"Invisible" radioactive cesium atoms revealed: Pollucite inclusion in cesium-rich microparticles (CsMPs) from the Fukushima Daiichi Nuclear Power Plant.

Understanding radioactive Cs contamination has been a central issue at Fukushima Daiichi and other nuclear legacy sites; however, atomic-scale characterization of radioactive Cs in environmental samples has never been achieved. Here we report, for the first time, the direct imaging of radioactive Cs atoms using high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). In Cs-rich microparticles collected from Japan, we document inclusions that contain 27 - 36 wt% of Cs (reported as Cs2O) in a zeolite: pollucite. The compositions of three pollucite inclusions are (Cs1.86K0.11Rb0.19Ba0.22)2.4(Fe0.85Zn0.84X0.31)2.0Si4.1O12, (Cs1.19K0.05Rb0.19Ba0.22)1.7(Fe0.66Zn0.32X0.41)1.4Si4.6O12, and (Cs1.27K0.21Rb0.29Ba0.15)1.9(Fe0.60Zn0.32X0.69)1.6Si4.4O12 (X includes other cations). HAADF-STEM imaging of pollucite, viewed along the [111] zone axis, revealed an array of Cs atoms, which is consistent with a simulated image using the multi-slice method. The occurrence of pollucite indicates that locally enriched Cs reacted with siliceous substances during the Fukushima meltdowns, presumably through volatilization and condensation. Beta radiation doses from the incorporated Cs are estimated to reach 106 - 107 Gy, which is more than three orders of magnitude less than typical amorphization dose of zeolite. The atomic-resolution imaging of radioactive Cs is an important advance for better understanding the fate of radioactive Cs inside and outside of nuclear reactors damaged by meltdown events.

Anterior Placement of Cages in Posterior Lumbar Interbody Fusion for Obtaining Good Lumbar Lordosis Formation.

Introduction: Posterior lumbar interbody fusion (PLIF) is a common treatment for nerve root disease associated with lumbar foraminal stenosis or lumbar spondylolisthesis. At our institution, PLIF is usually performed with high-angle cages and posterior column osteotomy (PLIF with HAP). However, not all patients achieve sufficient segmental lumbar lordosis (SLL). This study determined whether the location of PLIF cages affect local lumbar lordosis formation. Methods: A total of 59 patients who underwent L4/5 PLIF with HAP at our hospital, using the same titanium control cage model, were enrolled in this cohort study. The mean ratio of the distance from the posterior edge of the cage to the posterior wall of the vertebral body/vertebral length (RDCV) immediately after surgery was 16.5%. The patients were divided into two groups according to RDCV <16.5% (group P) and ≥16.5% (group G). The preoperative and 6-month postoperative slip rate (%slip), SLL, local disk angle (LDA), ratio of disk height/vertebral height (RDV), 6-month postoperative RDCV, ratio of cage length/vertebral length (RCVL), and ratio of posterior disk height/anterior disk height at the fixed level (RPA) were evaluated via simple lumbar spine X-ray. The preoperative and 6-month postoperative Japanese Orthopedic Association (JOA) and low back pain visual analog scale (VAS) scores were also evaluated. Results: Groups G and P included 31 and 28 patients, respectively. The preoperative %slip, SLL, LDA, RDV, JOA score, and low back pain VAS score were not significantly different between the groups. In groups G and P, 6-month postoperative %slip, SLL, LDA, RDV, RDCV, RCVL, and RPA were 3.3% and 7.9%, 18.6° and 15.4°, 9.7° and 8.0°, 36.6% and 40.3%, 21.1% and 10.1%, 71.4% and 77.0%, and 56.1% and 67.7%, respectively. The 6-month postoperative SLL, LDA, RDV, RDCV, RCVL, and RPA significantly differed (p=0.03, 0.02, 0.02, <0.001, <0.001, and <0.001, respectively). Conclusions: Anterior PLIF cage placement relative to the vertebral body is necessary for good SLL in PLIF.

Mechanism Analysis for the Enhancement of Low-Temperature Impact Toughness of Nodular Cast Iron by Heat Treatment.

The low-temperature impact toughness of nodular cast iron can be significantly enhanced by heat treatment, and thus meet the severe service requirements in the fields of high-speed rail and power generation, etc. In order to explore the enhancement mechanism, microstructure, hardness, composition and other characteristics of as-cast and heat-treated nodular cast iron is systematically tested and compared by optical microscopy, microhardness tester, EBSD, SEM, electron probe, and impact toughness testing machine in this study. The results show that heat treatment has little effect on the morphology and size of graphite in nodular cast iron, ignores the effect on the grain size, morphology, and distribution of ferritic matrix, and has little effect on the hardness and exchange of elements, while it is meaningful to find that heat treatment brings about significant decrease in high-angle grain boundaries (HAGB) between 59° and 60°, decreasing from 10% to 3%. Therefore, the significant enhancement of low-temperature impact toughness of nodular cast iron by heat treatment may result from the obvious decrease in HAGB between 59° and 60°, instead of other reasons. From this perspective, the study can provide novel ideas for optimizing the heat treatment process of nodular cast iron.

Long-term outcome evaluation in ankylosing spondylitis with high-angle thoracolumbar kyphotic deformity corrected by one-stage single-level pedicle subtraction osteotomy augmented with Ponte osteotomy: A case series.

INTRODUCTION AND IMPORTANCE: A high-angle thoracolumbar kyphotic deformity (TLKD) may complicate surgical rectification of AS patients since one-stage two-level pedicle subtraction osteotomy (PSO), which provides high-angular correction, leads to excessive blood loss, neurological deficits and fixation failures. This case series presents the long-term results of one-stage single level PSO with Ponte osteotomy (PO) in the treatment of AS patients with high-angle TLKD. CASE PRESENTATION: This case series presents two AS patients with high kyphotic angles (KAs) of 86.1o. We collected data retrospectively from our institution's database between 2019 and 2023. A sagittal axis imbalance was the only complaint initially, no neurological deficits or other problems. A PSO augmented by PO was performed with a decompression laminectomy. Intraoperative monitoring (IOM) during reduction was used to observe neurological deficits. Blood loss at the highest rate was 1000 cc. It corrected 57.8o of KA postoperatively without neurological deficits. We found consistent results over 36 months. CLINICAL DISCUSSION: A thorough analytical approach may help diagnose AS. One-stage single-level PSO may correct high-angle TLKD in AS patients effectively. To achieve greater angular correction, PO, a less risky osteotomy, must be added. Decompression laminectomy is vital before osteotomy and IOM is crucial during reduction to prevent nerve injury. Even with two osteotomies, there was less blood loss than previously reported. These impressive long-term results call for further research. CONCLUSION: Combined PSO and PO with IOM efficiently magnifies the angular correction without postoperative neurological deficits or excessive blood loss in AS patients with high-angle TLKD.

Cone-beam computed tomography study of root length of maxillary and mandibular anterior teeth and central incisor crown-root morphology in high-angle Class Ⅱ open bite patients / 口腔疾病防治

Objective@#This study aimed to explore the root length of maxillary and mandibular anterior teeth and central incisor crown-root morphology in patients with high-angle skeletal Class Ⅱ open bite, aiming to provide a reference for clinical treatment.@*. Methods@#This study was reviewed and approved by the Ethics Committee, and informed consent was obtained from the patients. CBCT images of eighty-one untreated patients (40 anterior open bite patients and 41 normal overbite patients) with high-angle skeletal Class Ⅱ malocclusion were selected before treatment. Dolphin software was used to study the root length of maxillary and mandibular anterior teeth and central incisor crown-root morphology, and the differences between the two groups were analyzed.@*Results@#There was no statistical significance in the root length of maxillary lateral incisor and canine between the open bite group and the normal overbite group, significant differences were found in the root length of maxillary central incisor （11.12 ± 1.37） mm、mandibular central incisor（10.15 ± 1.09）mm, mandibular lateral incisor（11.27 ± 1.15）mm and mandibular canine（12.81 ± 1.48）mm between the open bite group and the normal overbite group（P<0.05）. On the other hand, the two groups were significantly different in crown-root morphology of the maxillary central incisor (1.10° ± 3.62° vs. 4.53° ± 2.30°, P<0.01) but not in the mandibular central incisor.@*Conclusion@#The root length of the maxillary central incisor, mandibular central incisor, mandibular lateral incisor, mandibular canine in high-angle Class Ⅱ open bite patients is shorter than that in high-angle Class Ⅱ normal overbite patients, and the long axis of the crown of the maxillary central incisor in high-angle Class Ⅱ open bite patients obviously deviates toward the labial side relative to the long axis of the root. The crown-root angle is smaller, which is beneficial to torque control or adduction movement of the anterior teeth in high-angle Class Ⅱ open bite patients.

Differences in the effects of orthodontic treatment on airway-craniocervical functional environment in adult and adolescent patients with skeletal class II high-angle: a retrospective pilot study.

INTRODUCTION: This retrospective cohort study aimed to compare the change in upper airway and craniocervical posture after orthodontic treatment between adolescent and adult patients with Class II high-angle malocclusion. METHODS: A total of 12 adolescent (mean ± standard deviation age = 13.0 ± 2.0 years) and 12 adult patients with Class II high-angle malocclusion (mean ± standard deviation age = 23.7 ± 6.4 years) were selected in this study. The lateral cephalograms and cone beam computed tomography images of adolescent and adult patients were taken before and after treatment, which can be employed to evaluate the variables of craniofacial morphology, upper airway, and craniocervical posture through paired t tests, respectively. An independent sample t test was performed to observe the differences between two groups after orthodontic intervention. For adults and adolescents, the correlation between craniofacial morphology, upper airway, and craniocervical posture was determined through Pearson correlation analysis. RESULTS: In all subjects, the improvements in vertical and sagittal facial morphology after treatment were observed. Anterior and inferior movements of the hyoid bone, an increase of upper airway dimension, posterior tipping of the head and a reduction of cervical inclination in the lower and middle segments post-treatment were identified in adolescence (P < 0.05). Adults displayed anterior movements of the hyoid bone, whereas no significant difference was observed in upper airway dimension and craniocervical posture (P < 0.05). Notable differences were identified in the change of hyoid position and airway volume between two groups (P > 0.05). Mandibular plane inclination, growth pattern, occlusal plane inclination, and chin position were all significantly correlated with craniocervical posture in adolescent patients. Besides, the mandibular growth pattern and chin position in adult patients were significantly correlated with craniocervical posture (P < 0.05). CONCLUSIONS: Orthodontic treatment is capable of enhancing the facial profile of patients with skeletal class II high-angle while improving their upper airway morphology and craniocervical posture, where adolescents and adults differ substantially in that the former exhibit a more favorable alteration in the airway-craniocervical functional environment.

Torque control with set-up and auxiliary spring in an adult severe class II case treated by lingual straight-wire appliance, premolar extractions and orthognathic surgery.

This case report describes a complex full-step class II high angle case in an adult patient treated with lingual straight-wire appliance, premolar extractions and orthognathic surgery. With the twofold aim of obtaining ideal occlusal relationship and aesthetic improvement, surgical treatment with appropriate biomechanical strategies, including extraction choice and torque control during space closure, are needed to achieve the planned results. This case report demonstrates the possibility of solving successfully severe sagittal, transverse and vertical discrepancies in an adult patient with surgical treatment by means of an invisible technique. This report also underlines the need for precise biomechanical control, including set-up overcorrections and an auxiliary spring to manage teeth inclination, in lingual orthodontics extraction cases.

Long term stability of a high-angle skeletal Class II open bite treated with high-pull headgear and modified transpalatal arch: A case report.

This case report describes the treatment of an adolescent patient with an Angle Class II malocclusion, severe open bite and overjet, proclined incisors, skeletal Class II anteroposterior dysplasia, high mandibular plane angle and convex profile. The importance of stopping of a prolonged thumb sucking habit, which was a major causative factor of the open bite is discussed. A combination of a high-pull headgear and a modified transpalatal arch with a loop embedded with resin, at a distance from the palate, were used along with an Edgewise appliance. Treatment timing, favourable growth and good patient response led to an optimal outcome with excellent stability of the treatment results five years and five months post-treatment.

Study on the ideal sagittal position of the lower third of the face in high-angle patients with different forehead forms / 口腔疾病防治

Objective@#To explore the ideal sagittal position of the lower third of the face in high-angle patients with different forehead forms and to provide a reference for clinical treatment. @*Methods@#Informed consent and portrait authorization were obtained from all patients, and the study passed the ethical review of the unit. We categorized forehead forms into four types: straight, rounded, type I angular (angled at the middle third of the forehead) and type II angular (angled at the upper third of the forehead). Profiles of high-angle patients with different forehead forms were collected. The initial position was when the facial axis point (FA point) was positioned at the goal anterior-limit line (GALL). After being silhouetted, the lower third of the face was moved forward and backward by 1 mm, 2 mm, 3 mm, and 4 mm each, plus the initial silhouetted picture, to obtain 9 images for each patient. A survey was created with these lateral profile silhouettes, and the silhouette images were ranked by 30 orthodontists and 30 laypersons. @*Results@# There were significant differences in profile scores at different movement distances of the lower third of the face among high-angle patients with different forehead shapes (P<0.05). Overall, high-angle patients with straight or type II angular foreheads had higher scores when the lower third of the face did not move. For high-angle patients with a rounded forehead, orthodontists and laypersons gave the highest scores when the lower third of the face was moved backward by 2 mm and 4 mm, respectively. For high-angle patients with a type I angular forehead, orthodontists thought the scores of backward movement of 4 mm were the highest, and laypersons thought the scores of backward movement of 3 mm were the highest. No significant difference was found in scores between orthodontists and laypersons (P>0.05). @*Conclusion @#The forehead forms and the sagittal position of the lower third of the face will affect the face’s profile aesthetics. Patients with straight and type Ⅱ angular foreheads has the best profile when the FA point is located on the GALL line. For patients with rounded and type Ⅰ angular foreheads, a posterior location of the lower third of the face is more desirable than the initial position.

Enhanced Strength and Hardness of AS41 Magnesium Alloy Fabricated by Selective Laser Melting.

AS41 magnesium alloy possesses outstanding performance features such as light weight, high strength to toughness ratio and excellent heat resistance due to the addition of Si element, while traditional casting methods are prone to inducing large grain size and coarse Mg2Si phase. In this study, we first reported utilizing the selective laser melting (SLM) technique, fabricating AS41 samples and exploring the effect of laser energy densities on the metallurgical quality by characterizing and investigating the microstructure and mechanical properties. Results showed that the optimal laser energy density range was 60 to 100 J/mm3. Average grain size of only 2.9 µm was obtained with weak texture strength of 1.65 in {0001} orientation. Meanwhile, many dispersed secondary ß-Mg17Al12 and Mg2Si phases were distributed inside the α-Mg matrix. It was confirmed that the SLM process introduced more grain recrystallization, inducing giant high-angle grain boundaries (HAGBs) and hindering the movement of dislocations, therefore forming dislocation strengthening while achieving grain refinement strengthening. Finally, three times the ultimate tensile strength of 313.7 MPa and higher microhardness of 96.4 HV than those of the as-cast state were obtained, verifying that the combined effect of grain refinement, solid solution strengthening and precipitation strengthening was responsible for the increased strength. This work provides new insight and a new approach to preparing AS41 magnesium alloy.

A case of skeletal maxillary protrusion with high angle and gummy smile treated with anchor screws.

This report discusses a case of a 20 year and 7-month-old female patient with a skeletal maxillary protrusion with gummy smile, crowding, and high angle due to horizontal protrusion of the maxillary anterior teeth. The gummy smile in this case was improved by an upward movement of the occlusal plane associated with maxillary molar intrusion and sufficient lingual movement while performing maxillary anterior teeth intrusion. Following treatment, it was stable even after 8 years of retention. Thus, it is important to ascertain the cause of gummy smile, and establish whether it is due to the vertical maxillary excess in the maxillary anterior teeth, or the horizontal protrusion of the maxillary anterior teeth.

Atomic layer deposited Al2O3 as a protective overlayer for focused ion beam preparation of plan-view STEM samples.

Preservation of analyte integrity during focused ion beam (FIB) sample preparation is a significant challenge in the scanning transmission electron microscopy (STEM) characterization of plan-view samples with sensitive surface chemistries. This can preclude the characterization of atomic arrangements, nanoscale surface coverages, and distributions and morphologies of functional molecular materials composed of surface-immobilized metal nanoparticles, clusters or coordination complexes. This work demonstrates effective protection of Pt nanoparticle (NP) morphology through a plan-view FIB lift-out and thinning procedure by encapsulating the sample surface in an Al2O3 overlayer grown by atomic layer deposition (ALD). High-angle annular dark field (HAADF)-STEM analysis was used in concert with energy dispersive X-ray spectroscopy (EDS) to identify and image sub-10 nm features attributed to Pt and to evaluate the distribution of implanted Ga+ (derived from the FIB milling beam). ALD is a mild chemical vapor deposition (CVD) technique that has the capability to generate dense, pinhole-free films with tunable compositions and properties, making this ALD-FIB procedure applicable to many sample architectures for plan-view lamella preparation and STEM analysis.

Broadband Enhancement of Anti-reflectivity for a High Angle of Incidence Using Nanocone Geometry.

The broadband antireflective (AR) effect for wide incident angles has a significant effect on the photoconversion efficiency of photovoltaics and visibility of large-format display panels. The fabrication of surface nanostructures has continued to attract research interest as an effective way to provide such optical performance. However, the effects of different nanostructure geometries are not fully understood, especially for wide-angle AR effects. In this work, we conduct a systematic analysis of the effect of periodic nanostructures such as nanocones (NCs) and inverted nanocones (INCs) on anti-reflectivity at high angles of incidence (AOIs) in terms of light scattering, guided-mode resonance (GMR), and internal reflections. NCs provide good coupling of light scattering and GMR because of their protruding geometry; hence, reduced reflectance can be obtained in the short wavelength region. Further, NCs exhibit relatively weaker GMR intensities and internal reflections, resulting in low reflectance in the long wavelength region. Therefore, NCs offer a superior broadband AR effect for high AOIs compared with INCs. Based on this analysis, we demonstrate an extremely low average reflectance (5.4%) compared to that of the bare substrate (34.7%) for the entire visible range at an AOI of 75° by fabricating NCs on both sides of the substrate.

Non-surgical adult class II high-angle treatment with an invisible appliance: A case report.

This case report describes the complex situation of a young adult Class II hyperdivergent patient treated by premolar extraction with a straight wire lingual appliance. Despite the patient's refusal to undergo surgical treatment, the dual goals of ideal occlusal relationship and profile improvement were achieved through a well thought-out biomechanical strategy with appropriate extraction choice and anchorage control during space closure. This case report demonstrates the possibility of successfully resolving severe sagittal and vertical discrepancies in an adult patient without surgical treatment using a completely invisible technique. This report also highlights the need for careful planning during the diagnostic and treatment phases.

Morphological analysis of mandibular anterior alveolar bone in high-angle adult females assessed with cone-beam computed tomography / 口腔疾病防治

Objective@#To investigate the features of alveolar bone morphology of mandibular central incisors in high-angle adult females using cone-beam computed tomography (CBCT) and evaluate the influence of aging in these patients.@*Methods@# CBCT and lateral cephalometric images of 142 untreated adult female patients were selected and grouped by facial growth pattern. The number of high-angle cases was increased to 164 to further explore the difference within high-angle adult females who were divided into two groups according to age. The indexes of alveolar bone height and thickness in the lower incisor region and inclination of the lower incisors were measured by Dolphin software. The data was statistically analyzed.@*Results@#Compared with the average-angle group, the high-angle group had a lower alveolar bone attachment level (P < 0.05) and less bone thickness at the root apex level (P < 0.05). The thickness of lingual alveolar bone decreased with labial inclination of the lower incisors in both the high-angle and average-angle groups (r = -0.251, P = 0.025; r = -0.428, P = 0.001, respectively). In hyperdivergent female patients, the middle-aged group had a lower attachment level of alveolar bone than the young group (P < 0.05), but no significant difference in bone thickness at the root apex level (P > 0.05) was found between the two groups@*Conclusion @# High-angle adult females had thinner mandibular anterior alveolar bone with significantly lower attachment levels. Aging and inclination of lower incisors influenced bone morphology and should be taken into careful consideration.

Electron Crystallographic Investigation of Crystals on the Mesostructural Scale.

The precise structural solution of crystals on a mesostructural scale is challenging due to the difficulties in obtaining electron diffraction and the complicated relationship between the crystal structure factors (CSFs) and the conventional underfocus phase-contrast transmission electron microscopy (TEM) images due to the large unit cell and the complex structures. Here, we present the structural investigation of mesostructured crystals via the combination of electron crystallographic Fourier synthesis and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) that only relies on the mass-thickness contrast. The three-dimensional electrostatic potential is reconstructed from the amplitudes and phases extracted from the Fourier transforms of the corresponding HAADF-STEM images and merged into a set of CSFs. This method is verified on silica scaffolds following a shifted double-diamond surface network with space group I41/amd. The results indicate that electron crystallography reconstruction by HAADF-STEM images is more suitable and accurate in determining the structure in comparison with conventional TEM electron crystallography reconstruction. This approach transfers the contrast of mesostructured crystals to images more accurately and the relationship between the Fourier transforms of HAADF-STEM images and the CSFs is more intuitive. It shows great advantages for the structural solution of crystals on the mesostructural scale.

Cone-beam Computed Tomography-based three-dimensional cephalometric analysis of mandible symmetry and the occlusal plane of adult patients with high-angle skeletal class III malocclusion and jaw deformity.

OBJECTIVE: To use cone beam computed tomography (CBCT) scans to analyze mandibular symmetry, the occlusal plane and their correlations in patients with high-angle skeletal class III malocclusion and jaw deformity. DESIGN: Reconstructed images simulated of CBCT data of 20 adult patients with high-angle skeletal class III malocclusion and jaw asymmetry (Experimental group) and 20 adult patients of skeletal class I with normal faces (Control group) were measured with a three-dimensional (3D) geometric morphological measurement system. Related landmarks, lines and planes were marked and relevant distances and angles of 3D craniofacial structures were measured. The Student t-test was performed to assess symmetry. With the help of the Pearson correlation and Linear regression, we explored the correlations and other relationships among them. RESULTS: Compared with control group, the symmetrical differences in experimental group were concentrated in condyle, coracoid process, mandibular angle, mandibular first molar area and the chin (P < 0.05). A strong positive correlation was found between the degree of mandibular deviation and the inclination of the occlusal plane in the coronal position (r = 0.860, P < 0.001) and a linear relationship between them was found: Y = 1.300 + 0.419X (the inclination of occlusal plane was Y, and the mandibular deviation was X). CONCLUSIONS: Certain characteristics of mandibular symmetry and the occlusal plane were found in patients with high-angle skeletal class III malocclusion and jaw asymmetry. These findings provide references for doctors to pay attention to the degree and location of mandibular asymmetry and to determine the occlusal plane.

Significantly Enhanced Thermoelectric Performance of Graphene through Atomic-Scale Defect Engineering via Mobile Hot-Wire Chemical Vapor Deposition Systems.

Over the years, numerous studies have attempted to develop two-dimensional (2D) materials for improving both the applicability and performance of thermoelectric devices. Among the 2D materials, graphene is one of the promising candidates for thermoelectric materials owing to its extraordinary electrical properties, flexibility, and nontoxicity. However, graphene synthesized through traditional methods suffers from a low Seebeck coefficient and high thermal conductivity, resulting in an extremely low thermoelectric figure of merit (ZT). Here, we present an atomic-scale defect engineering strategy to improve the thermoelectric properties of graphene using embedded high-angle tilt boundary (HATB) domains in graphene films. These HATB domains serve as both energy filtering sites to filter out lower-energy charge carriers and scattering sites for phonons. Compared to the conventionally grown chemical vapor deposited graphene, the graphene with HATB domains shows an improved Seebeck coefficient (50.1 vs 21.1 µV K-1) and reduced thermal conductivity (382 vs 952 W m-1K-1), resulting in a ZT value that is ∼7 times greater at 350 K. This defect engineering strategy is promising not only for graphene-based materials but also for 2D materials, in general, where further research and optimization could overcome the limitations of conventional bulk thermoelectric materials in energy-harvesting systems.

Optimizing Nonrigid Registration for Scanning Transmission Electron Microscopy Image Series.

Achieving sub-picometer precision measurements of atomic column positions in high-resolution scanning transmission electron microscope images using nonrigid registration (NRR) and averaging of image series requires careful optimization of experimental conditions and the parameters of the registration algorithm. On experimental data from SrTiO3 [100], sub-pm precision requires alignment of the sample to the zone axis to within 1 mrad tilt and sample drift of less than 1 nm/min. At fixed total electron dose for the series, precision in the fast scan direction improves with shorter pixel dwell time to the limit of our microscope hardware, but the best precision along the slow scan direction occurs at 6 µs/px dwell time. Within the NRR algorithm, the "smoothness factor" that penalizes large estimated shifts is the most important parameter for sub-pm precision, but in general, the precision of NRR images is robust over a wide range of parameters.

Surgical Orthodontic Treatment in Case of Severe High Angle Skeletal Class II Malocclusion and Mandibular Retrusion.

This report describes a patient with severe high angle class II malocclusion and mandibular retrusion in whom surgical orthodontic treatment to prevent an increase in ramus height resulted in a significant improvement in esthetics and long-term stability. The patient was a woman aged 30 years 5 months who presented with the chief complaint of maxillary protrusion. She had a convex facial type, a chin button on lip sealing, and a gummy smile. Cephalometric analysis revealed a normal maxilla anterior-posterior position, but significant mandibular retrusion with pronounced clockwise rotation. The anterior maxillary tooth axis was standard, but labially inclined in the mandible. Based on these findings, the diagnosis was skeletal class II high angle malocclusion and mandibular retrusion. The proposed treatment plan comprised 2-jaw surgery with premolar extraction. Le Fort I osteotomy, in particular, was planned in the maxilla to move the ANS upward by 3.0 mm and the PNS downward by 3.0 mm. Sagittal split ramus osteotomy (SSRO) was planned to adjust the mandible and move the mandible forward by 10.0 mm. To prevent postoperative relapse, the short lingual split method was used in performing the SSRO. The mandible was split to minimize stretching of the median pterygoid muscle. Postoperatively, the ANS, PNS, and pogonion showed movement of 2.0 mm upward, 3.0 mm downward, and 8.0 mm forward, respectively. Additionally, lip closure was now natural, and the gummy smile had markedly improved. At 6 years postoperatively, there has been no change skeletally or dentally. Follow-up is being continued to monitor further progress.