obtained. Moreover, similar microstructural alterations as for dry cutting were detected. The best cutting conditions in terms of surface quality were assessed using the central composite face (CCF) design and surface response methodology. Optimization of the surface roughness under industrially viable cutting conditions was achieved with an average surface roughness value, Ra, of 0.29 µm (feed rate of 0.05 mm/rev, a cutting speed of 54.6 m/min and a depth of cut of 0.125 mm).

Novel short Agave americana based biocomposite and nanobiocomposites for automotive applications

Short fibers of Agave Americana (AA) was extracted from its plant leaf, was chemically treated with Ac2O, HCOOH, H2O2, KMnO4 and NaOH, and then characterized by Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermo-gravimetric/differential thermo-gravimetric (TGA/DTG), and field emission-scanning electron microscopy (FE-SEM). PVA stabilized copper nanoparticles from chemical reduction method was characterized using field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), powder X-ray diffraction (PXRD), Dynamic light scattering analysis (DLS), UV–visible absorption spectroscopy, Fourier Transform infrared (FT-IR) spectroscopy and Thermogravimetric analysis/differential thermogravimetry (TGA/DTG). Bio-composites (AA + Polyester Resin (PE) and hybrid nano bio-composites (AA + Polyester Resin (PE) + Cu) were prepared from the untreated and treated AA fibers and further characterized. The synergistic effect of chemical treatment on morphological (SEM), thermal (TGA/DTG), mechanical properties (flexural, tensile, impact and compressive strength) followed by % water absorption were examined. The average surface roughness values (Ra) of chemical treated fiber was identified to be in decreasing manner along with compression strength of biocomposite in the order of untreated (10.74 μm, 44.01 MPa) > NaOH (8.55 μm, 45.07 MPa) > HCOOH (3.49 μm, 24.10 MPa) Ac2O (3.24 μm, 22.10 MPa) > H2O2 (2.51um, 17.9 MPa) > KMnO4 (1.52 μm, 15.1 MPa) treated fibers. Subsequently, the addition of 2s@PVA led to reverse the order namely, the compressive strength of the bionanocomposites were Untreated (10.74 μm, 9.0 MPa) < NaOH (8.55 μm, 0.1 MPa) < HCOOH (3.49 μm, 3.6 MPa) < Ac2O (3.24 μm, 7.6 MPa) < H2O2 (2.51um, 13.3 MPa) < KMnO4 (1.52 μm, 44.1 MPa) treated fibers. Similarly, the biocomposite where the fibres were treated with NaOH, HCOOH were more rough and had, good interconnection between fiber/PE matrix along with enhanced mechanical properties. On addition of nanobiocomposite, only KMnO4 treated fiber composite possed significant mechanical properties. Therefore, mixing CuNPs@PVA with KMnO4 treated fibers led to significant boost to the mechanical properties and minimised the % water absorption properties when compared to the untreated AA/PE biocomposites. The KMnO4 treatment of the AA fiber and addition of copper nanoparticles caused the enhancement of thermal properties, tensile strength and flexural strength. But, these nanobiocomposites were observed to have low impact strength; while, H2O2 treated nanobiocomposites had highest impact strength. The chemical treatment of the AA fiber with NaOH, Ac2O and KMnO4 developed the water resistance of the respective biocomposites. All the nanobiocomposites with chemically treated AA fibers (except Ac2O) were found to have high water resistance. So, they can be used in automotive industry for non-structural applications.

Effect of tabebuia heterophylla plant leaves extract on corrosion protection of low carbon steel in 1M HCl medium: Electrochemical, quantum chemical and surface characterization studies.

In the current study the chemical constituents of Tabebuia heterophylla plant leaves extract (THLE) evaluated as corrosion inhibitor for low carbon steel (LCS) in 1 M HCl. The major component present in plant extract was Hexadecanoic acid 2-hydroxy-1-(hydroxymethyl) ethyl ester confirmed by Gas Chromatography with Mass spectroscopic (GC-MS) analysis. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarisation (PDP) and weight loss measurements were used to evaluate the THLE ability to protect low-carbon steel surface against corrosion in 1M HCl medium. The maximum inhibition efficiency reported as 95.45%, 93.99% and 94.79% by weight loss measurements, EIS and PDP methods respectively. In the prolongation of the work, the entropy of adsorption (Δ Sa*), enthalpy of adsorption (Δ Ha*), Gibbs free energy of adsorption (Δ Ga*), and activation energy (Ea) of the reaction were calculated. In absence of inhibitor, the Ea value was found to be minimum 49.38 kJ/mol whereas for optimum concentration of THLE it was found to be 77.2 kJ/mol implies more energy is required to undergo corrosion. The surface morphological observation from Scanning Electron Microscope (SEM), Atomic Force Microscopic (AFM) and Contact angle explored the effective adsorption of THLE. AFM values revealed that average surface roughness (Ra) value of LCS is high (188.08), where as in the presence of THLE, Ra values significantly reduced to minimum value of 37.226. Further chemical interactions between THLE and the low-carbon steel surface as well as inhibitory mechanism were further elucidated by theoretical simulations such as Density Functional Theory (DFT) calculations and Molecular dynamics (MD) simulations.

The effect of tobacco leave pastes (Nicotiana tabacum L.) 50% concentration as a denture cleanser on the surface roughness of thermoplastic nylon

Microporosity of thermoplastic nylon can lead to increased surface roughness values. Surface roughness of thermoplastic nylon can facilitate colonization of microorganisms that can lead to denture stomatitis. The mechanical cleaning process of denture using an electric toothbrush and denture cleaning paste is considered effective for removing plaque and microorganisms attached. To reduce surface roughness, the use of natural materials such as tobacco leaves is considered beneficial because it can reduce the content of abrasive materials. This study aims to determine the effect of tobacco leaf paste as a denture cleanser on the surface roughness of thermoplastic nylon. This study using a laboratory experimental design with a post test only control group design involving 27 samples sized 60 x 10 x 2.5 mm which were divided into three groups including the brushing control group without paste, the brushing group with placebo paste, and the brushing group with 50% tobacco leaf paste (TLP). The results showed that tobacco leaf paste was considered effective as a thermoplastic nylon denture cleanser and had an effect on reducing surface roughness values with an average surface roughness value that was still acceptable to the oral cavity. In conclusion, 50% tobacco leaf paste is recommended as an effective denture cleanser and produces surface roughness values acceptable to the oral cavity.

Pengaruh Kedalaman Pemakanan dan Kecepatan Potong pada Pembubutan Finishing Material Baja SKD 11 terhadap Kekasaran Permukaan Benda Bubutan

One important factor in achieving good quality value for a product in the machining process is to look at the level of roughness produced in the machining process. This research aims to determine the effect of feed depth and cutting speed on surface roughness. The process variables used in this research are feeding depth (mm) and cutting speed (m/min). Each variable has 3 levels, namely feeding depth of 0.5, 0.6 and 0.7 mm. Cutting speed 65, 70 and 75 m/min. In this research method, researchers used the full factorial method. The material used in this research is SKD 11 steel. The conclusion obtained from the research is that the minimum surface roughness is at a cutting depth of 0.6 mm with a cutting speed of 65 m/minute, with the average surface roughness value obtained being 0.883 (µm ). The maximum surface roughness is at a feed depth of 0.6 mm with a cutting speed of 70 m/minute with an average surface roughness value of 1.254 (µm).

Active Compliance Smart Control Strategy of Hybrid Mechanism for Bonnet Polishing.

Compliance control strategies have been utilised for the ultraprecision polishing process for many years. Most researchers execute active compliance control strategies by employing impedance control law on a robot development platform. However, these methods are limited by the load capacity, positioning accuracy, and repeatability of polishing mechanisms. Moreover, a sophisticated actuator mounted at the end of the end-effector of robots is difficult to maintain in the polishing scenario. In contrast, a hybrid mechanism for polishing that possesses the advantages of serial and parallel mechanisms can mitigate the above problems, especially when an active compliance control strategy is employed. In this research, a high-frequency-impedance robust force control strategy is proposed. It outputs a position adjustment value directly according to a contact pressure adjustment value. An open architecture control system with customised software is developed to respond to external interrupts during the polishing procedure, implementing the active compliance control strategy on a hybrid mechanism. Through this method, the hybrid mechanism can adapt to the external environment with a given contact pressure automatically instead of relying on estimating the environment stiffness. Experimental results show that the proposed strategy adapts the unknown freeform surface without overshooting and improves the surface quality. The average surface roughness value decreases from 0.057 um to 0.027 um.

Effect of different polishing methods applied to denture base materials on microbial adhesion and surface roughness

Aim: The aim of our study was to investigate the effect of various polishing processes applied to different types of PMMA (polymethyl methacrylate) denture base materials on the surface roughness and microbial adhesion of the base material. Methods: Sixty specimens each were prepared from heat-polymerized conventional PMMA (G), heat-polymerized injectable PMMA (E), and prepolymerized CAD/CAM PMMA (C) denture base materials. All sample surfaces were sanded with 800, 1000, 1200, and 2500 grit silicone carbide abrasives. The specimens of each denture base material were divided into three subgroups (n=20) in which different polishing methods were applied. The first group was mechanically polished (M), and the other two groups were chemically polished with light polymerized glaze liquids [Palaseal (Ps), Optiglaze Color (Og)]. A profilometer device was used to evaluate the surface roughness. Colony counting was performed to evaluate bacterial colonization after one day. The data obtained from all these measurements were evaluated using an analysis of variance, and Bonferroni corrected test was used for multiple comparisons of means (p=0.05). The interaction between surface roughness and bacterial colonization was examined by the Pearson correlation test. Regression analysis was performed to determine the relationship between them. Results: When PMMA base materials were compared, the lowest average surface roughness (Ra) values and bacterial colonization values were obtained in Group C. When polishing methods were compared, the lowest average surface roughness values were obtained in Group M. As a result of bacterial colonization measurement, lower colonization values were obtained with standardized mechanical polishing compared to other groups. Conclusion: There was no difference between the different PMMA base materials in terms of surface roughness, but there were statistical differences in bacterial colonization. The results of our study showed that mechanical polishing gave better results than light-activated glazing agents. How to cite this article: Yarar S, Değer Y, Tekin S. Effect of different polishing methods applied to denture base materials on microbial adhesion and surface roughness. J Med Dent Invest 2023; 4: e230351. https://doi.org/10.5577/jomdi.e230351

Morphology, phase composition, surface roughness evolution and growth mechanism of hot-dip aluminum coating on Mo substrate

The Al-rich hot-dip aluminum composite coatings were synthesized on Mo surface by hot-dip aluminizing under different deposition processes. The aluminide coatings present a very smooth dense coating structure with a lower surface roughness and fine grain size, the average surface roughness (RSa) values are only 0.118–0.869 μm, and the corresponding surface area growth rate (Sdr) values are 3.85–80.19 %. Increasing the deposition temperature is beneficial for the transition of low melting point compounds of the coating surface to high melting point compounds, and extending the hot dip time is profit for the diffusion and enrichment of Al atoms on the coating surface. Besides, increasing the deposition temperature or time can also promote the growth of Al4Mo grains, thereby significantly increasing the coating thickness. When the deposition temperature is 750 °C, the thicknesses of Al4Mo and Al8Mo3 layers increases in a parabolic law with deposition time, and the Kp values both of them are 3.46 × 10−13 m2/s and 1.47 × 10−15 m2/s, respectively. The growth of the coating depends on the continuous diffusion of Al atoms towards the substrate direction, and the difference in chemical potential between Al atoms in each phase is the main driving force for coating growth.

INVESTIGATION OF ELECTROEROSION MACHINING PERFORMANCE OF METAL MATRIX COMPOSITE MATERIALS PRODUCED USING STIR AND INDIRECT SQUEEZE METHOD

In this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 [Formula: see text]s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively. Based on the ANOVA results, the [Formula: see text]2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively.