Occlusal Area Research Articles

An occluded cherry tomato recognition model based on improved YOLOv7.

The typical occlusion of cherry tomatoes in the natural environment is one of the most critical factors affecting the accurate picking of cherry tomato picking robots. To recognize occluded cherry tomatoes accurately and efficiently using deep convolutional neural networks, a new occluded cherry tomato recognition model DSP-YOLOv7-CA is proposed. Firstly, images of cherry tomatoes with different degrees of occlusion are acquired, four occlusion areas and four occlusion methods are defined, and a cherry tomato dataset (TOSL) is constructed. Then, based on YOLOv7, the convolution module of the original residual edges was replaced with null residual edges, depth-separable convolutional layers were added, and jump connections were added to reuse feature information. Then, a depth-separable convolutional layer is added to the SPPF module with fewer parameters to replace the original SPPCSPC module to solve the problem of loss of small target information by different pooled residual layers. Finally, a coordinate attention mechanism (CA) layer is introduced at the critical position of the enhanced feature extraction network to strengthen the attention to the occluded cherry tomato. The experimental results show that the DSP-YOLOv7-CA model outperforms other target detection models, with an average detection accuracy (mAP) of 98.86%, and the number of model parameters is reduced from 37.62MB to 33.71MB, which is better on the actual detection of cherry tomatoes with less than 95% occlusion. Relatively average results were obtained on detecting cherry tomatoes with a shade level higher than 95%, but such cherry tomatoes were not targeted for picking. The DSP-YOLOv7-CA model can accurately recognize the occluded cherry tomatoes in the natural environment, providing an effective solution for accurately picking cherry tomato picking robots.

Laser Speckle Contrast Imaging Guides Needling Treatment of Vascular Complications from Dermal Fillers.

Although laser Doppler imaging (LDI) accurately delineates a hypoperfused area to help target hyaluronidase treatment, laser speckle contrast imaging (LSCI) is more appropriate for assessing microvascular hemodynamics and has greater reproducibility than LDI. This study investigated the use of LSCI in the evaluation and treatment of six patients who developed vascular complications after facial dermal filler injections. The areas of vascular occlusion were accurately defined in real time by LSCI and were more precise than visual inspections or photographic evidence for guiding needling and hyaluronidase treatment. All patients had achieved satisfactory outcomes as early as Day 2 of treatment and no procedure-related complications were reported after a median follow-up of 9.5 (7-37) days. LSCI accurately and noninvasively delineated vascular occlusions in real time among patients experiencing complications of facial dermal filler injections. Moreover, LSCI was more accurate than visual and photographic evaluations. Clinicians can use LSCI to reliably follow-up therapeutic outcomes after salvage interventions for vascular occlusions. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Efficient virtual-to-real dataset synthesis for amodal instance segmentation of occlusion-aware rockfill material gradation detection

Image-based gradation detection methods of rockfill materials mostly ignore occluded regions of particles, and for the mainstream methods with deep learning, dataset annotation is time-consuming and labour-intensive. This study proposes an efficient virtual-to-real dataset synthesis method for rapid dataset synthesis and occlusion-aware gradation detection. Instead of photographing or scanning real particles with large time cost and labour input, Diffusion-GAN, which is trained with 600 virtual images generated by 3D modeling, efficiently generates 50,000 various individual particle images to synthesize initial stacked particle images and amodal annotations. Post-processing CycleGAN is subsequently proposed to preserve the background with image processing based on CycleGAN, which superiorly converts the style of synthetic images from virtual to real. The proposed dataset synthesis method is 50 times faster than manual labelling. Occlusion-aware gradation detection employs Bilayer Convolutional Network (BCNet) to predict both visible and occluded areas of particles, whose maximum absolute error is 4.72%, less than the error of 7.73% produced by ignoring occluded regions. The AP50 of BCNet trained with the synthetic dataset is 0.941, extraordinarily close to the result trained with the real dataset.

Environment-aware Multi-person Tracking in Indoor Environments with MmWave Radars

Device-free indoor localization and tracking using commercial millimeter wave radars have attracted much interest lately due to their non-intrusive nature and high spatial resolution. However, it is challenging to achieve high tracking accuracy due to rich multipath reflection and occlusion in indoor environments. Static objects with non-negligible reflectance of mmWave signals interact with moving human subjects and generate time-varying multipath ghosts and shadow ghosts, which can be easily confused as real subjects. To characterize the complex interactions, we first develop a geometric model that estimates the location of multipath ghosts given the locations of humans and static reflectors. Based on this model, the locations of static reflectors that form a reflection map are automatically estimated from received radar signals as a single person traverses the environment along arbitrary trajectories. The reflection map allows for the elimination of multipath and shadow ghost interference as well as the augmentation of weakly reflected human subjects in occluded areas. The proposed environment-aware multi-person tracking system can generate reflection maps with a mean error of 15.5cm and a 90-percentile error of 30.3cm, and achieve multi-person tracking accuracy with a mean error of 8.6cm and a 90-percentile error of 17.5cm, in four representative indoor spaces with diverse subjects using a single mmWave radar.

The assessment of the relationship between the traits of temporal muscle and the massiveness of the supraorbital region of the Homo sapiens crania including the influence of the neurocranial shape and size of the occlusal surface of the upper molars – preliminary study

The knowledge about the pattern of the relationship between the morphological variability of the supraorbital region of human skulls and the features of the temporal muscle is far from complete. The main aim of this study was to determine the relationships between the traits of human temporal muscle (i.e., its relative height and length) and the relative massiveness of the supraorbital region of the frontal bone with taking into account the potential influence of the neurocranial shape and the relative area of the occlusal surface of the upper molars. Skulls of African and Australian males (n = 44) exhibiting high variability in the massiveness of the supraorbital region, the presence of two types of the upper molars (first and second, n = 88) and a good state of the preservation of the braincase with the clearly visible inferior temporal line were examined. The qualitative scales were used to assess the degrees of the massiveness of the supraorbital regions. Metric traits of temporal muscle and that used to calculate the index of the neurocranial shape, size of the braincase and the facial skeleton were collected. Values of the occlusal areas of the molars were obtained using the ImageJ software. Spearman’s rank correlation and partial rank correlation analyses were performed. The results of our study showed the relationships between the traits of the temporal muscle and only the degree of the robusticity of most lateral part of the supraorbital area (trigonum). However, when the influences of the neurocranial shape and the relative occlusal area of molars were excluded, these relationships disappeared. The greatest importance of the neurocranial shape for the formation of the morphology of the trigonum was indicated. The results of the study were discussed from the perspective of the potential role of the temporal muscle as the part of the mastication apparatus for the development of the robusticity of the cranial supraorbital region.

Research on occlusion face recognition based on deep networks

Based on the spread of the new crown epidemic, the use of masks has been popularized, so it has a significant impact on the development of face recognition under the cover. The study of how to improve the performance of face recognition under occlusion conditions is also an important topic in the field of face recognition in the future. At the same time, the neural network model is one of the most important models in deep learning, in the field of image classification, face recognition based on deep network has also been proved to be an efficient feature extraction method, this paper divides the face recognition method based on occlusion into two categories: local feature class based on non-occlusion area and feature class based on recognition occlusion area; The basic processes of these two types of methods are summarized, and the specific cases of these two types of occlusion face recognition methods are analyzed. Further summarize the advantages and disadvantages of each and elaborate them. At the end of the article, the shortcomings and future development trends of the current shielding face recognition research are summarized.

Point Cloud Scene Completion with Joint Color and Semantic Estimation from Single RGB-D Image.

We present a deep reinforcement learning method of progressive view inpainting for colored semantic point cloud scene completion under volume guidance, achieving high-quality scene reconstruction from only a single RGB-D image with severe occlusion. Our approach is end-to-end, consisting of three modules: 3D scene volume reconstruction, 2D RGB-D and segmentation image inpainting, and multi-view selection for completion. Given a single RGB-D image, our method first predicts its semantic segmentation map and goes through the 3D volume branch to obtain a volumetric scene reconstruction as a guide to the next view inpainting step, which attempts to make up the missing information; the third step involves projecting the volume under the same view of the input, concatenating them to complete the current view RGB-D and segmentation map, and integrating all RGB-D and segmentation maps into the point cloud. Since the occluded areas are unavailable, we resort to a A3C network to glance around and pick the next best view for large hole completion progressively until a scene is adequately reconstructed while guaranteeing validity. All steps are learned jointly to achieve robust and consistent results. We perform qualitative and quantitative evaluations with extensive experiments on the 3D-FUTURE data, obtaining better results than state-of-the-arts.

Knee Bone Models From Ultrasound.

The number of total knee arthroplasties performed worldwide is on the rise. Patient-specific planning and implants may improve surgical outcomes but require 3-D models of the bones involved. Ultrasound (US) may become a cheap and nonharmful imaging modality if the shortcomings of segmentation techniques in terms of automation, accuracy, and robustness are overcome; furthermore, any kind of US-based bone reconstruction must involve some kind of model completion to handle occluded areas, for example, the frontal femur. A fully automatic and robust processing pipeline is proposed, generating full bone models from 3-D freehand US scanning. A convolutional neural network (CNN) is combined with a statistical shape model (SSM) to segment and extrapolate the bone surface. We evaluate the method in vivo on ten subjects, comparing the US-based model to a magnetic resonance imaging (MRI) reference. The partial freehand 3-D record of the femur and tibia bones deviate by 0.7-0.8 mm from the MRI reference. After completion, the full bone model shows an average submillimetric error in the case of the femur and 1.24 mm in the case of the tibia. Processing of the images is performed in real time, and the final model fitting step is computed in less than a minute. It took an average of 22 min for a full record per subject.

RemainNet: Explore Road Extraction from Remote Sensing Image Using Mask Image Modeling

Road extraction from a remote sensing image is a research hotspot due to its broad range of applications. Despite recent advancements, achieving precise road extraction remains challenging. Since a road is thin and long, roadside objects and shadows cause occlusions, thus influencing the distinguishment of the road. Masked image modeling reconstructs masked areas from unmasked areas, which is similar to the process of inferring occluded roads from nonoccluded areas. Therefore, we believe that mask image modeling is beneficial for indicating occluded areas from other areas, thus alleviating the occlusion issue in remote sensing image road extraction. In this paper, we propose a remote sensing image road extraction network named RemainNet, which is based on mask image modeling. RemainNet consists of a backbone, image prediction module, and semantic prediction module. An image prediction module reconstructs a masked area RGB value from unmasked areas. Apart from reconstructing original remote sensing images, a semantic prediction module of RemainNet also extracts roads from masked images. Extensive experiments are carried out on the Massachusetts Roads dataset and DeepGlobe Road Extraction dataset; the proposed RemainNet improves 0.82–1.70% IoU compared with other state-of-the-art road extraction methods.

Endodontic operative field asepsis: a comparison between general dentists and specialists

Objective The aim was to evaluate the establishment of an aseptic endodontic operative field in general dentistry by assessing general dentists’ ability to reduce the amount of contamination to a non-cultivable level, and to compare the operative field asepsis at a general dentistry clinic with that at an endodontic specialist clinic. Materials and Methods A total of 353 teeth were included in the study (153 in general dentistry, 200 at the specialist clinic). After isolation, control samples were taken, the operative fields disinfected with 30% hydrogen peroxide (1 min) followed by 5% iodine tincture or .5% chlorhexidine solution. Samples were collected from the access cavity area and buccal area, placed in a fluid thioglycolate medium, incubated (37°, 7 d), evaluated for growth/non-growth. Results Significantly more contamination was observed at the general dentistry clinic (31.6%, 95/301), than at the endodontic specialist clinic (7.0%, 27/386) (p <.001). In general dentistry, significantly more positive samples were collected in the buccal area than in the occlusal area. Significantly more positive samples were collected when the chlorhexidine protocol had been used, both in general dentistry (p <.001) and at the specialist clinic (p =.028). Conclusions The result from this study shows insufficient endodontic aseptic control in general dentistry. At the specialist clinic, both disinfection protocols were able to reduce the amount of microorganisms to a non-cultivable level. The observed difference between the protocols may not reflect a true difference in the effectiveness of the antimicrobial solutions, as confounding factors may have contributed to the result.

THE USE OF CHLORHEXIDINE MOUTHWORKS CAN REDUCE THE ACCUMULATION OF DENTAL PLAK IN USERS OF FIXED ORTHODONTIC DEVICES

Introduction: Treatment of malocclusion with fixed devices is common for us to encounter everyday. In using this device there are parts that are glued to the teeth and cannot be disassembled by the patient himself. This allows food debris and plaque to adhere more easily to the teeth and the fixed appliance. Review: Dental plaque is a transparent thin layer that adheres tightly to the teeth, which contains bacteria and their products in the form of organic and inorganic materials, oral fluids, loose epithelial cells and blood cells. Plaque is influenced, among other things, by bacteria, buffers and salivary flow, the presence of fluoride and the frequency of carbohydrates consumed, crowding of teeth, rough surfaces, areas that are difficult to clean, position of teeth outside the area of occlusion, and multiplication of bacteria. Therefore, during the process of fixed orthodontic treatment, it is necessary to control plaque which is carried out mechanically or chemically. Mechanical plaque control can be done by brushing teeth and using dental floss, while chemical plaque control can be done by using mouthwash. The mouthwash that has proven to be the most effective of the other therapeutic plaque control agents is chlorhexidine because it is able to ionically adhere to teeth and oral mucosal surfaces in high concentrations for hours. Chlorhexidine 0.2% can affect the number of salivary bacterial colonies due to the phenol content contained therein. Chlorhexidine itself has a very strong binding ability in the oral cavity, which is its advantage compared to other ingredients. Conclusion: Gargling with chlorhexidine can reduce plaque accumulation and improve oral hygiene status in fixed orthodontic users

Evolution Law of Dominant Flow Channel and Enhanced Oil Recovery Measures for Water Flooding in Reservoirs with Partially Sealed Faults.

The presence of strongly sealed faults can divide a reservoir into complex fault blocks, while partially sealed faults can be created by farewell faults within each block, leading to more intricate fluid migration and residual oil distribution. However, oilfields often overlook these partially sealed faults, focusing instead on the entire fault block, which can impact the efficiency of the production system. In addition, the current technology struggles to quantitatively describe the evolution of the dominant flow channel (DFC) during the water-flooding process, especially in reservoirs with partially sealed faults. This limits the ability to formulate effective enhanced oil recovery measures during the high water cut stage. To address these challenges, a large-scale sand model of a reservoir with a partially sealed fault was designed, and water flooding experiments were conducted. Based on the results of these experiments, a numerical inversion model was established. By combining percolation theory and the physical concept of DFC, a new method was proposed to quantitatively characterize DFC using a standardized flow quantity parameter. The evolution law of DFC was then studied, considering the variations of volume and oil saturation of DFC, and the water control effect of different measures was evaluated. The results revealed that, during the early stage of water flooding, a vertical uniform dominant seepage zone formed near the injector. As the water was injected, DFCs from the top of the injector to the bottom of the producers gradually formed in the unoccluded area. However, DFC was only formed at the bottom in the occluded area. During water flooding, the volume of DFC in each area gradually increased and then tended to stabilize. The development of the DFC in the occluded area lagged behind due to gravity and fault occlusion, leading to the formation of an unswept area near the fault in the unoccluded area. The volume of the DFC in the occluded area was the slowest, and the volume was the smallest after stabilization. Although the volume of the DFC near the fault in the unoccluded area grew the fastest, the volume was only higher than that in the occluded area after stabilization. During the high water cut period, the remaining oil was mainly distributed in the upper part of the occluded area, the area near the unoccluded fault, and the top of the reservoir in other areas. The plugging of the lower part of the producers can increase the volume of DFC in the occluded area, and the DFC moves up throughout the entire reservoir. This improves the utilization degree of the remaining oil at the top of the entire reservoir, but the remaining oil near the fault in the unoccluded area remains inaccessible. The combination of producer conversion, drilling infill wells, and producer plugging can alter the injection-production relationship and weaken the occlusion effect of the fault. The occluded area forms a new DFC, leading to a significant increase in the recovery degree. The deployment of infill wells near the fault in the unoccluded area can effectively control the area and improve the utilization of the remaining oil.

Occlusal Changes with Clear Aligners and the Case Complexity Influence: A Longitudinal Cohort Clinical Study.

Clear aligners (CA) are used 22 h daily, creating a bite-block effect. This work aims to (i) analyze occlusal changes before the beginning of treatment, after the first set of CA and after the use of additional aligners; (ii) compare planned occlusal contacts with the ones obtained after the first set of CA; (iii) analyze the occlusal changes occurred after reaching the orthodontic goals after 3 months of using CA only at night; (iv) evaluate and characterize which tooth movements did not allow the treatment to be completed at the end of the first set of aligners, and finally (v) verify the possible relation between the changes in occlusal contact and areas and parameters such as case complexity and facial biotype. A quantitative, comparative, and observational longitudinal cohort study design was implemented to evaluate the clinical data and the complexity levels of cases receiving CA. A non-probabilistic and convenience sample of 82 individuals was recruited. The orthodontic malocclusion traits were classified as simple, moderate, or complex corrections based on the basis of the Align® recommendations with the Invisalign® evaluation tool. According to the Invisalign® criteria, patients need only one complex problem for their case to be classified as complex. Meshlab® v. 2022.02, ClinCheck® version Pro 6.0, My-Itero® version 2.7.9.601 5d plus, and IBM® SPSS Statistics software (Statistical Program for Social Sciences), version 27.0 for Windows were the software® used. A statistically significant decrease in area and occlusal contacts number were observed from before the start of orthodontic treatment (T0) to the end of treatment (T1). The changes in the occlusal area (from T0 to T1) were statistically different between hyperdivergent (28.24 [15.51-40.91]) and hypodivergent (16.23 [8.11-24.97]) biotypes (p = 0.031). A significant difference between the hyperdivergent (4.0 [2.0-5.0]) and normodivergent (5.5 [4.0-8.0]) group was found in T1 for the anterior contacts (p = 0.044). Anterior contacts obtained were significantly higher than the planned (p = 0.037) Between T1 and T2 statistically significant increases of occlusal areas, posterior and total contacts were observed. Occlusal contact and area were decreased, either at the end of the first set or after the use of additional aligners. Anterior occlusal contacts obtained were higher than planned as opposed to posterior occlusal contacts obtained. The hardest tooth movements to achieve to complete the treatment were distalization, rotation, and posterior extrusion. After completing orthodontic treatment (T1) to 3 months after (T2) using additional aligners only at night, posterior occlusal contacts were significantly increased, which could be due to the natural settling of the teeth in this period.

Feature Correlation Transformer for Estimating Ambiguous Optical Flow

Cost volume is widely used to establish correspondences in optical flow estimation. However, when dealing with low-texture and occluded areas, it is difficult to estimate the cost volume correctly. Therefore, we propose a replacement: feature correlation transformer (FCTR), a transformer with self- and cross-attention alternations for obtaining global receptive fields and positional embedding for establishing correspondences. With global context and positional information, FCTR can produce more accurate correspondences for ambiguous areas. Using position-embedded feature allows the removal of the context network; the positional information can be aggregated within ambiguous motion boundaries, and the number of model parameters can be reduced. To speed up network convergence and strengthen robustness, we introduce a smooth L1 loss with exponential weights in the pre-training step. At the time of submission, our method achieves competitive performance with all published optical flow methods on both the KITTI-2015 and MPI-Sintel benchmarks. Moreover, it outperforms all optical flow and scene flow methods in KITTI-2015 foreground-region prediction.

Template-update-based visual tracking for automatic cell manipulation in FluidFM

Visual tracking is an essential process for performing automated cell manipulation tasks. However, Real-time accurate cell tracking in FluidFM is challenging due to probe occlusion during manipulation. This study presents a correlation filtering-based tracking method for real-time, high-precision position tracking of cells and probes. In this method, a target template update strategy is proposed to realize cell tracking under probe occlusion, which abandons the use of pixel values in the occlusion area and reduces the interference of the occlusion area in model learning. Cell tracking and automated manipulation experiments were carried out to validate the proposed method. The Experimental results show that the proposed tracking method can accurately measure the positions of occlusion cells and probe. Furthermore, combined with the precise force control of the FluidFM’s probe, the automated cell Pick & Place experiments was accomplished with high accuracy and robustness.

Assessment of the Relationship between the Total Occlusal Area of the Human Permanent Upper First and Second Molars and the Robusticity of the Facial Skeleton in Sex-Different Cranial Samples of Homo Sapiens: A Preliminary Study.

The aim of this study was to establish whether there is a significant relationship between the total occlusal area (TOCA) of two types of permanent upper molars (first-M1 and second-M2) and facial robusticity, as well as which of the examined facial regions indicate a relationship concerning the grade of their massiveness with the TOCA of analyzed molars in different sex adult Homo sapiens cranial samples. To obtain the values of the TOCA of the molars (n = 145), a morphometric method was performed based on the calibrated digital images of their occlusal surface using ImageJ software. The grades of the massiveness of six facial regions were assessed using qualitative scales of their expression, and an index of general facial robusticity was calculated. Two types of analyses were performed concerning standardized and non-standardized traits to the facial size, including Spearman's/or Pearson's correlations and partial rank correlations. The obtained results indicated the presence of a positive relationship between the relative TOCA of M2s and the relative general facial robusticity, as well as between the TOCA of both types of molars and the massiveness of trigone region of the facial skeleton in male crania. However, most of the obtained results were not consistent with the assumptions of the "localized masticatory stress hypothesis".

Flexible sensor concept and an efficient integrated sensing controlling for an efficient human-robot collaboration using 3D local global sensing systems.

Human-robot collaboration with traditional industrial robots is a cardinal step towards agile manufacturing and re-manufacturing processes. These processes require constant human presence, which results in lower operational efficiency based on current industrial collision avoidance systems. The work proposes a novel local and global sensing framework, which discusses a flexible sensor concept comprising a single 2D or 3D LiDAR while formulating occlusion due to the robot body. Moreover, this work extends the previous local global sensing methodology to incorporate local (co-moving) 3D sensors on the robot body. The local 3D camera faces toward the robot occlusion area, resulted from the robot body in front of a single global 3D LiDAR. Apart from the sensor concept, this work also proposes an efficient method to estimate sensitivity and reactivity of sensing and control sub-systems The proposed methodologies are tested with a heavy-duty industrial robot along with a 3D LiDAR and camera. The integrated local global sensing methods allow high robot speeds resulting in process efficiency while ensuring human safety and sensor flexibility.

Middle Pleistocene Pongo from Ganxian Cave in southern China with implications for understanding dental size evolution in orangutans

The Pongo fossil record of China extends from the Early Pleistocene to the Late Pleistocene, but to date, no late Middle Pleistocene samples of Pongo with precise absolute dating have been identified in southern China. Here, we report the recovery of 106 fossil teeth of Pongo from Ganxian Cave in the Bubing Basin, Guangxi, southern China. We dated the speleothems using Uranium-series and dated the two rhinoceros teeth using coupled electron spin resonance/Uranium-series dating methods to between 168.9 ± 2.4 ka and 362 ± 78 ka, respectively. These dates are consistent with the biostratigraphic and magnetostratigraphic age estimates. We further describe the fossil teeth from Ganxian Cave and compare them metrically to samples of fossil Pongo (i.e., Pongo weidenreichi, Pongo duboisi, Pongo palaeosumatrensis, Pongo javensis, and Pongo sp.) from the Early, Middle, and Late Pleistocene and to extant Pongo (i.e., Pongo pygmaeus and Pongo abelii) from Southeast Asia. Based on overall dental size, a high frequency of lingual cingulum remnants on the upper molars, and a low frequency of moderate to heavy wrinkling on the molars, we attribute the Ganxian fossils to P. weidenreichi. Compared with Pongo fossils from other mainland Southeast Asia sites, those from Ganxian confirm that dental size reduction of Pongo occurred principally during the Early and Middle Pleistocene. From the Middle to Late Pleistocene, all teeth except the P3 show little change in occlusal area, indicating that the size of these teeth remained relatively stable over time. The evolutionary trajectory of the Pongo dentition through time may be more complex than previously thought. More orangutan fossils with precise dating constraints are the keys to solving this issue.

Comparative evaluation of the accuracy of 3D-printed denture teeth

ObjectiveThis in vitro study compares the accuracy and trueness of various 3D-printed denture teeth. MethodsA total of 30 specimens were created using various 3D-printed resins, 10 each using Asiga DentaTOOTH resin (Asiga, Australia), Formlabs Denture Teeth Resin (Formlabs GmbH, Germany), and NextDent C&B MFH (Micro Filled Hybrid) resin (Nextdent B.V., Netherlands), respectively. A prefabricated mandibular first molar was scanned using a desktop laser scanner (E3, 3Shape A/S) to create a standard tessellation language file, which served as a “reference tooth” scan. That file was sent to each corresponding printer for printing according to manufacturer recommendations. The printed teeth were scanned with an intraoral scanner (TRIOS 3, 3shape, Copenhagen, Denmark). Trueness and precision were assessed using 3D morphometric analysis software (Geomagic Control X, 3D Systems, Rock Hill, SC, USA). One-way ANOVA was used to analyze the data (α = 0.05). Root mean square error and mean deviations were also calculated. Data analysis was carried out using SPSS (IBM Corp., New York, NY, USA) software. One-way ANOVA with Tukey’s post hoc analysis was used. P-values of<0.05 were regarded as statistically significant. ResultsThe overall trueness of teeth followed a similar pattern, with the highest trueness recorded with NextDent specimens, while ASIGA specimens had the lowest. When precision was assessed, there were significant differences in occlusal areas between FormLabs and NextDent specimens (p = 0.01) and between FormLabs and ASIGA specimens (p = 0.002). However, ASIGA and NextDent did not differ from one another (p = 0.9). The precision analysis shows that all tested groups had similar values, with no significant differences among them. ConclusionThe trueness values of the tested printing systems varied, although the precision values were similar. All evaluated printing systems achieved printing accuracy falling within the clinically acceptable range.

Corrosion Behavior of Petroleum Pipeline Steel in the Sulfur Ion Enriched Solution with Quinoline

Localized corrosion is a serious, hazardous destroyer of steel petroleum pipelines meant for long-time use. However, previous studies on localized corrosion primarily focused on local corrosion morphology and corrosion rate of bulk metals because detecting the corrosion state of occlusive metals is difficult. Herein, we employ a simulating occluded battery unit to disclose the local corrosion behavior of the steel petroleum pipeline (N80 steel) in an occlusive S2–-enriched solution. After simulating localized corrosion in the S2–- containing corrosion solution using the occluded battery unit, the occlusive solution was acidified and the migration amount of S2– to the occluded area increased. Despite the increase of S2– concentration, the addition of quinoline corrosion inhibitor (0.8 wt%) still effectively impedes the corrosion of the occluded metal. Moderately raising the environmental temperature can stimulate the activity of the inhibitor and promote the inhibition effect. The quinoline corrosion inhibitor displays the maximum inhibition rate at an elevated temperature of 50°C. Meanwhile, a maximum over the temperature of 60°C-70°C will likely accelerate the failure of the inhibitor.