Skeletal Angles Research Articles

Abnormal sitting posture recognition based on multi-scale spatiotemporal features of skeleton graph

To fuse the spatial dimension, temporal dimension, and whole-body skeleton features of human abnormal sitting posture to improve the recognition accuracy, we propose an abnormal sitting posture recognition method based on the multi-scale spatiotemporal features of skeleton graph (ASPR) from the perspective of changes of human posture. Firstly, we build a human abnormal sitting posture dataset (HASP) with multidimensional features. Then, based on the structure of high-to-low resolution subnetworks, we use the spatiotemporal graph convolution module as the feature extraction unit A multiple scale spatiotemporal feature extraction model based on graph convolutional network (M2SGCN) is proposed. It is used to capture the spatiotemporal features. Next, a feature extraction model of local skeletal angles based on recurrent neural network is proposed to capture the change rule of skeletal angles of human sitting posture. Finally, we investigate the optimal parameters of ASPR by checking its performance with different human skeleton combination schemes and different features fusion coefficient. Experiment results show that ASPR achieves excellent performance compared with four state-of-the-art models and their combined models. ASPR shows an average recognition accuracy, a recall rate, an F1 score, and average time of 95.24%, 95.61%, 95.14%, and 7.094 ms, respectively.

Correlation of skeletal and dental parameter in Sagittal plane

Background: The skeletal correlations in a sagittal plane do not correlate to the dental relationship each time. For orthodontic treatment planning, differential identification In the past, the terms overjet and overbite were used to examine sagittal jaw connections. The goal of the study was to see how closely a dental characteristic (overjet) correlated with skeletal angles (ANB, WITTS). Objectives: This research aims to see if occlusal characteristics are used in evaluating cranial and facial connections in the vertical and sagittal planes. The sagittal connection of upper with lower teeth is studied using the metrics overjet. Methodology: This study is done at the orthodontics department, Institute of Dentistry, LUMHS, Jamshoro. The total sample size was 110, random sampling technique was utilized to select the subject. For the patients coming to the orthodontic department data was collected from previous and new patients. The overjet and overbite value will be measured on dental casts using vernier caliper. The impression of patient will be taken by irreversible hydrocolloid and the cast will be poured with orthodontic hard plaster. This study also includes pre-treatment digital cephalometric xrays.

Comparison of Steiner Cephalometric analysis of lateral skull X-ray images with CBCT in a group of students of the dental school of the University of Cuenca

The Steiner analysis from images obtained from cone beam computed tomography is one of the essential tools today for diagnosis in the area of orthodontics, within this aspect its high value for the study of points, angles and cephalometric planes allows the prediction of the possible treatment plan for each patient according to the specific characteristics resulting in each patient. Objective: To compare the results in Steiner cephalometric measurements obtained in 2D lateral skull radiographs and in 3D cephalograms generated from Cone Beam Computed Tomography (CBCT). Methodology: Type of comparative analytical study. A non-probabilistic sample was established by convenience consisting of 29 diagnostic studies divided into: 29 lateral skull X-rays and 29 standardized CBCT. Subsequent localization, tracing and measurement of skeletal and dental angles were performed according to Steiner's cephalometric analysis using Nemostudio 2022 software. The study and analysis was performed using the Intraclass Correlation Coefficient. Results: The mean difference between the skeletal angles SNA, SNB, ANB, SND and Occlusal Plane Angle showed that there is no significant discrepancy when performing a cephalometric analysis in three-dimensional images compared to two-dimensional images. Conclusion: There is a high degree of reliability and accuracy of cephalometric measurements for obtaining skeletal and dental angles in two-dimensional images obtained from a CBCT with respect to a lateral radiograph.

Determining the Age Range Based on Machine-Learning Methods From Facial Skeletal Angles (Glabella and Maxilla Angle and Length and Width of Piriformis) in CT Scan

Background: One of the main steps in identifying a person in forensic medicine is determining the age of skeletal remains, including the skull. This study aimed to investigate the possibility of predicting age from facial angles (glabella, piriformis, and maxillary angle and measuring peripheral length and width) with artificial intelligence in a CT scan. Methods: The cross-sectional study method is simple random sampling using a questionnaire. Accurately measurable CT scan samples are selected. For exclusion criteria, gender uncertainty, and the possibility of measurement based on CT scan quality, the researchers examined the facial angles (angle of the glabella and maxilla and length and width of the piriformis) for 100 men and 100 women. The Mean±SD of the age was 39.16±2.22 years for men and 47.84±2.46 years for women. The samples were classified based on age differences, and then the data were analyzed using machine learning algorithms to determine the age group. Results: After determining the exact amount of measurement, the data were evaluated by machine learning algorithms to determine the age group. Accordingly, in the age group classification based on the World Health Organization (WHO) (with an age difference of 10 years) (years±5) with 100% accuracy and in the second classification (with an age difference of 5 years) (years±2.5) with 88% accuracy and 79% precision of the age group was predicted. Conclusion: The obtained data show the importance of new artificial intelligence methods, including machine learning, in providing new methods to determine age groups (age±2.5) through skull angles with high accuracy in cases where even cranial remains are found in identification in forensic medicine.

Rehabilitacja narządu żucia w przypadku wrodzonej obustronnej agenezy kłów stałych – opis przypadku

Bilateral agenesis of the permanent maxillary canines in healthy individuals is extremely rare. This paper presents the case of a Polish patient diagnosed with congenital bilateral agenesis of the permanent maxillary canines as well as occlusal abnormalities in the form of left-side crossbite. To restore proper aesthetics and function, interdisciplinary therapeutic treatment was implemented. In the case presented in this paper, the aim of oral rehabilitation was to restore a functional balance by obtaining proper skeletal relationships, create optimal occlusal conditions and obtain arch continuity. After a course of orthodontic treatment involving fixed appliances on both dental arches, implantation was performed in positions 13 and 23, followed by prosthetic reconstruction. A comparative analysis of lateral cephalometric radiographs taken before the orthodontic treatment and after the completion of the combined orthodontic and implant-prosthetic treatment showed stable skeletal relationships. The values of the skeletal angles did not change, whereas the value of angle H, which describes the position of the upper lip in relation to Ricketts’ e-line, increased from 1.4° to 2.8°, which reflects an improvement in facial profile aesthetics. In the case of maxillary canine agenesis accompanied by malocclusion, interdisciplinary treatment is recommended in order to achieve optimum aesthetic and functional results.

The inclination of mandibular incisors revisited

To reassess the inclination of lower incisors and evaluate possible associations with gender, age, symphyseal parameters, and skeletal pattern. Twelve hundred and seventy-two (605 females, 667 males) cephalograms of untreated subjects of a craniofacial growth study (age: 8-16 years) were evaluated. Correlations between the angulation of the lower incisors and age, symphyseal distances (height, width, and depth), symphyseal ratios (height-width, height-depth), and skeletal angles (divergence of the jaws and gonial angle) were investigated for all ages separately and for both sexes independently. The inclination of lower incisors increased over age (8 years: girls = 93.9° [95% CI, 92.3°-95.7°], boys = 93.3° [95% CI, 91.8°-94.9°]; 16 years: girls = 96.1° [95% CI, 94.1°-98.2°], boys = 97.1° [95% CI, 95.6°-98.6°]). Inclination of lower incisors correlated with the divergence of the jaws for all ages significantly or highly significantly, except for boys and girls 9 years of age and girls 11 and 12 years of age, for which only a tendency was observed. Similarly, a strong correlation to gonial angle could be observed. No correlation could be found between the inclination of lower incisors and any symphyseal parameters (absolute measurements and ratios), except for symphyseal depth. Lower incisor inclination is linked to the subject's sex, age, and skeletal pattern. It is not associated with symphyseal dimensions, except symphyseal depth. Factors related to natural inclination of lower incisors should be respected when establishing a treatment plan.

Morphological and Functional Parameters in Patients with Tooth Wear before and after Treatment

Advanced tooth wear often results in lost vertical dimension and impacts facial aesthetics. Complex restorative treatment can replace the lost tooth structure and improve functional occlusal and facial skeleton parameters.Purpose:The aim of the study is to assess changes in the morphological and functional occlusal parameters of the facial skeleton after prosthetic rehabilitation that increased lost occlusal vertical dimension.Material and Methodology:50 patients with advanced tooth wear were clinically examined, to assess the degree of wear. Each subject underwent cephalometric analysis, digital occlusal analysis, and electromyographic analysis, of the anterior temporalis, superficial masetter, anterior digastric, and the sternocleidomastoid muscles. Prosthodontic treatment was performed to restore the occlusal vertical dimension of each subject’s occlusion, which was followed by repeating the pretreatment analyses. Pre and post treatment parameters were statistically compared.Results:Pre-treatment cephalometric analysis showed that lost vertical dimension reduced anterior facial height and resulted in small angular skeletal parameters. Post treatment anterior facial height increased from the increased occlusal vertical dimension. The mean value of functional electrical activity during clenching post treatment, increased compared to pretreatment.Conclusion:Increasing the vertical dimension of occlusion improved facial aesthetics by positively affecting facial skeletal angles. The restored occlusal surface morphology changed the pre treatment flat broad occlusal contacts into more point contacts. The increased vertical dimension of occlusion after treatment also increased muscle activity levels over the pretreatment levels after three months period of adaptation.

Cranial base morphology in different skeletal classes (A cross-sectional lateral cephalometric study)

It was stated in scientific literatures that the entire craniofacial complex is influenced by the growth of the cranial base structures. Nevertheless, many times this is not the case, and this point is subject to great controversy so the aim of this study is to evaluate the possible differences in cranial base shape and flexure between different skeletal classes for both genders and to investigate any possible correlation between cranial base variables and other skeletal base variables. Materials and Methods: The sample include 75 lateral cephalometric radiographs of Iraqi adults aged between 18-25 years (39 males, 36 females), collected from patients and undergraduate students in the orthodontic department of College of Dentistry-Baghdad University. The total sample was divided to three major categories depending on ANB angle and dental occlusion into class I control group (12 males, 13 females), class II group (13 males, 12 females) and class III group (14 males, 11 females). Results: The results revealed that no significant difference in all the angular measurements of both skeletal and cranial bases existed between genders, while all linear and area measurements were usually higher in males than females and there was no significant difference in all the skeletal and cranial bases angles existed between different skeletal classes in both genders meaning that there is no relationship between cranial base flexure and skeletal classes. The angles N-S-Ar, N-S-Ba and SN-FH were always correlated negatively with both the angles SNA and SNB in all skeletal classes for both genders, while the angle SBa-FH showed weaker correlation with the angles SNA and SNB than the angle SN-FHin all skeletal classes for both genders. Conclusion: Cranial base flexure is not the main cause of skeletal malocclusions.

Cross-Sectional Growth Changes in Skeletal and Soft Tissue Cephalometric Landmarks of Children

In order to provide standard values for craniofacial growth of normal children, we evaluated the growth changes of skeletal and soft tissue cephalometric landmarks from lateral cephalograms of 180 Japanese children. They were divided into three groups: primary dentition, mixed dentition, and permanent dentition. Specific skeletal angles and distances showed significant gender differences with increasing age. The only significant soft tissue gender difference was nose height in the oldest group. Upper pharynx dimension and nose height differed significantly among the groups in both genders. Positions of both the upper and lower lip changed significantly between the intermediate and oldest groups of both genders. Nasolabial angle did not change significantly with growth. The results of this study should be useful for predicting craniofacial growth and development or determining the effect of orthodontic treatment.

An ab initio study of the structure and methyl rotational barriers of methylphosphonic dihalides

The molecular structure and the barriers to methyl rotation of symmetric methylphosphonic dihalides (CH 3POX 2, X=F, Cl, Br) and of the corresponding non-halogenated molecule (methyl phosphine oxide, X=H) were determined through ab initio calculations at the MP2/6-31+G(2d,p) level. The four molecules adopt the staggered conformation, with skeletal angles decreasing in the order OPC ˆ > OPX ˆ > XPC ˆ > XPX ˆ . The strong electron-withdrawing effect of the halogen atoms decreases the electron density on the oxygen atom, and increases the double bond character of the phosphoryl group. This, in turn, leads to an increase of the hyperconjugative interactions between this group and the two C–H bonds lying out of the OPC plane, and results in a slight lengthening of these bonds relative to the in-plane C–H bond. Methyl rotations were followed by means of intrinsic reaction coordinate calculations (IRC), and the calculated energy barriers were 1.61, 2.41, 2.77 kcal/mol for the difluoride, dichloride and dibromide, respectively, and 2.01 kcal/mol for methyl phosphine oxide. Structural evidences suggest that hyperconjugation stabilizes the transition structure for methyl rotation in the difluoride molecule, which explains the comparatively low value of its rotational barrier.

The effect of education on backpack wearing and posture in a middle school population

{\it Purpose:} The effect of education on proper wearing of a backpack was studied to determine whether or not a middle school population would improve posture during load carriage by maintaining a more natural posture and to determine if schoolchildren would comply with proper backpack wearing. {\it Method:} 17 middle school children with a mean age of 12.7 years were randomized into control and intervention groups. Participants were videotaped in four conditions from an anterior view and from a lateral view. Members of both groups participated in Sessions A and C, which consisted of videotaping of the four conditions. Intervention members additionally participated in Session B, consisting of education on how to wear a backpack properly. All participants were interviewed concerning their participation and its effect on how they wore their backpack. Video footage was analyzed to calculate the change in skeletal angles as a result of different methods of load carriage. Interview data was coded and analyzed. {\it Results:} No quantitative significance was found between control and intervention groups in regards to education on proper backpack wearing improving posture. Interviews revealed that intervention group members benefited from the education on proper wearing of a backpack. 87.5% of the intervention group members proceeded to continue wearing the backpack properly after the education intervention. {\it Conclusions:} Education regarding proper wearing of a backpack may impact the middle school aged child by improving quality of life as noted through decrease in reports of musculoskeletal pain by participants.

Validity of cephalometric landmarks. An experimental study on human skulls.

Cephalometric landmark validity (the difference between the estimated landmark and the true landmark) has surprisingly not previously been comprehensively evaluated, and no previous study has examined the validity of cephalometric angles and distances. The aim of this study was to investigate the validity of 15 commonly used skeletal and dental cephalometric landmarks, and the subsequent effects on 17 angles and distances. Small steel balls were glued on to 30 Chinese dry skulls to represent the true anatomical landmarks. The skulls were mounted in a purpose-designed skull holder and two cephalograms recorded of each skull, one with and one without the steel balls on the landmarks. Validity was expressed as the difference in the measurements between the assessments made with and without the steel ball markers. Measurements were made relative to X and Y co-ordinates which were constructed from reference points (steel balls) glued intracranially to the skulls. Seven out of the 10 skeletal landmarks and all five dental landmarks, were found to be non-valid along the X or the Y axes (P < 0.05). The standard deviations of the validity errors were large, being 1.0-2.5 mm, along at least one axis, for eight of the skeletal landmarks and three of the dental landmarks. Four of the cephalometric angles (SNA, SN/MnP, MxP/MnP, and LI/MnP) and three of the distances (N-Me, MxP-Me, and lower incisor edge to APg) were also found to be invalid (P < 0.05). The validity errors were greater for angles involving dental landmarks and for angles dependent on four landmarks compared to those dependent on three. The standard deviations of the validity errors for the skeletal angles ranged from 0.9 to 1.8 degrees, except for ANB (0.4 degrees), and for the dental angles from 3.2 to 5.8 degrees.

Crystal structure of polychlorotrifluoroethylene

AbstractThe crystal structure of polychlorotrifluoroethylene has been studied. The pseudohexagonal lattice parameters are a = 6.438, c = 41.5 Å. The polymer chain is found to be helical with on the average 16.8 monomer units in one turn of the helix (equal to c). The skeletal angles on the CF2 and CFCI atoms are found to differ by 5 to 7 degrees. The polymer chain is found to accommodate these alternating angles by twisting around the axis of the helix. The result of the x‐ray diffraction study agrees best with the assumption that the polymer is atactic with random position of the chlorine substituent. This randomness affects the microstructure of the polymer chain to such an extent that the diffraction effects are those of a system of continuous helices.

Maximum overlap hybridization in cyclopropane and some related molecules

The hybridization in cyclopropane, spiropentane, nortricyclene and 1,1 -dimethyl cyclopropane is calculated applying the criterion of maximum overlap. The s-p content in the general hybrids is found to be sensitive to changes in the interorbital angle Θ ij. The results give information about the strain associated with bent bonds and its delocalization. The application also allows calculations of skeletal angles, such as ∢ C1 C2 C3 in nortricyclene, which determine the geometry of the molecule.