Ink Removal Research Articles

AN AGAROSE GEL-BASED APPROACH FOR THE REMOVAL OF METALLIC-BASE INK STAIN FROM THE PAPER SURFACES OF A 17TH CENTURY BOOK

Removing ink stains from the pages of ancient and valuable books is a very challenging and sometimes impossible task. Only in some circumstances, restorers are able to improve the appearance of an ink-stained page by lightening the spots using an ink eradicator. This paper reports on an approach for the removal of ink stains from a 17th century book using a combination of two commercial houseware products, the rust remover for textile and bleach. The products were chosen on the basis of their active ingredients such as hydrofluoric acid (HF), which facilitates the removal of metal ions contained in the inks (such as iron and chromium) and sodium hypochlorite (NaClO), known for its whitening abilities. The products were first tested by direct application to one of the several stained pages as a control experiment. The ink stain was successfully removed from the book, but by SEM analysis the page results in a clear detachment of the cellulose fibers from the paper pulp, which reflect a significant change in the paper fine structure. Moreover, the mixing of chemicals occurring during this procedure generated toxic vapors and the entire protocol could only be performed under a chemical fume hood. A new procedure was developed to mitigate these negative effects. Each of the two commercial products was dispersed in a 2% agarose solution shortly before its gelification and the two gels thus obtained were applied consecutively on the surface of the paper to be cleaned. The results showed an effective removal of the ink stain from treated page, avoiding irreparable damage to the paper structure and improving the working conditions of the restorers. Hence, the proposed gel cleaning procedure offers three main advantages: i) a simple and practical tool for effective removal of metallic ink stains from the paper surface; ii) reduction of damage caused by aggressive reagents (HF and NaClO) contained in cleaning products for a better conservation of paper fibers; iii) a great decrease of the risk of accidentally exposing the operators to harmful toxic vapor (produced by accidental mixing of aforementioned chemical reagents).

Evaluating the properties of deinking paper sludge from the Mediterranean area for recycling in local areas as a soil amendment and to enhance growth substrates

AbstractRecycling of paper generates large quantities of paper sludge that is rich in organic matter and can be exploited to counteract organic matter loss in agricultural soils, especially in some geographical areas, such as the Mediterranean. In order for deinking paper sludge (DPS) to be recycled, chemical and physical characterizations are required along with an analysis of possible contaminants. DPS from Italy and Tunisia, resulting from various deinking processes, were analyzed and compared in terms of their chemical properties (pH, OM, total N, C/N ratio, mineral nutrients, and trace metals), surface chemistry [diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy], and thermal stability [thermogravimetric analysis (TGA)]. The aim was to improve their use as amendments in soils or growth substrates. Elemental analysis revealed higher carbon concentrations in the Tunisian DPS and similar nitrogen contents, high mineral nutrient levels, and potentially toxic trace element levels below the limits allowed for soil amendment. No evidence was found for the presence of organic pollutants, pathogens, or toxic heavy metals. Surface chemical analysis revealed comparable materials rich in aromatic, phenolic, aliphatic, and polysaccharide structures along with clay minerals and carbonates. The thermal analysis revealed similar decomposition temperatures for the organic matter. Practical implications of the results are discussed, highlighting the similar properties of sludge following ink removal by different processes and the need to integrate the N content in order to be able to employ sludge as an amendment in soil and growing media. Given the similarity of the compositions of the materials, appropriate DPS management is key to improving soil fertility, reducing paper waste disposal, and implementing a circular economy in the Mediterranean, where climate change is having a significant impact.

Cellulolytic Aerobic Bacteria Isolated from Agricultural and Forest Soils: An Overview.

This review provides insights into cellulolytic bacteria present in global forest and agricultural soils over a period of 11 years. It delves into the study of soil-dwelling cellulolytic bacteria and the enzymes they produce, cellulases, which are crucial in both soil formation and the carbon cycle. Forests and agricultural activities are significant contributors to the production of lignocellulosic biomass. Forest ecosystems, which are key carbon sinks, contain 20-30% cellulose in their leaf litter. Concurrently, the agricultural sector generates approximately 998 million tons of lignocellulosic waste annually. Predominant genera include Bacillus, Pseudomonas, Stenotrophomonas, and Streptomyces in forests and Bacillus, Streptomyces, Pseudomonas, and Arthrobacter in agricultural soils. Selection of cellulolytic bacteria is based on their hydrolysis ability, using artificial cellulose media and dyes like Congo red or iodine for detection. Some studies also measure cellulolytic activity in vitro. Notably, bacterial cellulose hydrolysis capability may not align with their cellulolytic enzyme production. Enzymes such as GH1, GH3, GH5, GH6, GH8, GH9, GH10, GH12, GH26, GH44, GH45, GH48, GH51, GH74, GH124, and GH148 are crucial, particularly GH48 for crystalline cellulose degradation. Conversely, bacteria with GH5 and GH9 often fail to degrade crystalline cellulose. Accurate identification of cellulolytic bacteria necessitates comprehensive genomic analysis, supplemented by additional proteomic and transcriptomic techniques. Cellulases, known for degrading cellulose, are also significant in healthcare, food, textiles, bio-washing, bleaching, paper production, ink removal, and biotechnology, emphasizing the importance of discovering novel cellulolytic strains in soil.

Development and Optimization of Chemical Deinking of Laser-Printed Paper

For the recycling paper process, the main problem is a high residual ink left on the paper, affecting the recycled paper's quality. Especially for laser-printed paper, ink strongly interacts with the paper fiber. A conventional chemical deinking has been used to remove laser ink with a high deinking efficiency but a low yield of recycled paper pulp. Recently, enzymatic deinking has gained attention due to its friendly environment. However, a complex procedure is required, and ink removal efficiency is lower than the conventional method. This research aims to simplify a chemical deinking process by decreasing reaction time, optimizing chemical components, and reducing experimental steps. Without pulping step, the laser-printed paper sheet was immersed in the chemical solution for a specific time, and the ink was removed by water spray. Results revealed that the chemical solution containing 1.5% sodium hydroxide, 2% sodium silicate, 1% hydrogen peroxide, and 0.3% tween-80 with a reaction time of 5 min at 60°C gave the highest paper yield of 97.3% and the lowest dirt count of 89.0 mm2/m2. The final product was still in the form of a paper sheet.

In vitro studies of factors affecting debridement of dental implants by tricalcium phosphate powder abrasive treatment

Peri-implantitis is a common complication characterized by inflammation in tissues surrounding dental implants due to plaque accumulation, which can lead to implant failure. While air flow abrasive treatment has been found to be effective for debriding implant surfaces, little is known about the factors that affect its cleaning capacity. This study systematically examined the cleaning capacity of air powder abrasive (APA) treatment with β-tricalcium phosphate (β-TCP) powder, using various powder jetting strengths and different particle sizes. Three sizes of β-TCP powder (S, M, and L) were prepared, and different powder settings (low, medium, and high) were tested. The cleaning capacity was determined by quantifying ink removal, which simulated biofilm removal from the implant surfaces at different time points. The results of the systematic comparisons showed that the most efficient cleaning of implant surfaces was achieved using size M particles with medium setting. Additionally, the amount of powder consumed was found to be critical to cleaning efficiency, and the implant surfaces were altered in all tested groups. These systematically analyzed outcomes may provide insights into the development of potential non-surgical strategies for treating peri-implant diseases.

Investigation of deinking efficiencies of trigromi laserjet printed papers depending on the number of recycling

PurposeThis study aims to determine the ink removal efficiency of papers with different recycling numbers and to examine some electrophotographic printing properties.Design/methodology/approachThe base papers prepared according to the INGEDE 11p standard are subjected to six recycling stages (RS) under equal conditions. The physical-optical properties of the papers obtained at the end of each RS are measured and CMYK (cyan, magenta, yellow, key) color measurement scales are printed on each paper with electrophotographic printing. Color measurements of the printed papers are measured using the X-Rite eXact spectrophotometer, adhering to the ISO 13655:2017 standard. According to the measurement results of the optical properties, the ink removal efficiency of each recycling step is determined as a percentage (%) using some formulas.FindingsAs general, according to DEMLab and IERIC data, it is determined that the ink removal efficiency increased as the recycling repetition increased. In DEMf factor values, the highest deinking efficiency is obtained after the fourth RS. There is no significant difference between the printing properties of the samples.Originality/valueIt has been a matter of curiosity that papers lose their properties after how many RS. Many studies have been carried out on this subject and it has been presented by experimental methods that the printability properties of papers increase or decrease after which RS. This study can be a pioneer for future studies.

Key characterization efforts to support the graffiti ink removal and care of Mark Rothko’s painting ‘Black on Maroon’ 1958

Analytical characterization efforts carried out in support of the conservation treatment of Mark Rothko's painting 'Black on Maroon' 1958 (Tate T01170), involving the removal of graffiti (tag) ink, are summarized. The proprietary ink product, of unfamiliar and unknown composition, was investigated using a suite of analytical techniques (IR spectroscopy, GC–MS, ICP-MS, pyrolysis GC–MS, thin layer chromatography, SEC, MALDI-TOF–MS, and UHPLC-MS) to identify key colorants and other components. The ink solubility properties proved vital to informing the solvent selection process for the ink removal procedure, which helped enable the re-display of the painting at Tate Modern in 2014. The possible impact of ink residues remaining within the cotton duck canvas support of the conserved painting was also explored using mockup canvas mechanical strength data, measured before and after ‘soiling’ at two ink levels to assess whether the ink residues had any immediate and possible longer-term effects on canvas properties. These findings, elucidated using a range of complementary analytical techniques, provide information on this hitherto-unknown graffiti product, contribute to a growing body of knowledge in this area, and offer analytical approaches which may be useful for the characterization of similar unknown materials, whether used to damage, augment, or create works of art.

In vitro effect of different implant decontamination methods in three intraosseous defect configurations.

This in vitro investigation was aimed to evaluate the cleaning ability of four mechanical devices designed for decontaminating implant surfaces. Ninety-six implants were coated with permanent ink and inserted into 3D-printed resin blocks simulating three different intraosseous defect configurations (types Ib, Ic, and Ie). The four tested mechanical decontamination devices (air-polishing with glycine powder, rotating titanium brush, polyetheretherketone [PEEK]-coated ultrasonic tip, and stainless steel ultrasonic tip) were randomly applied onto the 5 mm exposed implant surface. Standardized photographs were taken from a frontal perspective and with a 30° angle coronally and apically to the implant axis. The area with remnant ink on the implant surface was calculated. Although none of the groups achieved complete ink removal, air-polishing with glycine and titanium brushes demonstrated a higher cleaning ability when compared with ultrasonic devices either with standard or PEEK tips for all three defect configurations. For the three tested models, the best cleaning ability in all groups was shown on implant surfaces without facing an intraosseous wall. Titanium brush was the most effective when the intraosseous walls existed. Cleaning effectiveness diminished in the threads located in the apical third, especially when using air-polishing and ultrasonic devices. Titanium brushes and air-polishing devices were more effective in removing artificial biofilm using this in vitro model, although their effectiveness was influenced by the presence of the intrabony component.

Experimental and numerical investigation on erosion of circular and elliptical immersed tubes in fluidized bed

The erosion of immersed tube is studied by experimental and simulation methods. The results of the ink removal experiment show that the severe erosion is located on both sides of the lower part of the immersed tube. The dense discrete phase model (DDPM) method is adopted to simulate the erosion law of the immersed tube. The results show that the variation law of erosion rate with operating parameters is consistent with that of χ with operating parameters. A new dimensionless parameter of χ is defined to characterize the erosion state of immersed tube, which represents the ratio of particle flow characteristics to particle fluidization characteristics. Particle flow characteristics ( M p ) and particle fluidization degree ( M g ) are directly and inversely proportional to erosion rate respectively. In addition, the erosion rate of EA type elliptical immersed tube is proved to be 53.68% lower than that of circular immersed tube, which is obtained from the simulation results. • The analysis on oily ink removal of the erodible paraffin immersed tube is carried out. • The erosion laws of immersed tubes are simulated by DDPM method. • A new dimensionless parameter is defined to analyze the erosion of immersed tube. • From the numerical simulation, the erosion rate of EA type elliptical immersed tube is 53% lower than that of the circular tube.

Development of a usability checklist for public health dashboards to identify violations of usability principles.

To develop a usability checklist for public health dashboards. This study systematically evaluated all publicly available dashboards for sexually transmitted infections on state health department websites in the United States (N = 13). A set of 11 principles derived from the information visualization literature were used to identify usability problems that violate critical usability principles: spatial organization, information coding, consistency, removal of extraneous ink, recognition rather than recall, minimal action, dataset reduction, flexibility to user experience, understandability of contents, scientific integrity, and readability. Three user groups were considered for public health dashboards: public health practitioners, academic researchers, and the general public. Six reviewers with usability knowledge and diverse domain expertise examined the dashboards using a rubric based on the 11 principles. Data analysis included quantitative analysis of experts' usability scores and qualitative synthesis of their textual comments. The dashboards had varying levels of complexity, and the usability scores were dependent on the dashboards' complexity. Overall, understandability of contents, flexibility, and scientific integrity were the areas with the most major usability problems. The usability problems informed a checklist to improve performance in the 11 areas. The varying complexity of the dashboards suggests a diversity of target audiences. However, the identified usability problems suggest that dashboards' effectiveness for different groups of users was limited. The usability of public health data dashboards can be improved to accommodate different user groups. This checklist can guide the development of future public health dashboards to engage diverse audiences.

MODIFYING RESIN VISCOELASTICITY BY MULTIFUNCTION CAVITATION PROCESSING IN A MAGNETIC FIELD

The viscoelastic properties of polyamide 11 samples were modified by subjecting these specimens to multifunction cavitation within a magnetic field, using a device equipped with a 0.1 mm water jet nozzle. During these trials, a magnetic field was applied to the entire water jet stream while varying the distance between the nozzle and the specimen. The effects of various processing conditions were assessed by monitoring the removal of ink applied to sample surfaces. The results obtained using this technique with and without a magnetic field were also evaluated.

Effects on hand-sheet paper properties of pH in deinking process

Abstract In today’s world where natural resources are rapidly decreasing, recycling printed papers, and their use in paper production will reduce the environmental pollution caused by waste paper. Thus, energy savings can be achieved with less energy consumption. Although many methods are used in the deinking of printed papers, the effectiveness of these methods varies depending on many parameters, such as the type of paper to be de-inked, the type of printed ink in the printing system, and the chemicals used in deinking. In this study, the effect of pH in the deinking process was studied. Electrophotographic printed papers were used as the printed paper in this study, and the INGEDE method was applied as the deinking method. In this method, 3 different pH environments were prepared and an ink removal process was carried out in this environment. Optical and physical properties were determined by producing hand-sheet papers from the deinked pulp. In addition, test prints were made to determine the printability of the produced hand-sheet papers in the electrophotographic printing system.

Water consumption optimization in cardboard industry by experimental design

AbstractThis work was performed into a cardboard plant in order to reduce the freshwater consumption. Statistical experimental design was applied to investigate the effect of cleaning program, ink colour class and detergent concentration on ink circuit cleaning operation of flexographic printing machines. The results indicated that the proposed models fitted well with residual ink removal and cleaning water consumption (R2 > 0.99). For a better residual ink removal of the first colour class, it is suitable to employ cleaning program number 1 with 2% of detergent. However, if a residual ink of second colour class has to be removed, cleaning program number 2 and 2% of detergent are appropriate. At the optimum conditions, the volume of water required for residual ink removal from flexographic machines can be reduced by up to 26%. These results can contribute to the development of water consumption reduction models in cardboard plants and clean production implementation.

Study of sacrificial ink-assisted embedded printing for 3D perfusable channel creation for biomedical applications.

For an engineered thick tissue construct to be alive and sustainable, it should be perfusable with respect to nutrients and oxygen. Embedded printing and then removing sacrificial inks in a cross-linkable yield-stress hydrogel matrix bath can serve as a valuable tool for fabricating perfusable tissue constructs. The objective of this study is to investigate the printability of sacrificial inks and the creation of perfusable channels in a cross-linkable yield-stress hydrogel matrix during embedded printing. Pluronic F-127, methylcellulose, and polyvinyl alcohol are selected as three representative sacrificial inks for their different physical and rheological properties. Their printability and removability performances have been evaluated during embedded printing in a gelatin microgel-based gelatin composite matrix bath, which is a cross-linkable yield-stress bath. The ink printability during embedded printing is different from that during printing in air due to the constraining effect of the matrix bath. Sacrificial inks with a shear-thinning property are capable of printing channels with a broad range of filaments by simply tuning the extrusion pressure. Bi-directional diffusion may happen between the sacrificial ink and matrix bath, which affects the sacrificial ink removal process and final channel diameter. As such, sacrificial inks with a low diffusion coefficient for gelatin precursor are desirable to minimize the diffusion from the gelatin precursor solution to minimize the post-printing channel diameter variation. For feasibility demonstration, a multi-channel perfusable alveolar mimic has been successfully designed, printed, and evaluated. The study results in the knowledge of the channel diameter controllability and sacrificial ink removability during embedded printing.

Towards Sustainable Museum Conservation Practices: A Study on the Surface Cleaning of Contemporary Art and Design Objects with the Use of Biodegradable Agents

Green contemporary art conservation cleaning methods are explored as sustainable museum practices, ensuring the conservator’s health and reducing the environmental impact. The performance of selected biodegradable cleaning agents, namely deionised (DI) water, a chelate based on trisodium salt of methylglycinediacetic acid (MGDA), Trilon® M, a non-ionic surfactant based on alkoxylated fatty alcohols (Plurafac® LF900), and two solvents, limonene and ethyl lactate, was evaluated for the surface cleaning of polymethyl methacrylate (PMMA), polylactic acid (PLA), polypropylene (PP), and plasticized polyvinyl chloride (pPVC). Plastic mockups were used untreated or artificially soiled, simulating particulate matter or sebum stains produced by handling. Furthermore, the efficacy of ink removal from the plastic’s surface was evaluated. Surface examination was carried out using optical microscopy (OM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), while μ-Raman and gloss measurements complemented the cleaning assessment methodology. The cleaning agents’ potency depends on the type of plastic, precluding a general cleaning protocol. However, their cleaning efficacy is very promising, enriching the available choices for the cleaning of plastics, using sustainable materials and practices. This study offers valuable information to the conservation field regarding the effects of the selected biodegradable cleaning agents on each type of plastic, their application method, and their cleaning efficacy for the removal of different types of soil and ink.

Preparation of cellulose nanocrystals from deinked waste newspaper and their usage for papermaking

Cellulose nanocrystals (CNC) were successfully prepared from waste newspapers through a simple pretreatment and hydrolysis process. The Fourier transform infrared spectroscopy (FTIR) result for the CNC suggested that no new chemical bonds were formed during the preparation of CNC. X-ray diffraction results indicated that the crystallinities of the deinked and untreated waste newspapers were 66% and 73.8%, respectively. Greater smoothness of the deinked waste newspapers fibers could be clearly observed by scanning electron microscope (SEM), which was attributed to the removal of ink from the chemical treatment. The transmission electron microscopy (TEM) and atomic force microscopy (AFM) results of the CNC revealed a needle-like natural fiber with a length of 300 nm to 600 nm, a diameter of 10 nm to 30 nm, and an aspect ratio in the 10 to 60 range. The obtained CNC particles were found to improve the physical properties of paper sheets, specifically that of the tear, tensile, and burst indices. The maximum increase in the physical properties was achieved with a 5.5% CNC addition.

Biodeinking: an eco-friendly alternative for chemicals based recycled fiber processing

Abstract Recycling of recovered paper is an inevitable process for saving resources and the environment. Due to strict forest conservation regulations and limitations of the agro-forestry sector, the paper industry is facing the woody fiber crisis for decades. The recycling of waste paper for its utilization as a source of cellulosic fibers for papermaking is a resource-saving and eco-friendly approach and is a need of time. Deinking is an important stage in the recycling of recovered paper. In the conventional deinking process, chemicals have been used for removal of inks and other impurities from waste paper pulp slurry with some certain drawbacks like deinking inefficiency, fiber damage and generation of chemicals and fiber-rich effluent. The application of enzymes for deinking purposes is known as biodeinking and is considered as the potent and environmentally friendly deinking approach. The present write-up provides comprehensive information on various aspects of biodeinking.

Dicom_wsi: A Python Implementation for Converting Whole-Slide Images to Digital Imaging and Communications in Medicine Compliant Files

Background: Adoption of the Digital Imaging and Communications in Medicine (DICOM) standard for whole slide images (WSIs) has been slow, despite significant time and effort by standards curators. One reason for the lack of adoption is that there are few tools which exist that can meet the requirements of WSIs, given an evolving ecosystem of best practices for implementation. Eventually, vendors will conform to the specification to ensure enterprise interoperability, but what about archived slides? Millions of slides have been scanned in various proprietary formats, many with examples of rare histologies. Our hypothesis is that if users and developers had access to easy to use tools for migrating proprietary formats to the open DICOM standard, then more tools would be developed as DICOM first implementations. Methods: The technology we present here is dicom_wsi, a Python based toolkit for converting any slide capable of being read by the OpenSlide library into DICOM conformant and validated implementations. Moreover, additional postprocessing such as background removal, digital transformations (e.g., ink removal), and annotation storage are also described. dicom_wsi is a free and open source implementation that anyone can use or modify to meet their specific purposes. Results: We compare the output of dicom_wsi to two other existing implementations of WSI to DICOM converters and also validate the images using DICOM capable image viewers. Conclusion: dicom_wsi represents the first step in a long process of DICOM adoption for WSI. It is the first open source implementation released in the developer friendly Python programming language and can be freely downloaded at https://github.com/Steven N Hart/dicom_wsi.

Image-to-image translation for automatic ink removal in whole slide images.

Purpose: Deep learning models are showing promise in digital pathology to aid diagnoses. Training complex models requires a significant amount and diversity of well-annotated data, typically housed in institutional archives. These slides often contain clinically meaningful markings to indicate regions of interest. If slides are scanned with the ink present, then the downstream model may end up looking for regions with ink before making a classification. If scanned without the markings, the information regarding where the relevant regions are located is lost. A compromise solution is to scan the slide with the annotations present but digitally remove them. Approach: We proposed a straightforward framework to digitally remove ink markings from whole slide images using a conditional generative adversarial network based on Pix2Pix. Results: The peak signal-to-noise ratio increased 30%, structural similarity index increased 20%, and visual information fidelity increased 200% relative to previous methods. Conclusions: When comparing our digital removal of marked images with rescans of clean slides, our method qualitatively and quantitatively exceeds current benchmarks, opening the possibility of using archived clinical samples as resources to fuel the next generation of deep learning models for digital pathology.

Comparison between four different implant surface debridement methods: an in-vitro experimental study.

Peri-implantitis treatment is a very challenging topic to discuss. What is certain is that preventive/supportive therapy plays a key-role in peri-implant tissues' health maintenance and non-surgical implant surface mechanical debridement remains one of the solid pillars in the therapeutic pathway. In this perspective, many surface decontaminating methods have been proposed and tested to remove hard and soft bacterial deposits. The aim of this study was to compare four different commonly used non-surgical implant debridement methods in terms of cleaning potential in vitro, using a peri-implant pocket-simulating model. Sixty-four dental implants were ink-stained and placed into a simulated peri-implant pocket. Samples were then divided into four groups and treated with different debridement methods: stainless-steel ultrasonic tip (PS), peek-coated ultrasonic tip (PI), sub-gingival air-polishing with erythritol powder (EHX) and sub-gingival air-polishing with glycine powder (GLY). For each treatment group, half of the samples were treated for 5 seconds and the other half for 45 seconds. High-resolution images were taken using a digital microscope and later analyzed with a light processing software for measuring the cleaned area percentage (ink-free). Two different images were captured for every sample: a first image with the implant positioned perpendicular to the microscope lenses (90°) and a second one with the implant placed with a 45° vertical angulation, with the smooth neck towards the ground. Percentage of removed ink was statistically modelled using a generalized linear mixed model with the implant as a random (clustering) factor. A paired comparison between all treatments in terms of debridement potential (cleaned area percentage) was performed. In 5s and with 90° sample angulation EHX/PS comparison showed an odds ratio of 2.75 (P<0.001), PI/EHX an OR of 0.20 (P<0.001), GLY/PS an OR of 2.90 (P<0.001), PI/GLY an OR of 0.19 (P<0.001) and PI/PS an OR of 0.56 (P=0.105). With the same sample angulation and 45s treatment time, the OR was 6.97 (P<0.001) for EHX/PS comparison, 0.14 (P<0.001) for PI/EHX comparison, 4.99 (P<0.001) for GLY/PS, 0.19 (P<0.001) for PI/GLY and 0.95 for PI/PS (P =0.989). With 5s of treatment time and 45° sample angulation, EHX/PS comparison shows a 3.19 odds ratio (P<0.001), PI/EHX a 0.14 odds ratio (P<0.001), GLY/PS a 3.06 odds ratio (P<0.001), PI/GLY a 0.15 odds ratio (P<0.001) and PI/PS a 0.46 odds ratio (P=0.017). With the same sample angulation but 45s treatment time, EHX/PS comparison produced an odds ratio of 4.90 (P<0.001), PI/EHX an OR of 0.20 (P<0.001), GLY/PS an OR of 8.74 (P<0.001), PI/GLY an OR of 0.11 (P<0.001) and PI/PS an OR 0.96 of (P =0.996). Among the four treatments considered, air-polishing therapy represents the best one in terms of ink removal from the implant surface. Furthermore, increasing the treatment time to 45 seconds, air-polishing resulted considerably more efficient.