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After the cleaning procedures carried out during a recent restoration work, the Matera Cathedral's (UNESCO World Heritage Site) façade needed the application of a water repellent treatment. Aqueous emulsions of silanes/siloxanes, also in a mixture with acrylic polymer and an alkyl/alkoxysilanic resin (by BEL CHIMICA S.r.l. and PHASE restauro S.r.l), have been tested as representative of the most used formulations in the restoration of buildings in Italy, especially in the last decade. This paper focuses on the best practices to be adopted for the identification of the suitable protective product in terms of effectiveness, harmfulness and durability, in particular respect to photo-aging and thermo-hygrometrical aging. The conservation materials have been tested in situ and in laboratory on a stone block expressly extracted from the monument. The chemical composition of the products and their degradation processes were characterized by means of FT-IR and PY-GC-MS. The performance of the treatments was evaluated, both in laboratory by permeability, color and capillarity measurements and in situ by non-destructive techniques (IR reflectance spectroscopy, color measurements, water absorption tests by contact sponge). Silane/siloxane emulsion presented more pronounced degradation phenomena after artificial aging, while the mixture of silanes/siloxanes and acrylic polymers decreased the permeability to water vapour. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the mechanical properties and behavior of a self-locking taper connection with three different techniques: three-dimensional finite element analysis (FEA), ultimate failure loading, and cyclic loading analysis. Materials and Methods: The implant-abutment complex was embedded vertically in the center of an acrylic resin support block (Young's modulus > 3 GPa). All materials used in this study were assumed to be homogenous and isotropic, but while the resin was assumed to be linearly elastic, the titanium was assumed to have a multilinear behavior to better represent the implant system in its plastic phase and compare as closely as possible the numeric simulation with the experimental tests. An 800-N 30-degree off-axis load was applied to the occlusal surface of the abutment. In addition to the FEA, static and dynamic tests were carried out. Results: The greatest von Mises stresses were concentrated in the coronal portion of the abutment's tapered connection, while at the implant neck they were lower and less extensive than the abutment ones. Experimental results confirmed the FEA findings, in which the structural limit of the system was reached, with permanent deformation of the abutment that exceeded a predefined limit, rather than fracture. Conclusion: Within the limitations of the reported analyses, these static and dynamic tests appear to supply congruent results, thus allowing evaluation of the mechanical behavior of a self-locking tapered-connection implant system. High resistance to an off-axis load was exhibited, exceeding that usually offered by screw-retained implant systems, thus indicating good stability of the implant-abutment connection. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to compare definitive acrylic resin prostheses with or without a cast metal framework that were immediately loaded and supported by axial and tilted implants in completely edentulous patients after 3 years of function. Materials and Methods: Patients who were completely or partially edentulous in one or both arches with severe atrophy of the posterior regions were selected for this study. All patients immediately received prosthetic rehabilitations, each supported by four implants (two axial and two tilted). The patients were randomized to receive a definitive prosthesis with a cast metal framework or one made of acrylic resin only. Follow-up visits were performed up to 36 months after implant insertion and included radiographic assessments of bone levels around the implants. Results: Thirty-six patients participated, and 44 complete-arch immediately loaded prostheses (24 maxillary and 20 mandibular), each supported by four implants (in total 176 implants), were placed. In all, 21 screw-retained full-arch acrylic resin prostheses and 23 cast-metal-framework prostheses were delivered to the patients. The 3-year overall implant survival rate was 100% for axially positioned implants and 96.59% for tilted implants. Implant survival rates were 98.96% in the maxilla and 97.5% in the mandible. None of the 44 fixed prostheses were lost during the observation period, representing a prosthetic survival rate of 100%. No statistically significant differences were seen in crestal bone loss between tilted and axial implants at 12, 24, and 36 months in either arch. Conclusions: The same clinical outcome was seen for patients treated with the so-called All on Four protocol, regardless of whether the acrylic resin restorations were reinforced with metal. [ABSTRACT FROM AUTHOR]

The aim of this clinical study was to evaluate the 24-month clinical outcomes of immediate provisionalization of dental implants placed in fresh extraction sockets using a flapless technique. Fifteen patients were included under strict inclusion and exclusion criteria. All patients required one or two teeth to be extracted for lesions with a hopeless prognosis in the maxillary monoradicular or first premolar region. Twenty implants were placed immediately after tooth extraction, and immediate provisionalization was performed. Sixteen implants had a diameter of 5 mm, and four implants had a diameter of 3.80 mm, all with a 13-mm length. After 24 months of follow-up, a cumulative survival rate of 100% was reported for all implants. Modified Bleeding Index (mBI), modified Plaque Index (mPI), probing depth (PD), marginal gingiva level (MGL), and keratinized mucosa (KM) remained stable for up to 24 months. Mean MGL at 24 months was 0.22 ± 0.15 mm; no significant changes occurred in MGL between baseline and 24 months. Mean KM remained stable from baseline to 24 months. At 24 months, a mean bone loss of 0.83 ± 0.52 mm was measured. The results of this study indicate that flapless surgery for immediately provisionalized implants placed in fresh extraction sockets provides soft tissue and marginal bone maintenance for up to 24 months of follow-up. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this in vitro study was to compare the dimensional accuracy of the pickup impression technique using a modular individual tray (MIT) and using a standard individual tray (ST) for multiple internal-connection implants. The roles of both materials and geometric misfits were considered. Materials and Methods: First, because the MIT relies on the stiffness and elasticity of acrylic resin material, a preliminary investigation of the resin volume contraction during curing and polymerization was done. Then, two sets of specimens were tested to compare the accuracy of the MIT (test group) to that of the ST (control group). The linear and angular displacements of the transfer copings were measured and compared during three different stages of the impression procedure. Experimental measurements were performed with a computerized coordinate measuring machine. Results: The curing dynamic of the acrylic resin was strongly dependent on the physical properties of the acrylic material and the powder/liquid ratio. Specifically, an increase in the powder/liquid ratio accelerated resin polymerization (curing time decreases by 70%) and reduced the final volume contraction by 45%. However, the total shrinkage never exceeded the elastic limits of the material; hence, it did not affect the coping's stability. In the test group, linear errors were reduced by 55% and angular errors were reduced by 65%. Conclusions: Linear and angular displacements of the transfer copings were significantly reduced with the MIT technique, which led to higher dimensional accuracy versus the ST group. The MIT approach, in combination with a thin and uniform amount of acrylic resin in the pickup impression technique, showed no significant permanent distortions in multiple misalignment internal-connection implants compared to the ST technique. [ABSTRACT FROM AUTHOR]

Purpose: To develop a method to measure the depth profile of microvacuoles (MVs) in intraocular lenses (IOLs) and to characterize, after accelerated aging, the glistening of an acrylic hydrophobic IOL., Setting: University of Milano-Bicocca, Milan, Italy., Design: In vitro study., Methods: A heat treatment was applied in vitro to Basis V IOLs exposed to deionized water (24 hours at 45 ± 1°C, rapid cooling, and 24 hours at 24 ± 1°C). Thirty images (area 1.2 mm) of each IOL were acquired by a microscope, focusing on sequential planes every 23 ± 2 μm. By tracking the traces of each MV in consecutive images, the coordinates of the MV centroids along the IOL thickness were construed by an automated procedure, and in the generated single-focus stacked image, MVs were counted by an automated method., Results: MV density was found normally distributed along the IOL depth profile (Jarque-Bera test). In focus-stacked images, the MV automated counting was found accurate within 5% vs manual counting, and MV volume density of the order of 10 mm was estimated. It was observed that stacks of 15 images provided a 4% lower MV volume density compared with the stacking of 30 images., Conclusions: The assessment of the number of MVs by the acquisition of a single image of an IOL was influenced by the distance of the selected plane from the IOL surface. The decrease in MV density approaching the IOL edges can be explained as a consequence of the diffusion of water toward the external environment after accelerated aging.

The article provides an assessment of surface consolidation and protection treatments used on selected archaeological monuments in Rome, Italy, during the 1980s. The author explains that research was done by the Italian National Research Council (CNR) and the Federation of European Chemical Societies (FECS), discusses the protective materials used, including an acrylic resin Paraloid B-72 and an inorganic consolidant Wacker OH, and assesses the condition of the ancient marble studied.

Gel dosimeters in form of layers have shown noticeable potentiality for in-phantom dose profiling and imaging in BNCT neutron fields. Such dosimeters give the possibility of achieving spatial dose distributions of each dose contribution in neutron fields. The various dose components are separated by means of pixel-to-pixel manipulations of pairs of images acquired with gel dosimeters having different isotopic compositions. The reliability of polymer-gel-layer dosimeters (PGLD) for BNCT has been studied and their utilisation limits have been inspected.

Surfaces are continuously exposed to physical, chemical and biological degradation. Among the biological agents that cause deterioration, microorganisms are of critical importance. This work is part of a research programme for the characterisation of the alterations of the Milan Cathedral (Italy). Four stone samples of the Milan Cathedral were chemically analysed and the microbiological growth assessed. X-ray diffraction (XRD) showed that calcite was always present in each sample and one sample was also characterised by the chemical form of alteration gypsum. Using Fourier Transform Infrared Spectroscopy (FTIR) together with Scanning Electron Microscopy (SEM), it was possible to prove that the samples were consolidated with the synthetic acrylics and epoxy resins. The green-black biological patinas of the specimens were studied using cultivation, microscope observations and a method for single-cell detection. Sampling for fluorescent in-situ hybridisation (FISH), with ribosomal RNA targeted oligonucleotide probes, was also performed using adhesive tapes. The bulk of the prokaryotes were Bacteria but some Archaea were also found. The bacterial cells were further characterised using specific probes for Cyanobacteria, and alpha-, beta-and gamma-Proteobacteria. In addition, black fungi isolated from the stone and the fungi of the standard ASTM G21-96(2002) method were employed to test if the detected synthetic resins could be used as the sole source of carbon and energy. One isolated Cladosporium sp. attacked the freshly dried acrylic resin. Results show that the detected bacteria and fungi can cause severe damage both to the stone monument and its synthetic consolidants.

Monuments and artistic stone surfaces are often consolidated and protected with synthetic polymers, in particular, acrylics. Although it is generally thought that acrylic polymers are resistant to biodeterioration, we report for the first time the systematic occurrence of dematiaceous meristematic fungi on many marble samples of the cathedral in Milan (Italy) previously treated with this material. Fourier transform infrared spectroscopy applied to the Milan cathedral stone samples revealed characteristic features of biodeteriorated synthetic resins that differentiated them from the aged but nonbiodeteriorated samples. Samples showing biological colonization were analyzed for the presence of fungi. Cultivation and morphological characterization and methods independent from cultivation, such as denaturing gradient gel electrophoresis coupled with partial 18S rRNA gene sequencing and immunofluorescence staining with melanin-binding antibodies, showed that melanin-producing species are heavily present on stone surfaces protected with acrylic resins. This observation raises the question of the effectiveness of acrylics in protecting stone artworks.