Spatio-temporal variation and ecological risk assessment of microplastics along the touristic beaches of a mediterranean coast transect (Valencia province, East Spain).

Annually, the Mediterranean region attracts around one-third of the global coastal tourism, which is acknowledged as a substantial contributor to plastic pollution. Coastal municipalities mitigate this through periodic sand and shore cleaning. However, the efficacy of these measures remains uncertain. In this study, the occurrence of MPs (10 µm-5 mm) in sand from seven different, regularly cleaned, touristic beaches of the coastline of Valencia province (E Spain) was assessed. Two different sampling campaigns were performed in winter and in summer (2022) to compare the results and understand the influence of the high touristic activity, as well as, the efficiency of the measures taken against MPs pollution. The methodology used was designed specifically for the matrix and employed density separation using a Sediment Microplastic Isolation (SMI) Unit. In addition to conventional visual inspection and ATR-FTIR, automatic quantification and identification of the polymers of lower size was performed by µFTIR. The average MPs concentration in the summer (339 ± 92 MP kg-1 by stereomicroscopy and 339 ± 189 MP kg-1 by µFTIR) was significantly higher than in the winter (71 ± 92 MP kg-1 and 143 ± 85 MP kg-1) (p < 0.05). The combination of these analytical tools provides comprehensive information about the MPs present in beach sand. Fibers were the most abundant form of MPs, while most of the polymers analyzed were polyethylene (PE) and halogenated polystyrene (Cl-PS and Br-PS) with food packaging, swimming equipment and fishing nets being their most probable sources. Ecological risk assessment was performed through the Pollution Load Index (PLI), the Hazardous Index (HI) and the Risk Quotient (RQ), with the results indicating potential risk that ranges from moderate to high depending on the applied approach.

Characterization and source apportionment of microplastics in Indian composts.

Microplastics (MP), small plastic particles under 5 mm, are pollutants known to carry heavy metals in ecosystems. Composts are a significant source of soil microplastics. This study examined MSW composts from Kochi and Kozhikode in India for microplastic concentrations and heavy metals' accumulation thereon. Microplastics were isolated using zinc chloride density separation, with Fenton's reagent used for organic matter oxidation. Resin types were identified using FTIR analysis that showed the presence of PE, PP, PS, nylon, PET, and allyl alcohol copolymer. In Kozhikode's compost, the average concentration of microplastics was 840 ± 30 items/kg, while Kochi had 1600 ± 111 items/kg, mainly polyethylene films. PE was the most prevalent resin, comprising 58.3% in Kozhikode and 73.37% in Kochi. Heavy metal analysis of MP showed significant concentrations of lead, cadmium, zinc, copper, and manganese adsorbed on the surface of microplastics. The concentrations of heavy metals in the MP before Fenton oxidation ranged from 1.02 to 2.02 times the corresponding concentrations in compost for Kozhikode and 1.23 to 2.85 times for Kochi. Source apportionment studies revealed that 64% of microplastics in Kozhikode and 77% in Kochi originated from single-use plastics. Ecological risk indices, PLI and PHI, showed that composts from both locations fall under hazard level V. The study revealed that compost from unsegregated MSW can act as a significant source of microplastics and heavy metals in the soil environment, with single-use plastics contributing major share of the issue.

Comparison of fiber reinforcing methods of composite resin: A flexural strength and stereo microscopy study.

This study aimed to compare the effect of fiber reinforcing methods on the flexural strength and failure modes of indirect composite resins. Based on the reinforcement methods, the bar specimens (3 × 3 × 25 mm) were divided into five groups (n = 20). Glass or polyethylene fibers were used for reinforcement of indirect composite resins. Fibers were either light polymerized and mixed with indirect composite resin or mixed with indirect composite resin after resin application and polymerized together. Indirect composite resin without fiber reinforcement was used as control. All five types of specimens were stored in distilled water at 37°C for 24 h. Half of the specimens were additionally thermocycled. Then the specimens were tested in a three-point bending test. Failure types were examined and categorized by using stereo microscope. The data were analyzed using two-way ANOVA and Tukey HSD test. Flexural strength was found to be significantly higher for fiber-reinforced indirect resin composites than control. However, the fiber-reinforced groups did not present any significant difference. Analysis revealed aging does not affect the flexure strength of fiber reinforcement of indirect composite resin. The study concluded that the flexure strength of indirect composite resins was improved with fiber reinforcement. Different fiber reinforcement methods demonstrated similar effects on the flexure strength of indirect composite resin. Reinforcement with glass or polyethylene fibers presented the potential to improve the mechanical properties of indirect composite resins. RESEARCH HIGHLIGHTS: Flexural strength of indirect composite resins are affected by the reinforcement of composites with glass or polyethylene fibers. Aging with thermocycling has no effect on the flexural strength of the indirect composite resins, however can cause catastrophic failures in material.

Stereomicroscopic and Microscopic Study of Dental Structural Aspects Derived from Iatrogenic and Pathological Processes Suffered by a Second Mandibular Premolar - A Case Study.

Microscopic studies performed on extracted human teeth after their preparation in advance is helpful in a relatively good reestablishment of the treatment steps that have been applied to these teeth, as well as an evaluation of the quality of such treatments. Therefore, we have used stereo- and optical microscopy, highlighting aspects of external morphology, as well as root canal space of an extracted mandibular second premolar, subjected to prosthetic and endodontic treatment. In order to verify some technical errors that might occur during the endodontic and restorative treatment, we tried to appreciate the quality of the root canal filling and cervical defect and access cavity restoration of an extracted premolar #45.Without having the data from clinical records, we concluded that the method used for root canal filling was the warm lateral condensation technic; we also appreciated the quality of the fusion of the gutta-percha cones used, so the introduction of heated spreaders only in the central part of the bunch of cones makes it possible to clearly detect the boundaries between these cones towards the outside of the filling.

Comparison of microcomputed tomography, cone beam tomography, stereomicroscopy, and scanning electron microscopy techniques for detection of microcracks on root dentin and effect of different apical sizes on microcrack formation.

The aim of the study was to compare different imaging methods in the diagnosis of microcracks on root dentin and to evaluate the frequency of dentinal microcracks observed after root canal preparation using the ProTaper Universal (PTU) system of different sizes. A total of 30 mandibular molars' mesial roots were scanned with microcomputed tomography (micro-CT) and cone beam computed tomography (CBCT) imaging methods before instrumentation. Root canal instrumentation was performed up to PTU F2 and F4 files. After instrumentation stages, the roots were scanned again with micro-CT and then with CBCT in same parameters. All roots were sectioned horizontally at 2, 4, 6, 8, and 10 mm from the apices of the specimens. The sections were imaged under a stereomicroscope. Finally, imaging of the sections was done by scanning electron microscopy (SEM). Statistical data analysis of instrumentation steps was performed using Friedman and Wilcoxon tests, and the data of imaging methods were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p = .05). Instrumentation with the PTU system up to F2 and F4 files significantly increased the number of microcracks compared with preoperative samples according to micro-CT imaging (p < .05). For detecting microcracks on the root dentin, there were no statistically significant differences between micro-CT (43.9%) and stereomicroscopy (45.8%) (p < .05). SEM showed significantly higher percentage of microcracks (88.3%) (p > .05). No microcrack was observed using the CBCT method. There were no statistically differences between micro-CT and stereomicroscopy. SEM showed more dentinal microcracks while no microcrack was observed with CBCT.

Evaluation of marginal gap of lithium disilicate glass ceramic crowns with optical coherence tomography.

Marginal gap (MG) was the most important factor to evaluate the success of crowns. The study was to assess the MG of lithium disilicate glass ceramic crowns with spectral domain optical coherence tomography (OCT) and stereomicroscopy in vitro, and to provide evidence to measure the MG with OCT. Consistency was observed between OCT and stereomicroscopy to measure the MG after cementation. There was no significant difference between the MG of lithium disilicate glass ceramic crowns using OCT and stereomicroscopy (OCT 59.55 ± 7.22 µm, stereomicroscope 59.48 ± 6.53 µm, P = 0.736) after cementation. OCT was a noninvasive diagnostic technique to measure the MG of lithium disilicate glass ceramic crowns.

Feeding Ecology in Oligocene Mylodontoid Sloths (Mammalia, Xenarthra) as Revealed by Orthodentine Microwear Analysis.

Recently, dental microwear analysis has been successfully employed to xenarthran teeth. Here, we present new data on use wear features on 16 molariforms of Orophodon hapaloides and Octodontotherium grande. These taxa count among the earliest sloths and are known from the Deseadan SALMA (late Oligocene). Modern phylogenetic analyses classify Octodontotherium and Orophodon within Mylodontoidea with whom they share lobate cheek teeth with an outer layer of cementum and a thick layer of orthodentine. Similar target areas of 100µm2 were analyzed on the orthodentine surface of each tooth by stereomicroscopic microwear and by SEM microwear. Results were unlike those of extant sloths (stereomicroscopic microwear: Bradypus, Choloepus) and published data from fossil sloths (SEM microwear: Acratocnus, Megalonyx, Megatherium, Thinobadistes); thus, both approaches independently indicate a different feeding ecology for the Oligocene taxa. The unique microwear results suggest that both taxa fed on plant material with low to moderate intrinsic toughness (foliage, twigs) but also proposes intake of tougher food items (e.g., seeds). Frequent gouging of the tooth surfaces can be explained by exogenous influence on microwear, such as possible intake of abrasive grit. We suggest an unspecialized herbivorous diet for Octodontotherium and Orophodon utilizing diverse food resources of their habitat. These interpretations support the reconstruction of (1) Deseadan environments as open habitats with spreading savannas/grasslands and (2) both taxa as wide-muzzled bulk feeders at ground level.

Saw marks in bones: A study of "secondary features" of false start lesions.

In this experiment, 170 experimental false starts on human (120 lesions) and pig bones (50 lesions) were analyzed under stereomicroscope. The goal was to evaluate the potential of three "secondary" features (patterns of striae on the kerf floor, blade drift and bone islands) to diagnose saw class and saw set. We also assessed the performance of each of these features in ambiguous cases observed in a previous study, based on three main characters (minimum width of the kerf, shape of the kerf walls, and shape of the kerf profile). Among these three "secondary" features, striae on the kerf floor proved to be useful: the undulating or undulating/straight pattern of the striae on the kerf floor indicates an alternating set whereas thin and straight striae indicates a wavy set. Blade drift and bone islands may be indicative of large teeth size. These secondary features, in combination with the three main characters previously studied, may help identify the class of the saw.

A new flash-free orthodontic adhesive system: A first clinical and stereomicroscopic study.

OBJECTIVE: To analyze the clinical and laboratory properties of the recently introduced APC flash-free orthodontic adhesive. MATERIAL AND METHODS: After bonding of 80 brackets on human teeth (group A: APC flash-free adhesive n  =  40, group B: APC Plus adhesive n  =  40), the following measurements were recorded: time for bonding, stereomicroscopic evaluation of excess adhesive, color penetration (methylene blue, 0.5%/24 h), and Adhesive Remnant Index (ARI) score after debonding. RESULTS: The time needed for bonding differed significantly between the two groups (A: 19.5 s/tooth vs B: 33.8 s/tooth). The adhesive excess, which was metrically measured from the bracket edge, ranged from 166.27 µm to 81.66 µm (group A) and 988.53 µm to 690.81 µm (group B). After methylene coloration in group A, 52 of 80 measurements showed discoloration on the bracket-adhesive and/or adhesive-enamel interface, while for group B, 78 of 80 were coloration positive. The ARI scores did not differ, with an average ARI score of 2.0 for group A and 2.8 for group B. CONCLUSION: The flash-free adhesive significantly reduced the time needed for the bonding process. The excess resin expanded 0.16 to 0.08 mm over the bracket margin. The new technology seems to facilitate a smooth and sufficient marginal surface of the adhesive, which clinically might improve reduction of plaque accumulation.

3D scanning electron microscopy applied to surface characterization of fluorosed dental enamel.

The enamel surfaces of fluorotic teeth were studied by scanning electron stereomicroscopy. Different whitening treatments were applied to 25 pieces to remove stains caused by fluorosis and their surfaces were characterized by stereomicroscopy in order to obtain functional and amplitude parameters. The topographic features resulting for each treatment were determined through these parameters. The results obtained show that the 3D reconstruction achieved from the SEM stereo pairs is a valuable potential alternative for the surface characterization of this kind of samples.

Quasi-Instantaneous Bacterial Inactivation on Cu-Ag Nanoparticulate 3D Catheters in the Dark and Under Light: Mechanism and Dynamics.

The first evidence for Cu-Ag (50%/50%) nanoparticulate hybrid coatings is presented leading to a complete and almost instantaneous bacterial inactivation in the dark (≤5 min). Dark bacterial inactivation times on Cu-Ag (50%/50%) were observed to coincide with the times required by actinic light irradiation. This provides the evidence that the bimetal Cu-Ag driven inactivation predominates over a CuO/Cu2O and Ag2O oxides inducing a semiconductor driven behavior. Cu- or Ag-coated polyurethane (PU) catheters led to bacterial inactivation needing about ∼30 min. The accelerated bacterial inactivation by Cu-Ag coated on 3D catheters sputtered was investigated in a detailed way. The release of Cu/Ag ions during bacterial inactivation was followed by inductively coupled plasma mass-spectrometry (ICP-MS) and the amount of Cu and Ag-ions released were below the cytotoxicity levels permitted by the sanitary regulations. By stereomicroscopy the amount of live/dead cells were followed during the bacterial inactivation time. By Fourier transform infrared spectroscopy (FTIR), the systematic shift of the -(CH2) band stretching of the outer lipo-polysaccharide bilayer (LPS) was followed to monitor the changes leading to cell lysis. A hydrophobic to hydrophilic transformation of the Cu-Ag PU catheter surface under light was observed within 30 min followed concomitantly to a longer back transformation to the hydrophobic initial state in the dark. Physical insight is provided for the superior performance of Cu-Ag films compared to Cu or Ag films in view of the drastic acceleration of the bacterial inactivation observed on bimetal Cu-Ag films coating PU catheters. A mechanism of bacterial inactivation is suggested that is consistent with the findings reported in this study.

Comparative analysis of the clinical techniques used in evaluation of marginal accuracy of cast restoration using stereomicroscopy as gold standard.

PURPOSE: This study assessed the effect of preparation design on marginal adaptation and also compared the sensitivity and specificity of clinical evaluation techniques for marginal accuracy of cast restorations to stereomicroscopy. MATERIALS AND METHODS: Three Ivorine molar teeth of different designs were prepared. (A)-A complete crown preparation with buccal shoulder and beveled finish line. (B)-A complete crown preparation with chamfer finish line. (C)-A three-quarter crown preparation with proximal boxes and beveled finish line. Twenty four castings were prepared with eight castings for each design respectively. Each casting underwent examination with an explorer, disclosing media, and a stereomicroscope. Stereomicroscopy at a value less than or equal to 30 microns was used as a gold standard to evaluate the significance of different designs on marginal adaptation. Chi-square tests of independence and Kruskal-Wallis were used to evaluate the effect of preparation design and compare the agreement between examination methods for detection of marginal gap size of greater than or equal to 30 microns (α=.05). Sensitivity and specificity for explorer and disclosing media as compared to stereomicroscope was calculated using statistical formula given by Park. RESULTS: The preparation design did not significantly affect overall marginal adaptation. Examination by explorer and disclosing media at 30 µm revealed 39% and 10.06% sensitivity and 91% and 82% specificity respectively. CONCLUSION: Preparation designs examined in this study did not significantly affect the marginal adaptation of the castings. Commonly used clinical evaluation techniques using explorer and disclosing media appeared to be inadequate for assessment of marginal accuracy.

Effectiveness of hand and Mtwo TM Instruments in preparing oval-shaped root canals: in vitro study

Objective: This study evaluated through stereomicroscopy the effectiveness of hand and rotary instrumentation techniques, either isolated or combined, in the preparation of oval-shaped root canals. Materials and method: Thirty single-rooted human mandibular incisors were selected. After endodontic access and coronal preflaring, teeth were mounted in a modified Bramante muffle and then sectioned transversely at 3 and 6 mm from the root apex. Images of each section were made under a stereomicroscope at 30× magnification. Teeth were reassembled in the muffle and divided into three groups (n=10) according to the root canal preparation technique: GI - rotary preparation with Mtwo™ basic sequence (10/.04; 15/.05; 20/.06; 25/.06), followed by Mtwo™ complementary instruments (30/.05; 35/.04; 40/.04); GII - rotary preparation with Mtwo™ basic sequence, complemented by hand instruments (#30, #35 and #40); GIII - hand instrumentation using the conventional technique (#10 to #40). All instruments were used in brushing motion. The muffles were separated again so that new images of each section could be obtained. The following parameters were evaluated in pre- and postoperative images: root canal area; perimeter; mesiodistal (MD) and buccolingual (BL) diameters; and mesial (M) and distal (D) wall thickness. Next, the values measured in post- and preoperative images were subtracted for comparison of experimental groups. Data were analyzed using the Kruskal-Wallis test (α=0.05). Results: No significant difference between groups was observed for all parameters. Conclusion: There was no difference among hand, rotary, or combined instrumentation; all techniques were able to increase root canal area, perimeter, and diameter in MD and BL directions. Moreover, the amount of dentin wear on proximal root canal walls was similar for all tested groups. Keywords: Endodontics. Microscopy. Root canal preparation. Root canal therapy. Stereomicroscopy.

A stereomicroscopic in- vitro study to investigate the root canal morphology of mandibular third molars using clearing technique

AIM: To analyse the root canal morphology of mandibular third molars using clearing technique. MATERIAL AND METHODS: Ninety permanent extracted mandibular third molar teeth were collected based on inclusion and exclusion criteria. Teeth were then decalcified and were made transparent Methylene Blue Dye was injected to color the pulp space. These teeth were then observed under sterio Microscope and root canal systems were identified according to Vertucci's Classification. RESULTS: The most common anatomical morphology found was having two roots. Overall type I Vertucci's configuration was the most common pattern of canals. Other canal patterns that were found included type II, III, IV and V. In this study no canal of type VI, VII or VIII were found. CONCLUSION: The morphological variations in root patterns and canal configuration of mandibular third molar should be given consideration for successful endodontic treatment.

Characteristics of secondary caries lesion around composite resin restorations / Características da cárie secundária adjacente a restaurações de resinacomposta

Objetivo: O objetivo deste estudo foi analisar as características de cárie secundária e sua relação com a presença de restaurações com defeitos marginais como gap, degrau negativa (NL, a falta de material restaurador) e degrau positiva (PL, saliência). Materiais e Métodos: Oitenta superfícies proximais de restaurações de resina classe II foram fotografados e analisados utilizando um microscópio estereoscópico (X40). Foi registrada a presença de cáries secundárias externas, gaps, NL, PL e após a remoção de restaurações, a presença de lesão interna. Todos os exames foram realizados em 10 pontos bem definidos. Resultados: A prevalência de cárie secundária e gap foram associados com margem gengival. As restaurações com defeitos marginais (NL e PL) não foram associados a qualquer local específico (vestibular, lingual ou gengival). Observou-se uma relação entre esses defeitos com a prevalência de cárie secundária. A presença da lesão interna foi associada com lesão externa. Embora, em 141 pontos foi observada lesão interna, sem a presença de lesão externa. A maioria destas lesões mostraram envolvimento de esmalte interno. Apenas 8 por cento tinham desmineralização restrito a dentina, que poderia sugerir cárie residuais.

Objective: The aim of this study was to analyze the features of secondary caries and their relationship with the presence of restorations marginal defects as gap, negative ledge (NL, lack of restorative material) and positive ledge (PL, overhang). Materials and methods: Eighty proximal surfaces of Class II resin restorations were photographed and analyzed using a stereomicroscope (X40). It was recorded the presence of external secondary caries, gaps, NL, PL and after the restorations removal, the presence of internal lesion. All the exams were done in 10 welldefined points. Results: The prevalence of secondary caries and gap were associated with gingival margin. The restorations marginal defects (NL and PL) were not associated with any specific location (buccal, lingual or gingival). It was observed a relationship between these defects with secondary caries prevalence (gap: p= 0.004; NL and PL: p= 0.017). This association could be explained by the biofilm accumulation usually observed in the interface tooth surface/ restoration marginal defects. The presence of internal lesion was associated with external lesion. Although, in 141 points was observed internal lesion without the presence of external lesion. The majority of these lesions showed internal enamel involvement. Only 8 percent had demineralization restricted to dentine, which could suggest residual caries. Conclusion: The results of this study showed that secondary caries lesion frequently began externally on the interface tooth/restoration, where diagnose, control and arrestment of the lesions is possible.