Non-contact Optical Profilometry Research Articles

Effects of boron doping on the surface modification and defect evolution of silicon induced by proton implantation and annealing

Ultra-thin silicons can be obtained using SMART CUT technology, but there is a lack of systematic research on the effect of boron doping. This paper reports the effects of boron doping on surface modification and defect evolution. Monocrystalline silicon samples with different concentrations of boron doping were implanted to 3.5 × 1017H+/cm2 using a 1.52 MeV High Intensity Proton Implanter (HIPI) and annealed at 300, 400, and 550 ℃. The annealed samples were analyzed by non-contact optical profilometry, Raman spectroscopy, SEM, and TEM. The results show that appropriate boron doping can reduce the surface roughness of the exfoliated samples; excessive boron doping leads to a significant increase in surface roughness (∼525 nm) and produces a step-like morphology. Boron doping leads to changes in the type, concentration and dissociation temperature of hydrogenated defects during implantation. These changes result in the width of damage band changes vary with doping concentration. The density and diameter of the hydrogenated extended defects also changed, which results in the surface modification of samples, such as the change of the surface morphology and substrate roughness. In the end of the paper, the paper discusses the correlation between surface morphology and internal damage for different concentrations of boron doping.

Antifouling performance of TiO2-based SiO2–Na2O–K2O glass-ceramic coatings in marine environments

Biofouling refers to the accumulation of organisms on artificial surfaces. This phenomenon poses significant challenges in industrial processes, including reduced energy efficiency and increased fuel consumption. Antifouling coating systems are designed to prevent biofouling on artificial surfaces. Currently, there is a growing focus on developing eco-friendly solutions to mitigate the environmental impact of these antifouling coatings. In this study, the antifouling (AF) performance of a TiO2-based borosilicate glass-ceramic coating (Ti-GCC) system was evaluated in terms of barnacle settlement on the coating surface. To create anatase crystals in a coating, a special precursor glass (Ti-PG) formulation, Na2O–K2O–TiO2–B2O3–Al2O3–SiO2–P2O5–F, with <10 % of Na2O and 20 % TiO2 along with other components was used. The Ti-PG was characterised through X-ray fluorescence (XRF) spectroscopy to determine the chemical composition. The milled Ti-PG with additives was applied on a steel substrate using a spray gun and devitrified at 550 °C and 860 °C for 6 min. The phase determination, surface evaluation, thermal behaviour analysis, and AF evaluation of the Ti-GCC were conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), non-contact optical profilometry (NCOP), and thermogravimetric-differential thermal analysis (TG-DTA). The anatase crystal was determined to exist in the Ti-GCC structure. Although the AF evaluation results revealed that the Ti-GCC system had barnacle settlement (73.9 barnacles/cm2), the surface could be easily cleaned. Additionally, the EDS results confirmed that no biofilm was formed on the Ti-GCC's surface. The roughness of the surface before the AF evaluation and after the cleaning procedure was measured using NCOP, and the difference in surface roughness was examined. The small difference in the roughness of the surfaces suggested that the Ti-GCC system exhibited resistance to microbially induced corrosion (MIC). Furthermore, EDS mapping did not provide any evidence of barnacle diffusion into the coated layer. Furthermore, the thickness measurements of the cross-sectional area of the Ti-GCC before and after AF evaluation through SEM proved that coating depletion did not occur.

Wide field 3D optical profilometry using a diffraction Lloyd's mirror interferometer.

Interference fringe projection is used as a non-contact optical profilometry method for accurate 3D measurements. In interferometric fringe projection schemes, the maximum measurable size of the test object is limited by the optics of the interferometer. In this work, we report the application of a diffraction Lloyd's mirror interferometer (DLMI) as a wide-field sinusoidal fringe projection system for 3D shape measurement. The DLMI works on diffracted light and therefore generates interference fringes over a large area. This enables measurement of large objects using DLMI as compared to a conventional Lloyd's mirror interferometer. The performance of the proposed system is evaluated in terms of its stability and reproducibility of the results through measurement of the standard deviation in the phase values.

Copper ferrite inverse spinel-based highly sensitive and selective chemiresistive gas sensor for the detection of formalin adulteration in fish

The unexpected presence of food preservatives such as formalin in food can cause significant health hazards e.g., severe damage to the pulmonary and nervous system, kidney, lungs, eyes, etc. In this work, semiconducting Copper ferrite (CuFe2O4) inverse spinel nanoparticles-based gas sensor for the detection of formalin adulteration in fish has been reported. The nanopowder was synthesized by a simple sol-gel route. The nanopowder was characterized by multiple sophisticated techniques, viz., XRD, XPS, FESEM, TEM, EDS, UV-Vis spectroscopy, laser diffraction-based particle size distribution measurement, current-Voltage (I-V) measurement, infra-red imaging, and non-contact optical profilometry. The developed sensor exhibits high p-type sensitivity towards trace formalin gas (5–30 ppm), rapid response (∼2.7 s) and recovery times (∼34 s), and appreciable selectivity with respect to other gases in trace concentrations, such as acetone, ethanol etc., and saturated moisture at moderate operating temperature (260 °C). The excellent long-term stability of the sensor for at least 6 months renders it suitable for commercial applications.

Wear behavior of ceramic, composite, and ceramic/composite interfaces

Objective. This study has aimed to evaluate the effects of toothbrushing on the wear behavior of two composites, three ceramic materials, and ceramic/composite interfaces. Material and Methods. Nanofilled (Filtek Ultimate), and nanohybrid composites (Spectra ST HV) were used for the repair of a hybrid ceramic (Vita Enamic), resin nanoceramic (Katana Avencia), and zirconia block (Katana Zirconia). Composites, ceramics, and ceramic/composite interfaces were examined before and after a period of one-month and one-year of toothbrush abrasion testing using non-contact optical profilometry and scanning electron microscopy (SEM). Data were analyzed by two-way ANOVA and Bonferroni correction. The statistical significance level was set at p < 0.05. Results. No difference was found between the surface roughness of the Vita Enamic, Katana Avencia, Filtek Ultimate, and Spectra surfaces after one month and one year of toothbrushing. Sa values in Katana Zirconia material were found to be significantly lower than those in the control group after one year of brushing. The surface roughness of the repair interfaces formed by repairing hybrid ceramic and resin nanoceramic CAD/CAM materials with nanofilled and nanohybrid composite materials was found to be similar after different brushing times. Conclusion. Vita Enamic, Katana Avencia, Filtek Ultimate, and Spectra materials can be preferred in clinical repair applications, since they exhibit similar wear behavior after brushing at different times. For the zirconia material, the repair interface had similar surface roughness as the ceramic and composite surfaces after one year of brushing. Periodic recalls and re-polishing may thus be necessary when these products are used clinically.

Influence of the cutting blade shape on the technical hemp stalks slicing quality

The article presents the results of in-depth scientific research, including cutting of technical hemp stems with a blade of various shapes and interference of the cut surface by non-contact optical profilometry. Three-dimensional images and characteristic profilograms of the cut surfaces of stems depending on the shape of the cutting edge are obtained. The parameters of the microgeometry of the cut surface and the optimal profile of the cutting edge are determined.

Dynamic pressure scuffing initiation of a grade 250 flake graphite cast iron

The dynamic contact pressures experienced at the ring-liner interface of an engine are difficult to replicate in laboratory based reciprocating tribometers utilising a sliding Hertzian line contact, not least due to wear of the mating surfaces. A grade 250 flake graphite cast iron flat plate test geometry was designed to allow dynamic contact pressures between 8 and 62 MPa experienced in a heavy-duty diesel engine liner to be achieved on a reciprocating tribometer during the compression and expansion stroke.A constant normal load of 311 N was applied by sliding at 25 mm stroke length in PAO4 at 15 Hz against a 52100 rectangular contact area (2 × 20 mm). The temperature was slowly increased at 4 °C/min to initiate scuffing between the mating surfaces. Severe scuffing initiated at 250.8 ± 2.6 °C for all specimens. The spatially resolved friction force and non-contact optical profilometry suggested scuffing did not always initiate in the region of the highest contact pressure, whilst electron microscopy revealed that subsequent to lubricant failure, a transient low friction iron oxide layer was formed prior to removal and catastrophic adhesive wear.

Electrification effects on dry and lubricated sliding wear of bearing steel interfaces

In electric vehicles' powertrains, bearings can be susceptible to failure more rapidly than some of the other components mainly because of accelerated fatigue, corrosion and wear. Specifically, due to much severe operating conditions (including high speeds, torques, temperatures) of such vehicles combined with the presence of an electrical environment in which uncontrollable or stray electrical currents discharge through the contact interfaces can further exacerbate the situation and reduce their service lives by triggering much severe adhesive, abrasive and oxidative wear. In this work, we explore the effects of DC current discharges through the contact interfaces of AISI 52100 bearing steel using a novel two-electrode cell-based micro-abrasion tester under electrified dry and boundary lubricated contact conditions. A mineral base oil (as a reference), a gear oil and an automatic transmission fluid (ATF) with different dielectric strengths were tested under unelectrified and DC electrified (1.5 A) conditions. Overall, our test results suggest that passing DC current increases coefficient of friction (CoF) and wear of dry sliding contacts while it slightly reduces CoF but increases wear significantly for lubricated contacts due to accelerated oxidation by electrification. SEM, Raman spectroscopy and non-contact optical profilometry were used for analyzing the physical and chemical nature of worn surfaces and understanding of the specific wear modes and mechanisms.

Surface analysis of latex and silicone pacifier nipples after exposure to acidic artificial saliva: a pilot study

Objective: To measure surface changes of pacifier nipples after immersion in acidic artificial saliva. Methods: Two types of pacifier nipples (latex and silicone) were selected. Five copies of each type were used. The protocol consisted of immersion in acidic artificial saliva (pH = 5.97) for 16 days. The nipples of the pacifier remained in direct contact with saliva in an individualized, opaque and closed container in a bacteriological incubator at 37ºC. The samples were examined before and after exposure to saliva through qualitative (based on images obtained in a 100 mm macro lens and three-dimensional images with 10% amplification obtained in the profilometry) and quantitative (roughness data obtained in non-contact 3D optical profilometry). Data were obtained in duplicate and analyzed using descriptive and inferential statistics. The findings were tested for normality (Shapiro-Wilk). Paired t-test or Wilcoxon was used to compare before and after roughness data. Results: In the image analysis, it was observed that only the surface of the latex pacifier's nipples showed an irregular appearance after exposure to saliva. In the quantitative evaluation, no differences were found between the roughness values before and after (p&gt;0.05). Conclusion: This pilot study demonstrated qualitative changes in the surface of latex pacifiers. However, it was not able to demonstrate statistically significant differences for the roughness parameters before and after exposure to acidic artificial saliva in the nipples of latex and silicone pacifiers.

Optical, electronic, and microstructural properties of mixed phase RF magnetron sputtered vanadium oxide thin films on quartz and aluminized quartz

Amorphous vanadium pentoxide (major phase) thin films of various thicknesses were grown on the substrates that possessed low (aluminized quartz) and high (quartz) infrared (IR) emittance property utilizing radio frequency (RF) magnetron sputtering technique. Microstructural characterizations are carried out by several techniques such as noncontact optical profilometry, energy dispersive X‐ray (EDX) spectroscopy, X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and X‐ray diffraction (XRD). The as‐grown amorphous films show stoichiometric vanadium oxide, where vanadium is in V5+ as a major proportion compared with V4+ states. Thermo‐optical properties, namely, solar transmittance (τs), reflectance (ρs), absorptance (αs) and IR emittance (εir) along with optical constant, for example, optical band gap, are evaluated. A modified Urbach equation was used to simulate the optical absorption data to understand the presence optical absorption below the band edge.

Modification of the Surface Microtopography of a Bronze Alloy under Irradiation with a Scanning Beam of Nanosecond Laser Radiation Pulses

Using noncontact optical profilometry, atomic force microscopy, scanning electron microscopy, and optical microscopy methods, the effect of the treatment with a scanning beam of nanosecond laser pulses with a wavelength of 355 nm on the surface of a Cu–Cr–Zr bronze alloy is studied. The formation of periodic spherical structures with a diameter of less than 500 nm arranged on conical pedestal supports about 1 μm in height is observed on the bronze alloy surface after laser treatment. It is found that the surface topology of the bronze alloy depends on the laser pulse energy density in the range of 0.2–1.7 J/cm2 and on the scanning rate of the laser beam (0.5–1.0 mm/s) at a pulse repetition rate of 100 Hz.

Comparative Effect of Calcium Mesoporous Silica Versus Calcium and/or Fluoride Products Against Dental Erosion.

The aim of this study was to compare the effects of a single application of a new calcium mesoporous silica nanoparticle (Ca2+-MSN) versus other calcium and/or fluoride products against dental erosion. Enamel blocks were half-covered and assigned to six groups (n = 10): Ca2+-MSNs; casein phosphopeptide-amorphous calcium phosphate mousse (CPP-ACP); CPP-ACP/F- (900 ppm F-); titanium tetrafluoride (TiF4 1%); sodium fluoride (NaF 1.36%); and Milli-Q® water (negative control). A single application for each product was completed on the exposed areas of the blocks and were submitted to an erosive challenge. Differences in volumetric roughness (Sa), and tooth structure loss (TSL) by use of three-dimensional noncontact optical profilometry were evaluate. Scanning electron microscopy (SEM) was performed. Analysis of variance and Tukey's test for Sa and the Kruskal-Wallis and Mann-Whitney U tests (p< 0.05) for TSL, respectively. Results: When evaluating Sa, all products presented differences in roughness when compared with the control group (p< 0.05) but not with each other (p > 0.05). However, when analyzing the TSL, it was observed that Ca2+-MSNs, TiF4, and NaF were more effective in preventing dental erosion versus CPP-ACP, CPP-ACP/F-, and Milli-Q® water (p< 0.05). In the SEM images, the negative control presented the worst loss of dental structure, with more porous enamel. Ca2+-MSNs were as effective as TiF4 and NaF to reduce the tooth structure loss.

Surface cleaning and sample carrier for complementary high-resolution imaging techniques

Nowadays, high-resolution imaging techniques are extensively applied in a complementary way to gain insights into complex phenomena. For a truly complementary analytical approach, a common sample carrier is required that is suitable for the different preparation methods necessary for each analytical technique. This sample carrier should be capable of accommodating diverse analytes and maintaining their pristine composition and arrangement during deposition and preparation. In this work, a new type of sample carrier consisting of a silicon wafer with a hydrophilic polymer coating was developed. The robustness of the polymer coating toward solvents was strengthened by cross-linking and stoving. Furthermore, a new method of UV-ozone cleaning was developed that enhances the adhesion of the polymer coating to the wafer and ensures reproducible surface-properties of the resulting sample carrier. The hydrophilicity of the sample carrier was recovered applying the new method of UV-ozone cleaning, while avoiding UV-induced damages to the polymer. Noncontact 3D optical profilometry and contact angle measurements were used to monitor the hydrophilicity of the coating. The hydrophilicity of the polymer coating ensures its spongelike behavior so that upon the deposition of an analyte suspension, the solvent and solutes are separated from the analyte by absorption into the polymer. This feature is essential to limit the coffee-ring effect and preserve the native identity of an analyte upon deposition. The suitability of the sample carrier for various sample types was tested using nanoparticles from suspension, bacterial cells, and tissue sections. To assess the homogeneity of the analyte distribution and preservation of sample integrity, optical and scanning electron microscopy, helium ion microscopy, laser ablation inductively coupled plasma mass spectrometry, and time-of-flight secondary ion mass spectrometry were used. This demonstrates the broad applicability of the newly developed sample carrier and its value for complementary imaging.

Comparative Effect of Calcium Mesoporous Silica Versus Calcium and/or Fluoride Products on the Reduction of Erosive Tooth Wear and Abrasive Enamel Lesion

Objective: To evaluate the effect of a calcium nanocompound on the reduction of erosive tooth wear and abrasion. Material and Methods: Bovine enamel specimens (BE), were randomly assigned to the following groups (n = 10): G1 = Calcium mesoporous silica nanoparticles (Ca 2+ MSNs); G2 = casein phosphopeptide-amorphous calcium phosphate (CPP-ACP, 2% CPP-ACP, GC ® ); G3 = casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACFP, 2% CPP-ACP + 900 ppm F - , GC ® ); G4 = sodium fluoride NaF (900 ppm F-, positive control); and G5 = distilled and deionized water (negative control). Each product was applied to the exposed area for one minute, three times per day for three consecutive days, and followed by the immersion of the specimens in Sprite Zero™ - a low-pH solution (2.58) for five minutes (Coca-Cola™). After the first and last erosive challenges of the day, the specimens were submitted to abrasion in a toothbrush machine for 15 seconds (200 g/BE). The specimens were analysed using 3D non-contact optical profilometry, with tooth structure loss (TSL) measurements and scanning electron microscopy (SEM). TSL values were analysed by Kruskal-Wallis and Mann-Whitney tests (p<0.05) . Results: There were no significant differences between G1 (10.95 µm) and G3 (10.80 µm) treatments for TSL values; however both resulted in significantly reduced TSL values compared with the G5 (16.00 µm) (p<0.05). The G4 (12.26 µm) showed no statistically significant difference when compared to the G5 (16.00 µm). The groups G1 and G3 presented higher surface preservation than the G5 . Conclusion: Ca 2+ MSNs was effective for reducing tooth surface loss caused by erosive tooth wear and abrasion.

The use of a new calcium mesoporous silica nanoparticle versus calcium and/or fluoride products in reducing the progression of dental erosion.

Objective There is increasingly common the consumption more times a day of foods and acidic drinks in the diet of the population. The present study aimed to evaluate and compare the effects of a calcium mesoporous silica nanoparticle single application of other calcium and/or fluoride products in reducing the progression of dental erosion.Methodology Half of the eroded area was covered of 60 blocks of enamel, after which the block was submitted to the following treatments: (Ca2+-MSN), casein phosphopeptide–amorphous calcium phosphate (CPP-ACP); CPP-ACP/F-(900 ppm F−); titanium tetrafluoride (TiF4 1%) (positive control); sodium fluoride (NaF 1.36%) (positive control); and Milli-Q® water (negative control) before being submitted to a second erosive challenge. A surface analysis was performed via a three-dimensional (3D) noncontact optical profilometry to assess the volumetric roughness (Sa) and tooth structure loss (TSL) and and through scanning electron microscopy (MEV). An analysis of variance (ANOVA) and Tukey’s test were performed.Results Regarding Sa, all experimental groups exhibited less roughness than the control (p<0.05). The TSL analysis revealed that the Ca2+-MSN and NaF groups were similar (p>0.05) and more effective in minimizing tooth loss compared with the other groups (p<0.05).Conclusions The Ca2+-MSN and NaF treatments were superior compared with the others and the negative control.

Topography and Microhardness Changes of Nanofilled Resin Composite Restorations Submitted to Different Finishing and Polishing Systems and Erosive Challenge

Objective: To evaluate the topography and microhardness of composite resin restorations submitted to different finishing and polishing systems before and after erosive challenge. Material and Methods: Thirty standardized cavities prepared in enamel-dentin blocks of bovine incisors were restored with Z350 composite resin, and randomly distributed into three groups (n=10) according to the finishing and polishing systems: G1 = Soflex 4 steps, G2 = Soflex Spiral 2 steps and G3 = PoGo (single step). The specimens were half protected with nail varnish and submitted to five immersions in Pepsi Twist®, for 10 minutes each, five times/day during six consecutive days. The initial and final challenge surface microhardness (SMHinitial and SMHfinal) of the composite resin was evaluated and the percentage of SMH loss (%SMHL) was calculated. After protection removal, the topographic change linear (Ra) and volumetric (Sa) roughness was evaluated in initial and final areas by using 3D non-contact optical profilometry and scanning electron microscopy (SEM). Data were analyzed by paired Student's t-test, Kruskal-Wallis test, and by ANOVA and Tukey’s test. Results: There was significant intra-group %SMHL in composite resin (p<0.05). Differences among groups in %SMHL, Ra/Sa in resin composite were not observed (p>0.05). SEM images revealed structural changes between the initial and final surfaces for all groups. Conclusion: The three types of finishing and polishing systems had a similar influence on %SMHL, Ra and Sa in the nanofilled composite resin.

Abrasive wear behaviour of 27MnB5 steel used in agricultural tines

Understanding the wear mechanisms in wear parts is a crucial element of tribological investigation, particularly in agricultural applications where the knowledge about abrasive micro-mechanisms of soil engaging tools are limited. In the current research, symmetrical skew wedge cultivator tines of 27MnB5 steel were wear tested to investigate the change in mass, linear dimensions, hardness and microstructure, aiming at prolonging the lifetime of these parts through design and material. The wear mechanisms were identified and characterized by non-contact 3D optical profilometry. Test results clearly shows a zone specific wear micro-mechanism based on the tine geometry. The cutting edge of the tine can be segmented into micro-cutting and micro-ploughing zone. Vickers hardness and microstructural analysis were performed on the cross-section of the sliding interface. Tribo-layer was observed on the worn surface. Degree of penetration from the wear scratches was calculated to justify the wear micro-mechanisms. A Discrete Element Method (DEM) model was developed to investigate the soil flow during the tillage process. The model results and field test wear scars are in good agreement with each other with respect to the wear patterns.

Influence of textural statistics on drag reduction by scalable, randomly rough superhydrophobic surfaces in turbulent flow

We investigate the influence of statistical measures of surface roughness on the turbulent drag reduction (DR) performance of four scalable, randomly rough superhydrophobic (SH) textures. Each surface was fabricated using readily scalable surface texturing processes to generate a random, self-affine height profile on the base substrate. The frictional drag on all four SH surfaces was measured when fully submerged in shear-driven turbulent flow inside a bespoke Taylor-Couette apparatus at Reynolds numbers in the range 1 × 104 ≲ Re ≲ 1 × 105. An “effective” slip length quantifying the overall drag-reducing ability for each surface was extracted from the resulting Prandtl-von Kármán friction plots. Reductions in the frictional drag of up to 26% were observed, with one of the hierarchically textured surfaces exceeding a wall shear stress of 26 Pa (corresponding to a Reynolds number Re ≈ 7 × 104) before the onset of flow-induced plastron collapse. The surface morphology of each texture was characterized using noncontact optical profilometry, and the influence of various statistical measures of roughness on the effective slip length was explored. The lateral autocorrelation length was identified as the key textural parameter determining the drag-reducing ability for randomly rough SH textures, playing the role analogous to the spatial periodicity of regularly patterned SH surfaces. A large autocorrelation length, a small surface roughness, and the presence of hierarchical roughness features were observed to be the three important design requirements for scalable SH textures for optimal DR in turbulent flows.

Tribocorrosion of Polyethylene/Cobalt Contact Combined with Real-Time Fluorescence Assays on Living Macrophages: Development of A Multidisciplinary Biotribocorrosion Device

The test conditions currently used in biotribocorrosion devices often differ greatly from the physiological conditions of joint replacements, contributing to discrepancies between the simulated and actual life span of joint replacements. In this study, a multidisciplinary biotribocorrosion device was developed based on the limitations of existing tribocorrosimeters. The set-up enables corrosion measurements to be simultaneously performed with real-time visualization of living cells using fluorescence microscopy under dynamic loads and movements. The device was configured to simulate the joint contact of ankle prostheses, and the wear of ultra-high-molecular-weight polyethylene/cobalt alloy (CoCrMo) implants surrounded by murine macrophages was tested. Various characterization techniques (non-contact optical profilometry, scanning and fluorescence electron microscopy and quantitative analyses of metal ions and pro-inflammatory cytokines) were combined in-depth multidisciplinary study. Two experimental conditions were used to promote the production of either polyethylene wear particles or metal ions. The first results indicated two distinct tribocorrosion mechanisms: 1) adhesive wear coupled with slow ionic depassivation of the cobalt alloy. The main degradation products were micrometric spherical polyethylene particles that seem to have little impact effect on the metabolic activity of the macrophages. 2) Ionic wear with the production of small, fibrillar polyethylene particles was observed. The production of metal ions, mainly chromium, was the predominant degradation process. The cytotoxicity of the chromium ions was evaluated based on the secretion of pro-inflammatory cytokines (prostaglandin E2). Our findings indicate that simulated conditions that result in low mechanical wear but high ions release appear to be more harmful to cells.

The quantification of surface roughness on root caries using Noncontact Optical Profilometry\u2014An in vitro study

PurposeThe aim of this study was to quantify surface roughness of carious dentine using noncontact optical profilometry (NCOP) in vitro.MethodsA total of 20 extracted teeth with root caries were examined according to clinical assessment criteria. NCOP (Proscan 2000, Scantron, Taunton, UK) was used to carry out the surface roughness measurements in vitro. Selection of sampling rate measurements were subsequently performed.ResultsResults showed that the surface roughness (Ra) values were most accurately obtained at a sampling rate of 30 Hz. All lesions had rough texture, with cavitation ranging from 0.5 to 4 mm. Most lesions were leathery, whilst remaining few were soft. There was a significant difference in surface roughness between the carious and sound dentine (p < 0.05). Pearson’s correlation coefficient tests failed to show any significant linear correlation between surface roughness measurements and cavitation (r 0.39; p > 0.05) whilst there was a significant correlation between the hardness and surface roughness (r 0.47, p = 0.04). There was an inverse relationship trend between surface roughness measurements and severity of root caries.ConclusionsThere are limitations due to the sophisticated layout of collage network within the root carious dentine especially cavitated lesions. The NCOP could be considered for the quantification of surface roughness on noncavitated carious dentine in a laboratory setting.Clinical significanceThe effect of different oral health care products on root caries using the NCOP without causing any potential damage to the noncavitated root surface could be assessed prior to the large-scale clinical studies.