Horizontal Thickness Research Articles

Analytical Solutions for Axisymmetric Diffusion of Organic Pollutants in a Circular‐Shaped Cutoff Wall System

ABSTRACTThrough the variable substitution and separated variable methods, this study develops a two‐dimensional (2‐D) axisymmetric diffusion analytical solution for organic pollutants in a circular‐shaped cutoff wall (CCW) system for the first time, which can more precisely and reasonably simulate the diffusion behaviors in “circular‐shaped” vertical barriers. Then, the proposed analytical solution's reasonableness is verified by comparing it with an existing analytical solution and a corresponding finite‐difference solution. Meanwhile, the comparison suggests that this solution will degrade to a 2‐D diffusion analytical solution when the pollution source radius is large enough. Furthermore, the presented analytical solution can also be simplified to a one‐dimensional axisymmetric diffusion analytical solution, or to the axisymmetric diffusion analytical solutions in a single‐layered medium. These exact analytical solutions can not only be applied to study axisymmetric diffusion behaviors under specific scenarios, but also be used to validate other complex numerical models. Last, a case study is conducted to investigate the impacts of pollution source concentration distribution, CCW horizontal thickness, and defined equivalent diffusion coefficient on the barrier performance. Overall, the proposed analytical solutions and obtained diffusion laws in this study can provide guidance for the service effect assessment and the engineering design of cutoff walls.

The impact of collagen membrane fixation protocols on volume stability in horizontal ridge augmentation in the aesthetic area: A retrospective study.

This study aimed to evaluate the impact of different collagen membran fixation protocols on the volume stability in horizontal ridge augmentation in the aesthetic area. A total of 48 patients with 65 augmented sites were included in this study. Implants were placed in the aesthetic region, and simultaneous guided bone regeneration (GBR) surgery was performed for horizontal ridge augmentation. Participants were divided into four groups, each comprising 12 patients, based on different absorbable collagen membrane fixation protocols. Group 1: without fixation; Group 2: fixation with absorbable sutures; Group 3: fixation with titanium pins; Group 4: fixation with titanium pins and absorbable sutures. Cone beam computed tomography (CBCT) was performed immediately after surgery and at 6 months post-surgery, respectively. The horizontal thickness of the augmented region was analyzed for volume stability at the implant shoulder (H0) and 1-5 mm apical to the implant shoulder (H1-H5). Changes in labial thickness during bone healing were calculated as absolute values (mm) and relative values (%). After 6 months of bone healing, horizontal thickness was significantly reduced at all levels (H0-H5) in all groups compared to immediate post-surgery results (p < 0.05). At H1-H5, horizontal bone loss in group 1 was significantly higher than in the other three groups (p < 0.05). Group 4 exhibited significantly less horizontal bone loss compared to group 2 at H0-H2 (p < 0.05) and group 4 compared to group 3 at H0-H1 (p < 0.05). No significant difference in horizontal bone loss between groups 2 and 3 was detected at H0-H5 (p > 0.05). Guided bone regeneration in the aesthetic area with additional membrane fixation demonstrated superior volume stability of the augmented region compared to cases without fixation. There was no significant difference in bone volume stability between membrane fixation with titanium pins and fixation with absorbable sutures. However, the combined use of pins and absorbable sutures yielded superior volume stability.

Ridge Preservation Combined With Open Barrier Membrane Technique in Case of Postextractive Oroantral Communication: A Case Series Retrospective Study.

After dental extraction, a physiological phenomenon of reabsorption of the dentoalveolar process is triggered, especially if periradicular lesions are present, which can sometimes be associated with oroantral communication in the upper posterior maxilla. To investigate a minimally invasive approach, 19 patients undergoing tooth extraction in the posterosuperior maxilla were recruited. All cases presented an oroantral communication with a diameter of 2-5 mm after tooth extraction and the alveolar process and, in some cases, with a partial defect of 1 or more bony walls. In these cases, a single surgical procedure was used to preserve the alveolar ridge using an open barrier technique with an exposed dense polytetrafluoroethylene membrane. The bottom of the extraction socket was filled with a collagen fleece. The residual bone process was reconstructed using a biomaterial based on carbonate-apatite derived from porcine cancellous bone. After 6 months, all patients were recalled and subjected to radiographic control associated with an implant-prosthetic rehabilitation plan. Data relating to the sinus health status and the average height and thickness of the regenerated bone were collected. Radiographic evaluation verified the integrity of the maxillary sinus floor with new bone formation, detecting a vertical bone dimension between 3.1 mm and 7.4 mm (average 5.13 ± 1.15 mm) and a horizontal thickness between 4.2 mm and 9.6 mm (average 6.86 ± 1.55 mm). The goal of this study was to highlight the advantage of managing an oroantral communication and, simultaneously, obtain the preservation and regeneration of the alveolar bone crest. The open barrier technique appears to be effective for the minimally invasive management of oroantral communication up to 5 mm in diameter in postextraction sites, with a good regeneration of hard and soft tissue.

Guided bone regeneration for peri-implant augmentation: Aretrospective study comparing two surgical techniques with a mean follow-up of 26 months.

To introduce a modified guided bone regeneration (GBR) technique using intact periosteum and deproteinized bovine bone mineral (DBBM) for peri-implant augmentation and compare the clinical outcomes with those of conventional GBR. Patients who received peri-implant augmentation in posterior sites between 2015 and 2021 were reviewed in this study. Group A was treated with a modified GBR technique, and Group B was treated with conventional GBR. For group comparison, propensity score matching was performed with a sensitivity analysis. The implant survival rate, dimensional changes in hard tissue, marginal bone loss (MBL), and peri-implant parameters were evaluated. In total, 114 implants from 98 patients were included. The implant survival rates were 95.74% in Group A and 95.00% in Group B during the follow-up period. At 6 months, the median horizontal thickness was recorded at 0.87 mm (IQ1-IQ3 = 0.00-1.75 mm) in Group A, exhibiting a relatively lower value compared to the corresponding measurement of 0.98 mm (IQ1-IQ3 = 0.00-1.89 mm) in Group B (p = .937). Vertical height displayed no statistically significant intergroup difference between the two groups (p = .758). The mean follow-up period was 25.83 ± 12.93 months after loading in Group A and 27.47 ± 21.29 months in Group B (p = .761). MBL and peri-implant parameters were comparable between the two groups. Within the limitations of this study, the modified GBR technique using intact periosteum and DBBM grafting might be a viable alternative to correct bone defects around implants in molar and premolar sites.

A Horizontal Distribution Model of Static Ice Cover Generated by Static and Dynamic Water Considering the Heat Transfer of Riverbanks

The thermal factor is the main reason for winter ice cover with a low Froude number flow, and the heat transfer to narrow and deep river banks accelerates ice cover formation and ice thickness change. The freezing of water flow to freezing thickening is a nonisothermal-flow phase transition process coupled with the water flow temperature, environment and riverbank. Here, the Nusselt number and viscous dissipation are used to consider the flow velocity influence on icing, and a thermodynamic model of static ice cover horizontal distribution considering riverbed heat transfer is established. The initial ice time, freezing time and static ice cover thickness formed by static and dynamic water calculated by the model were consistent with measured data. The model reflects the horizontal growth process of the static ice cover, which was significant for narrow and deep channels. The horizontal distribution of the static ice cover was thin in the center and thick on both sides. The maximum horizontal thickness difference of −20 °C indoor freezing for 24 h reached 15% of the central ice thickness. Compared with the degree-day method for calculating ice thickness, the numerical model and dimensionless formula better reflect the growth law and horizontal distribution characteristics of static ice cover and provide a theoretical basis for safe water conveyance under ice cover in winter and ice cover formation in reservoirs and lakes in cold regions.

Correlation between abdominal visceral volume measured by a simple procedure and bulging at the abdominal free flap donor site for breast reconstruction

Breast reconstructions using autologous abdominal tissue result in breasts with a natural shape and consistency. One of the major complications is abdominal bulging. Because of the increased abdominal wall tension, high visceral volume (not visceral fat alone) may increase the occurrence rate of abdominal bulging. A simple procedure involving CT imaging was used to assess this relationship in patients undergoing an abdominal free flap for unilateral breast reconstruction. A total of 278 patients were enrolled in this study. The patients' demographics, the thicknesses of visceral volume were compared (Bulging (+) vs. Bulging (-)). Visceral volume was investigated based on the horizontal thickness, which was measured at the thickest part at the level of the umbilical fossa between both sides under the transverse abdominis muscles. Bulging (+) consisted of 39 patients (14.0%), whereas Bulging (-) included 239 patients. Patients with Bulging (+) were significantly older, had higher gestational history rate, and had thin rectus abdominis muscle. In terms of visceral volume, the Bulging (+) group had significantly higher horizontal thicknesses (median 233mm vs. 219mm, P<0.001). No significant differences were observed with respect to other factors (age, BMI, history of laparotomy, and operative details). The multivariate logistic regression analysis revealed that the thickness of the rectus abdominis muscle, horizontal visceral volume, and gestational history were independently significant predictors. Not only the patients with thin rectus abdominis muscle but also patients with a thick horizontal visceral volume may have a higher risk of abdominal bulging.

Numerical simulation on pore-scale pool boiling mechanisms of horizontal gradient porous metals

Horizontal gradient porous metals are proposed to solve the problem of nonuniform temperature distribution on the heating surface. The model of horizontal gradient porous metal is established based on the thermal response of metal skeletons. Pool boiling heat transfer performances of horizontal gradient porous metals are studied by phase-change lattice Boltzmann model. Horizontal porous metal layer thickness, wettability and thermal conductivity gradient effects on bubble behavior and heating surface temperature distribution uniformity are statistically analyzed. The results show that porous metals with horizontal thickness gradient can realize liquid-vapor channel separation, reduce the resistance of bubble rising, and improve the fresh liquid supplement. Compared with the uniform porous metal, the horizontal gradient porous metal with lateral hydrophobic surface or higher thermal conductivity has better boiling heat transfer performance and promotes heating surface uniform temperature distribution at low heat fluxes. The results provide a novel solution to improve the chip wall temperature uniformity for the stable operation of electronic equipment.

Investigation of the effect of caving height on the efficiency of the longwall top coal caving production method applied in inclined and thick coal seams by physical modeling

The longwall top coal caving (LTCC) production method, applied by forming a face in the horizontal thickness of the seam and also called horizontal section top coal caving, especially in studies originating from China, is widely used in the production of inclined and thick coal seams. In this production method, in addition to the top coal losses that occur behind the face in the traditional LTCC production method, and top coal loss zone occurs above the tail part of the face. Here, the caving height is an effective parameter in the top coal losses occurring behind the face and on the tail part of the face, and in this study, the effect of caving height on the efficiency of the LTCC method applied in inclined and thick coal seams was investigated. In the study, a physical model was used, which was tested with field data and achieved a minimum success rate of 93.4% in the test parameters. In order to determine the effect of the caving height on the efficiency of the LTCC method, a total of 15 tests were performed with the physical model in 3 different seam slopes. As a result of the tests, it was determined that the amount of top coal and waste rock drawn and top coal loss increased with the increase in the caving height value. On the other hand, it was determined that the rock mixture ratio first decreased and then increased with the increase in the caving height value. In addition, the flow angle of the top coal was determined as an average of 74.9° in the coal loss zone between the top coal and the floor and 73.4° on the gob.

Systematic calculation of flying buttress parameters by means of geometric regression

This paper investigates the geometric parameters of a flying buttress: position of the center O of the intrados arch, radius R of the intrados arch, inclination α, rise F, span distance L and horizontal thickness E of the culée. Using photogrammetrical techniques, point cloud control, vector redrawing and geometric regression, this paper provides an objective, non-arbitrary procedure to determine the center O and the radius R of a flying buttress arch. This results in two outcomes: 1) Non-arbitrary determination of the remaining parameters α, F, L and E; 2) Non-arbitrary classification of flying buttress arches into two types, according to the criterion laid down by Viollet-le-Duc in 1854.

Investigation of the efficiency of longwall top coal caving method applied by forming a face in horizontal thickness of the seam in steeply inclined thick coal seams by using a physical model

The longwall top coal caving (LTCC) is a widely used method for producing thick coal seams. This method is applied in two different ways in steeply inclined thick coal seams by forming a longwall at the horizontal thickness of the seam and the slope of the seam. In the LTCC method, the top coal loss is generally expressed as the coals remaining behind the support units after the face advance. However, in addition to this coal loss in steeply inclined coal seams, a coal loss zone is formed in the upper part of the tail of the face that is not affected by the top coal drawing process. In this study, top coal loss and rock mixture ratio in this region were investigated with a physical model developed. Field studies were carried out at Alpagut Dodurga Lignite Enterprises and the data obtained were tested in the physical model. Between the physical model data and the field data, 93.71% similarity in top coal loss and 99.8% similarity in rock mixture ratio were determined. In order to investigate the efficiency of the LTCC method, the effects of top coal drawn height, seam slope, face slope, support unit drawing sequence change parameters on top coal loss and rock mixture ratio were investigated. As a result, it was determined that the top coal loss increased linearly with the increase in the upper coal withdrawal height, the top coal loss decreased with the increase of seam slope, the face slope did not significantly affect the top coal loss and the rock mixture ratio decreased by 18.3% with the change in the drawing order of the support units. In addition, a new longwall design has been proposed in the study, and with this design, the top coal loss has decreased from 17.3% to 2% geometrically.

Augmentation stability and early wound healing outcomes of guided bone regeneration in peri‐implant dehiscence defects with L‐ and I‐shaped soft block bone substitutes: A clinical and radiographic study

To retrospectively evaluate whether guided bone regeneration (GBR) with L- and I-shaped demineralized bovine bone mineral with 10% collagen (DBBM-C) differs from GBR with DBBM in terms of augmentation stability and early wound healing outcomes in peri-implant dehiscence defects. A total of 91 peri-implant defects were grafted with 24 L- (GBR-L), 22 I (GBR-I)-shaped DBBM-C, and 45 DBBM (GBR-P). Cone-beam computed tomography images were obtained after surgery and at 5months follow-up. The horizontal thickness (HT0, HT2, HT4), vertical thickness (VT), and VT at 45° angle (45-VT) of the augmented hard tissue were measured. Early postoperative discomfort and wound healing outcomes were assessed 2weeks after surgery, and periotest values were also measured at 5months in all groups. At 5months follow-up, the change at HT0 and VT of the GBR-L (HT0: -0.63±0.55mm, VT: -0.77±0.60mm) and GBR-I (HT0: -0.68±0.53mm, VT: -0.91±0.73mm) groups was significantly more stable than that of the GBR-P (HT0: -1.30±0.77mm, VT: -1.57±0.67mm) group (p<.05). The GBR-L group (-0.74±0.54mm) showed better augmentation stability than the other two groups at the change at 45-VT. Early postoperative discomfort, wound healing outcomes, and periotest values did not differ significantly between the three groups. Within the limitations of this study, L- and I-shaped DBBM-Cs used for GBR were more beneficial in terms of horizontal augmentation stability than DBBM after a 5-month healing period.

Bone quality and quantity of the mandibular symphyseal region in autogenous bone grafting using cone-beam computed tomography: a cross-sectional study

BackgroundBone volume plays a pivotal role in the success of dental implant treatment. Autogenous bone grafts should be harvested from reliable sites in the maxillofacial region. This study sought to assess the quantity and quality of bone in the mandibular symphysis for autogenous bone graft harvesting using cone-beam computed tomography (CBCT).MethodsThis cross-sectional study evaluated the CBCT scans of 78 adults presenting to three oral and maxillofacial radiology centers. The vertical (VD) and horizontal (HD) alveolar bone dimensions, cortical thickness (CT), and cancellous to cortical bone ratio (C/C) were measured in the interforaminal region of the mandible at the sites of central incisor to first premolar teeth. The interforaminal distance (ID) and the anterior loop length were also measured. Nonparametric statistical tests were used to analyze the data with respect to sex, age, and tooth position.ResultsThe median VD, HD, and CT of the symphysis were 20.21 (3.26), 4.13 (0.37), and 2.25 (0.23) mm, respectively. The median C/C was 1.51 (0.11). The median ID was 52.24 (8.24) mm, and the median anterior loop length was 1.82 (1.06) mm. Significant differences were observed in all parameters among different teeth. Most of the measured parameters were greater in males compared with females. There were significant differences in ID, VD, and CT between different age groups.ConclusionsThe quantity and quality of the available bone in the mandibular symphysis for bone graft harvesting vary by gender, age, and harvesting site, necessitating careful preoperative evaluation.

3-D tomographic observations of Rossby wave breaking over the North Atlantic during the WISE aircraft campaign in 2017

Abstract. This paper presents measurements of ozone, water vapour and nitric acid (HNO3) in the upper troposphere/lower stratosphere (UTLS) over North Atlantic and Europe. The measurements were acquired with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the Wave Driven Isentropic Exchange (WISE) campaign in October 2017. GLORIA is an airborne limb imager capable of acquiring both 2-D data sets (curtains along the flight path) and, when the carrier aircraft is flying around the observed air mass, spatially highly resolved 3-D tomographic data. Here, we present a case study of a Rossby wave (RW) breaking event observed during two subsequent flights 2 d apart. RW breaking is known to steepen tracer gradients and facilitate stratosphere–troposphere exchange (STE). Our measurements reveal complex spatial structures in stratospheric tracers (ozone and nitric acid) with multiple vertically stacked filaments. Backward-trajectory analysis is used to demonstrate that these features are related to several previous Rossby wave breaking events and that the small-scale structure of the UTLS in the Rossby wave breaking region, which is otherwise very hard to observe, can be understood as stirring and mixing of air masses of tropospheric and stratospheric origin. It is also shown that a strong nitric acid enhancement observed just above the tropopause is likely a result of NOx production by lightning activity. The measurements showed signatures of enhanced mixing between stratospheric and tropospheric air near the polar jet with some transport of water vapour into the stratosphere. Some of the air masses seen in 3-D data were encountered again 2 d later, stretched to very thin filament (horizontal thickness down to 30 km at some altitudes) rich in stratospheric tracers. This repeated measurement allowed us to directly observe and analyse the progress of mixing processes in a thin filament over 2 d. Our results provide direct insight into small-scale dynamics of the UTLS in the Rossby wave breaking region, which is of great importance to understanding STE and poleward transport in the UTLS.

Corneal Vertical and Horizontal Thickness Profiles Generated by UHR-OCT for Suspected and Subclinical Keratoconus Diagnosis.

To verify the diagnostic power of vertical and horizontal thickness profiles of the corneal sublayers generated by ultra-high resolution optical coherence tomography (UHROCT) in subclinical and suspected keratoconus. In this cross-sectional study, 25 eyes with confirmed keratoconus, 63 eyes with suspected keratoconus, 15 eyes with subclinical keratoconus, and 42 normal eyes were investigated. Vertical and horizontal thickness profiles of the corneal epithelium, Bowman's layer, and stroma were measured by UHR-OCT. Diagnostic indices included ratios of thickness distribution and multimeric discriminant functions calculated by multiple logistic regression based on them. Receiver operating characteristic curves were used to verify the predictive accuracy by the area under the curve (AUC). Function consisting of two indices (vertical maximum ectasia index of epithelium and horizontal maximum ectasia index of Bowman's layer) performed well to discriminate subclinical keratoconus (AUC = 0.967) and suspected keratoconus (AUC = 0.932) from normal. In addition, when four indices were combined, the diagnostic power for subclinical keratoconus (AUC = 0.984) and suspected keratoconus (AUC = 0.971) was further increased. However, both binary and quaternary functions could not adequately discriminate suspected from subclinical keratoconus. UHR-OCT-generated thickness indices from the vertical and horizontal thickness profiles of the corneal epithelium and Bowman's layer showed an evident diagnostic efficacy in discriminating suspected and subclinical keratoconus from normal eyes. The early changes in keratoconus might prefer thickness distribution in corneal sublayers rather than corneal thickness or topography. [J Refract Surg. 2021;37(7):438-445.].

Short-term use of an exposed polypropylene barrier in the preservation of alveolar bone after extraction: randomized clinical trial

This study was performed to evaluate the short-term preservation of alveolar bone volume with or without a polypropylene barrier and exposure of the area after extractions. Thirty posterior tooth extraction sockets were distributed randomly to a control group (n=15; extraction and suture) and a barrier group (n=15; extraction, barrier, and suture). All sutures and barriers were removed 10 days postoperatively. Cone beam computed tomography scans taken with the aid of a tomographic guide were obtained preoperatively, immediately postoperative, and at 120 days postoperative. A visual analysis of the coronal sections of the alveolus was performed, and vertical loss in the mesial, distal, buccal, and lingual bone ridges and horizontal thickness were evaluated. The mean vertical loss after extraction did not differ significantly between the control and barrier groups (Student t-test: mesial P= 0.989, buccal P= 0.997, lingual/palatal P= 0.070, distal P= 0.107). The mean vertical loss at 120 days postoperative did not differ significantly between the control (0.65 mm) and barrier (0.52 mm) groups (P> 0.05), with an effect size of 0.13 mm. At 120 days, the barrier group presented a mean resorption in thickness (0.45 mm) that was significantly lower than that in the control group (0.76 mm) (P= 0.021), with an effect size of 0.31 mm. The polypropylene barrier reduced the horizontal resorption in sockets of posterior teeth after extraction.

The effects of laser displacement on femtosecond laser-assisted conjunctival autograft preparation for pterygium surgery.

AimsTo evaluate the effects of no-suction femtosecond laser (FSL) stability on conjunctival autograft (CAG) dissection in pterygium surgery.MethodsProspective analysis of 35 eyes from 34 subjects who underwent femtosecond laser-assisted pterygium surgery with the Ziemer Z8 laser (Ophthalmic Systems AG, Switzerland). Intraoperative absolute FSL displacements were measured and correlated with the duration and ease of CAG peel, CAG thickness, measured with intraoperative optical coherence tomography, and deviation from intended graft thickness.ResultsThe median absolute FSL displacement was 22 μm (interquartile range [IQR] 14.7 to 60.8), while median vertical FSL displacement was 14.7 μm (IQR 7.3 to 44) and median horizontal FSL displacement was 22.0 μm (IQR 14.7 to 44). 65.7% had a grade 1 peel, 11.4% had grade 2 peel, 14.3% had grade 3 peel and 8.6% had grade 4 peel. The median duration of CAG peel was 5.4 seconds (IQR 3 to 21.4). The median CAG thickness was 69 μm (IQR 60.3 to 78.5), and the median deviation from targeted graft thickness was 9 μm (IQR 1 to 16). Eyes with more difficult peels and longer duration of CAG peels had significantly greater vertical FSL displacements (p = 0.04 and 0.02 respectively), but not horizontal displacement, age, ethnicity, CAG thickness or deviation from original thickness, compared to those with better quality and shorter duration peels. 1 eye (2.9%) had an incomplete CAG peel with a buttonhole and 2 eyes had graft tears (5.7%).ConclusionMicro-displacements during the suction-free CAG preparation are common but they did not affect the quality of the CAG peel, duration of peel, or CAG thickness. However, vertical globe displacement during FSL-assisted CAG creation was significantly associated with a more difficult and longer CAG peel duration. This highlights the importance of the cornea traction suture fixation to ensure stability of the eye during FSL application.

Relationship between corneal biomechanical parameters and corneal sublayer thickness measured by Corvis ST and UHR-OCT in keratoconus and normal eyes

BackgroundTo explore the relationship between corneal biomechanical parameters and corneal sublayer thickness using corneal visualization Scheimpflug technology (Corvis ST) and ultrahigh-resolution optical coherence tomography (UHR-OCT) in clinical and suspected keratoconus and normal eyes.MethodsCross-sectional prospective study. A total of 94 eyes of 70 participants were recruited. Twenty five eyes of 19 keratoconus patients, 52 eyes of 34 patients showing high risk of developing keratoconus according to the Belin/Ambrosio Enhanced Ectasia Display, and each eye of 17 normal subjects were enrolled. All participants underwent Corvis ST, Pentacam, and UHR-OCT examinations at the same time. Stiffness parameter A1 (SP-A1), deformation amplitude ratio (DA ratio), and other biomechanical parameters were recorded using Corvis ST. The vertical and horizontal thickness profiles of central 3 mm corneal epithelium, Bowman’s layer, and stroma as measured by the perpendicular distance between the neighboring interfaces were generated using UHR-OCT. The flat keratometry and steep keratometry were obtained using Pentacam. Analysis of correlation was applied to explore the association between variables.ResultsMost of the biomechanical parameters and corneal sublayer thickness profiles showed statistical differences among three groups. A statistically significant linear relationship was noted between SP-A1 and DA ratio in all three groups. SP-A1 was found to be positively correlated with epithelial and Bowman’s layer thickness in the keratoconus (KC) group, and with stromal thickness in all three groups. In the normal and suspected keratoconus (SKC) groups, only stromal thickness was included in the stepwise linear regression to predict SP-A1, whereas in the KC group, steep keratometry and Bowman’s layer thickness were included.ConclusionsSignificant and different correlations were noted between corneal stiffness and corneal sublayer thickness in different groups, indicating that corneal sublayers may play different roles in maintaining corneal biomechanical stability between keratoconus and normal eyes.

Variations in the configuration of pulp chambers subjacent to protostylids.

This study aimed to clarify the positional relationship between the crown contour and pulp chamber of protostylids using three-dimensional reconstructed images. Fourteen molars with protostylids from Japanese subjects were subjected to micro-computed tomography. The external surface configurations of the teeth and pulp chambers were reconstructed. Hard tissue thicknesses in appointed buccal areas were measured on the reconstructed images. Well-developed protostylids exhibited pulp-prominences above or at the cervical line level. Those that were moderately developed exhibited bulges of the pulp chamber subjacent to the protostylids. Ten of the 14 teeth had prominences in the crown pulp above or at the cervical line level. In addition, 13 teeth exhibited pulp chamber bulges surrounding the lower tooth trunk. No significant differences were apparent in the buccal horizontal thickness of the hard tissue between the protostylids with pulp chamber prominences and the protostylids without pulp chamber prominences at the cervical line level. Pulp chamber configurations subjacent to protostylids vary based on the development of the traits of the protostylids. Minimum possible taper should be applied during standard vital tooth preparations, as reduced residual dentin thickness is predicted in well- and moderately developed protostylids.

Clinical and Radiographic Evaluation of Simultaneous Alveolar Ridge Augmentation by Means of Preformed Titanium Meshes at Dehiscence-Type Peri-Implant Defects: A Prospective Pilot Study.

Background: bone augmentation by means of manually shaped titanium mesh is an established procedure to regenerate atrophic alveolar ridges and recreate a proper contour of the peri-implant bone anatomy. Conversely, current literature on the use of preformed titanium meshes instead of traditional grids remains lacking. Therefore, the aim of the present prospective study was to evaluate the use of preformed titanium mesh to support bone regeneration simultaneously to implant placement at dehiscence-type defects from clinical, radiological, and patient-related outcomes. Methods: 8 implants showing buccal dehiscence defects were treated with preformed titanium mesh directly fixed to flat abutments screwed to the implant. Intrasurgical clinical measurements and radiographic evaluations by means of cone-beam computed tomography scans were performed to assess the horizontal bone gain after 8 months from the augmentation surgery. Biological and patient-centered outcomes were also evaluated.; Results: clinically, a mean horizontal bone gain of 4.95 ± 0.96 mm, and a mean horizontal thickness of the buccal plate of 3.25 ± 0.46 mm were found. A mean horizontal bone gain of 5.06 ± 0.88 mm associated with a mean horizontal thickness of the buccal plate of 3.45 ± 0.68 mm were observed radiographically. From a macroscopic aspect, the remodeled graft appeared well integrated with the host bone. Well vascularized newly formed bone-like tissue was observed in intimate contact with the implants. Conclusions: preformed titanium mesh may be effective in supporting simultaneous horizontal bone regeneration at dehiscence-type peri-implant defects. Titanium mesh exposure still remain an issue in this type of surgery.

Designing bioinspired brick-and-mortar composites using machine learning and statistical learning

The brick-and-mortar structure inspired by nature, such as in nacre, is considered one of the most optimal designs for structural composites. Given the large number of design possibilities, extensive computational work is required to guide their manufacturing. Here, we propose a computational framework that combines statistical analysis and machine learning with finite element analysis to establish structure–property design strategies for brick-and-mortar composites. Approximately 20,000 models with different geometrical designs were categorized into good and bad based on their failure modes, with statistical analysis of the results used to find the importance of each feature. Aspect ratio of the bricks and horizontal mortar thickness were identified as the main influencing features. A decision tree machine learning model was then established to draw the boundaries of good design space. This approach might be used for the design of brick-and-mortar composites with improved mechanical properties.