Skeletal Landmarks Research Articles

Facial asymmetry of the hard and soft tissues in skeletal Class I, II, and III patients

To investigate and compare the facial asymmetry (hard and soft tissues) among skeletal Class I, II, and III patients. A total of 221 subjects, including skeletal Class I (n = 80), skeletal Class II (n = 75), and skeletal Class III (n = 66), were included in the study. CBCT, 22 skeletal landmarks, and 10 soft tissue landmarks were used for the measurements and the asymmetry index was calculated to assess the facial asymmetry. Statistical analyses included one-way ANOVA, Kruskal–Wallis test, and Spearman correlation analysis. The skeletal Class III patients presented greater asymmetry than Class II patients for 10 hard tissue landmarks and 3 soft tissue landmarks (p < 0.05). High correlation of asymmetry was found between four soft tissue landmarks and their corresponding skeletal landmarks (rs ≥ 0.71), as well as Me and ANS (r > 0.86). The ANS and Me in 21.3% patients deviated to contralateral sides. The skeletal Class III patients had more facial asymmetry than the Class II patients. Soft tissues showed similar asymmetry as the underlying hard tissues rather than a compensation of the hard tissue asymmetry. The inconsistency in the deviation of Me and ANS may exacerbate facial asymmetry.

The relationship between eye canting and vertical craniofacial skeletal asymmetry in adult patients with dento-maxillofacial deformities

BackgroundWhether eye canting in patients with asymmetric dento-maxillofacial deformities is the result of anatomical asymmetry or a compensatory head position remains controversial. ObjectiveThis cross-sectional study aims to verify whether eye canting is correlated with craniofacial skeletal asymmetry. Methods & materialsThis study was performed by measuring the computed tomographic scans of 223 patients with dento-maxillofacial deformities in Mimics 21.0 software. First grouping was determined based on the intersection angle between the line passing through bilateral lateral canthus point and Frankfurt horizontal plane, and final grouping was based on measurements of the pregroups. ResultsThe patients were finally categorized into three groups: symmetry group (n = 163), asymmetry subgroups 1 (n = 33) and asymmetry subgroups 2 (n = 27). The results of multiple linear regression and comparisons among groups suggests the presence of orbital skeletal asymmetry in patients with eye canting and the eye canting is partly increment dependent of orbital skeletal asymmetry when using bilateral ears as the reference. The result also reveals that there is a greater angle between the line through bilateral ocular landmarks and the line through the bilateral ear landmarks in patients with ocular canting compared to patient without eye canting. ConclusionPatients with asymmetric dento-maxillofacial deformities and with eye canting have vertical asymmetry of the orbital and cranial skeletal landmarks. These symmetry differences between the eyes and ears may affect the overall craniofacial symmetry after orthognathic surgery

Predicting Mandibular Bone Growth Using Artificial Intelligence and Machine Learning: A Systematic Review

Introduction The accurate prediction of mandibular bone growth is crucial in orthodontics and maxillofacial surgery, impacting treatment planning and patient outcomes. Traditional methods often fall short due to their reliance on linear models and clinician expertise, which are prone to human error and variability. Artificial intelligence (AI) and machine learning (ML) offer advanced alternatives, capable of processing complex datasets to provide more accurate predictions. This systematic review examines the efficacy of AI and ML models in predicting mandibular growth compared to traditional methods. Method. A systematic review was conducted following the PRISMA guidelines, focusing on studies published up to July 2024. Databases searched included PubMed, Embase, Scopus, and Web of Science. Studies were selected based on their use of AI and ML algorithms for predicting mandibular growth. A total of 31 studies were identified, with 6 meeting the inclusion criteria. Data were extracted on study characteristics, AI models used, and prediction accuracy. The risk of bias was assessed using the QUADAS-2 tool. Results. The review found that AI and ML models generally provided high accuracy in predicting mandibular growth. For instance, the LASSO model achieved an average error of 1.41 mm for predicting skeletal landmarks. However, not all AI models outperformed traditional methods; in some cases, deep learning models were less accurate than conventional growth prediction models. Discussion. The variability in datasets and study designs across the included studies posed challenges for comparing AI models’ effectiveness. Additionally, the complexity of AI models may limit their clinical applicability. Despite these challenges, AI and ML show significant promise in enhancing predictive accuracy for mandibular growth. Conclusion. AI and ML models have the potential to revolutionize mandibular growth prediction, offering greater accuracy and reliability than traditional methods. However, further research is needed to standardize methodologies, expand datasets, and improve model interpretability for clinical integration.

Validation of Machine Learning Models for Craniofacial Growth Prediction.

This study identified the most accurate model for predicting longitudinal craniofacial growth in a Japanese population using statistical methods and machine learning. Longitudinal lateral cephalometric radiographs were collected from 59 children (27 boys and 32 girls) with no history of orthodontic treatment. Multiple regression analysis, least absolute shrinkage and selection operator, radial basis function network, multilayer perceptron, and gradient-boosted decision tree were used. The independent variables included 26 coordinated values of skeletal landmarks, 13 linear skeletal parameters, and 17 angular skeletal parameters in children ages 6 to 12 years. The dependent variables were the values of the 26 coordinated skeletal landmarks, 13 skeletal linear parameters, and 17 skeletal angular parameters at 13 years of age. The difference between the predicted and actual measured values was calculated using the root-mean-square error. The prediction model for craniofacial growth using the least absolute shrinkage and selection operator had the smallest average error for all values of skeletal landmarks, linear parameters, and angular parameters. The highest prediction accuracies when predicting skeletal linear and angular parameters for 13-year-olds were 97.87% and 94.45%, respectively. This model incorporates several independent variables and is useful for future orthodontic treatment because it can predict individual growth.

Surgical Anatomy of the Ligamentous Attachments in the Superoposterior Scalp Region.

Hairline-lowering surgery has become increasingly popular in recent years, but little investigation into the surgical anatomy of the scalp has been performed. The aim of this study was to describe findings based on clinical observation and anatomic study of ligamentous attachments in the superoposterior region of the scalp. Six fresh cadaveric heads were dissected to identify connective tissue structures in the superoposterior scalp region. The areas of interest were along the sagittal suture towards the lambda, the obelion, and around the lambdoid suture. The location and dimensions of identified connective tissue attachments were documented with reference to described skeletal landmarks. Three distinct structures could be identified: (1) a cylindrical structure that sits at the posterior end of the sagittal suture with the parietal foramina in its base. This ligamentous structure extends from the pericranium into the galea, causes dimpling in the skin, and contains emissary veins. As this fulfills the criteria for an osseocutaneous retaining ligament, the term "cranial retaining ligament" is proposed. (2) Anterior to this ligament a connective tissue thickening was identified running along the sagittal suture and blending into the ligament, for which the term "sagittal adhesion" is proposed. (3) Another adhesion was identified just superior to the lambdoid suture, posterior to the retaining ligament, for which the term "supralambdoid adhesion" is proposed. Identification and better understanding of ligamentous structures in the superoposterior scalp allows for a safer and more effective advancement of the scalp in hairline-lowering surgery, which is a benefit to both patients and surgeons.

Evaluation of optimal anterior-posterior position of upper incisors through ANS point: a retrospective study on a Chinese sample.

This study was designed to determine the optimal anterior-posterior (AP) position of upper incisors through Anterior Nasal Spine (ANS) point. Lateral cephalometric radiographic images of 690 patients were collected and divided into a derivation group and a validation group, and the former were subdivided into a proper AP position (PAP) group and an improper AP position (iPAP) group. The distance from facia-axis (FA) point of upper incisors to the line perpendicular to Frankfort horizontal (FH) plane through ANS (FA-ANS) was measured, and the relationship between FA-ANS and several cephalometric indices were studied through Pearson correlation analysis. Receiver operating characteristic (ROC) curves for different clinical indices were analyzed to evaluate the diagnostic efficiency of optimal AP position of upper incisors. The average value of FA-ANS in PAP group was 0.57±1.99, which was significantly different from FA-ANS in iPAP group. Cephalometric indices such as U1-NA, U1-SN, AB-NPo, UL-TVL, Wits, and ANB were found to be correlated with FA-ANS. The receiver operating characteristic (ROC) curves represented a greater diagnostic efficiency of FA-ANS compared with other clinical indices. ANS point, as a stable skeletal landmark, could be used to access an optimal AP position of upper incisors, providing aids to clinical diagnosis and treatment goal determination for clinical practice. A new index FA-ANS, together with other traditional indices, could help determine the optimal position of upper incisors and provide a personalized therapeutic plan.

Probing real-world Central European population midfacial skeleton symmetry for maxillofacial surgery.

Symmetry is essential for computer-aided surgical (CAS) procedures in oral and maxillofacial surgery (OMFS). A critical step for successful CAS is mirroring the unaffected side to create a template for the virtual reconstruction of the injured anatomical structure. The aim was to identify specific anatomical landmarks of the midfacial skeleton, to evaluate the symmetry in a group of the real-world Central European population, and to use these landmarks to assess midfacial symmetry in CT scans. The retrospective cross-sectional study defined landmarks of the midface's bony contour using viscerocranial CT data. The distances of the skeletal landmarks (e.g., the frontozygomatic suture and temporozygomatic suture) of the left and right sides from the midline were measured and statistically compared. Midfacial symmetry for reference points was defined as a difference within 0mm and their mean difference plus one standard deviation. We examined a total of 101 CT scans. 75% of our population shows symmetrical proportions of the midface. The means of the differences for the left and right sides ranged from 0.8 to 1.3mm, averaging 1.1 ± 0.2mm for all skeletal landmarks. The standard deviations ranged from 0.6 to 1.4mm, with a computed mean of 0.9 ± 0.3mm. We established a methodology to assess the symmetry of the bony midface. If the determined differences were equal to or lower than 2.5mm in the mentioned midfacial skeletal landmarks, then the symmetry of the bony midface was considered present, and symmetry-based methods for CAS procedures are applicable. Many CAS procedures require facial symmetry. We provide an easy-to-apply method to probe for symmetry of the midface. The method may be used for population-based research, to check for proper reduction of fractures after reposition or to screen for symmetry prior to CAS planning.

The Presence of Unusual Foramina in the Femoral Intercondylar and Trochanteric Fossae on Skeletonized Individuals from Tanzania

According to the standard nomenclature, skeletal land marks are all identified by their given names in the world of human skeletal anatomy. But it is also clear that the discovery of new anatomical features continues because human beings have so many anatomical variations caused by genetics, functions, geographical adaptations, and diseases; they are all described and given names. Therefore, an anatomical feature that is rare and undescribed is certainly a discovery and it deserves to be recorded. The discovery of anatomical features on the epiphyseial ends of the femur reported here adds two new names, namely the intercondylar fossa foramen and the trochanteric fossa foramen in that long list of human skeletal anatomical structures. The intercondylar fossa foramen is an outlet found in the intercondylar fossa of the distal femur. It passes through the diaphysis of the femur and emerges in the trochanteric fossa of the femoral neck; and vice versa is the trochanteric fossa foramen. This feature was first observed on one skeletonized archaeological individual and later on five cadaveric remains. There seems to be a presence of this anatomical variation within the Tanzanian population. Only a small percentage of people have this unusual anatomical feature of the intercondylar fossa foramen, which might be a developmental ossification failure or a particular genetic-based trait. These features were assessed in the laboratory of the Anatomy Department at the Muhimbili University of Health and Allied Sciences (MUHAS) using a Dino-lite digital microscope and X-ray images.

Multi‐feature gait analysis approach using deep learning in constraint‐free environment

AbstractA quantitative gait assessment system is crucial for clinical analysis and decision‐making. Such rigorous evaluation involves costly clinical setups and domain experts for observation and analysis. To circumvent such constraints, the proposed work is conducted in a markerless environment and divided into three stages: First, we prepared a markerless gait database using videos from MNIT RAMAN LABORATORY in Jaipur. Second, we adapt the skeletal landmark data to generate kinematic gait characteristics comparable to gold‐standard marker‐based techniques. We provide a novel set of parameters based on video sequences and spatiotemporal and sagittal kinematic parameters to optimize accuracy and reliability. Third, we develop multi‐feature based gait analysis, an ensemble model based on Convolutional Neural Networks + LSTM (Long‐Short Term Memory), for gait classification. In addition, we deployed transfer learning models to correlate with our ensemble model. The findings indicate that gait analysis can be used successfully in a low‐cost clinical gait monitoring system in a constraint‐free environment. While considering the multiple gait variables, our proposed model attained an accuracy of 95.3%. Our model for quantifying gait analysis will improve access to quantitative gait analysis in clinics and rehabilitation centers and enable researchers to conduct large‐scale studies for gait‐related disorders.

What Is the Linear Accuracy of Regional Voxel-Based Registration for Orthognathic Surgery Landmarks?

While regional voxel-based registration (R-VBR) has been shown to have excellent reproducibility and angular accuracy, there are limited data on the linear accuracy of R-VBR for common orthognathic surgery landmarks, or on whether angular accuracy correlates with linear accuracy. The purpose of this study was to estimate the linear accuracy of R-VBR for several skeletal landmarks commonly used in orthognathic surgical planning, and to measure the correlation between angular and linear discrepancies. This is a retrospective cross-sectional study of consecutive patients treated at a single center with nonsegmental LeFort I and bilateral sagittal split osteotomy surgery from January 2019 to November 2020. Cone beam computed tomography at the preoperative (T0) and immediate postoperative (T1) stages were analyzed to measure the postoperative positional changes of 11 orthognathic landmarks in 4 regions of interest (ROI) using R-VBR performed twice by two examiners. Pairwise correlation analysis and canonical correlation analysis were performed for the angular discrepancies (primary predictor variable) and the linear discrepancies (primary outcome variable) to measure the correlation between the two. In cone beam computed tomography analysis of 28 eligible subjects (16 males, 12 females; mean age 18.9years, range 15 to 25), the mean absolute (MA) angular discrepancies ranged from 0.15° to 0.55°, while the corresponding MA linear discrepancies ranged from 0.05 to 0.41mm. There was a strong correlation between angular and linear discrepancies that was statistically significant (P=.001 to .04, Spearman's rank correlation coefficient 0.38 to 0.87). For nonsegmental LeFort I osteotomies and bilateral sagittal split osteotomy, R-VBR has excellent linear accuracy within a single voxel size (0.3mm) for commonly used orthognathic landmarks in the maxillary and distal mandibular ROI. The MA linear discrepancy for the proximal mandibular segment ROI was greater than a single voxel size, with a maximum of 0.41mm.

Maxillary dimensions and arch shape with palatally displaced canines.

The aim of this study was to explore the effect of palatally displaced canines on maxillary dimensions and arch shape. Occlusal and skeletal landmarks were plotted on cone beam computed tomography (CBCT) images of 156 orthodontic patients: 78 with palatally displaced canines (PDC) (27 left, 28 right, and 23 bilateral) and 78 controls using Mimics™ (Materialise, Belgium). Arch forms were created, and arch width, depth, and skeletal dimensions were measured. T-test (P < 0.05) was used to compare the groups. Geometric Morphometrics (GM) analysis was used to compare the groups and to explore the pattern of covariation between two sets of landmarks. The unilateral PDC group showed an increased first premolar, second premolar, molar widths, and an increased molar depth. No significant difference was found in arch form. The skeletal measurements were generally larger in the PDC group, but the transverse measurements were the most significant. Discriminant Function Analysis (DFA) with cross-validation allowed an accurate classification of 85.9% of the control group and 66.7% of the PDC group. The Mahalanobis distance displayed significant differences among three combinations of groups. Strong covariance was found between the second premolar and all other landmarks. The small sample sizes of the stratified groups precluded recognition of statistical significance. Patients with unilateral PDC displayed significantly wider first, second premolar, and first molar widths, and increased first molar depths. There were no significant differences in arch form; however, GM showed significant differences between the groups and a prominent covariance function for the 2nd premolars.

Comparison of velopharyngeal morphology of two palatoplasty techniques in patients with hard and soft cleft palate.

The study aims to compare the velopharyngeal morphology of hard and soft cleft palate (HSCP) patients after Furlow and Sommerlad palatoplasty. A total of 51 patients (20 cases in Furlow palatoplasty group, 16 cases in Sommerlad palatoplasty group and 15 normal children in the control group) were included in our study. Velopharyngeal function and speech outcomes of patients with HSCP who had either Furlow palatoplasty or Sommerlad palatoplasty for cleft palate repair were evaluated by perceptual speech assessment (PSA), lateral cephalometric radiographs and nasopharyngoscopy. To assess velopharyngeal morphology of patients treated with two techqiques, we analyzed measurements such as velar length, pharyngeal depth, and the Adequate ratio (the ratio of velar length to pharyngeal depth). Furthermore, skeletal landmarks including cranial base, cervical vertebrae, posterior nasal spine which were defined as the pharyngeal triangle were measured. Finally, the position of the point U relative to the pharyngeal triangle were compared. Velopharyngeal closure (VPC) rate in Furlow palatoplasty group accounted for 90%, while that in Sommerlad palatoplasty group was 81.3%. PSA of the former group was significantly better than that of the latter group (P < 0.05). Velar length, pharyngeal depth and the Adequate ratio (1.37 ± 0.14 vs. 1.41 ± 0.15) were comparable between the Furlow group and control group (P > 0.05), while Sommerlad group had a shorter velar length, deeper pharyngeal depth and a smaller Adequate ratio (1.20 ± 0.18) compared to the above two groups (P < 0.05). Furhermore, the point U of Sommerlad group in the pharyngeal triangle was higher than that of the other two groups. In the treatment modality of patients with HSCP, both Furlow palatoplasty and Sommerlad palatoplasty seem to be effective. Furlow palatoplasty appears to have velopharyngeal morphology similar to normal control group., while Sommerlad group shows a shorter velar length, deeper pharyngeal depth and a smaller Adequate ratio.

Morphological evaluation of mental foramen using cone-beam computed tomography: A retrospective observational study

ABSTRACT Aim: This study aimed to assess the shape, size, symmetry, and location of mental foramen (MF) in relation to mandibular dental and skeletal landmarks using cone-beam computed tomography (CBCT). Methods: This retrospective observational study was performed on 135 CBCT images of 74 males (mean age 36.16 ± 13.49 years) and 61 females (mean age 37.13 ± 13.53 years). Two independent observers performed the morphometric measurements of MF using CBCT images using Invivo software. Independent t-test and Mann–Whitney test were employed to evaluate the gender differences. A comparison of categorical data was performed using Chi-square test. Intraclass correlation coefficient and Kappa statistics were used to assess interobserver reliability. Results: The most common horizontal and vertical location of MF was the long axis of the second premolars (52.2%) and below the bicuspid root apices (70%), respectively. The most common shape was round (56.6%). Significant gender differences were observed for the MF size (mean width 0.35 mm larger in males), the distance of MF to lower border of mandible (16.10 ± 1.77 mm in males and 14.81 ± 1.48 mm in females), and MF to pogonion (28 ± 2.13 mm in males and 26.62 ± 1.98 mm in females). The horizontal and vertical locations were bilaterally symmetrical in 67.4% and 79.26% of subjects, respectively. Conclusion: Right and left sides of the mandible require separate evaluations since there are differences in the location of the MF on each side. Gender differences were observed in location of MF in the relation to skeletal landmarks. Nevertheless, skeletal landmarks are reliable for locating the MF.

Lateral cephalometric values of FKG ULM students Banjar ethnic according to Steiner analysis

Objectives: This study aimed to determine the value of dentocraniofacial measurements of FKG ULM students from Banjar ethnic in terms of lateral cephalometric radiography using Steiner analysis.&#x0D; Materials and Methods: Cephalometric measurements were performed using the Steiner analysis method on skeletal landmarks: SNA, SNB and ANB; dental: UI-NA, LI-NB, and interincisal angle. Data analysis was performed by descriptive statistical method.&#x0D; Results: The average skeletal and dental value of the FKG ULM students from Banjar ethnic at the SNA angle is 86.31°± 4.49°, the SNB is 81.33°± 4.39°, the ANB is 4.98°± 2.05°, the UI-NA angle is 19.69°± 8.22°, the LI-NB angle is 28.65°± 6.76°, the UI-NA distance is 4.45± 2.86 mm, the LI-NB distance is 8.58± 3.19 mm and the interincisal angle is 126.43°± 10.51°.&#x0D; Conclusion: The dental and skeletal averages showed that the FKG ULM students from Banjar ethnic had more prognathic maxillary and mandibular positions and more protrusive maxillary and mandibular incisor positions than the normal standard of Steiner's analysis.

A Novel Method to Combine Maxilla-Based Coordinate System and Mandibular Voxel-Based Superimposition with Cone-Bean Computed Tomography.

Background: The objective of this study was to propose a method that combines a maxilla-based coordinate system and mandibular voxel-based superimposition for an accurate evaluation of mandibular structural and positional changes and a direct comparison between maxillary and mandibular structural changes with the same 3D vectors. Methods: Mandibular voxel-based superimposition was firstly performed to reorient the mandibles and eliminate the mandibular positional changes. Then, a maxilla-based coordinate system was constructed with four maxillary skeletal landmarks (ANS, PNS, OrL and OrR). After settling the reoriented mandibles into this coordinate system, the mandibular structural changes were accurately evaluated. To assess the accuracy and reproducibility of this method, CBCT images of a skull specimen before and after orthodontic treatment (which was simulated by rearranging the skull and the mandible) were collected. Five mandibular skeletal landmarks, three mandibular dental landmarks and two mandibular measurement planes of this skull were used to evaluate the linear and angular changes in the mandibular structures. Results: There were significant differences in the linear and angular measurements of the mandibular structures of the skull (p ˂ 0.05), which indicated mandibular positional changes after orthodontic treatment. After mandibular voxel-based superimposition, there were no significant differences in the linear and angular measurements of mandibular structures, which indicated that the mandibular positional changes were eliminated. The intraclass correlation coefficient (ICC) value of the inter- and intra-observer agreement of all measurements was 0.99. Conclusions: This method has proven advantages in terms of accuracy, reproducibility and validity; with this method, mandibular structural and positional changes can be accurately evaluated and maxillary and mandibular structural changes can be directly compared with same 3D vectors.

Evaluation of an individualized facial growth prediction model based on the multivariate partial least squares method.

To develop a facial growth prediction model incorporating individual skeletal and soft tissue characteristics. Serial longitudinal lateral cephalograms were collected from 303 children (166 girls and 137 boys), who had never undergone orthodontic treatment. A growth prediction model was devised by applying the multivariate partial least squares (PLS) algorithm, with 161 predictor variables. Response variables comprised 78 lateral cephalogram landmarks. Multiple linear regression analysis was performed to investigate factors influencing growth prediction errors. Using the leave-one-out cross-validation method, a PLS model with 30 components was developed. Younger age at prediction resulted in greater prediction error (0.03 mm/y). Further, prediction error increased in proportion to the growth prediction interval (0.24 mm/y). Girls, subjects with Class II malocclusion, growth in the vertical direction, skeletal landmarks, and landmarks on the maxilla were associated with more accurate prediction results than boys, subjects with Class I or III malocclusion, growth in the anteroposterior direction, soft tissue landmarks, and landmarks on the mandible, respectively. The prediction error of the prediction model was proportional to the remaining growth potential. PLS growth prediction seems to be a versatile approach that can incorporate large numbers of predictor variables to predict numerous landmarks for an individual subject.

DeepLabCut increases markerless tracking efficiency in X-ray video analysis of rodent locomotion.

Despite the prevalence of rat models to study human disease and injury, existing methods for quantifying behavior through skeletal movements are problematic owing to skin movement inaccuracies associated with optical video analysis, or require invasive implanted markers or time-consuming manual rotoscoping for X-ray video approaches. We examined the use of a machine learning tool, DeepLabCut, to perform automated, markerless tracking in bi-planar X-ray videos of locomoting rats. Models were trained on 590 pairs of video frames to identify 19 unique skeletal landmarks of the pelvic limb. Accuracy, precision and time savings were assessed. Machine-identified landmarks deviated from manually labeled counterparts by 2.4±0.2 mm (n=1710 landmarks). DeepLabCut decreased analysis time by over three orders of magnitude (1627×) compared with manual labeling. Distribution of these models may enable the processing of a large volume of accurate X-ray kinematics locomotion data in a fraction of the time without requiring surgically implanted markers.

Belt fit for children in vehicle seats with and without belt-positioning boosters

Objective The purpose of the current study is to use 3D technology to measure in-vehicle belt fit both with and without booster seats across different vehicles among a large, diverse sample of children and to compare belt fit with and without a booster. Methods Lap and shoulder belt fit were measured for 108 children ages 6–12 years sitting in the second-row, outboard seats of three vehicles from October 2017 to March 2018. Each child was measured with no booster, a backless booster, and a high-back (HB) booster in three different vehicles. Alternative high-back (HB HW) and backless boosters that could accommodate higher weights were used for children who were too large to fit in the standard boosters. Lap and torso belt scores were computed based on the belt location relative to skeletal landmarks. Results Both lap and torso belt fit scores were significantly different across vehicles when using the vehicle belt alone (no booster). In all vehicles, lap belt fit improved when using boosters compared with no booster among children ages 6–12 years in rear seats—with one exception of the HB HW booster in the minivan. Torso belt fit improved when using boosters compared with no booster in the sedan, and torso belt fit improved in the minivan and SUV with the use of HB and HB HW boosters when compared with no booster. Conclusions Lap and torso belt fit for children ages 6–12 years in rear seats was substantially improved by using boosters. Parents and caregivers should continue to have their children use booster seats until vehicle seat belts fit properly which likely does not occur until children are 9–12 years old. Decision makers can consider strengthening child passenger restraint laws with booster seat provisions that require children who have outgrown car seats to use booster seats until at least age 9 to improve belt fit and reduce crash injuries and deaths.

Evaluation and comparison of stresses and displacements generated by four different types of asymmetric maxillary expansion appliances in true unilateral crossbite using finite element method

True unilateral posterior crossbite can be efficiently treated by using asymmetric expansion appliances that essentially exert unilateral expansion forces thereby minimizing iatrogenic overexpansion of the normal pretreatment side. To evaluate and compare the stresses and displacements generated by four different types of asymmetric maxillary expansion appliances in true unilateral crossbite using the finite element method. A CBCT image of the skull was obtained from a 12-year-old female patient with a true unilateral posterior crossbite on the right side, for the FEM study. Asymmetrically split acrylic plate with jackscrew (ASAPJ), NORD crossbite expander, Asymmetric Maxillary Expansion appliance (AMEX), Asymmetrical Rapid Maxillary Expansion (ARME) appliances were simulated with a given force specific to the appliance. Von Mises stresses, displacements in the x, y, z-axis, and changes in the axial inclination were evaluated and compared on the selected skeletal and dental landmarks. Overall ARME seemed to generate the highest asymmetric von Misses stress on skeletal landmarks followed by NORD; ASAPJ and lowest by the AMEX. ARME also produced the highest asymmetric expansion followed by AMEX; NORD and lowest with the ASAPJ. NORD produced the minimum extrusion and buccal tipping of the canine and 1st molar followed by ASAPJ; AMEX and maximum by the ARME. Each of the four appliances expanded the maxillary arch more on the crossbite side as compared to the non-crossbite side, but the pattern of stress distribution, displacement and change in the axial inclination were unique for each appliance.

Development of a mannequin lab for clinical training in a chiropractic program.

Faced with COVID-19 safety protocols that severely limited the ability to conduct chiropractic technique instruction in the usual manner, our university invested the resources to develop a new mannequin lab for hands-on training, which would help supplement the loss of person-to-person contact. Training mannequins could enable student learning of palpation and adjustment skills while avoiding close human-human contact. The university had developed a mannequin over the previous 4 years consisting of a full-sized human torso with individually movable and palpable vertebrae, pelvis, and thighs. In the mannequin, 64 pressure sensors are attached to particular vertebral and skeletal landmarks and provide feedback on palpation location and level of force applied. We assembled 3 teams to produce 20 copies of that mannequin for student use. Mannequins were produced in 7 weeks, and space was built out for a special lab. Faculty members are developing classroom procedures to introduce the mannequin to students, phase in the skills from static and motion palpation, and practice thrust performance. The production run was successful, and the resulting equipment, well-received by students and faculty. In addition to helping teach manual skills, the lab serves as a platform for educational research to test the efficacy of mannequin-based training protocols. With the pressure sensors on known locations along the spine, future research may be able to test the ability of students to identify and contact specific target locations for adjustive thrusts.