Point Angle Research Articles

Upper Airway Dimensions among Different Skeletal Malocclusions: A Retrospective Observational Study by Cephalometric Analysis.

In this retrospective cross-sectional study, lateral cephalometric radiographs of adult patients referred for orthodontic consultation were collected. Cephalometric tracing was performed with dedicated software. For each measure, descriptive statistics were calculated. Cephalometric measurements between the different skeletal classes were compared. Linear regressions were performed between upper airway diameters and cephalometric measurements, sex and age. Significance was predetermined for p < 0.05. Lateral cephalometric radiographs of 120 patients were reviewed. Nasopharynx length (NL) and depth (PD) measurements were significantly shorter in skeletal class III patients (p < 0.05). The superior pharyngeal airway space (SPAS) was found to be significantly shorter in class III patients as compared to class II patients (p < 0.05), and the mean airway space (MAS) of class I patients was found to be significantly shorter compared to class II patients (p < 0.05). Palate length (PL) values were found to be significantly longer in class I (p < 0.05). Linear regressions showed that the sella-nasion-A point angle (SNA) and Riedel's angle between point A, the nasion and point B (ANB) significantly influenced NL and PD (p < 0.05). Class III patients show significantly shorter nasopharynx measurements; clinicians should consider that this sagittal discrepancy could be related to an altered anatomy of the upper respiratory tract.

A strain energy density field method to predict the life of metallic notched components under multiaxial fatigue loading

A method based on strain energy density field (SEDF) has been proposed to predict the angle of fatigue critical points and multi-axial life of the notched parts under multi-axial cyclic loading. The point bearing the maximum strain energy density was taken as the fatigue crack initiation point (fatigue critical point). The influence of stress-strain gradient around the notches were considered via combining SEDF and the critical distance theory (TCD) to calculate the multi-axial notch life. The predictive results indicate that the maximum deviation of the fatigue critical point (FCP) was 7.0°. The most of the predictive life was within the 3-time error band.

Conditions of Existence and Uniqueness of Limit Cycle for Grid-Connected VSC With PLL

This paper investigates the large disturbance stability of single voltage source converter (VSC) connected to the infinite bus system through the transmission line. One conservative stable region is obtained via the direct method of Lyapunov. Based on the Poincaré Theorem, it is interesting to find there might exist limit cycle between the obtained stable boundary and the angle of unstable equilibrium point (UEP). Accordingly, the nonlinear damping effect on the system stability is defined, and one limit cycle exists when the positive and negative damping effect over one period is mutually balanced. A conservative existence condition of limit cycle is further derived by constructing a proper piece-wise curve to approximate one specified unstable system trajectory. The derived analytical existence condition can directly predict the limit cycle without numerical simulations. Finally, the paper also proves that the studied dynamic system has at most one limit cycle, and if it exists, it is unstable.

Cephalometric Evaluation of Soft-tissue Profile Changes in Class-II Division 1 Patients with Varied Growth Patterns Treated with all First Premolar Extractions: A Cross-sectional Study

Introduction: Knowledge of the facial skeleton and its overlying soft-tissue is essential in determining facial harmony. Additionally, an individual’s growth pattern may influence posttreatment facial profiles and needs to be considered during treatment planning. Aim: To evaluate the soft-tissue profile changes in treated Class-II malocclusion patients with varied mandibular growth patterns and to compare these changes with patients having a skeletal Class-I relationship and a balanced facial profile. Materials and Methods: The present cross-sectional cephalometric study was conducted in the Department of Orthodontics, Faculty of Dental Sciences, SGT University, Gurugram, Haryana, India, from June 2021 to December 2022. The study included 210 lateral cephalograms of 120 patients. The cephalograms were divided into four groups based on the Frankfort horizontal Mandibular plane Angle (FMA): Group-1 (control, n=30): skeletal Class-I (FMA=22°-28°); Group-2 (n=30): skeletal Class-II with a horizontal growth pattern (FMA&lt;22°); Group-3 (n=30): skeletal Class-II with an average growth pattern (FMA=22°-28°); and group-4 (n=30): skeletal Class-II with a vertical growth pattern (FMA&gt;28°). All patients in the groups2,3, and 4 were treated with all first premolar extractions using a 0.022˝ McLaughlin, Bennett and Trevisi (MBT) appliance. The student’s t-test and post-hoc test was used to analyse skeletal, dental and soft-tissue parameters using Statistical Package for the Social Sciences (SPSS) software (version 22.00 for Windows; SPSS Inc., Chicago, USA). Results: Of the total, 120 patients, 52 were males and 68 females with an age range of 18-28 years. On intergroup analysis, significant changes (p-value&lt;0.05) in the Sella, Nasion and A point (SNA) and Sella, Nasion and B point (SNB) angles were observed in group-3. Clinically insignificant changes were found in the A point, Nasion and B point (ANB) angle across all experimental groups. However, a significant change (p-value&lt;0.001) in the post-treatment ANB angle was observed in group-2, followed by group-3 and 4 when compared with group-1. The soft-tissue profile angle showed a significant change in Group-2 when compared with Group-1 (p-value=0.012). Conclusion: The post-treatment soft-tissue profiles of the experimental groups were comparable to the balanced profile of the control group patients.

Peach LAZY1 and DRO1 protein-protein interactions and co-expression with PRAF/RLD family support conserved gravity-related protein interactions across plants.

IGT/LAZY proteins play a central role in determining gravitropic set point angle and orientation of lateral organs across plant species. Recent work in model systems has demonstrated that interactions between IGT/LAZY proteins and BREVIS RADIX (BRX)-domain containing proteins, such as PH, RCC1, AND FYVE/RCC1-LIKE DOMAIN (PRAF/RLD), and BREVIS RADIX LIKE (BRXL) family members, are mechanistically important for setting gravitropic set point angle. Here, we identified peach PRAF/RLD proteins as interactors of the peach IGT/LAZY proteins PpeLAZY1 and DEEPER ROOTING 1 (PpeDRO1) from a yeast-two-hybrid screen. We also show that the BRX domains of these interacting proteins have high sequence similarity with PRAF/RLD and BRX family proteins from rice and Arabidopsis. Further, PpeLAZY1 and the peach PRAF/RLD interactors are all expressed at relatively high levels in leaf, meristem, and shoot tip tissues. Together, this evidence supports the importance and conservation of IGT/LAZY-BRX-domain interactions, which underlie setting gravitropic set point angle across angiosperms.

Long-Term Follow-Up of Orthognathic Surgery in 19 Patients with Juvenile Idiopathic Arthritis.

Dentofacial deformity following juvenile idiopathic arthritis with temporomandibular joint involvement is associated with functional, aesthetic, and psychosocial impairment. Surgical treatment may involve combinations of orthognathic surgery. The aims of this retrospective study were to assess orofacial symptoms, functional and aesthetic status, and stability after orthognathic surgery. Nineteen patients with juvenile idiopathic arthritis of the temporomandibular joint (TMJ) and dentofacial deformities were included. All patients were treated with combinations of bilateral sagittal split osteotomy, Le Fort I and/or genioplasty, between September 10, 2007 and October 17, 2017. Analysis of patient symptoms and clinical registrations, and frontal/lateral cephalograms was performed pre- and postoperative and long-term (mean: 3.8 and 2.6 years, respectively). Patients experienced no changes in orofacial symptoms or TMJ function, and stable normalisation of horizontal and vertical incisal relations at long-term (horizontal overbite; vertical overbite: P < 0.05). Mandibular lengthening was achieved postoperatively (from mean 79.7 to 87.2 mm; P = 0.004) and was stable. Sella-nasion to A point (SNA) and sella-nasion to B point (SNB) angles increased postoperatively (SNA, mean 79.9° to 82.8°; P = 0.022 and SNB, mean 73.9° to 77.8°; P = 0.003), however, largely reverted to preoperative status at long-term. Orthognathic surgery normalized incisal relations while providing stable mandibular lengthening without long-term deterioration of temporomandibular joint function or orofacial symptoms. No long-term effect on jaw advancements was observed.

Evaluation of natural head position changes in the treatment of class II malocclusions with functional appliance

Objectives: The position of the head to the neck is affected by various factors, including respiratory tract features, temporomandibular joint disorders, type of occlusion, and physical aspects. In addition, malocclusion can negatively affect the head-neck position. The present study aimed to evaluate changes in natural head position following treatment of Class II malocclusions with Farmand II functional appliance. Material and Methods: The present study was implemented as a historical cohort with the before and after design. Pre- and post-treatment lateral cephalometric radiographs of 33 skeletal Class II patients treated with the Farmand II functional appliance were included in the present study. The cephalometric analysis was done by tracing the related lines and landmarks. Facial angles and angles determining the natural head and neck position including craniohorizontal, craniocervical, craniovertical (CCV), and cervical curvature (CCI) were measured. Collected data were entered in Statistical Package for the Social Sciences (SPSS)-version 17 software. Paired t-test was used to evaluate the changes in cephalometric indices before and after treatment. P &lt; 0.05 was defined to be statistically significant for all the tests. Results: The results of the present study, showed a significant reduction in the mean values of A point, nasion, B point (ANB) angle and angle of convexity following treatment (P &lt; 0.001); also, Sella-nasion/Odontoid process tangent (SN/OPT) angle showed a substantial decrease in treated patients (P = 0.033), which is indicative of head flexion following treatment. Moreover, the decrease in the mean values of the craniocervical angles, including True vertical line (NL/VER) and Sella-nasion/true vertical line (SN/VER), suggests downward bending of the head in patients treated with this appliance (P-values of 0.029 and 0.012, respectively). The odontoid process tangent/cervical vertebra tangent (OPT/CVT) angle showed an insignificant increase (P = 0.260). Conclusion: The present study showed that patients treated with the Farmand II functional appliance tend to flex their heads and maintain their cervical vertebra in a more upright and straight position.

Changes in needle maneuver space and optimal insertion site for midline neuraxial puncture with progressive age: an analysis in computed tomography scans

IntroductionWe systematically describe the morphology and accessibility of interspinous spaces across age groups of patients. Our primary goal was to objectively estimate if the maneuver space for a virtual spinal...

Dimensional synthesis of motion generation in a spherical four-bar mechanism

A new objective function for optimizing spherical, four-bar mechanisms for motion generation is presented. Rigid-body poses of a spherical four-bar mechanism in a standard installation position are investigated, and a normalization processing method is proposed. After processing the coupler points of the mechanism, the feature points generated are located on the circles. The formation principle of the feature coupler circles is analysed, and the internal relationship between the centre angle of the adjacent feature points on the feature coupler circles and the coupler angle of the spherical four-bar mechanism is determined. An input angle determination method is proposed for the spherical four-bar mechanism in a general installation position. An objective function is then established to optimize the basic dimensional types, relative input angles, and installation position parameters of the desired spherical four-bar mechanism. The proposed method is applicable to both prescribed and unprescribed timing problems. Notably, the dimension of the optimization variables is only eight, which is exceptionally low for multiple position motion generation without prescribed timing; therefore, the global optimal solution is more easily obtained. The optimization process is carried out by the genetic algorithm. The feasibility and effectiveness of our proposed method are demonstrated by examples.

Machine Learning-Based Measurement of Regional and Global Spinal Parameters Using the Concept of Incidence Angle of Inflection Points.

This study delves into the application of convolutional neural networks (CNNs) in evaluating spinal sagittal alignment, introducing the innovative concept of incidence angles of inflection points (IAIPs) as intuitive parameters to capture the interplay between pelvic and spinal alignment. Pioneering the fusion of IAIPs with machine learning for sagittal alignment analysis, this research scrutinized whole-spine lateral radiographs from hundreds of patients who visited a single institution, utilizing high-quality images for parameter assessments. Noteworthy findings revealed robust success rates for certain parameters, including pelvic and C2 incidence angles, but comparatively lower rates for sacral slope and L1 incidence. The proposed CNN-based machine learning method demonstrated remarkable efficiency, achieving an impressive 80 percent detection rate for various spinal angles, such as lumbar lordosis and thoracic kyphosis, with a precise error threshold of 3.5°. Further bolstering the study's credibility, measurements derived from the novel formula closely aligned with those directly extracted from the CNN model. In conclusion, this research underscores the utility of the CNN-based deep learning algorithm in delivering precise measurements of spinal sagittal parameters, and highlights the potential for integrating machine learning with the IAIP concept for comprehensive data accumulation in the domain of sagittal spinal alignment analysis, thus advancing our understanding of spinal health.

Machining fiber-reinforced glass-epoxy composites with cryo-treated and untreated HSS cutting tools of varying geometries

Depending on the expanding application areas of glass fiber reinforced composite materials, quality machining of such materials also receives increasing interest. However, since the cutting tools used for machining such composites generally have standard geometric properties, both the life of the cutting tool and the quality of the machined composite workpiece are adversely affected by. In this study, the performance and the most optimum drilling geometries of untreated (UT) and cryo-treated&tempered (DCT&T) HSS cutting tools used for machining of fiber-reinforced glass-epoxy composites were investigated. Moreover, Taguchi experimental design was employed to reduce the number of experiments, and also the analysis of variance (ANOVA) and regression analysis were performed. Furthermore, XRD analysis and microhardness tests were applied to UT and DCT&T HSS cutting tools. From the highest and lowest delamination factor (Fd) values obtained using UT and DCT&T HSS drills, it was understood that DCT&T HSS drills achieved better results by 0.8% and 0.7%, respectively. According to average surface roughness (Ra) values obtained, the performances of DCT&T HSS drills were 14.76% (for the highest Ra value) and 2.69% (for the lowest Ra value), better than UT HSS drills. When the highest and lowest cutting force values were compared, it was seen that the cutting force values obtained using DCT&T HSS drills were 24.54% and 16.15% less than the cutting force values obtained using UT HSS drills, respectively. According to the S/N ratios for the cutting forces, the most optimum geometries of the cutting tool were found to be 128° point angle, 33° helix angle and 8° clearance angle, respectively. With respect to S/N ratios for Fd values, the most optimum geometries of the cutting tool were found to be 118° point angle, 26° helix angle and 8° clearance angle, respectively. Based on S/N ratios for Ra values, the most optimum geometries of the cutting tool were found to be 128° point angle, 26° helix angle and 8° clearance angle, respectively. On the other hand, as a result of the regression analysis, R2 values obtained over 90% show that the regression models are quite successful. Besides, it was observed (from SEM and thermal camera images) that the epoxy resins in the chips produced at high spindle speeds melted because of high temperature, which indicated that the integrity of the composite workpieces started to deteriorate.

Investigation of rivers planform change in a semi-arid region of high vulnerability to climate change: A case study of Tigris River and its tributaries in Iraq

In this paper, the planform changes of rivers in a semi-arid region, which are particularly vulnerable to the impacts of climate change, were investigated. This research provides valuable insights into the adaptation and mitigation efforts necessary for effective climate change risk management in this area. A comprehensive analysis was carried out using satellite images and GIS to investigate the changes in the planform of the Mosul-Makhool reach of the Tigris River and its Lesser Zab and Greater Zab tributaries as a case study. To date, no studies have examined the impact of dam construction and climate change on the planform changes of these rivers. A survey was conducted to analyze the channel planform from 1979 to 2021. Various channel planform features were computed, including sinuosity index, braiding index, erosion and accretion, migration rate, confluence point, and junction angle. Results demonstrated that the Tigris River has low meandering features, the Lesser Zab has moderate meandering features, and the Greater Zab has the highest sinuosity index value of 1.95, which indicates very high meandering features. The change in the sinuosity index was fairly small. Generally, the rivers tended slightly towards deposition rather than erosion. The migration rate of the meandering rivers was high, with the highest value recorded in the Tigris River and Greater Zab. The average movement rate of the Greater Zab-Tigris River confluence was 31.81 m/year, and the Lesser Zab-Tigris River confluence moved 20.2 m/year. The study results demonstrate that climate change and dam construction significantly impact the rivers' planform in semi-arid regions. This investigation holds significant importance in evaluating morphodynamic changes in river systems worldwide with great detail and accuracy using satellite data.

Cars Identification from partial images using norm angle of feature points.

Cars Identification from partial images using norm angle of feature points.

Design and application of a B-ultrasound-guided deep vein puncture precise positioning device

Deep venipuncture catheterization is a routine and basic operation in the treatment of critically ill patients, and it is the most effective way to quickly correct the shock. Clinical B-ultrasound guided deep vein catheters can improve the success rate of puncture, but in the process of operation, the short axis needs to be replaced by the long axis. In the replacement process, the stability of the novice is insufficient, the positioning is difficult, and the operation time is too long. If only short axis puncture is used, it is impossible to know whether the current position of the puncture needle, and the puncture may be too deep and stray into the artery. The accuracy of the 45 degree angle of the injection point requires a very experienced operator. In view of the above shortcomings, doctors in the department of critical care medicine of Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine designed a B-ultrasound puncture equipment, which has obtained the National Invention Patent of China (ZL 2016 1 0571557.X). The device is composed of B-ultrasound probe fixing frame, sliding scale plate, simulation slide rule, puncture needle, sliding device. By sliding device the angle of the pinhole channel, it is conducive to the accurate positioning of the puncture target, optimizing the operation procedure, improving the puncture speed and accuracy, effectively reducing the occurrence of puncture complications, ensuring patient safety, reducing unnecessary waste of human and material resources. It can reduce the workload of medical staff and is worthy of clinical practice.

Drilling of Cross-Ply UHMWPE Laminates: A Study on the Effects of the Tool Geometry and Cutting Parameters on the Integrity of Components.

Ultrahigh-molecular-weight polyethylene (UHMWPE) is used in the defence industry mainly owing to its properties, such as excellent dimensional stability, excellent ballistic performance, and light weight. Although UHMWPE laminates are generally studied under impact loads, it is crucial to understand better the optimal machining conditions for assembling auxiliary structures in combat helmets or armour. This work analyses the machinability of UHMWPE laminates by drilling. The workpiece material has been manufactured through hot-pressing technology and subjected to drilling tests. High-speed steel (HSS) twist drills with two different point angles and a brad and spur drill that is 6 mm in diameter have been used for this study. Cutting forces, failure, and main damage modes are analysed, making it possible to extract relevant information for the industry. The main conclusion is that the drill with a smaller point angle has a better cutting force performance and less delamination at the exit zone (5.4 mm at a 60 m/min cutting speed and a 0.05 mm/rev feed) in the samples. This value represents a 46% improvement over the best result obtained in terms of delamination at the exit when using the tool with the larger point angle. However, the brad and spur drill revealed a post-drilling appearance with high fuzzing and delamination.

Stochastic Flood Simulation Method Combining Flood Intensity and Morphological Indicators

The existing flood stochastic simulation methods are mostly applied to the stochastic simulation of flood intensity characteristics, with less consideration for the randomness of the flood hydrograph shape and its correlation with intensity characteristics. In view of this, this paper proposes a flood stochastic simulation method that combines intensity and morphological indicators. Using the Foziling and Xianghongdian reservoirs in the Pi River basin in China as examples, this method utilizes a three-dimensional asymmetric Archimedean M6 Copula to construct stochastic simulation models for peak flow, flood volume, and flood duration. Based on K-means clustering, a multivariate Gaussian Copula is employed to construct a dimensionless flood hydrograph stochastic simulation model. Furthermore, separate two-dimensional symmetric Copula stochastic simulation models are established to capture the correlations between flood intensity characteristics and shape variables such as peak shape coefficient, peak occurrence time, rising inflection point angle, and coefficient of variation. By evaluating the fit between the simulated flood characteristics and the dimensionless flood hydrograph, a complete flood hydrograph is synthesized, which can be applied in flood control dispatch simulations and other related fields. The feasibility and practicality of the proposed model are analyzed and demonstrated. The results indicate that the simulated floods closely resemble natural floods, making the simulation outcomes crucial for reservoir scheduling, risk assessment, and decision-making processes.

Pulp delignification and refining: impact on the supramolecular structure of softwood fibers

The effect on softwood fiber wall nanostructure of kraft cooking, oxygen delignification and refining was evaluated by X-ray scattering. A recently developed simulation method for modelling small angle X-ray scattering (SAXS) data was used to estimate the apparent average sizes of solids (AAPS) and interstitial spaces in the fiber wall (AACS). Fiber saturation point and wide angle X-ray scattering were also used to calculate the pore volume in the fiber wall and the crystallite size of the fibril, respectively. The experimental modelled SAXS data was able to give consistent values for each kraft-cooked and oxygen-delignified pulp. Kraft delignification seems to have the major influence on the fiber nanostructure modification, while oxygen delignification has little or no significant impact even for different kappa numbers. The particle sizes values were more stable than the cavities sizes and no significant differences were seen between different delignification processes, refining or delignification degree. Pulps evaluated after PFI-refining, showed an increase in the fiber wall porosity evaluated by FSP and an increase in the interstitial spaces in the fiber wall, while the crystallite size and the particle sizes were very little or not affected at all.

Gearing Effect in Clockwise Rotational Orthognathic Surgery.

The standard procedure for managing skeletal class III malocclusion is maxillary advancement with mandibular setback. Occlusal plane-altering orthognathic surgery, such as jaw rotation, is useful as well. Although clockwise jaw rotation is a common procedure, its mechanism has not been well investigated. With this study, the authors aim to introduce the gearing effect to correct class III malocclusion in Asians by maxillary posterior impaction using clockwise rotation without advancing the maxilla. Patients with class III correction with clockwise rotation of the maxillomandibular complex without maxillary advancement were included; those who underwent genioplasty were excluded. Various facial skeletal cephalometric landmarks were measured using artificial intelligence-based cephalometric analysis software. The gearing effect was determined by dividing the lower anterior facial height (LAFH) in relatively short and long groups compared with those in the anterior nasal spine to posterior nasal spine length. In a total of 29 patients, the amount of menton setback between group 1 ( n = 15; short LAFH) and group 2 ( n = 14; long LAFH) was 1.67 ± 0.66 and 2.74 ± 0.99 mm per 1 mm of posterior nasal spine impaction, respectively ( P = 0.002), and 1.58 (interquartile range, 0.78) and 1.95 (interquartile range, 1.05) mm per 1 degree of clockwise rotation of the palatal angle, respectively ( P = 0.007). The convexity of the A point was improved without any significant change in the sella-nasion-A point angle before and after surgery. This article addresses the scientific evidence regarding the impact of clockwise rotational orthognathic surgery based on the gearing effect. The mandibular setback turned out to be more effective in patients with a long LAFH. Risk, II.

Relationship between vertical facial morphology and dental arch measurements in class II malocclusion: a retrospective study.

To evaluate the relationship between dental arch measurements and the vertical facial pattern determined in skeletal Class II untreated patients. Lateral cephalograms and plaster models were obtained from 124 untreated female adults (average age: 17.6 ± 3.8 years). Class I (CI), Class II Division 1 (CII/1) and Class II Division 2 (CII/2) malocclusions were divided into three subgroups according to their vertical morphology as hypodivergent, normodivergent and hyperdivergent. The multivariate variance analysis (MANOVA) method was used in the comparison of measurement values according to vertical and sagittal morphology. The relationship between both A point-Nasion-B point (ANB) and Frankfurt-mandibular plane (FMA) angles and dental arch measurements was examined by Pearson correlation analysis. The significance level was received as p < 0.05. While vertical morphology has a statistically significant effect on mandibular arch length, sagittal morphology affects maxillary arch depth. The parameters influenced by both morphologies are maxillary and mandibular arch length, as well as maxillary intermolar width. The mandibular arch length was significantly shorter in hyperdivergent-CII-2 malocclusion (50.5 ± 7.4 mm). Larger values were obtained in both mandibular arch length and maxillary arch depth measurements in CII-1 malocclusion compared to CII-2 malocclusion. The maxillary intermolar width was significantly shorter in hypodivergent-CII-1 malocclusion (46.8 ± 3.4 mm), while it was higher in hypodivergent-CI malocclusion (51.1 ± 3.4 mm). The maxillary arch length was the lowest in hyperdivergent-CI malocclusion (63.1 ± 13.3 mm) and the highest in hypodivergent-CI malocclusion (72.8 ± 7.6 mm). Additionally, a positive but weak correlation was found between ANB and FMA angles. Dental arch measurements have been found to be affected by both vertical facial morphology and skeletal sagittal relationship. A positive correlation was found between ANB and FMA angles.

Effect of L5 spinal canal type on pedicle screw placement based on CT imaging: a retrospective clinical study.

The objective of this study was to investigate the optimal entry point and pedicle camber angle for L5 pedicle screws of different canal types. CT imaging data were processed by Mimics for simulated pedicle screw placement, and PD (Pedicle diameter), PCA (Pedicle camber angle), LD (Longitudinal distance), TD (Transverse distance), and PBG (Pedicle screw breach grade) were measured. Then they were divided into the Round group and Trefoil group according to the type of spinal canal. When comparing PD, PCA, LD, TD, and PBG, the two sides of the pedicle were compared separately, so they were first divided into the round-type pedicle group and the trefoil-type pedicle group. In the round-type pedicle group (n = 134) and the trefoil-type pedicle group (n = 264), there was no significant difference in PD and LD, but there was a significant difference in PCA between the two groups (t = - 4.072, P < 0.05). A statistically significant difference in the distance of the Magerl point relative to the optimal entry point (t = - 3.792, P < 0.05), and the distance of the Magerl point relative to the optimal entry point was greater in the trefoil-type pedicle group than in the round-type pedicle group. The optimal entry point for L5 is more outward than the Magerl point, and the Trefoil spinal canal L5 is more outwardly oriented than the Round spinal canal L5, with a greater angle of abduction during pedicle screw placement.