Contributions to a More Realistic Characterization of Corrosion Processes on Cut Edges of Coated Metals Using Scanning Microelectrochemical Techniques, Illustrated by the Case of ZnAlMg-Galvanized Steel with Different Coating Densities

Corrosion processes at cut edges of galvanized steels proceed as highly localized electrochemical reactions between the exposed bulk steel matrix and the protective thin metallic coating of a more electrochemically active material. Scanning microelectrochemical techniques can thus provide the spatially resolved information needed to assess the corrosion initiation and propagation phenomena, yet most methods scan cut edge sections as embedded in insulating resin to achieve a flat surface for scanning purposes. In this work, the galvanized coatings on both sides of the material were concomitantly exposed to simulated acid rain while characterizing the cut edge response using SECM and SVET techniques, thereby maintaining the coupled effects through the exposure of the whole system as rather realistic operation conditions. The cut edges were shown to strongly promote oxygen consumption and subsequent alkalization to pH 10-11 over the iron, while diffusion phenomena eventually yielded the complete depletion of oxygen and pH neutralization of the nearby electrolyte. In addition, the cathodic activation of the exposed iron was intensified with a thinner coating despite the lower presence of sacrificial anode, and preferential sites of the attack in the corners revealed highly localized acidification below pH 4, which sustained hydrogen evolution at spots of the steel-coating interface.

Supplementation of Energy Drinks with Green Tea Extract: Effect on In Vitro Abrasive/Erosive Dentin Wear

PURPOSE

To investigate the effect of the supplementation of energy drinks with green tea extract on abrasive and erosive dentin wear.

MATERIALS AND METHODS

Six groups, each comprising 15 bovine dentin samples, were prepared, yielding a total of 90 samples. Erosion was performed by immersing the samples in Red Bull and Red Bull light with and without green tea extract. Tap water with and without green tea extract was used as the control groups. The samples were subjected to abrasive/erosive cycling for five days. The following cycling was performed daily: toothbrush abrasion (20 brushstrokes; 2.5 N); eight erosive cycles (2 min storage in the respective solutions); in between the erosive cycles, storage in artificial saliva (60 min) and again toothbrush abrasion (20 brushstrokes; 2.5 N). During the night, samples were again stored in artificial saliva. Abrasive/erosive dentin wear was measured using a stylus profilometer (µm, accuracy = 40 nm). The measured dentin loss results from the vertical position shift on the y-axis from base to final profile after the wear process in 2D. Pairwise comparisons between the groups were carried out using Wilcoxon signed-rank test.

RESULTS

The following dentin wear (median [IQR]) was measured: Red Bull: 1.9 µm (0.5); Red Bull Light: 1.3 µm (0.3); Red Bull with green tea extract: 0.8 µm (0.3); Red Bull Light with green tea extract: 0.3 µm (0.5); Tap water with green tea extract: -0.2 µm (0.7); Tap water: -1.0 µm (1.2). The comparison of all tested groups to each other proved to be statistically significant (p < 0.05).

CONCLUSION

The supplementation of energy drinks with green tea extract provide a protective effect against erosive/abrasive wear in vitro.

Selective Area Epitaxy of Highly Strained InGaAs Quantum Wells (980-990 nm) in Ultrawide Windows Using Metalorganic Chemical Vapor Deposition

We employed the selective-area-epitaxy technique using metalorganic chemical vapor deposition to fabricate and study samples of semiconductor heterostructures that incorporate highly strained InGaAs quantum wells (980-990 nm emission wavelength). Selective area epitaxy of InGaAs quantum wells was performed on templates that had a patterned periodic structure consisting of a window (where epitaxial growth occurred) and a passive mask (where epitaxial growth was suppressed), each with a width of 100 µm for every element. Additionally, a selectively grown potential barrier layer was included, which was characterized by an almost parabolic curvature profile of the surface. We conducted a study on the influence of the curvature profile of the growth surface on the optical properties of InGaAs quantum wells and the spatial distribution of composition in an ultrawide window. Our results showed that, under fixed selective-area-epitaxy conditions, the composition of the InxGa1-xAs and the wavelength of the quantum-well emission changed across the width of the window. Our study demonstrates that increasing the curvature profile of the growth surface of highly strained quantum wells leads to a transition in the photoluminescence wavelength distribution profile across the window, from quasi-parabolic to inverted parabolic.

Deterioration of direct restorative materials under erosive conditions with impact of abrasion and attrition in vitro

Objective

To compare the cumulative impact of sequential wear on mechanical properties and appearance of a composite resin (CR), Filtek Z250^®, a glass ionomer GI, Fuji IX GP^®, and a glass hybrid (GH), Equia Forte^®.

Material and Methods

Six equally sized specimens of each material were subjected to wear tests, i.e., simulation of brushing, chewing and acidic liquid exposure, mimicking at least 6 months of clinical exposure. Surface roughness, hardness, substance loss and degree of shade lightness were determined.

Results

Following wear tests, significant increase in surface roughness and decrease in hardness values were observed for all materials (p < .05). Significantly larger substance loss was found in Equia Forte^® specimens compared to Filtek Z250^® (p < .05), while that of Fuji IX^® exceeded the measurement capacity of the instrument. Opposite to the two other materials, the shade of Filtek Z250^® became darker.

Conclusions

Sequential wear exposure mimicking abrasion, erosion and attrition to products representing CR, GI and GH, caused weakening and change in appearance of the materials. The composite resin was the most mechanically resistant to the sequential wear.

Anti-erosion effect of an experimental varnish on eroded dentin

This in vitro study evaluated the effect of an experimental varnish containing 20% nano-hydroxyapatite (nHAP) associated with 5% stannous chloride (SnCl2) against erosive-abrasive wear on bovine dentin. Samples of bovine cervical dentin were pre-eroded (0.3% citric acid, pH 2.6 for 10 minutes) and randomized into 4 groups (n=10): Control group - experimental varnish without active ingredient (CG); experimental varnish containing 20% nHAP (nHG); experimental varnish containing 5% SnCl2 (24.800 ppm Sn2+) (SnG); experimental varnish containing 20% nHAP associated with 5% SnCl2 (18.300 ppm Sn2+) (nHSnG). After applying the materials, the erosive-abrasive challenges were performed for five days. Erosive dentin loss and analysis of the pattern of dentinal obliteration were performed by 3D confocal laser microscopy. A one-way ANOVA/Bonferroni test was performed to analyze the data (α=0.05). The SnG and nHSnG experimental groups presented more effectiveness in preventing erosive wear when compared to the other groups (p<0.05). There was no statistically significant difference between the SnG and nHSnG groups (p = 0.731) in tooth structure dentin loss. Regarding the amount of open dentinal tubules, the highest amount of obstructed dentinal tubules was demonstrated in SnG and nHSnG (p < 0.05) when compared to the others. Between SnG and nHSnG there was no significant difference (p = 0.952) in the amount of closed dentinal tubules in the dentin. Experimental varnishes containing 5% SnCl2 associated or not with 20% nHAP showed to be a promising strategy in preventing erosive-abrasive wear of dentin. In addition, nHSnG was able to obliterate dentinal tubules.

Eggshell composition and surface properties of avian brood-parasitic species compared with non-parasitic species

The eggs of avian obligate brood-parasitic species have multiple adaptations to deceive hosts and optimize development in host nests. While the structure and composition of the eggshell in all birds is essential for embryo growth and protection from external threats, parasitic eggs may face specific challenges such as high microbial loads, rapid laying and ejection by the host parents. We set out to assess whether eggshells of avian brood-parasitic species have either (i) specialized structural properties, to meet the demands of a brood-parasitic strategy or (ii) similar structural properties to eggs of their hosts, due to the similar nest environment. We measured the surface topography (roughness), wettability (how well surfaces repel water) and calcium content of eggshells of a phylogenetically and geographically diverse range of brood-parasitic species (representing four of the seven independent lineages of avian brood-parasitic species), their hosts and close relatives of the parasites. These components of the eggshell structure have been demonstrated previously to influence such factors as the risk of microbial infection and overall shell strength. Within a phylogenetically controlled framework, we found no overall significant differences in eggshell roughness, wettability and calcium content between (i) parasitic and non-parasitic species, or (ii) parasitic species and their hosts. Both the wettability and calcium content of the eggs from brood-parasitic species were not more similar to those of their hosts' eggs than expected by chance. By contrast, the mean surface roughness of the eggs of brood-parasitic species was more similar to that of their hosts' eggs than expected by chance, suggesting brood-parasitic species may have evolved to lay eggs that match the host nest environment for this trait. The lack of significant overall differences between parasitic and non-parasitic species, including hosts, in the traits we measured, suggests that phylogenetic signal, as well as general adaptations to the nest environment and for embryo development, outweigh any influence of a parasitic lifestyle on these eggshell properties.

Adhesion of Modified Epoxy Resin to a Concrete Surface

The protection of building elements exposed to the weather using hydrocarbon-based agents is a comprehensive group of analyses. These agents are characterized by very high chemical resistance, waterproofness, as well as adhesion to surfaces made of various materials, i.e., concrete, steel, ceramics and wood. Modification of adhesion, which ultimately leads to an increase in the durability of a protective/face coating made of such a material, can lead to a longer life of these layers and a less frequent need for replacement or restoration. The following paper describes an experimental research program on the possibility of increasing the adhesion and durability of epoxy resin modified with the use of powder fillers. The resin can be used as a protective or top coat on the surface of concretes or mortars. The main objective of the study was to increase the adhesion of the resin to the concrete substrate, modified by grinding and sandblasting to increase the roughness. For the series studied, both the changes in physicochemical parameters, which determine how the resin penetrates the irregularities of the substrate and mechanical parameters, which mainly determine the durability of the layer made in this way, were identified. A modified version of the pull-off test was used as a method to directly evaluate the effectiveness of the modified resins.

Surface texture analysis of different focal knee resurfacing implants after 6 and 12 months in vivo in a goat model

The clinical success of osteochondral implants depends significantly on their surface properties. In vivo, an implant may roughen over time which can decrease its performance. The present study investigates whether changes in the surface texture of metal and two types of polycarbonate urethane (PCU) focal knee resurfacing implants (FKRIs) occurred after 6 and 12 months of in vivo articulation with native goat cartilage. PCU implants which differed in stem stiffness were compared to investigate whether the stem fixating the implant in the bone influences surface topography. Using optical profilometry, 19 surface texture parameters were evaluated, including spatial distribution and functional parameters obtained from the material ratio curve. For metal implants, wear during in vivo articulation occurred mainly via material removal, as shown by the significant decrease of the core-valley transition from 91.5% in unused implants to 90% and 89.6% after 6 and 12 months, respectively. Conversely, for PCU implants, the wear mechanism consisted in either filling of the valleys or flattening of the surface by dulling of sharp peaks. This was illustrated in the change in roughness skewness from negative to positive values over 12 months of in vivo articulation. Implants with a softer stem experienced the most deformation, shown by the largest change in material ratio curve parameters. We therefore showed, using a detailed surface profilometry analysis, that the surface texture of metal and two different PCU FKRIs changes in a different way after articulation against cartilage, revealing distinct wear mechanisms of different implant materials.

Thermo-Mechanical Fatigue Crack Growth and Phase Angle Effects in Ti6246

A bespoke TMF crack growth test set-up has been developed and validated for use throughout this study and the effects of phasing between mechanical loading and temperature have been investigated. The study shows that TMF cycles may show increased crack growth rate behaviour when compared to isothermal fatigue. The phase angle of the applied TMF cycle can also affect crack growth behaviour, with in-phase (IP) test conditions showing faster crack growth rates than out-of-phase (OP) test conditions. Propagating cracks interact with the microstructure of the material, in particular, the α/β interfaces within the prior beta grains and supporting fractography evidences subtle differences in fracture mechanisms as a result of phase angle.

What we know about the scleral profile and its impact on contact lens fitting

Scleral contact lens fitting has provided practitioners with one of the earliest pieces of evidence that the sclera was more often asymmetric than symmetric. Some preliminary observations such as different haptic alignment patterns over the sclera in 360 degrees, the appearance of fogging in the fluid chamber and excessive tear out-in flow through specific meridians, quadrants, or areas of the haptic provide evidence of some scleral asymmetry. The advent of technologies that allowed measurement of the scleral profile led to formal research confirming that only about 6% of scleras are symmetric, while the rest are toric, quad-specific, or irregular. This has an evident impact on how to focus scleral lens fitting. Measuring the scleral profile also provided us with true ocular sagittal height data for cord diameters beyond the cornea. Although high variability was expected in pathological eyes, healthy eyes also showed a wide range of ocular sagittal heights. Due to this variability among healthy eyes, a discussion has emerged on whether the one-size-fits-all approach to soft lens fitting is a proper strategy to fit the whole spectrum of sagittal heights. The traditional mode of selecting the parameters for custom soft lenses through corneal parameters is also questioned.

The Effect of Surface Processing on the Shear Strength of Cobalt-Chromium Dental Alloy and Ceramics

Porcelain fused to metal is widespread dental prosthetic restoration. The survival rate of metal-ceramic restorations depends not only on the qualifications of dentists, dental technicians but also on the adhesive strength of ceramics to a metal frame. The goal of the research is to determine the optimal parameters of the surface machining of the metal frame to increase the adhesion of metal to ceramics. Adhesion of cobalt-chromium alloy and ceramics was investigated. A profilometer and a scanning electron microscope were used to analyze the morphology. To estimate the adhesion the shear strength was measured by the method based on ASTM D1002-10. A method of surface microrelief formation of metal samples by plasma-electrolyte treatment has been developed. Regimes for plasma-electrolyte surface treatment were investigated according to current-voltage characteristics and a surface roughness parameter. The samples were subjected to different surface machining techniques such as polishing, milling, sandblasting (so-called traditional methods), and plasma-electrolyte processing. Morphology of the surface for all samples was studied and the difference in microrelief was shown. The roughness and adhesive strength were measured for samples either. As a result, the mode for plasma- electrolytic surface treatment under which the adhesive strength was increased up to 183% (compared with the traditional methods) was found.

Enamel surface roughness evaluation after bracket debonding: Comparison between light cure and self cure adhesive resin 3-Dimensional profilometric study

Introduction

After fixed orthodontic treatment, following bracket removal, the debonding procedure should lead to restitutio ad integrum of the enamel or, at least, restore the enamel surface as closely as possible to its pretreatment condition. Adhesion of brackets in orthodontics is that they should be strong enough to prevent failure during all treatment but also low enough, so that enamel damage would be minimal during bracket removal after treatment.

Material and Methods

A total of 60 premolars were collected and stored in distilled water. The extracted teeth were divided into two groups of 30 each, group A was to be bonded with self-cure adhesive while group B light cure adhesive was to be used. A standardised protocol was followed for adhering the brackets to the tooth surfaces. All the teeth were bonded with metal brackets (3M Unitek, Gemini Twin Brackets 0.022 slot). In group A, bonding adhesive (3M Unitek self cure adhesive primer) was applied. In group B, the bonding adhesive (3M Unitek light cure adhesive primer) was photopolymerized for 10 seconds after application.

Results

Surface roughness of enamel as assessed by profilometry shows that light cure adhesive creates more roughness as compared to self cure adhesive. To conclude, self cure adhesive is clinically better than light cure adhesive.

Discussion

In the present study enamel surface roughness were compared after debonding. Enamel surface roughness after bracket debonding depends on a host of factors, which include - brackets, adhesive used and method of remnant removal.

Mechanical and Microstructural Characterisation of Cooling Pipes for the Compact Muon Solenoid Experiment at CERN

The Compact Muon Solenoid (CMS) is a particle physics experiment situated on the Large Hadron Collider (LHC) at CERN, Switzerland. The CMS upgrade (planned for 2025) involves installing a new advanced sensor system within the CMS tracker, the centre of the detector closest to the particle collisions. The increased heat load associated with these sensors has required the design of an enhanced cooling system that exploits the latent heat of 40 bar CO₂. In order to minimise interaction with the incident radiation and improve the detector performance, the cooling pipes within this system need to be thin-walled (~100 μm) and strong enough to withstand these pressures. The purpose of this paper is to analyse the microstructure and mechanical properties of thin-walled cooling pipes currently in use in existing detectors to assess their potential for the tracker upgrade. In total, 22 different pipes were examined, which were composed of CuNi, SS316L, and Ti and were coated with Ni, Cu, and Au. The samples were characterised using computer tomography for 3D structural assessment, focused ion beam ring-core milling for microscale residual stress analysis, optical profilometry for surface roughness, optical microscopy for grain size analysis, and energy dispersive X-ray spectroscopy for elemental analysis. Overall, this examination demonstrated that the Ni- and Cu-coated SS316L tubing was optimal due to a combination of low residual stress (20 MPa axial and 5 MPa hoop absolute), low coating roughness (0.4 μm Ra), minimal elemental diffusion, and a small void fraction (1.4%). This result offers a crucial starting point for the ongoing thin-walled pipe selection, development, and pipe-joining research required for the CMS tracker upgrade, as well as the widespread use of CO₂ cooling systems in general.

Effect of prophylactic instrumentation on surface roughness of tooth-colored restorative material: An in vitro study

Aim:

To compare and evaluate the surface characteristics of different restorative materials used for restoration of cervical defects when subjected to periodontal prophylactic instrumentation techniques.

Materials and Methodology:

Sixty box-shaped cavities were prepared on the labial surface of decoronated permanent maxillary anterior teeth which were randomly divided into two groups (n = 30) based on the instrumentation technique Group I: Manual instrumentation using curettes and Group II: Ultrasonic instrumentation. The samples were further divided into three subgroups based on restorative material subgroups I V and II V-restored with Vitremer, subgroups I F and II F-restored with Filtek Z 250 XT and subgroups I D and II D-restored with Dyract flow, respectively. After finishing and polishing, the samples were subjected to surface profilometry analysis for determining the surface roughness values (Ra). Thereafter, the restored surfaces of all the samples in different subgroups were subjected to prophylactic instrumentation with Gracey's curettes (Group I) and ultrasonic scalers (Group II). Ra values were recorded again after prophylactic instrumentation and after polishing. The data thus obtained were subjected to the statistical analysis using the independent t-test and one-way ANOVA (p<0.05).

Results:

Ra values were significantly higher for both manual and ultrasonic prophylaxis compared to preprophylaxis and postpolishing in all the three restorative materials. Ultrasonic scaling produced significantly higher Ra for subgroup V as compared to subgroup F and subgroup D, whereas the difference between the materials was not significant for manual scaling.

Conclusion:

Manual prophylaxis resulted in significant reduction in surface roughness of all the three restorative materials while ultrasonic prophylaxis resulted in significant reduction for Vitremer only. Polishing after scaling significantly reduced the effect of both manual and ultrasonic prophylaxis on surface roughness.

Impact of Endodontic Instrumentation on Surface Roughness of Various Nickel-Titanium Rotary Files

OBJECTIVES

 The aim of the present study was to evaluate the surface roughness (SR) of various nickel-titanium (NiTi) rotary endodontic instruments (ProTaper Next [PTN], WaveOne Gold [WOG], and ProTaper Gold [PTG]) before and after root canal instrumentation.

MATERIALS AND METHODS

 For each type (PTN, WOG, and PTG), the endodontic instrumentation was performed using extracted mandibular molar teeth's curved mesial root canals (curvature: 20-40 degrees) after determining the working length. Each NiTi file was cleaned, and sterilized following preparation of four root canals and characterized for surface properties before and after endodontic instrumentation using a contact-mode three-dimensional surface profiler. The data were analyzed statistically using Statistical Package for the Social Sciences for SR parameters including average surface roughness value (Sa), root mean square roughness (Sq), and peak to valley height (Sz).

RESULTS

 Preinstrumentation assessment revealed a significant difference for all the three SR variables (p < 0.05) for the cutting blade and the flute area. WOG instruments showed the highest SR values (p = 0.000). The postinstrumentation assessment revealed significant differences in SR values in the blade and the flute between the three groups (p < 0.05), with WOG and PTG exhibiting the highest values in the blade and flute sections, respectively.

CONCLUSIONS

 The SR parameters of intact PTN, WOG, and PTG NiTi files vary and that was increased following the endodontic instrumentation.

Three-Dimensional Urethral Profilometry-A Global Urethral Pressure Assessment Method

Background: To present a new method of urethral pressure examination, and to evaluate diagnostic capabilities of three-dimensional profilometry, as an alternative to classical urethral profile (UPP). Using five channel catheters and dedicated software, a global urethral pressure image is obtained. The method eliminates the main limitation of classical urethral profilometry, where the catheter orientation determines the pressure picture limited to only one point in the urethral circumference; we observed up to 50% differences in pressure measures depending on the point of urethral circumference where the measurement was taken. Methods: This is a preliminary study containing a method presentation and analysis of the use in varied clinical cases of either healthy patients or patients with lower urinary tract symptoms (LUTS). The article includes a technique and equipment description and a full evaluation of selected cases, including three-dimensional urethral pressure distribution graphics. Results and Conclusions: Three-dimensional profilometry compared to the classical technique is comparable regarding the time, cost, technical difficulty and patient discomfort. At the same time, we obtained much more data on the urethral pressure and its distribution. The results are easy to interpret due to the 3D movable graphics created automatically by the dedicated software.

Relationship between Axial Length and Corneo-Scleral Topography: A Preliminary Study

The main objective of the current study was to investigate further the relationship of the overall length of the eye with a great variety of anterior segment parameters, including scleral geometry. A total of 64 eyes of 32 participants with ages from 12 to 52 years were included in this prospective non-randomized single-center study. All participants underwent a complete eye examination, including an analysis of corneo-scleral shape with a Fourier-domain profilometer. A strong negative correlation was found between axial length and temporal-nasal ocular sagittal height difference for different chord lengths. For the right eye, a consistent and stable linear model was obtained to predict the axial length from the spherical equivalent, the corneal diameter, the high-order aberrations root mean square, and the minimum sagittal height for 13- and 14-mm chord. For the left eye, a model was obtained to predict the axial length from the spherical equivalent and the mean corneal curvature, including other parameters such as corneal diameter or high-order aberrations, depending on the chord length, considered for estimating the sagittal height values. More studies with larger samples are needed to confirm these preliminary outcomes.

Green Tea Extract Reduces the Erosive Dentine Wear Caused by Energy Drinks In Vitro

PURPOSE

To investigate the effect of energy drinks supplementation with green tea extract on the erosive dentine wear.

MATERIALS AND METHODS

Six groups of bovine dentine samples (n = 15) were subjected to four cycles erosive attacks (10 min, 25 °C) and remineralisation (artificial saliva, 60 min, 37°C) using the following formulas: tap water; green tea extract; Red Bull; Red Bull supplemented with green tea extract; Red Bull Light; Red Bull Light supplemented with green tea extract. The erosive dentine wear - ie, the irreversible dentine loss - was measured using a stylus profilometer (µm, accuracy = 40 nm).

RESULTS

Median and interquartile range (IQR) of erosive dentine wear for the tested energy drinks before and after the supplementation with green tea extract were calculated as follows: Red Bull (before: 3.3 µm (1.0)); after: 1.2 µm (0.6)); Red Bull Light (before: 3.3 µm (0.9)); after: 2.0 µm (0.4)). The difference between the groups before and after the supplementation was statistically significant (P ˂0.05). The erosive dentine wear for the tap water group was calculated at 0.4 µm (0.6) and for the green tea extract group at -1.0 µm (1.3).

CONCLUSIONS

Supplementation of energy drinks with green tea extract could reduce the erosive dentine wear caused by energy drink in vitro.

Comparative Evaluation of the Influence of Different Sports/Energy Drinks and Alcoholic Beverages on the Surface Roughness of Three Different Flowable Esthetic Restorative Materials: An In Vitro Analysis

Objective:

This study aimed to evaluate the surface roughness of three flowable esthetic restorative materials after exposure to sports/energy drinks and alcoholic beverages.

Materials and Methods:

A total of 210 specimens of dimension (2cm diameter and 2 mm thickness) with giomer, compomer, and composite (70 samples with each esthetic material) were made with the help of plastic rings. The prepared samples were tested in six experimental sports/energy drinks (beer, whiskey, vodka, Gatorade, Red Bull, and Sting) and distilled water was considered as the control group. Profilometric analyses of all samples were recorded before immersing into the experimental and control solutions. Then, the samples were stored in the experimental and control group solutions for 5min for 30 days. The profilometric analysis was repeated after 30 days and records were statistically analyzed.

Results:

Flowable composite showed the minimum surface roughness, whereas the flowable compomer showed the maximum surface roughness in the present test conditions. When the erosive potential of the test solutions was evaluated, surface roughness values were more for sports/energy drinks when compared to that of alcoholic beverages.

Conclusion:

All the sports/energy drinks and alcoholic beverages evaluated in this study altered the surface roughness of the tested restorative materials. The effects ranged from slight to a markedly negative impact on the surface roughness of the test restorative materials.

Anterior Scleral Regional Variation between Asian and Caucasian Populations

Purpose: To evaluate the anterior scleral shape regional differences between Asian and Caucasian populations. Methods: The study included 250 Asian eyes and 235 Caucasian eyes from participants aged 22 to 67 years (38.5 ± 7.6). Three-dimensional (3D) corneo-scleral maps were acquired using a corneo-scleral topographer (Eye Surface Profiler, Eaglet Eye BV) and used to calculate sagittal height. For each 3D map, the sclera (maximum diameter of 18 mm) and cornea were separated at the limbus using an automated technique. Advanced data processing steps were applied to ensure levelled artefact-free datasets to build an average scleral shape map for each population. Results: Statistically, Asian and Caucasian sclerae are significantly different from each other in sagittal height (overall sclera, p = 0.001). The largest difference in sagittal height between groups was found in the inferior-temporal region (271 ± 203 µm, p = 0.03), whereas the smallest difference was found in the superior-temporal region (84 ± 105 µm, p = 0.17). The difference in sagittal height between Caucasian and Asian sclera increases with the distance from the limbus. Conclusions: Asian anterior sclera was found to be less elevated than Caucasian anterior sclera. However, the nasal area of the sclera is less elevated than the temporal area, independently of race. Gaining knowledge in race-related scleral topography differences could assist contact lens manufacturers in the process of lens design and practitioners during the process of contact lens fitting.

Characterization of the geometric properties of the sclero-conjunctival structure: a review

To revise the peer-reviewed literature on geometric properties of the scleral-conjunctival structure in order to define their clinical relevance and the potential relationship between their changes and myopia development or progression. A bibliographic search focused on the study of the geometry of conjunctiva and/or sclera as well as those studies evaluating the relationship between geometric changes in the scleral-conjunctival structure and myopia was carried out. Several studies have been performed with different diagnostic technologies, including optical coherence tomography, profilometry and Scheimpflug imaging, to detect geometric changes of the scleral-conjunctival tissue in different physiological conditions of the eye, after use of contact lenses and in different ocular pathologies. Likewise, these technologies have been shown to be a valuable clinical tool to optimize scleral contact lens fitting. Future studies should investigate new potential clinical applications of such technologies, including the evaluation of anterior scleral changes related to myopia, as well as to define standardized clinical standard operating procedures for obtaining accurate and reproducible clinical measurement of the scleral-conjunctival morphology.

[Interdisciplinary consensus on Russian-language terminology of anorectal sphincterometry and profilometry]

Aim to describe the results of a multidisciplinary discussion on the terminology of anorectal sphincterometry (AS) and profilometry (AP). We performed online survey with the use of public platform Google forms to harmonize Russian terms to be used to describe the results of AP and AS and their abbreviations. The invitation to participate in the survey was sent to the authors who use the results of AP and AS in clinical practice and perform the diagnostic procedures. The obtained answers were analyzed with the use of the aggregator and Statistica 10 (StatSoft Inc, USA) software. The level of consensus was analyzed with the use of modified Delphi criteria (C1 agreement of 90% of participants, C2 agreement of 75 to 90%, C3 less than 75%). Invitations sent 76, responses obtained 63 (response rate 82.9%). Consensus level 1 was reached for all the terms of AP and for 4out of 7 terms to describe the results of AS (3 out of 7 terms were of moderate agreement, C2). The need for the use of predefined abbreviations of terms for AS and AP was of a low rate of consensus (71.4%). The agreed terms of AS and AP should be used to prepare a conclusion for the diagnostic procedures and to publish scientific reports.

Comprehensive analysis of laserscanner validity used for measurement of wear

OBJECTIVES

The aims of this study were to test the hypotheses that (a) a laserscanner used for measuring maximum depth and volume loss will yield the same results as a surface profilometer; (b) the surface roughness will affect the maximum depth and volume loss measured with the laserscanner; (c) analytical results using the laserscanner from multiple operators have no more than 10% inter-rater difference and; (d) replicating samples using either stone or impression material is an accurate method for measuring wear using the laserscanner.

MATERIALS AND METHODS

The volume and maximum depth of indentations from fine, medium and rough burs on glass-ceramic disks were measured using two devices, a surface profilometer (Dektak II, Veeco) and a 3D Laserscanner (LAS-20, SD Mechatronik). Replicates of the indentations made from polyvinysiloxane impression material and gypsum were also measured.

RESULTS

Comparison of profilometer and laserscanner readings using ceramic disks demonstrated a mean error of 13.61% for depth and 25.32% for volume. Replication errors were minimal (2.6% for impression, 2.5% for stone). Surface profilometer data for volume measurements revealed a difference of 6.1% for impression and 6.5% for stone compared with ceramics. However, when measurements for replicates were compared between laserscanner and surface profilometer, depth had a mean error of 74% for impression and 51% for stone. Volume differences of 78% for impression and 44% for stone were recorded.

CONCLUSION

This work demonstrated that the laserscanner was a convenient device for measuring wear but there is a need to validate the accuracy of the measurements.

Effect of four different dentifrices applied by customized automated brushing device on enamel surface abrasion: An in vitro profilometric study

Aim:

The aim of this study is to evaluate the enamel surface abrasion using four different dentifrices and a customized automated brushing machine under a profilometer.

Materials and Methods:

A total of 30 enamel blocks (9 mm × 9 mm × 2 mm) were prepared from freshly extracted maxillary central incisors which were randomly divided into five equal groups (Group 1: specimens brushed with Colgate Total, Group 2: specimens brushed with Colgate Lemon and Salt, Group 3: specimens brushed with Colgate Visible White, Group 4: specimens brushed with Colgate Sensitive, and Group 5: intact enamel surface). Samples were brushed using a customized automated toothbrushing machine for 60 min. A profilometric read out (Ra value) was taken for each group subjected to brushing and also for the control group.

Statistical Analysis:

Statistical analysis used in this study was one-way analysis of variance followed by post hoc Tukey's test.

Results:

Statistically significant differences (P < 0.05) were observed in the values of enamel abrasion (Ra) among Group 1–Group 4 whereas Group 5 (control group) had no significant difference in enamel abrasion (P > 0.05).

Conclusion:

The highest enamel abrasion was observed in the group with Colgate Visible White toothpaste, and the least enamel abrasion was seen in the group with Colgate Sensitive Plus.

Do fluoride toothpastes have similar preventive effect in permanent and primary teeth against erosive tooth wear?

BACKGROUND

Little is known about fluoride toothpastes effect on primary teeth submitted to erosive tooth wear.

OBJECTIVES

To evaluate the preventive effect of different toothpastes on surface loss (SL) after severe erosion/abrasion model and to compare this effect between permanent (PT) and primary teeth (pt).

DESIGN

Enamel samples were randomly divided according toothpastes groups (n = 17). G1: placebo; G2: NaF; G3: AmF-NaF-SnCl2 anti-erosion; G4: SnF2 ; and G5: NaF anti-erosion for children. Samples were incubated in artificial saliva (1 hour), submitted to erosive challenge (3 minutes; 1% citric acid; pH3.6; at 25°C) and to toothbrush abrasion (2 minutes slurry immersion; 50 strokes; 200 g) during 30 cycles. Surface loss (μm; mean ± SD) was quantified by contactless profilometry. The effects of the two covariables "tooth" and "toothpaste" were analysed by non-parametric ANOVA, variables with significant effects were tested by Wilcoxon tests.

RESULTS

pt showed significantly higher surface loss than PT in all groups (P < 0.001). The mean values of SL of each group were: G1 PT 18.18(±3.98), pt 25.65(±9.21); G2 PT 14.76(±2.82), pt 18.11(±3.92); G3 PT 12.62(±5.29), pt 15.61(±6.70); G4 PT 17.12(±2.24), pt 23.41(±7.9); G5 PT 13.24(±1.29), pt 18.28(±8.96).

CONCLUSIONS

In permanent teeth, G3 showed the best preventive effect. In primary teeth, G1, G3, and G5 showed similar effect.

Differences in Trochlear Surface Damage and Wear Between Three Different Total Knee Arthroplasty Designs

INTRODUCTION

Trochlear design plays a role in patellofemoral kinematics. Little is known regarding differences in the contact properties between modern designs. The purpose of the present study was to analyze patellofemoral joint contact by identifying areas of joint surface damage and wear in retrieved femoral components of 3 modern designs.

MATERIALS

Eighteen retrieved femoral components featuring 3 different modern designs (Triathlon, SIGMA, and GENESIS II) were matched based on time-in-vivo, age, gender, and body mass index. Trochlear wear and surface damage were assessed using visual inspection, light microscopy, and light profilometry.

RESULTS

Visual inspection of the femoral components showed evidence of surface damage in all implant types. No significant differences between the groups were found with respect to surface damage and wear on visual inspection. Light profilometry of retrieved components showed that retrieved Triathlon (P = .002) and SIGMA (P = .009) components were significantly rougher than the corresponding reference components. The GENESIS II retrieved components were not substantially rougher than the reference components (P = .48). Light profilometry analysis showed significantly increased roughness of retrieved SIGMA components compared with Triathlon or GENESIS II components, particularly in the proximal trochlear groove and the medial trochlea.

CONCLUSION

As the volume and patient demands for total knee arthroplasty increase, a greater understanding of the patellofemoral joint is warranted. Patellofemoral kinematics can have an effect on the surface characteristics of total knee arthroplasty components. Retrieved SIGMA components appeared to have increased roughness compared with Triathlon or GENESIS II components. The etiology and long-term effects of increased trochlear roughness require further investigation.

Measuring UV Curing Parameters of Commercial Photopolymers used in Additive Manufacturing

A testing methodology was developed to expose photopolymer resins and measure the cured material to determine two key parameters related to the photopolymerization process: E_c (critical energy to initiate polymerization) and D_p (penetration depth of curing light). Five commercially available resins were evaluated under exposure from 365 nm and 405 nm light at varying power densities and energies. Three different methods for determining the thickness of the cured resin were evaluated. Caliper measurements, stylus profilometry, and confocal laser scanning microscopy showed similar results for hard materials while caliper measurement of a soft, elastomeric material proved inaccurate. Working curves for the five photopolymers showed unique behavior both within and among the resins as a function of curing light wavelength. E_c and D_p for the five resins showed variations as large as 10×. Variations of this magnitude, if unknown to the user and not controlled for, will clearly affect printed part quality. This points to the need for a standardized approach for determining and disseminating these, and perhaps, other key parameters.

A Profilometry-Based Dentifrice Abrasion Method for V8 Brushing Machines Part III: Multi-Laboratory Validation Testing of RDA-PE

OBJECTIVES

We have previously reported on progress toward the refinement of profilometry-based abrasivity testing of dentifrices using a V8 brushing machine and tactile or optical measurement of dentin wear. The general application of this technique may be advanced by demonstration of successful inter-laboratory confirmation of the method. The objective of this study was to explore the capability of different laboratories in the assessment of dentifrice abrasivity using a profilometry-based evaluation technique developed in our Mason laboratories. In addition, we wanted to assess the interchangeability of human and bovine specimens.

METHODS

Participating laboratories were instructed in methods associated with Radioactive Dentin Abrasivity-Profilometry Equivalent (RDA-PE) evaluation, including site visits to discuss critical elements of specimen preparation, masking, profilometry scanning, and procedures. Laboratories were likewise instructed on the requirement for demonstration of proportional linearity as a key condition for validation of the technique. Laboratories were provided with four test dentifrices, blinded for testing, with a broad range of abrasivity. In each laboratory, a calibration curve was developed for varying V8 brushing strokes (0, 4,000, and 10,000 strokes) with the ISO abrasive standard. Proportional linearity was determined as the ratio of standard abrasion mean depths created with 4,000 and 10,000 strokes (2.5 fold differences). Criteria for successful calibration within the method (established in our Mason laboratory) was set at proportional linearity = 2.5 ± 0.3. RDA-PE was compared to Radiotracer RDA for the four test dentifrices, with the latter obtained by averages from three independent Radiotracer RDA sites. Individual laboratories and their results were compared by 1) proportional linearity and 2) acquired RDA-PE values for test pastes.

RESULTS

Five sites participated in the study. One site did not pass proportional linearity objectives. Data for this site are not reported at the request of the researchers. Three of the remaining four sites reported herein tested human dentin and all three met proportional linearity objectives for human dentin. Three of four sites participated in testing bovine dentin and all three met the proportional linearity objectives for bovine dentin. RDA-PE values for test dentifrices were similar between sites. All four sites that met proportional linearity requirement successfully identified the dentifrice formulated above the industry standard 250 RDA (as RDA-PE). The profilometry method showed at least as good reproducibility and differentiation as Radiotracer assessments. It was demonstrated that human and bovine specimens could be used interchangeably.

CONCLUSIONS

The standardized RDA-PE method was reproduced in multiple laboratories in this inter-laboratory study. Evidence supports that this method is a suitable technique for ISO method 11609 Annex B.

Confocal microscopy and imaging profilometry: A new tool aimed to evaluate aesthetic procedures

According to the American Academy of Aesthetic Plastic Surgeons, more than 11 million cosmetic surgical and nonsurgical procedures were performed by board-certified plastic surgeons, dermatologists and otolaryngologists in the United States, totaling more than 12 billion dollars. We performed a retrospective observational multi-centric study on patients treated with a non-animal origin cross-linked hyaluronic acid with different molecular weights for nasolabial folds, evaluating through a new imaging system, profilometric techniques with the confocal microscopy, the durability, the efficacy and the safety of this product. From 25 patients, 150 silicone casts were obtained: 75 casts of the right nasolabial fold and 75 casts of the left nasolabial fold. Roughness arithmetical average of the right fold at T2 decreased by 50% versus T0 and by 40% compared to T1; at T2, it decreased by the 45% versus T0 and by 35% compared to T1. No side effects were reported. Results proved that the analysis of the skin microreliefs through confocal microscopy is a new imaging system that allows to evaluate with precision and safety the results of aesthetic treatments such as fillers objectively.

A Comparative Study of Laboratory Dentifrice Abrasion Measuring Methods

OBJECTIVES

Recently, a profilometry-based method for measuring toothpaste dentin abrasivity has been proposed to be equivalent to the traditional radiotracer RDA (relative dentin abrasion) procedure. This review outlines the findings and comparative assessment of laboratory studies used to measure the abrasivity of commercially available whitening dentifrices on human dentin. Traditional radiotracer and profilometry RDA-PE (Profilometry Equivalent) methods were assessed, with the objective of determining how they compare, and also to learn if the two techniques yield RDA values that are consistent with each other, specifically in ranking and potential for discrimination of three commercially available silica-based products. Chosen were regular toothpaste and two whitening dentifrices having abrasive properties against dentin ranging from medium to high.

METHODS

Dentin specimens underwent standard preparation, preconditioning, and abrasivity testing according to the ISO 11609 requirements for radiotracer method and RDA-PE. Three test dentifrices were used, each product containing various abrasive and polyphosphate agents, namely: Whitening Product A: Hydrated silica with disodium pyrophosphate (Crest® 3D Luxe); Product B: Hydrated silica (Crest® Cavity Protection); and Whitening Product C: Hydrated silica with tetrasodium pyrophosphate (Colgate® Ultrabrite Advanced Whitening). The products were chosen since they gave a range of RDA values from mid to high when compared with an ADA reference material that is given a value of 100.

RESULTS

The data were subjected to statistical and SNK (Student-Newman-Keuls) analyses. Both procedures yielded numerical RDA values that permitted a ranking of the three test dentifrices. However, there was no direct correlation of the RDA values obtained by profilometry with those from the conventional radiotracer method. Significantly, one dentifrice rated as most abrasive using the radiotracer method was rated as moderately abrasive using profilometry. Additionally, there was loss of statistical significance and discrimination between products with RDA-PE.

CONCLUSIONS

Given the lack of agreement between radiotracer and profilometry for the products tested in this study,it would appear that the RDA-PE method may not be equivalent to the traditional RDA radiotracer method, specifically in the higher abrasivity range.

The Impact of Selected Fluoridated Toothpastes on Dental Erosion in Profilometric Measurement

BACKGROUND

Some fluoridated toothpastes, available commercially, are described to have a protective effect against dental erosion.

OBJECTIVES

To evaluate the influence of the selected marketed toothpastes on the human enamel exposed to acid beverages.

MATERIAL AND METHODS

Enamel specimens from extracted human teeth were prepared (n = 40). Specimens were randomly divided into 10 experimental groups, 4 specimens each, which were subjected to acid challenge for 10 min using orange juice (pH 3.79) or Pepsi Cola (pH 2.58) and then immersed for 2 min into a slurry of five marketed toothpastes with distilled water (1 : 3 w/w). The tested toothpastes contained 1450 or 5000 ppm fluoride, CPP-ACP with 900 ppm fluoride, 1450 ppm fluoride with potassium nitrate 5%, all of them as sodium fluoride, and 700 ppm fluoride as amine and sodium fluoride with 3500 ppm SnCl2. Enamel roughness (Ra parameter) by contact profilometer at baseline and after exposure onto soft drinks and slurry was measured.

RESULTS

Exposure to both beverages caused a similar increase of enamel surface roughness. After the specimens immersion into slurries of toothpastes with 1450 or 5000 ppm fluoride, 1450 ppm fluoride with potassium nitrate 5% and CPP-ACP with 900 ppm fluoride the significant decrease of Ra values were found, reaching the baseline values. However, toothpaste with 700 ppm fluoride and 3500 ppm SnCl2 did not cause any fall in Ra value, probably due to other mechanism of action.

CONCLUSIONS

Within the limitation of the study we can conclude that the sodium fluoride toothpastes are able to restore the surface profile of enamel exposed shortly to acidic soft drinks.

Profilometry: A new statistical framework for the characterization of white matter pathways, with application to multiple sclerosis

AIMS

describe a new "profilometry" framework for the multimetric analysis of white matter tracts, and demonstrate its application to multiple sclerosis (MS) with radial diffusivity (RD) and myelin water fraction (MWF).

METHODS

A cohort of 15 normal controls (NC) and 141 MS patients were imaged with T1, T2 FLAIR, T2 relaxometry and diffusion MRI (dMRI) sequences. T1 and T2 FLAIR allowed for the identification of patients having lesion(s) on the tracts studied, with a special focus on the forceps minor. T2 relaxometry provided MWF maps, while dMRI data yielded RD maps and the tractography required to compute MWF and RD tract profiles. The statistical framework combined a multivariate analysis of covariance (MANCOVA) and a linear discriminant analysis (LDA) both accounting for age and gender, with multiple comparison corrections.

RESULTS

In the single-case case study the profilometry visualization showed a clear departure of MWF and RD from the NC normative data at the lesion location(s). Group comparison from MANCOVA demonstrated significant differences at lesion locations, and a significant age effect in several tracts. The follow-up LDA analysis suggested MWF better discriminates groups than RD.

DISCUSSION AND CONCLUSION

While progress has been made in both tract-profiling and metrics for white matter characterization, no single framework for a joint analysis of multimodality tract profiles accounting for age and gender is known to exist. The profilometry analysis and visualization appears to be a promising method to compare groups using a single score from MANCOVA while assessing the contribution of each metric with LDA.

Surface roughness of dental implants and treatment time using six different implantoplasty procedures

OBJECTIVES

To test whether or not one of six implantoplasty procedures is superior to the others rendering a minimal final implant surface roughness and a short treatment time.

MATERIAL AND METHODS

Forty-two one-piece implants were embedded in epoxy resin blocks with 6-mm rough implant surface exposed. The following implantoplasty polishing sequences were applied: Brownie(®) , Greenie(®) sequence (BG) (diamond rotary instruments 106-, 40-, 15-μm grit, Brownie(®) , Greenie(®) silicone polishers); Arkansas stone sequence (AS) (diamond 106-, 40-, 15-μm grit, Arkansas stone torpedo-shaped bur); Short diamond sequence (SD) (diamond 106-, 40-, 4-μm grit); Short diamond sequence with Greenie(®) (SDG) (diamond 106-, 40-, 4-μm grit, Greenie(®) ); Complete diamond sequence (CD) (diamond 106-, 40-, 15-, 8-, 4-μm grit); Complete diamond sequence with Greenie(®) (CDG) (106-, 40-, 15-, 8-, 4-μm grit, Greenie(®) ). The polished neck portion served as a positive control, the untreated sandblasted and acid-etched surface as negative control. Each implant was scanned with a contact profilometer rendering Ra values and Rz values as a measure of surface roughness. The time needed to polish the implant surface for each group was recorded. Simultaneous comparisons between more than two groups were done performing Kruskal-Wallis tests. Comparisons between two groups were analysed using Wilcoxon rank-sum tests.

RESULTS

Mean Ra values amounted to 0.32 ± 0.14 μm (BG), 0.39 ± 0.13 μm (AS), 0.59 ± 0.19 μm (SDG), 0.71 ± 0.22 μm (SD), 0.75 ± 0.26 μm (CDG), 0.98 ± 0.30 μm (CD), 0.10 ± 0.01 μm (PC) and 1.94 ± 0.47 μm (NC). Pairwise one-sided comparisons between the test group revealed statistically significant differences (P < 0.05). The shortest treatment time was recorded for group AS (13 ± 2 min) and the longest for CDG (21 ± 2 min) and BG (21 ± 4 min).

CONCLUSIONS

Considering final surface roughness and treatment duration, the use of rotary diamond burs in decreasing roughness, followed by an arkansas stone (group AS), appears to be an optimal treatment option.

Assessing the hierarchical structure of titanium implant surfaces

The physical texture of implant surfaces are known to be one important factor in creating a stable bone-implant interface. Simple roughness parameters (for e.g., Sa or Sz) are not entirely adequate when characterizing surfaces possessing hierarchical structure (macro, micro, and nano scales). The aim of this study was to develop an analytical approach to quantify hierarchical surface structure of implant surfaces possessing nearly identical simple roughness. Titanium alloys with macro/micro texture (MM) and macro/micro/nano texture (MMN) were chosen as model surfaces to be evaluated. There was no statistical difference (p > 0.05) in either Sa (13.56 vs. 13.43 µm) or Sz (91.74 vs. 92.39 µm) for the MM and MMN surfaces, respectively. However, when advanced filtering algorithms were applied to these datasets, a statistical difference in roughness was found between MM (Sa = 0.54 µm) and MMN (Sa = 1.06 µm; p < 0.05). Additionally, a method was developed to specifically quantify the density of surface features appearing similar in geometry to natural osteoclastic pits. This analysis revealed a significantly greater numbers of these features (i.e., valleys) on the MMN surface as compared to the MM surface. Finally, atomic force microscopy showed a rougher nano-texture on the MMN surface compared with the MM surface (p < 0.05). The results support recent published studies that show a combination of appropriate micron and nano surface results in a more robust cellular response and increased osteoblast differentiation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1083-1090, 2016.

An antiaging skin care system containing alpha hydroxy acids and vitamins improves the biomechanical parameters of facial skin

Background

The demand for antiaging products has dramatically increased in recent years, driven by an aging population seeking to maintain the appearance of youth. This study investigates the effects of an antiaging skin care system containing alpha hydroxy acids (AHAs) in conjunction with vitamins B₃, C, and E on the biomechanical parameters of facial skin.

Methods

Fifty two volunteers followed an antiaging skin care regimen comprising of cleanser, eye cream, day moisturizer, and night moisturizer for 21 days. Wrinkle depth (R_y) and skin roughness (R_a) were measured by skin surface profilometry of the crow’s feet area, and skin elasticity parameters R2 (gross elasticity), R5 (net elasticity), R6 (viscoelastic portion), and R7 (recovery after deformation) were determined for facial skin by cutometer, preapplication and after 7, 14, and 21 days. Volunteers also completed a self-assessment questionnaire.

Results

Compared to baseline, R_y and R_a significantly improved by 32.5% (P<0.0001) and 42.9% (P<0.0001), respectively, after 21 days of antiaging skin care treatment. These results were observed by the volunteers with 9 out of 10 discerning an improvement in skin texture and smoothness. Compared to baseline, R2 and R5 significantly increased by 15.2% (P<0.0001) and 12.5% (P=0.0449), respectively, while R6 significantly decreased by 17.7% (P<0.0001) after 21 days. R7 increased by 9.7% after 21 days compared to baseline but this was not significant over this time period.

Conclusion

An antiaging skin care system containing AHAs and vitamins significantly improves the biomechanical parameters of the skin including wrinkles and skin texture, as well as elasticity without significant adverse effects.

Surface geometry of various nanofiller composites using different polishing systems: A comparative study

AIM

This in vitro study assessed the surface quality of three nanoparticle composites with four commercially available polishing systems.

MATERIALS AND METHODS

A total of 180 specimens (10 × 2 mm) were prepared in metal molds using three nanocomposites, Filtek Z-350 XT, Ceram-X Mono, and Tetric N-Ceram. Sixty specimens of each material were then randomly assigned to five study groups. Control specimens were left untreated and the remaining specimens were subjected to polishing with SpinBrite, CompoMaster, AstroPol, and SofLex polishing systems. Average roughness (Ra) and average ten-point roughness (Rz) were calculated using Perthometer, and the data were analyzed by two-way analysis of variance (ANOVA) and post-hoc Tukey's tests.

RESULTS

For all the materials, the roughest surfaces were observed for control specimens, with no statistically significant differences between the material groups. For Filtek Z-350 XT, the decrease in surface roughness after two-step polishing was insignificant. For Ceram-X, SpinBrite specimens showed similar degree of roughness as control specimens. For Tetric N-Ceram, no significant decrease in roughness was observed after one-step polishing. Two-way ANOVA (interaction of subgroups and groups) did not show a significant association with the outcome.

CONCLUSIONS

For nanofilled composites (Filtek Z-350 XT), the surface roughness decreased with the increase in number of polishing steps, whereas one-step and multi-step polishing procedures produced similar quality of smoothness for nanohybrid composites (Ceram-X, Tetric N-Ceram). Ra and Rz values of surface roughness are a function of type of finishing/polishing only.

Three-dimensional surface profile intensity correction for spatially modulated imaging

We describe a noncontact profile correction technique for quantitative, wide-field optical measurement of tissue absorption (microa) and reduced scattering (micros) coefficients, based on geometric correction of the sample's Lambertian (diffuse) reflectance intensity. Because the projection of structured light onto an object is the basis for both phase-shifting profilometry and modulated imaging, we were able to develop a single instrument capable of performing both techniques. In so doing, the surface of the three-dimensional object could be acquired and used to extract the object's optical properties. The optical properties of flat polydimethylsiloxane (silicone) phantoms with homogenous tissue-like optical properties were extracted, with and without profilometry correction, after vertical translation and tilting of the phantoms at various angles. Objects having a complex shape, including a hemispheric silicone phantom and human fingers, were acquired and similarly processed, with vascular constriction of a finger being readily detectable through changes in its optical properties. Using profilometry correction, the accuracy of extracted absorption and reduced scattering coefficients improved from two- to ten-fold for surfaces having height variations as much as 3 cm and tilt angles as high as 40 deg. These data lay the foundation for employing structured light for quantitative imaging during surgery.