Lateral Excursion Research Articles

Responses of Vehicular Occupants During Emergency Braking and Aggressive Lane-Change Maneuvers.

To validate active human body models for investigating occupant safety in autonomous cars, it is crucial to comprehend the responses of vehicle occupants during evasive maneuvers. This study sought to quantify the behavior of midsize male and small female passenger seat occupants in both upright and reclined postures during three types of vehicle maneuvers. Volunteer tests were conducted using a minivan, where vehicle kinematics were measured with a DGPS sensor and occupant kinematics were captured with a stereo-vision motion capture system. Seatbelt loads, belt pull-out, and footrest reaction forces were also documented. The interior of the vehicle was 3D-scanned for modeling purposes. Results indicated that seatback angles significantly affected occupant kinematics, with small female volunteers displaying reduced head and torso movements, except during emergency braking with a upright posture seatback. Lane-change maneuvers revealed that maximum lateral head excursions varied depending on the maneuver's direction. The study concluded that seatback angles were crucial in determining the extent of occupant movement, with notable variations in head and torso excursions observed. The collected data assist in understanding occupant behavior during evasive maneuvers and contribute to the validation of human body models, offering essential insights for enhancing safety systems in autonomous vehicles.

An investigation of machine learning algorithms for prediction of temporomandibular disorders by using clinical parameters.

This study aimed to predict temporomandibular disorder (TMD) using machine learning (ML) approaches based on measurement parameters that are practically acquired in clinical settings. 125 patients with TMD and 103 individuals without TMD were included in the study. Pain intensity (with visual analog scale), maximum mouth opening (MMO) and lateral excursion movements (with millimeter ruler), cervical range of motion (with goniometer), pressure pain threshold (PPT; with algometer), oral parafunctional behaviors (with Oral Behaviors Checklist), psychological status (with Hospital Anxiety and Depression Scale), and quality of life (with Oral Health Impact Profile) were evaluated. The measurements were analyzed via over 20 ML algorithms, taking into account an extensive parameter tuning and cross-validation process. Results of variable importance were also provided. Bagging algorithm using Multivariate Adaptive Regression Spline (MARS) algorithm (accuracy = 0.8966, area under receiver operating characteristic curve = 0.9387, F1-score = 0.9032) was the best performing model regarding the performance criteria. According to this model, the 5 most important variables for predicting TMD were pain intensity, MMO, lateral excursion and PPT values of masseter and temporalis anterior muscles, respectively. The Bagging algorithm using the MARS algorithm is a robust model that, in combination with clinical parameters, assists in the detection of patients with TMD in settings with limited capabilities. The clinical parameters and ML algorithm proposed in this study may assist clinicians inexperienced in TMD to make a preliminary detection of TMD in clinics where diagnostic imaging tools are limited.

Simultaneous recording of lateral excursions using motion tracking technique

Simultaneous recording of lateral excursions using motion tracking technique

Influence of the surrounding environment on the response of seated midsize male volunteers subjected to lateral sled accelerations

Predicting vehicle occupants’ posture during evasive manoeuvres is crucial for assessing their safety in the event of a collision. Volunteer experiments have been performed in the past under lateral accelerations, both within a vehicle cabin and on a seat mounted on a sled. However, discrepancies in the volunteer responses between both setups have been identified. This study hypothesizes that the response of the volunteers differs as a consequence of the proximity to the frame in the vehicle cabin, in comparison to the absence of such a structure on the sled.The present study conducted a novel sled experiment, on which five volunteers with anthropometry comparable to the 50th percentile male were subjected to 0.3 g lateral accelerations, with three different surrounding environments. In twelve pulses, an additional lateral structure was placed to the right or left side of the seated volunteers. The volunteers were asked to either brace or relax their muscles.The results show significant differences between the configurations with and without the structure placed on the right side. This effect was observed for both the lateral excursion of the upper body and the corresponding rotation when the volunteers were relaxed (p < 0.01). The average maximum lateral head rotation decreased from 27° to 14° with the structure on the right. No significant difference in head rotation was found for the braced muscle configuration.This study supports the hypothesis that the proximity to a surrounding environment influences human responses during dynamic loading. Nevertheless, there was no significant difference in maximum muscle activation between the configurations, but a faster reaction of the sternocleidomastoid muscle with the presence of the structure.

TMJ Changes Before and After Implant of Posterior Partial Edentulous Patients Free of TMD Signs Under the Scope of Cadiax Compact II Device

Introduction: Assessing occlusion and TMJ discrepancies presents a persistent challenge for health professionals due to the complexity of the conditions that include accurate: diagnostic methods, treatment, associated comorbidities. Researches are being delved in this field. Cadiax Compact II is one of the technological innovations that can analyze and provide a simple and minimally invasive way, enabling early preventive action and treatment with a long-term impact on the good functioning of the masticatory system. Objectives: The objective of this research is to evaluate TMJ changes among dental implant patients. A comparison of the implant impact on posterior partial edentulous patient is taken place by the aid of Cadiax Compact II. Cadiax Compact II investigates in parameters such as Immediate Side-Shift (ISS), Sagittal Condylar Guidance (SCG), and Transverse Condylar Guidance (TCG) that are derived from mandible movements (opening, closing, protrusion, retrusion, and lateral excursion). The objective is to evaluate the changes in TMJ before and after implants in partial edentulous (posterior teeth) patients. Methods: Condylography using Cadiax Compatct II device (Gamma Dental, Klosterneuburg, Austria) was conducted on 40 patients. R statistical software was used to perform statistical analysis to perform a cephalometric analysis. Results: Age groups covered are (&lt;40), (40-49), (50-59), and (≥ 60). Alpha value, level of uncertainty, was chosen to be 0.05. There is no statistical evidence in the change of ISS, SCG, and TCG before and after implant in the age groups (&lt;40) and (40-49); however, there is a significant statistical change in age groups (50-59) and (≥ 60) with p-value &lt;0.05. Conclusions: This research extended from December 2022 to March 2024 to cover time changes on mandible bone structure. The research outcomes revealed that implant has pronounced impact on TMJ articulation during opening, protrusion, retrusion, and lateral movements through (ISS, SCG, and TCG or so-called Bennet Angle) variables. Evidence-based statical tests with p-value &lt; 0.05 showed that (ISS, SCG, TCG, and Bennet Angle) variables changed in age groups (50-59) and (≥ 60) from abnormal ranges to the normal ranges after implant. However, no statistical evidence was approved of the implant impact on age groups (&lt;40) and (40-49). Though these age groups have normal ranges before and after implants.

Assessment of the role of coronoid in restrictive jaw disorders and physiologic mandibular movements

Introduction: Restricted mouth opening has major health implications, such as malnutrition, difficulty in speech, and poor oral hygiene resulting in a functional shortage of the masticatory system. Reduced mouth opening can occur due to trismus, as in the oral submucous fibrosis (OSMF) condition. Excision of fibrous bands in OSMF leads to reestablishment of the mouth opening. Other than trismus, temporomandibular joint (TMJ) ankylosis is another common condition that causes fibrosis or bony ankylosis between articular surfaces. Coronoidectomy is a useful procedure that various authors nowadays apply. It is the most popular surgical procedure used as a conventional method of treatment, which includes the detachment of temporalis muscle. Materials and Methods: A group of 15 patients with OSMF and TMJ ankylosis with written informed consent were selected for the study and were operated on under general anesthesia. Preoperative and postoperative assessment was done for bite force management, measuring and comparing mandibular movements, and the electromyography (EMG) study. Results: Statistical analysis shows the increase in maximum mouth opening and lateral excursions in OSMF and TMJ ankylosis patients on the seventh, 15th, 90th days, and six months postoperatively treated either without coronoidectomy and with coronoidectomy; however, there was no significant difference was found in mean EMG and bite force readings in both groups. Conclusion: The present study concludes that the coronoidectomy not only increases the mouth opening, but masticatory efficacy is also improved with an increase in mandibular movements postoperatively in patients with OSMF and TMJ ankylosis.

An evaluation of a bespoke modified UCBL foot orthosis on subjects with flat foot using kinetic measurements and user comfort scores: A randomized controlled trial

AimThe purpose of this study was to assess and evaluate the effect of a bespoke Modified UCBL Foot Orthosis (MUFO) using both kinetic parameters (Centre of Pressure (CoP) and the Ground Reaction Force (GRF) pattern) and comfort scores in subjects diagnosed with flat foot. MethodThis study included thirty-four young adults with symptomatic flatfeet. Two Kistler force plates (100 Hz) were used to record the CoP sway and GRF pattern during four conditions; 1) an MUFO and standard-fit shoe; 2) the University of California-Berkley Lab (UCBL) insole and standard-fit shoe; 3) barefoot and 4) standard-fit shoe only. The magnitude of subject comfort with UCBL and MUFO also was measured by a 10 cm Visual Analogue Scale (VAS) during walking. ResultsThe MUFO decreased mean lateral displacement in the initial phase and midstance of gait compared to barefoot walking. During the propulsion phase use of the new MUFO produced more lateral excursion with a mean difference of 3 mm) P < 0.001(compared to barefoot walking and standard shoe wear. No significant difference in comfort rate was found between the MUFO and UCBL (P = 0.165). ConclusionThe MUFO produced effective pronation control and decreased the CoP displacement in all of stance phase.

Turbulence effect on disk settling dynamics

Turbulence can have a strong effect on the fall speed of snowflakes and ice crystals. In this experimental study, the behaviour of thin disks falling in homogeneous turbulence is investigated, in a range of parameters relevant to plate crystals. Disks ranging in diameter from 0.3 to 3 mm, and in Reynolds number $Re = 10\unicode{x2013}435$ , are dispersed in two air turbulence levels, with velocity fluctuations comparable to the terminal velocity. For each case, thousands of trajectories are captured and reconstructed by high-speed laser imaging, allowing for statistical analysis of the translational and rotational dynamics. Air turbulence reduces the disk terminal velocities by up to 35 %, with the largest diameters influenced most significantly, which is primarily attributed to drag nonlinearity. This is evidenced by large lateral excursions of the trajectories, which correlate with cross-flow-induced drag enhancement as reported previously for falling spheres and rising bubbles. As the turbulence intensity is increased, flat-falling behaviour is progressively eliminated and tumbling becomes prevalent. The rotation rates of the tumbling disks, however, remain similar to those displayed in still air. This is due to their large moment of inertia compared to the surrounding fluid, in stark contrast with studies conducted in water. In fact, the observed reduction of settling velocity is opposite to previous findings on disks falling in turbulent water. This emphasizes the importance of the solid-to-fluid density ratio in analogous experiments that aim to mimic the behaviour of frozen hydrometeors.

Treatment of temporomandibular joint internal derangement using MESNA injection

IntroductionThe development of temporomandibular disorders specifically emphasizes the biochemical changes occurring in the synovial fluid at different stages of temporomandibular joint disease. Research has indicated that inflammation may be a primary reason behind the pain and dysfunction in temporomandibular joint diseases. Since its clearance several years ago, MESNA (sodium 2-mercaptoethanesulfonate) has been used in various formulations as a mucolytic drug in the respiratory domain. It operates by disrupting the disulfide bonds present between polypeptide chains within mucus. MESNA exhibits minimal tissue distribution, with the material being swiftly and thoroughly eliminated via the kidneys.ObjectivesTo assess the efficacy of injecting MESNA directly into the Temporomandibular Joint to treat internal derangement.Materials and methodsA randomized clinical trial was conducted on sixty patients who exhibited non-responsiveness to conventional treatment and were diagnosed with TMJ anterior disc displacement with reduction. The patients were chosen from the outpatient clinic of the Oral and Maxillofacial Surgery Department at Tanta University Faculty of Dentistry. Two equal groups of patients were randomly assigned to each other. Group I (Mesna group) received intra-articular injection with MESNA solution. Group II (Standard group) received arthrocentesis with lactated ringer solution followed by injection of Hyaluronic Acid (HA). The data was gathered by functional examinations such as maximum interincisal opening (MIO) and clicking. A Visual Analogue Scale (VAS) assessed pain severity before and after treatments.ResultsBoth MESNA and HA showed significant improvement up to six months of the follow-up compared to preoperative status, as evidenced by better mouth opening, lateral excursion, lower clicking, and reduced pain score in patients with TMDs. MESNA showed significant improvement during follow-up compared to HA.ConclusionCompared to HA, MESNA showed a more noticeable improvement during the follow-up period.

Clinical effectiveness of polynucleotide TMJ injection compared with physiotherapy: a 3-month randomised clinical trial

Joint visco-supplementation is an effective therapeutic approach against the degenerative signs and symptoms of osteoarthrosis/osteoarthritis of the mandibular condyle. Supplements of choice are usually delivered inside the temporomandibular joint (TMJ) by intra-articular infiltration. The present study aimed to assess the clinical effectiveness of pericapsular injection of polinucleotides (PN) and hyaluronic acid (HA). Sixty patients suffering from TMJ osteoarthrosis were recruited and divided into two groups (test group: n = 30, pericapsular injection; control group: n = 30, self-delivered physiotherapeutic exercises). For each patient, maximum opening, right and left lateral excursion, and visual analogue scale (VAS) scores were recorded at four different timepoints by a blinded investigator. Paired Student’s t tests were used to compare consecutive measurements of the parameters evaluated within the groups, and unpaired Student’s t tests were used for between-group comparisons. All investigated parameters displayed a progressive clinical improvement in both groups, which was more accentuated in the test group. The decrease in VAS score differed significantly between groups (p < 0.0001). Maximum opening showed a continuous increase from baseline (mean (SD) 37.70 (8.33) mm) to T3 (39.68 (7.64) mm), reflecting a progressive improvement, but it was not statistically significant (p = 0.089 at T3 with respect to T0). PN HA pericapsular injection is a minimally invasive treatment that effectively reduces pain and improves mandibular kinematics.

Assessment of Long-Term Effects and Patient Satisfaction following TMJ Disc Replacement Surgery

ABSTRACT Objectives: The purpose of this research is to evaluate patient satisfaction and long-term consequences after temporomandibular joint (TMJ) disc replacement surgery in a tertiary care environment. Methods: 500 patients who had TMJ disc replacement surgery at a tertiary care facility between 2010 and 2015 were the subject of a retrospective investigation. Pre-operative clinical features, demographic information, and intraoperative information were gathered. Standardized measurements were used to evaluate functional results, pain levels, and patient-reported outcomes. Descriptive statistics, paired t-tests, and significance set at P &lt; 0.05 were all used in the statistical analysis. Results: There were notable improvements in functional outcomes, with a mean increase in lateral excursion from 8.7 mm to 12.6 mm (P &lt; 0.001) and maximal incisal opening from 30.5 mm to 40.2 mm (P &lt; 0.001). The pain level was found to have greatly diminished, as evidenced by the VAS scores falling from 7.8 to 3.2 (P &lt; 0.001). The Jaw Function Limitation Scale scores (42.6 to 21.8, P &lt; 0.001) and patient-reported outcome measures scores (58.3 to 76.5, P &lt; 0.001) exhibited significant increases in patient-reported outcomes. Conclusion: In conclusion, tertiary care TMJ disc replacement surgery shows positive long-term outcomes, such as enhanced jaw function, less discomfort, and high patient satisfaction. This research supports the ongoing use of TMJ disc replacement surgery as a potential therapy for refractory TMJ disease, although noting its limitations.

The Chimeric LFC and DCIA Flap in Combined Mandibular and Condylar Head and Neck Reconstruction-A Case Series.

Background: Defects of the ascending ramus of the mandible, including the condylar head and neck or the whole temporomandibular joint (TMJ), are difficult to reconstruct. Reconstruction is mainly based on the use of alloplastic joint prosthesis, costochondral grafting, distraction osteogenesis of the dorsal part of the mandibular ramus, or osseous microvascular flaps of various origin. With the objective of developing a method that overcomes the restrictions of these methods, we recently introduced a sequential chimeric flap consisting of a lateral femoral condyle flap (LFC) and deep circumflex iliac artery flap (DCIA) for reconstruction of up to half of the mandible and the condylar head and neck. Methods: The chimeric flap was used in four patients with the following diagnoses: therapy-refractory osteomyelitis, extended recurrent odontogenic keratozyst, Goldenhar syndrome, and adenocarcinoma of the parotid gland. After a diagnostic workup, LFC and DCIA flaps were harvested in all patients and used in a sequential chimeric design for the reconstruction of the mandibular body and condylar head and neck. Results: Follow-up from at least 24 months up to 70 month after surgery showed a successful reconstruction in all four patients. The LFC provided a cartilaginous joint surface, allowing for a satisfactory masticatory function with a stable occlusion and unrestricted mouth opening and preserved or regained lateral and medial excursions in all patients. The DCIA allowed for a bony reconstruction anatomically resembling a non-atrophied mandibular body. No flap-related complications were observed. Conclusions: The sequential chimeric LFC and DCIA flap is an appropriate method for reconstructing up to half of the mandible and the condylar head and neck. It is suitable in cases where alloplastic joint replacement cannot be used or where other methods have failed. Due to the necessity of harvesting two flaps, the burden of care is increased, and a careful indication is required. The technique is reserved for maxillofacial surgeons who have already gained significant experience in the field of microsurgery.

The effect of reclined seat-back angles on the LODC with and without a belt-positioning booster during far-side lateral-oblique impacts

Objective In frontal crashes belt-positioning boosters (BPB) may prevent submarining when the seatback is reclined. It is unclear if the BPB can also mitigate injuries in far-side lateral-oblique crashes in reclined conditions, where current restraints are less effective in reducing lateral excursion. This study aimed to understand reclined child injury risk during lateral-oblique impacts, with and without a booster seat, by using the Large Omni-Directional Child (LODC) test device. Methods The LODC was tested in nine lateral-oblique impact (80° from frontal) sled tests (target 31.3 km/h, duration 58 ms maximum, peak acceleration 21 g). Three seatback angles (25°, 45°, and 60°) with and without the BPB were compared on a production passenger seat with an integrated seatbelt. The LODC moved toward the buckle side during the far-side lateral-oblique impact. Abdominal pressure (left and right), seatbelt loads, anterior superioriliac spine (ASIS) forces, and pelvis lateral rotation were examined. The LODC head and knee excursions were extracted from a 3D-motion capture system. Results In the reclined noBPB condition, peak abdominal pressures on the buckle side reached up to 186 kPa and the ASIS forces demonstrated an early (∼ 50 ms) peak and a subsequent drop in the reclined noBPB conditions, suggesting that the belt slid into the abdomen. With the BPB, peak pelvis lateral rotation was greater than in the noBPB conditions but decreased with increasing reclined seatback angles (BPB: 31° to 36.5° vs no-BPB: −5° to −4.6°). Peak lap belt forces were greater in the reclined noBPB conditions (4.8-4.9 kN) compared to all conditions with the BPB (2.9-3.2 kN). The greatest lateral head excursion was observed in the BPB 25° condition (895 mm) and the lowest in the noBPB 45° condition (748 mm). Conclusions The BPB may prevent the lap belt intrusion into the abdomen in reclined configurations in far side lateral-oblique impacts. The greater pelvis lateral rotation and head displacement with the BPB may lead to contact with other rear-seated occupants and/or vehicle structures, although motion decreased with the BPB as the reclined seatback angle increased. This suggests that reclined seats may help reduce BPB-seated children’s lateral excursion in far-side lateral-oblique impacts.

Predicting masticatory muscle activity and deviations in mouth opening from non-invasive temporomandibular joint complex functional analyses.

A quantitative approach to predict expected muscle activity and mandibular movement from non-invasive hard tissue assessments remains unexplored. This study investigated the predictive potential of normalised muscle activity during various jaw movements combined with temporomandibular joint (TMJ) vibration analyses to predict expected maximum lateral deviation during mouth opening. Sixty-six participants underwent electrognathography (EGN), surface electromyography (EMG) and joint vibration analyses (JVA). They performed maximum mouth opening, lateral excursion and anterior protrusion as jaw movement activities in a single session. Multiple predictive models were trained from synthetic observations generated from the 66 human observations. Muscle function intensity and activity duration were normalised and a decision support system with branching logic was developed to predict lateral deviation. Performance of the models in predicting temporalis, masseter and digastric muscle activity from hard tissue data was evaluated through root mean squared error (RMSE) and mean absolute error. Temporalis muscle intensity ranged from 0.135 ± 0.056, masseter from 0.111 ± 0.053 and digastric from 0.120 ± 0.051. Muscle activity duration varied with temporalis at 112.23 ± 126.81 ms, masseter at 101.02 ± 121.34 ms and digastric at 168.13 ± 222.82 ms. XGBoost predicted muscle intensity and activity duration and scored an RMSE of 0.03-0.05. Jaw deviations were successfully predicted with a MAE of 0.9 mm. Applying deep learning to EGN, EMG and JVA data can establish a quantifiable relationship between muscles and hard tissue movement within the TMJ complex and can predict jaw deviations.

Evaluation of intra-articular injection of injectable platelet-rich fibrin, anterior repositioning splint and arthrocentesis in treatment of temporomandibular joint internal derangement

The current research paper was designed to assess the impact of an intra-articular injection of injectable platelet-rich fibrin (I-PRF) following arthrocentesis and the use of an anterior repositioning splint (ARS) as a proposed treatment approach for addressing symptomatic internal derangement of the temporomandibular joint (TMJ). This study comprised thirty patients who presented with bilateral disc displacement without reduction. The patients were evenly distributed into two groups: Group I underwent treatment involving ARS and arthrocentesis alone, while Group II underwent treatment with ARS, arthrocentesis, and the injection of I-PRF. Clinical assessment of all patients was done postoperatively in the following intervals; first week, first month, third month, and six months for maximum mouth opening (MMO), right and left lateral excursion, and pain score. Magnetic resonance imaging (MRI) assessment for all joints was done at the sixth month postoperatively. Both groups demonstrated improvement in MMO, lateral excursion, and pain. Significant statistical differences were observed in the mean values of MMO and Visual Analogue Scale (VAS), favouring the I-PRF group. MRI postoperatively showed no significant changes in disk position or morphology at the end of the sixth month. Administering an intra-articular I-PRF injection subsequent to arthrocentesis demonstrates effectiveness as a treatment approach for alleviating the signs and symptoms associated with internal derangement of the TMJ.

Efficacy of TENS Therapy, Therapeutic Ultrasound and Stabilization Splint as an Adjuvant to Pharmacotherapy for Temporomandibular Disorders

INTRODUCTIONThis study aims to assess the effectiveness of adjunctive treatments like transcutaneous electric nerve stimulation (TENS), therapeutic ultrasound (ThUs), and stabilization splint (SS) in combination with pharmacotherapy (PT) in enhancing pain relief, mouth opening, lateral excursion, joint sound reduction, muscle tenderness improvement, and jaw deflection in patients with temporomandibular disorders (TMDs), affecting the temporomandibular joint and masticatory muscles. MATERIAL AND METHODSThe study involved 90 patients divided into three groups. Pharmacotherapy (Tab. Myospaz) was prescribed to all patients, each group received either TENS, ThUs, or SS as adjunctive treatment. Outcomes were measured at baseline and various intervals post-treatment. RESULTSTMDs were more prevalent in younger age group (21-30 years) with female predilection (F:M =2.21:1). Significant differences were observed in pain scores, with TENS and ThUs groups showing greater reductions compared to SS. ThUs demonstrated superior results in mouth opening, while TENS showed better outcomes in lateral excursion and muscle tenderness reduction. CONCLUSIONThis study concluded that both TENS and therapeutic ultrasound effectively reduced pain with therapeutic ultrasound showing better results in improving mouth opening, and TENS demonstrating better results in lateral excursion and muscle tenderness reduction. No significant difference among three groups were found in reducing joint sounds and deviation/deflection.

Deep learning and predictive modelling for generating normalised muscle function parameters from signal images of mandibular electromyography.

Challenges arise in accessing archived signal outputs due to proprietary software limitations. There is a notable lack of exploration in open-source mandibular EMG signal conversion for continuous access and analysis, hindering tasks such as pattern recognition and predictive modelling for temporomandibular joint complex function. To Develop a workflow to extract normalised signal parameters from images of mandibular muscle EMG and identify optimal clustering methods for quantifying signal intensity and activity durations. A workflow utilising OpenCV, variational encoders and Neurokit2 generated and augmented 866 unique EMG signals from jaw movement exercises. k-means, GMM and DBSCAN were employed for normalisation and cluster-centric signal processing. The workflow was validated with data collected from 66 participants, measuring temporalis, masseter and digastric muscles. DBSCAN (0.35 to 0.54) and GMM (0.09 to 0.24) exhibited lower silhouette scores for mouth opening, anterior protrusion and lateral excursions, while K-means performed best (0.10 to 0.11) for temporalis and masseter muscles during chewing activities. The current study successfully developed a deep learning workflow capable of extracting normalised signal data from EMG images and generating quantifiable parameters for muscle activity duration and general functional intensity.

Musculoaponeurotic architecture of the human masseter muscle: an in vivo ultrasonographic study of architectural changes during mandibular protrusion and lateral excursions

ObjectiveThe present study evaluated the in vivo musculoaponeurotic architecture of the superficial head (SH) of the masseter muscle (MM) of asymptomatic participants in excursive mandibular movements compared to the relaxed state as examined with ultrasound imaging. It was hypothesized that the mean fiber bundle length (FBL) and mean height of the aponeurosis (HA) of the laminae of the SH would differ significantly between the relaxed state and protrusion, ipsilateral excursion, and contralateral excursion. Study DesignThe MM was studied volumetrically in 12 female and 12 male asymptomatic participants bilaterally by using ultrasound imaging. Mean FBL and HA in protrusion and ipsilateral and contralateral excursion were compared to these values in the relaxed state using paired t-tests (P < .05). The intraclass correlation coefficient was used to assess intraexaminer reliability. ResultsThe SH exhibited multiple laminae. Fiber bundles were found to attach to bone and the superior and inferior aponeuroses. Mean FBL was significantly shorter and mean HA significantly longer in protrusion and the excursions than in the relaxed state although the pattern of altered laminae and aponeuroses differed among the mandibular movements. Intraexaminer reliability was excellent. ConclusionSpecific changes in mean FBL and mean HA suggest differential contraction of the SH of the MM based on laminar morphology. These findings provide a baseline to investigate musculoaponeurotic changes in patients with myogenic masseter muscle pain.

Facial and mandibular landmark tracking with habitual head posture estimation using linear and fiducial markers.

This study compared the accuracy of facial landmark measurements using deep learning-based fiducial marker (FM) and arbitrary width reference (AWR) approaches. It quantitatively analysed mandibular hard and soft tissue lateral excursions and head tilting from consumer camera footage of 37 participants. A custom deep learning system recognised facial landmarks for measuring head tilt and mandibular lateral excursions. Circular fiducial markers (FM) and inter-zygion measurements (AWR) were validated against physical measurements using electrognathography and electronic rulers. Results showed notable differences in lower and mid-face estimations for both FM and AWR compared to physical measurements. The study also demonstrated the comparability of both approaches in assessing lateral movement, though fiducial markers exhibited variability in mid-face and lower face parameter assessments. Regardless of the technique applied, hard tissue movement was typically seen to be 30% less than soft tissue among the participants. Additionally, a significant number of participants consistently displayed a 5 to 10° head tilt.

Evaluation of the Relationship Between Zygomatic Arch Fracture Reduction and Mandibular Movements.

The aim of this study was to evaluate the relationship between surgical zygomatic arch fracture reduction and mandibular movements in different fracture types. Fractures were classified according to the Yamamoto classification. The extent of zygomatic arch reduction after surgery was evaluated by measuring three reference points on both fractured and normal side both before and after surgery. The selected reference points were: the most anterior (A1), the most posterior (B1) and the midpoint (C1) relative to midsagittal plane on the fracture side and the same points on the normal side (a1, b1, c1). Mouth opening, movements to right and left were recorded in these patients. The highest extent of zygomatic arch reduction was observed at the midpoint of the arch (p = 0.041). Surgery did not significantly alter other points of the zygomatic arch. The extent of reduction of the zygomatic arch was not significantly associated with mandibular movements. However, type of fracture correlated with lateral excursion to the right and left (p = 0.002 and p = 0.031, respectively). This study showed that the amount of post-surgical changes in zygomatic arch reduction was not significantly related to mandibular movements. In addition, the amount of lateral excursion two weeks after surgical correction of more severe types of zygomatic arch fractures was less compared with other fracture types. Patients with more severe fractures may need to be followed for a longer period of time in order to regain the normal mandibular movement range.