Hybrid Bright-Dark-Field Microscopic Fringe Projection System for Cu Pillar Height Measurement in Wafer-Level Package.

Cu pillars serve as interconnecting structures for 3D chip stacking in heterogeneous integration, whose height uniformity directly impacts chip yield. Compared to typical methods such as white-light interferometry and confocal microscopy for measuring Cu pillars, microscopic fringe projection profilometry (MFPP) offers obvious advantages in throughput, which has great application value in on-line bump height measurement in wafer-level packages. However, Cu pillars with large curvature and smooth surfaces pose challenges for signal detection. To enable the MFPP system to measure both the top region of the Cu pillar and the substrate, which are necessary for bump height measurement, we utilized rigorous surface scattering theory to solve the bidirectional reflective distribution function of the Cu pillar surface. Subsequently, leveraging the scattering distribution properties, we propose a hybrid bright-dark-field MFPP system concept capable of detecting weakly scattered signals from the top of the Cu pillar and reflected signals from the substrate. Experimental results demonstrate that the proposed MFPP system can measure the height of Cu pillars with an effective field of view of 15.2 mm × 8.9 mm and a maximum measurement error of less than 0.65 µm.

Automatic Detection of the Running Surface of Railway Tracks Based on Laser Profilometer Data and Supervised Machine Learning.

The measurement of the longitudinal rail profile is relevant to the condition monitoring of the rail infrastructure. The running surface is recognizable as a shiny metallic area on top of the rail head. The detection of the running surface is crucial for vehicle-based rail profile measurements, as well as for defect detection. This paper presents a methodology for the automatic detection of the running surface based on a laser profilometer. The detection of the running surface is performed based on the light reflected from the rail surface. Three rail surfaces with different surface conditions are considered. Supervised machine learning is applied to classify individual surface elements as part of the running surface. Detection by a linear support vector machine is performed with accuracy of >90%. The lateral position of the running surface and its width are calculated. The average deviation from the labeled widths varies between -1.2mm and 5.6mm. The proposed measurement approach could be installed on a train for the future onboard monitoring of the rail network.

Acoustic Roughness Measurement of Railway Tracks: Running Surface Detection and Compensation of Lateral Movements for Optical Measurements on a Train.

Rolling noise is a significant contributor to railway noise. Wheel and rail roughness are decisive for the emitted noise level. An optical measurement method installed on a moving train is suitable for closer monitoring of the rail surface condition. A measurement setup based on the chord method requires the sensors to be positioned in a straight line along the direction of measurement and in a stable lateral position. Measurements should always be performed within the shiny and uncorroded running surface, even when there are lateral movements of the train. In this study, concepts for the detection of the running surface and the compensation of lateral movements are investigated in a laboratory setting. The setup consists of a vertical lathe with a ring-shaped workpiece that incorporates an implemented artificial running surface. The detection of the running surface based on laser triangulation sensors and a laser profilometer is investigated. It is shown that the running surface can be detected using a laser profilometer that measures the intensity of the reflected laser light. It is possible to detect the lateral position and the width of the running surface. A linear positioning system is proposed to adjust the lateral position of the sensors based on the running surface detection of the laser profilometer. When the lateral position of the measuring sensor is disturbed by a movement with a wavelength of 18.85 m, the linear positioning system can keep the laser triangulation sensor inside the running surface for 98.44% of the measured data points at a velocity of approximately 7.5 km h-1. The mean positioning error is 1.40 mm. By implementing the proposed system on the train, future studies can be conducted to examine the lateral position of the running surface as a function of the various operational parameters of the train.

Is surface roughness of direct resin composite restorations material and polisher-dependent? A systematic review.

STATEMENT OF PROBLEM: Direct resin composite bonding offers a highly esthetic, minimally invasive option for the treatment of anterior teeth however the challenge to improve their longevity remains. Direct resin composite restorations are limited by the risk of staining which may be influenced by the final surface roughness (Ra) of composite achieved. PURPOSE: The purpose of this review is to investigate, using a systematic approach, whether the final surface roughness of anterior composite restorations is affected by the interaction between resin composite and polishing systems. MATERIALS AND METHODS: The review was conducted by 3 independent reviewers and included articles published up to January 21, 2021. Three electronic databases were searched: Medline, Embase, and Web of Science. Studies assessing a quantitative effect of polishing methods on the Ra of direct composite resin materials published after the year 2000 and restricted to the English language were included. RESULTS: The database search for the effect of polishing systems on composite materials retrieved 125 eligible studies. Twelve duplicate records were removed. The resulting records were screened using title and abstract leading to 38 reports which were sought for retrieval. Application of eligibility criteria led to 11 studies included in the review. Hand searching of these studies yielded no additional papers. CONCLUSIONS: There is insufficient evidence to determine whether combination of composite and polisher influences final Ra. More research is required to determine if there is an optimum combination of polisher and composite. CLINICAL IMPLICATIONS: Polishing should be completed following planned finishing procedures. The approximation to the final surface and which finishing burs to use, if any, should be considered when planning a restoration. Durafill VS predictably achieves an acceptable Ra by different polishers.

Effect of coffee on color stability and surface roughness of newly introduced single shade resin composite materials.

BACKGROUND: Dentists started to follow the era of using single-shade resin composite restorations to avoid color shade selection. Our study was done to evaluate and compare the color stability of two single-shade resin composite materials. METHODS: Sixty samples were randomly allocated into two main groups (n = 30) according to the composite resin used: Group O: (Omnichroma) samples and Group V: (Venus Peral) samples. Each group was then divided into two subgroups (n = 15): group O1 and V1: samples immersed in coffee. Group O2 and V2: samples immersed in distilled water. Color changes (ΔE) and roughness values (Ra) were evaluated at baseline, first, and 14th days of immersion. The color change was assessed using Vita Easyshade V, while surface roughness was assessed using a profilometer and Atomic Force Microscope (AFM). Data were collected and statistically analyzed using two-way variance analysis (ANOVA) and Tukey's post-hoc test (p < 0.05). RESULTS: Group O1 and V1 recorded the highest ΔE00 (P = 0.002, 0.0001, respectively) and Ra values (P < 0.001) with no significant difference between both materials at 14 days. CONCLUSION: Single shade resin composite with innovative chromatic material technology has dramatic color change and surface roughness that sacrifice esthetic success.

Effect of immersion and thermocycling in different beverages on the surface roughness of single- and multi-shade resin composites.

BACKGROUND: Resin composite restorations are highly esthetic restorations, which should have and maintain high surface polish. However, esthetic restorations are subjected to different beverages at variable temperatures, which may affect their surface roughness. This study aimed to evaluate the surface roughness of single-shade (Omnichroma) and multi-shade (Filtek Z350XT) composite materials, following aging by immersion and thermocycling in different beverages, simulating one year of clinical service. METHODS: Thirty specimens of each material were prepared and divided into 6 subgroups (n = 5). In each material, the grouping of the specimens was as follows: the first subgroup was the as-prepared specimens stored dry without immersion or thermocycling. The second, third, and fourth subgroups were immersed in saliva, tea, and red wine, respectively, for 12 days at 37 °C. The fifth and sixth subgroups were thermocycled for 10,000 cycles, in tea (the fifth between 37 and 57 °C) and in red wine (the sixth between 37 °C and12°C). The resultant surface roughness was measured by two different methods, stylus profilometer and atomic force microscopy (AFM). Intergroup comparison was performed using independent t test, while intragroup comparison was performed using one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. RESULTS: Intergroup comparison between both composites showed no statistically significant differences in all groups using the stylus profilometer roughness measurements (P>0.05), while the AFM measurements showed significant difference (P ≤ 0.05) within all storage media except the as-prepared control (P = 0.0645), where nanofilled Filtek Z350 XT showed lower nano-roughness. Intragroup comparison data were variable, depending on the material, aging conditions, and roughness assessment tool. However, the resultant average surface roughness (Ra) values in all groups did not exceed the threshold value of Ra 0.2 µm. CONCLUSIONS: Both resin composites attained and retained a clinically acceptable surface finish after immersion and thermocycling in different beverages.

Effect of Effervescent Denture Cleansers on 3D Surface Roughness of Conventional Heat Polymerized, Subtractively, and Additively Manufactured Denture Base Resins: An In Vitro Study.

PURPOSE: To compare the change in surface roughness of denture bases fabricated using three different techniques (additive manufacturing, subtractive manufacturing, and conventional heat-polymerizing) when immersed in two commonly available denture cleansers. MATERIALS AND METHODS: One hundred and seventeen disc-shaped denture base specimens (39/group), were fabricated by subtractive manufacturing (Wieland), additive manufacturing (NextDent Denture 3D+), and conventional heat-polymerizing (Meliodent) techniques, following the manufacturers' instructions. Specimens were randomly divided into 3 groups and immersed in two effervescent denture cleansing solutions and distilled water to simulate 180 days of denture cleansing. A 3D optical noncontact surface profilometer was used to record the surface roughness of the tested denture base materials before and after immersion. Two-way ANOVA, followed by Bonferroni post hoc test, was used to assess the effects of denture cleansers on surface roughness of tested denture base resins. RESULTS: When immersed in Fixodent and Fittydent effervescent denture cleansing solutions, the highest change in absolute surface roughness (∆Sa, in µm) was observed in additively manufactured denture base material (0.181 ±0.018 and 0.079 ±0.008), followed by heat-polymerized denture base material (0.149 ±0.012 and 0.059 ± 0.011), while subtractively manufactured denture base material showed the least change (0.110 ±0.026 and 0.038 ±0.007), respectively. There was a difference in the extent of change in surface roughness between the denture cleansers. The change in surface roughness was much higher with the Fixodent denture cleanser as compared to the Fittydent denture cleanser. CONCLUSION: Subtractively manufactured denture base resin displayed the lowest change while additively manufactured denture base resin displayed the highest change in surface roughness in both denture cleansers, but the extent of change in surface roughness was variable.

In Vitro Assessment of Different Toothbrush Designs on Enamel Surface Abrasion: A Profilometric Study.

AIM: The purpose of this study was to evaluate the impact of three different toothbrush designs on enamel surface abrasion. MATERIALS AND METHODS: Sixty intact freshly extracted maxillary central incisors were considered for the study. All of the extracted teeth's surfaces were severely trimmed, leaving only the labial surface intact. In the trial, a conventional teeth-whitening dentifrice slurry was utilized. A brushing model was created to deliver uniform force in unidirectional motion. Dontrix Gauge was used to control the tension of the spring. The force was kept constant at 180 ± 20 g. The mounted enamel samples were separated into three groups (20 samples each) at random: group A: toothbrushes have a flat trim bristle design, group B: toothbrushes have a zigzag pattern, and group C: toothbrushes have a bi-level bristle design. For 2 weeks, each sample was brushed twice daily for 2 minutes. A profilometer was used to measure the average surface roughness. RESULTS: After toothbrushing, the maximum mean surface roughness score was found in zigzag pattern group (2.10 ± 0.23), followed by bi-level bristle design group (2.06 ± 0.12) and the least was in the flat trim bristle design group (1.96 ± 0.09). There was a significant difference between the different toothbrush bristle pattern groups (p < 0.001). CONCLUSION: On conclusion, the results of this study showed that, in comparison to toothbrushes with zigzag patterns and bi-level bristle designs, flat trim toothbrush bristle designs cause the least amount of surface abrasion and are relatively safe to use. CLINICAL SIGNIFICANCE: Toothbrushing with toothpaste contributes significantly to dental abrasion. A variety of parameters, including toothpaste abrasivity and concentration, brushing frequency, brushing length, brushing force, and toothbrush bristle stiffness, have the potential to influence the abrasion process of dental hard tissue.

Assessment of Erosive Effect of Various Beverages on Esthetic Restorative Materials Used in Primary Teeth: An In Vitro Study.

AIM: The purpose of the current study was to evaluate the erosive impact of various beverages on the esthetic restorative materials utilized in primary teeth. MATERIALS AND METHODS: One hundred and twenty primary molars indicated for serial extraction or over-retention reason with sound buccal surfaces were collected. One millimeter above the cemento-enamel junction, standard Class V cavities were prepared. Following cavity preparation, all teeth were randomly assigned (20 samples per group for each beverage) to one of the three experimental groups based on the type of filling materials: group I: resin-modified glass ionomer cement (GC), group II: nanocomposite resin and group III nanohybrid ormocer-based composite. The samples were kept suspended in various containers containing 250 mL of each orange juice and cola at a temperature of 37°C for three hours per day and rest of day in distilled water. This procedure was repeated for 15 days. Using a 3D optical profilometer, a profilometric reading was recorded for each specimen. RESULTS: The minimum surface roughness was found in nanohybrid ormocer­based composite (1.816 ± 0.16 and 1.302 ± 0.08) followed by resin-modified glass ionomer cement (3.101 ± 0.12 and 2.946 ± 0.09) and nanocomposite resin (5.242 ± 0.20 and 4.488 ± 0.16) after immersed in the cola and orange juice, respectively. And there was a statistically significant difference found between the different esthetic restorative materials in both media. CONCLUSION: On conclusion, the current investigation demonstrates that when exposed to both beverages, the erosive effect was much lesser in nanohybrid ormocer-based composite, followed by resin-modified glass ionomer cement and nanocomposite resin. CLINICAL SIGNIFICANCE: Consuming high-calorie, low pH acidic foods and beverages such as carbonated beverages and fruit juices can lead to erosion, a frequent condition that results in irreparable damage to dental hard tissues and early deterioration of dental restorations.

Real-Time Reflectance Measurement Using an Astigmatic Optical Profilometer.

An astigmatic optical profilometer with a commercial optical pickup head provides benefits, such as high resolution, compact size, and low cost. To eliminate artifacts caused by complex materials with different reflectances, a z-axis modulation mode is proposed to obtain quantitative surface morphology by measuring S curves on all image pixels. Moreover, the slope of the linear region in the S curve shows a positive relationship with the surface reflectance. However, the slope was calculated using an offline curve fitting method, which did not allow real-time reflectance imaging. Furthermore, quantitative reflectance data were unavailable because of the lack of calibration. In this study, we propose a novel method for real-time reflectance imaging by measuring the amplitude of a focus error signal (FES). The calibration results displayed a linear relationship between the FES amplitude and reflectance. The reflectance image of a grating sample with chrome patterns on a glass substrate demonstrates accurate reflectance measurements with a micrometer spatial resolution.

Method for Film Thickness Mapping with an Astigmatic Optical Profilometer.

An astigmatic optical profilometer is a precision instrument with advantages such as high resolution, high bandwidth, a compact size, and low cost. However, current astigmatic optical profilometers measure only surface morphology, and their potential for capturing subsurface information remains underutilized. In this study, we developed a method for measuring the thickness of transparent thin films with an astigmatic optical profilometer. Experimental results demonstrate that the thickness of transparent films tens of micrometers thick can be accurately measured. The maximum thickness measurable through our system is approximately 100 µm, which may be increased to 1.2 mm through the use of a scanner with a greater travel range. A coupling problem occurs for films <25 µm in thickness. However, to solve this problem, we devised a decoupling method, which was experimentally implemented to successfully measure a 18-µm-thick film. Moreover, the ability to obtain 3D images, including of both the upper and lower surfaces, was demonstrated.

Silicon Cantilever for Micro/Nanoforce and Stiffness Calibration.

The paper deals with cantilevers made from monocrystalline silicon by processes of microtechnology. The cantilevers are passive structures and have no transducers. The application as a material measure for the inspection of stylus forces is in the center of investigations. A simple method is the measurement of the deflection of the cantilever at the position of load by the force if the stiffness of the cantilever at this position is known. Measurements of force-deflection characteristics are described and discussed in context with the classical theory of elastic bending. The methods of determining the stiffness are discussed together with results. Finally, other methods based on tactile measurements along the cantilever are described and tested. The paper discusses comprehensively the properties of concrete silicon chips with cantilevers to underpin its applicability in industrial metrology. The progress consists of the estimation of the accuracy of the proposed method of stylus force measurement and the extraction of information from a tactile measured profile along the silicon cantilever. Furthermore, improvements are proposed for approaches to an ideal cantilever.

Novel Methodology to Recover Road Surface Height Maps from Illuminated Scene through Convolutional Neural Networks.

Road surface properties have a major impact on pavement's life service conditions. Nowadays, contactless techniques are widely used to monitor road surfaces due to their portability and high precision. Among the different possibilities, laser profilometers are widely used, even though they have two major drawbacks: spatial information is missed and the cost of the equipment is considerable. The scope of this work is to show the methodology used to develop a fast and low-cost system using images taken with a commercial camera to recover the height information of the road surface using Convolutional Neural Networks. Hence, the dataset was created ad hoc. Based on photometric theory, a closed black-box with four light sources positioned around the surface sample was built. The surface was provided with markers in order to link the ground truth measurements carried out with a laser profilometer and their corresponding intensity values. The proposed network was trained, validated and tested on the created dataset. Three loss functions where studied. The results showed the Binary Cross Entropy loss to be the most performing and the best overall on the reconstruction task. The methodology described in this study shows the feasibility of a low-cost system using commercial cameras based on Artificial Intelligence.

Color stability of hybrid ceramics exposed to beverages in different combinations.

BACKGROUND: The aim of this study is to evaluate the color stability of hybrid ceramics stored in different combinations of beverages that are routinely consumed. METHODS: The specimens were prepared with resin nano-ceramic (Lava Ultimate, 3M Espe, USA) and hybrid ceramic (Vita Enamic, Vita Zahnfabrik, Germany). The specimens were aged in a thermocycler machine for 10,000 cycles. They were stored in different combinations of beverages (water, tea, coke, coffee, red wine, pomegranate juice, and turnip juice) for 12 + 12 h. Surface roughness measurements were performed using a profilometer. The specimen colors were measured using a spectrophotometer. The color values (L-a-b) of the specimens and mean surface roughness values (Ra) were recorded at the end of the 1st (D1), 7th (D7), 14th (D14) and 28th (D28) d. RESULTS: When the solution groups were examined, significant color changes were observed in the Lava coffee-tea, Enamic coffee-tea, Lava coffee-wine, and Enamic coffee-wine groups compared with the other groups (p < 0.01). Except for the samples in the Lava coffee-wine 28th day (D28) and Enamic coffee-wine 28th day (D28) groups, more color changes were observed in the Lava samples than in the Enamic samples across all groups and periods. CONCLUSION: Greater color changes (except for the samples stored in coffee-wine) were observed in the Lava samples than in the Enamic samples across all groups and periods. It was observed that the coffee-tea and coffee-wine beverage combinations produced the greatest color change in hybrid ceramics within the limitations of this study.

Effects of Grinding and Polishing on Surface Characteristics of Monolithic Zirconia Fabricated by Different Manufacturing Processes: Wet Deposition and Dry Milling.

PURPOSE: To evaluate the effects of grinding and polishing on surface characteristics of monolithic zirconia fabricated by two different manufacturing processes. MATERIALS AND METHODS: Two types of monolithic zirconia specimens, self-glazed zirconia (SZ) and conventional zirconia (CZ), were fabricated by wet deposition and dry milling, respectively. The specimens were randomly assigned into 4 groups (n = 10): as-sintered, ground, polished with a special zirconia polishing kit, and polished with a general-purpose ceramic polishing kit. Surface morphology and roughness (Ra ) were characterized, followed by one-way ANOVA analysis (α = 0.05). RESULTS: The as-sintered SZ exhibited a smooth surface with obvious different morphologies compared with the as-sintered CZ (Ra : 0.26 ± 0.05 µm versus 0.33 ± 0.10 µm). Ra of the ground SZ was significantly higher than that of the as-sintered SZ (p < 0.001) and the ground CZ (p = 0.011). For both SZ and CZ, Ra decreased significantly after polishing (p < 0.001), and there was no significant difference between the two groups with different polishing kits (SZ- p = 0.144; CZ- p = 0.322). Surface morphologies of SZ and CZ became similar after grinding and polishing. CONCLUSIONS: Monolithic zirconia SZ fabricated by wet deposition exhibited a smooth surface with specific patterns compared to the dry milled CZ. Grinding significantly changed the surface morphology of SZ and increased surface roughness of both zirconia specimens, which can be improved by polishing without being influenced by polishing kit selection.

Comparison of Enamel Surface Roughness after Bracket Debonding and Adhesive Resin Removal Using Different Burs with and without the Aid of a Magnifying Loupe.

AIM: This study aimed to evaluate the impact of using a magnifying dental loupe on enamel surface roughness during adhesive resin removal by different burs. MATERIALS AND METHODS: Ninety-six extracted premolar teeth were randomly divided according to the bur used with or without the aid of a magnifying loupe into four equal groups (N = 24): group I: naked eye tungsten carbide burs (NTC); group II: magnifying loupe tungsten carbide burs (MTC); group III: naked eye white stones (NWS); and group IV: magnifying loupe white stones (MWS). The initial surface roughness (Ra) T0 was evaluated using a profilometer, and the scanning electronic microscopy (SEM) technique. The metal brackets were bonded and debonded after 24 hours with debonding plier. After adhesive removal, Ra was evaluated again (T1) also the time spent on adhesive removal was recorded in seconds. The samples were finally polished by Sof-Lex discs and Sof-Lex spirals, and the third Ra evaluation was performed (T2). RESULTS: The results of two-way mixed analysis of variance (ANOVA) showed that all burs increased surface roughness at T1 as compared to T0 (p < 0.001) with the highest Ra values shown in group III followed by group IV, group I, and group II. After polishing, no significant difference was noted in Ra values in group I and group II at T0 vs T2 (p = 1.000), while it was significant in group III and group IV (p < 0.001). Regarding the time required for adhesive removal, the shortest time was in group IV followed by groups III, II, and I, respectively. CONCLUSION: The use of a magnifying loupe affects the quality of the clean-up procedure by reducing the enamel surface roughness and the time spent on adhesive removal. CLINICAL SIGNIFICANCE: Using a magnifying loupe was helpful during orthodontic debonding and adhesive removal.

Simultaneous Hand-Eye and Intrinsic Calibration of a Laser Profilometer Mounted on a Robot Arm.

A method for simultaneous laser profilometer and hand-eye calibration in relation to an industrial robot as well as its implementation is presented. In contrast to other methods, the new calibration procedure requires the measurement of only one reference geometry to calculate all the transformation parameters. The reference geometry is measured with a laser profilometer from 15 different poses. The intrinsic parameters of the profilometer, as well as the extrinsic (hand-eye) parameters, are then numerically optimized to achieve the minimum deviation between the reference and the measured geometry. The method was characterized with experiments that revealed a standard deviation of the displacements between the reference geometry after the calibration of less than 0.105 mm in the case of using the robot-arm actuator and 0.046 mm in case of using a 5-axis CNC milling machine. The entire procedure, including measurement and calculation, can be completely automated and lasts less than 10 min. This opens up possibilities for regular on-site recalibration of the entire system.

The Effects of Various Polishing Procedures on Surface Topography of CAD/CAM Resin Restoratives.

PURPOSE: To investigate the effects of different polishing procedures on surface properties of CAD/CAM resin blocks. MATERIALS AND METHODS: In this study, three different CAD/CAM restorative materials (Cerasmart, Lava Ultimate and Shofu Block HC) were used. CAD/CAM blocks were cut in 3-mm-thick slabs and divided into 5 groups. Group-1: Glaze; Group-2: Two-step Diamond Polisher; Group-3: One-step Diamond Polisher; Group-4: Three-step Diamond Polisher; Group-5: Polishing Discs+Diamond Paste. After polishing, top surfaces of the samples were prepared to screen by noncontact laser profilometer (Nanovea) for measurements. Data were analyzed using two-way analysis of variance (ANOVA). RESULTS: The arithmetical mean deviation of the profile was defined as Ra. The extension of Ra (a line's arithmetical mean height) to a surface was defined as Sa. Compared to the arithmetical mean of the surface, Sa expresses the difference in terms of each point's height as an absolute value. Sa was commonly used to assess surface roughness. The highest surface roughness (Ra) values in this study were 0.313 ± 0.05 for Cerasmart, 0.433 ± 0.10 for Lava Ultimate and 0.320 ± 0.05 for Shofu Block HC. The specimens in Group-4 displayed higher Ra values than other groups for each CAD/CAM material. According to surface topography (Sa) values, highest values were 2.936 ± 1.25 for Cerasmart, 2.633 ± 1.28 for Lava Ultimate and 3.489 ± 0.57 for Shofu Block HC. For Cerasmart, LAVA Ultimate and Shofu blocks, Group-1 exhibited significantly higher Sa values than other groups (p < 0.001). CONCLUSION: Optiglaze Color, Sof-Lex Diamond and Identoflex Diamond Ceramic Polisher create smooth CAD/CAM resin surfaces. However, surface roughness values of Cosmedent Nano/Microhybrid Diamond and Diapolisher Paste applied specimens were high. According to Sa values, highest roughness values belong to Optiglaze Color.

Comparison of Wear Resistance of Prefabricated Composite Veneers Versus Ceramic and Enamel.

PURPOSE: To measure surface roughness before and after wear-tests of two different prefabricated composite veneers and compare them to ceramic veneers and human dental enamel. MATERIALS AND METHODS: Roughness (Ra-values) of two prefabricated composite veneers (Visalys Veneer Chairside (VIS) and Componeer (COM)) were compared to lithium disilicate Veneers (e.max CAD) and dental enamel (DENT) in vitro. In total n = 45 specimens per material and enamel samples were used for wear-tests. Wear-out tests were conducted by abrasion tests with a toothbrush simulator (22,000 strokes/ 100 g load; approximately equal to two years of cleansing) and erosion tests were carried out using citric acid (pH 1.57). Ra- and Sa-values were detected by white light interferometer before and after wear-tests. Data were analyzed with ANOVA followed by Games-Howell post hoc test and t-test (α = 0.05). RESULTS: At baseline the lowest Ra- and Sa-values were found in VIS (Ra: 0.01 µm; Sa: 0.04 µm) while DENT revealed significantly higher surface roughness (Ra: 0.11 µm, p < 0.05; Sa: 0.30, p = 0.186). COM had significantly higher Ra-values (Ra: 0.10 µm; Sa: 0.22 µm) after abrasion, while e.max CAD was most resistant to the treatments (Ra: 0.01 µm, p < 0.05; Sa: 0.05 µm, p < 0.05). Compared to DENT all veneers were significantly less affected by citric acid (p < 0.001). CONCLUSIONS: Prefabricated composite veneers have demonstrated less wear after abrasion and erosion tests compared to DENT, nevertheless, they revealed more wear compared to e.max CAD.

Surface Morphology Analysis of Metallic Structures Formed on Flexible Textile Composite Substrates.

This paper compares methods for measuring selected morphological features on the surface of thin metallic layers applied to flexible textile substrates. The methods were tested on a silver layer with a thickness of several hundred nanometers, which was applied to a textile composite with the trade name Cordura. Measurements were carried out at the micro scale using both optical coherent tomography (OCT) and the traditional contact method of using a profilometer. Measurements at the micro-scale proved the superiority of the OCT method over the contact method. The method of contactless measurement employs a dedicated algorithm for three-dimensional surface image analysis and does not affect the delicate surface structure of the measured layer in any way. Assessment of the surface profile of textile substrates and the thin films created on them, is important when estimating the contact angle, wetting behavior, or mechanical durability of the created metallic structure that can be used as the electrodes or elements of wearable electronics or textronics systems.