Root Displacement Research Articles

Root hairs aid soil penetration by anchoring the root surface to pore walls.

The physical role of root hairs in anchoring the root tip during soil penetration was examined. Experiments using a hairless maize mutant (Zea mays: rth3-3) and its wild-type counterpart measured the anchorage force between the primary root of maize and the soil to determine whether root hairs enabled seedling roots in artificial biopores to penetrate sandy loam soil (dry bulk density 1.0-1.5g cm(-3)). Time-lapse imaging was used to analyse root and seedling displacements in soil adjacent to a transparent Perspex interface. Peak anchorage forces were up to five times greater (2.5N cf. 0.5N) for wild-type roots than for hairless mutants in 1.2g cm(-3) soil. Root hair anchorage enabled better soil penetration for 1.0 or 1.2g cm(-3) soil, but there was no significant advantage of root hairs in the densest soil (1.5g cm(-3)). The anchorage force was insufficient to allow root penetration of the denser soil, probably because of less root hair penetration into pore walls and, consequently, poorer adhesion between the root hairs and the pore walls. Hairless seedlings took 33h to anchor themselves compared with 16h for wild-type roots in 1.2g cm(-3) soil. Caryopses were often pushed several millimetres out of the soil before the roots became anchored and hairless roots often never became anchored securely.The physical role of root hairs in anchoring the root tip may be important in loose seed beds above more compact soil layers and may also assist root tips to emerge from biopores and penetrate the bulk soil.

A Management Strategy for Idiopathic Bone Cavities of the Jaws

Idiopathic bone cavities (IBCs) are benign osseous pseudocysts of unclear etiology. Their clinical course and response to treatment are poorly understood. The purpose of this study was to present a case series of patients with IBC with long-term follow-up. A retrospective case series of patients with IBC of the jaw was implemented. Medical records were reviewed for data on presentation and imaging. All patients underwent surgical exploration to confirm the diagnosis. Follow-up radiographs were evaluated for resolution or persistence after the procedure. Descriptive data were summarized. The sample included 45 patients (60% girls) with 47 IBCs who presented at a mean age of 13.5 ± 0.35years (range, 9 to 17yr). All lesions were asymptomatic and discovered as incidental findings; the average size was 2.0cm (range, 0.8 to 7cm). Most (n= 44) were solitary lesions of the mandible presenting within the body (n= 27), symphysis (n= 15), or ramus (n= 2). One patient had synchronous bilateral mandibular and maxillary IBCs. Common radiographic features included scalloping without root resorption or displacement and cortical thinning without expansion or perforation. Intraoperative findings showed an empty bone cavity often filled with blood-tinged serous fluid or blood. The histopathology of scrapings from the bony wall showed benign mixed fibrous tissue and no epithelial lining. Average radiographic follow-up was 32.7 ± 6.7months (range, 0 to 9yr). After exploration and curettage, 43% of patients had complete bone fill within 2 to 5years. The other 57% had no change in lesion size at an average of 2.25years (range, 2 to 9yr). No patients developed symptoms, had enlargement of the lesion, or had pathologic fracture. Many IBCs persist for years despite exploration and curettage. Nonetheless, unresolved lesions did not enlarge or cause harm. A single procedure to confirm the diagnosis is sufficient for management.

Back pain was less explained than leg pain: a cross-sectional study using magnetic resonance imaging in low back pain patients with and without radiculopathy.

BackgroundCross-sectional studies have shown associations between lumbar degenerative manifestations on magnetic resonance imaging (MRI) and low back pain (LBP). Disc herniations and other degenerative manifestations, however, frequently occur in asymptomatic individuals. The purpose of this cross-sectional study was to analyze for associations between pain intensity and degenerative manifestations and other pain variables in patients for whom prognostic factors have been published previously.MethodsIncluded were 141 consecutive patients with and without radiculopathy, all sick-listed 1–4 months due to low back pain and subsequently examined by MRI of the lumbar spine. Using different methods of grouping the degenerative manifestations, linear regression analyses were performed with the intensity of back + leg pain, back pain and leg pain as dependent variables covering actual pain and pain the preceding 2 weeks. The clinical classification into +/− radiculopathy was established before and independently of the standardised description of MRI findings.ResultsRadiculopathy was present in 43 % of the patients. Pain was best explained using rank-ordered degenerative manifestations on MRI. Back pain and leg pain were differently associated, and back pain was less explained than leg pain in the multivariate analyses (15 % vs. 31 % of the variation). Back pain intensity was higher in patients with type 1 Modic changes and in some patients with nerve root touch, but was not associated with disc herniations. Leg pain intensity was well explained by disc herniations causing MRI nerve root compromise and radiculopathy. In patients with radiculopathy, nerve root touch caused as much leg pain as nerve root displacement or compression. High intensity zones and osteophytes were not associated with back pain, but only associated with leg pain in patients with radiculopathy. Tender points explained some of the back pain, and widespread pain explained leg pain in some of the patients without radiculopathy.ConclusionsBack pain was associated with type 1 Modic changes, nerve root touch and tender points, whereas leg pain was associated with osteophytes, HIZ, disc herniation, all sorts of MRI nerve root compromise, radiculopathy and widespread pain.

MATHEMATICAL MODEL FOR ANALYSIS OF TRANSLATIONAL DISPLACEMENTS OF TOOTH ROOT

Analytical modeling of stress-strain state of a periodontal ligament in the case of the translational displacement of a tooth root was carried out. The tooth root was assumed as a rigid body. The boundary conditions corresponding to the translational displacement of the root and fixed external surface of the periodontal ligament in the dental alveolus were considered. The system of differential equations describing the periodontal ligament’s plane-strain state induced by the translational motion of the tooth were used as the governing equations. An analytical solution was found for the governing equations in the explicit form. Comparative analysis of the concentrated force generated by the prescribed translational motion of the tooth root was performed using the obtained analytical solution and the model of an incompressible periodontal ligament in the form of a circular paraboloid and hyperboloid. The mathematical model developed in this paper can be used to analyze stresses and strains in the periodontal tissue during orthodontic movement.

2015 Young Investigator Award Winner: Cervical Nerve Root Displacement and Strain During Upper Limb Neural Tension Testing: Part 2: Role of Foraminal Ligaments in the Cervical Spine.

A cross-sectional cadaveric examination of the mechanical effect of foraminal ligaments on cervical nerve root displacement and strain. To determine the role of foraminal ligaments by examining differences in cervical nerve root displacement and strain during upper limb neural tension testing (ULNTT) before and after selective cutting of foraminal ligaments. Although investigators have determined that lumbar spine foraminal ligaments limit displacement and strain of lumbosacral nerve roots, similar studies have not been conducted to prove that it is true for the cervical region. Because the size, shape, and orientation of cervical spine foraminal ligaments are similar to those in the lumbar spine, it is hypothesized that foraminal ligaments in the cervical spine will function in a similar fashion. Radiolucent markers were implanted into cervical nerve roots C5-C8 of 9 unembalmed cadavers. Posteroanterior fluoroscopic images were captured at resting and upper limb neural tension testing positioning before and after selective cutting of foraminal ligaments. Selective cutting of foraminal ligaments resulted in significant increases in inferolateral displacement (average, 2.94 mm [ligaments intact]-3.87 mm [ligaments cut], P < 0.05) and strain (average, 9.33% [ligaments intact]-16.31% [ligaments cut], P < 0.03) of cervical nerve roots C5-C8 during upper limb neural tension testing. Foraminal ligaments in the cervical spine limited cervical nerve root displacement and strain during upper limb neural tension testing. Foraminal ligaments seem to have a protective role, reducing displacement and strain to cervical nerve roots during tension events. 2.

Anatomical considerations for implant placements in first maxillary molar extracted sites in East Asian patients

With the advent of cone-beam computed tomography (CBCT) for maxillofacial imaging, there has been a paradigm shift from two dimensional panoramic radiography to three dimensional imaging. This study investigated the microanatomy of the maxillary permanent first molar socket and its relationship to the floor of the maxillary sinus, especially for immediate or early implant placement. Sixty CBCT scans of 30 Malay and 30 Chinese subjects were selected from over 300 archived images. Ninety-five percent of the subjects had sinus floor extending anterior to the first molar, while 72% had the floor dipping between the roots. Seventy-five percent of the patients had inter-radicular bone and almost 50% had intrusion of root apices into the floor of the maxillary sinus. The dimensions of the socket were as follows: the mean width was 11.42 ± 0.86 mm; the mean length was 7.70 ± 0.56 mm; the mean height on the coronal plane was 6.48 ± 3.77 mm while on the sagittal plane it was 6.85 ± 3.67 mm. Any implant length greater than the mean height of the socket (approximately 7 mm) has a fair chance of perforation into the maxillary sinus if placed without any additional adjunct procedures. In addition, 50% of the apices opened into the maxillary sinus, thereby risking the creation of perforations or root displacements into the maxillary sinus during exodontia-mandating CBCT scanning prior to any surgical implant procedures.

A rare tumour of cauda equina: a case report

Aims Description of a rare case of cauda equina: Capillary haemangioma. Method Review of histopathology, imaging and literature. Result A 44-year-old lady presented with recent-onset left-sided low back pain radiating to anterior thigh. She had a back injury nine years prior; magnetic resonance imaging (MRI) then showed a low termination of spinal cord at L2/3 level and a small intraspinal lipoma. The recent MRI showed an intraspinal enhancing mass at L2/3 with nerve root displacement to the right. In light of significant progression in size over the nine-year period, the intradural red fleshy tumour adherent to multiple nerve roots of the cauda equina was subsequently removed. A 22 × 10 × 5 mm dark-brown lobulated tumour was received. Histologically, there was a circumscribed pseudoencapsulated CH arising within a substantial nerve trunk. Variably sized vascular spaces were arranged in lobular pattern and lined by bland endothelial cells (ERG-positive and S100-negative). Discussion CHs are commonly seen as cutaneous and mucosal lesions. CHs of the cauda equina are extremely rare and clinically simulate schwannoma, ependymoma, or neurofibroma. To our knowledge, only 19 cases have been previously described since publication of the earliest report in 1987. It should be considered as a differential diagnosis in middle-aged patients with enhancing lesions of the cauda equina.

Study of the Influence of External Environment to Arc Channel in Argon with Laminar Flow

A 3D model is used to simulate free burning arc, and the influence of external environment to arc channel are discussed. The commercial CFD code FLUENT is used to model the plasma and the solid anode part. The cross-flow (2m/s, 5m/s, and 10m/s) and external magnetic fields (2mT, 5mT, and 10 mT) are applied to deflect arc. And then the condition they work together have also be discussed. Because the mechanisms of the influence are different, they only influences are reflect on the arc root displacement. The influence of arc root displacement to potential drop has been explained.

A Statistical Study on Characteristics and Treatment of Child and Adolescent Patients with Tooth Impaction

Impacted teeth are teeth with a delayed eruption time or that are expected to erupt incompletely. Those teeth can cause a series of potential problems such as root displacement and resorption, periodontal problems in adjacent teeth, referred pain and the formation of cysts and odontogenic tumors. The purpose of this study was to investigate characteristics and treatment of child and adolescent patients younger than 15 years of age that were diagnosed with an impacted tooth who visited the Chosun University Dental Hospital. The impacted tooth, its etiology, treatment and traction period were surveyed through electric medical records, radiographs in 335 patients. We excluded the impacted third molar, supernumerary and deciduous teeth from this study. The most frequently impacted teeth are upper canine, followed by the upper incisor. The most common etiologies of impaction were an abnormal eruption pathway and localized pathologic lesions. The treatment of an impacted tooth was mostly orthodontic traction. The traction period was relatively short in cases with distinct obstacles, with an impacted upper incisor and if patients were younger. An orthodontic traction is considered to be more unfavorable if the patient gets older. Therefore, an early diagnosis and a precise treatment plan through a regular check-ups are mandatory.

Biomechanical Evaluation of a Transtibial Pull-out Meniscal Root Repair

Background: A common treatment for posterior meniscal root tears is transtibial pull-out repair, which has been biomechanically reported to restore tibiofemoral contact mechanics to those of the intact knee. Biomechanical data suggest that there is significant displacement of the repaired meniscal root with cyclic loading, which may be responsible for the poor healing and meniscal extrusion demonstrated in some clinical studies. Hypothesis/Purpose: The purpose of this study was to quantify the time-zero displacement of the posterior meniscal root in response to cyclic loading after transtibial pull-out repair and to quantify the individual contributions to displacement of the following: (1) suture elongation, (2) button-bone interface, and (3) meniscus-suture interface. The meniscus-suture interface was hypothesized to result in significantly more displacement than the button-bone interface or suture elongation. Study Design: Descriptive laboratory study. Methods: Transtibial pull-out repair of the posterior medial meniscal root was performed in 6 porcine knees, and cyclic displacement was measured using a loading protocol representative of postoperative rehabilitation. Displacement from (1) suture elongation, (2) the button-bone interface, and (3) the meniscus-suture interface was determined by cyclically loading 6 specimens for each construct using the same loading protocol to determine the contribution of each component to the overall displacement of the repair construct. Results: After 1000 cycles, the repair construct displaced by a mean of 3.28 mm (95% CI, 2.07-4.49). The meniscus-suture component (mean, 2.52 mm; 95% CI, 2.21-2.83) displaced significantly more than the button-bone component (mean, 0.90 mm; 95% CI, 0.64-1.15; P = .006) and suture elongation component (mean, 0.71 mm; 95% CI, 0.36-1.06; P = .006) after 1000 cycles. Displacement of the button-bone and suture elongation components was not significantly different after 1000 cycles (P = .720). Conclusion: There was substantial displacement of the posterior medial meniscal root repaired with the transtibial pull-out technique under a cyclic loading protocol simulating postoperative rehabilitation. The meniscus-suture interface contributed to significantly more displacement than the button-bone interface and suture elongation in the transtibial pull-out repair construct. Clinical Relevance: The results provide a framework for optimizing the transtibial pull-out repair technique. Future studies should focus on improving suture fixation strength within the meniscus-suture interface.

Geometric Nonlinear Effect on Large Span Cable-Stayed Bridge

It is introduced that three main factors cause geometric nonlinear effects of long span cable-stayed bridge: large displacement effect, cable sag effect, and the combination of bending moment and axial force effect. The iteration method of geometrical nonlinear problem is also introduced. The bridge deformation was calculated by establishing a plane truss finite element model of a long-span single tower cable-stayed bridge under consideration of nonlinearity and compared with that done with linear method. It is concluded that nonlinearity influenced differently to the bending moment of main girder, the displacement of tower root and the vertical displacement of girder.

Measurement of the Lingual Position of the Lower Third Molar Roots Using Cone-Beam Computed Tomography

The aim of this study was to evaluate the distance between the roots of the impacted third molars and the floor of the mouth to predict the risk of lingual root displacement during surgery. Thirty-one patients (5 men and 26 women) were evaluated for this study using cone-beam computed tomography (CBCT). The teeth were grouped according to their position on the orthopantomogram as vertical, mesioangular, horizontal, and distoangular. The distance between 2 points on the roots and lingual soft tissues was measured. The average distance between the apex of the root, which is in the most lingual position, and the lingual cortical plate was 1.03 mm. The average distance between the most lingual point on the apical half of the root, which is in closer proximity, and the lingual cortical plate was 0.65 mm. The distance between the apices and the lingual plate is very short, which allows displacement of broken roots or teeth, especially when the lingual plate is perforated.

2014 Young Investigator Award Winner

Controlled radiological study.To investigate noninvasively in vivo spinal cord displacement in the vertebral canal during the passive straight leg raise (SLR) in asymptomatic subjects. The basic assumption is that the cord follows L5 and S1 nerve roots displacement by similar magnitude and direction (principle of linear dependence).It is generally accepted that the SLR produces some caudal movement mainly of L5 and S1 nerve roots, but the magnitude of this displacement is still a matter of debate.Sixteen asymptomatic volunteers were scanned with 1.5-T magnetic resonance scanner (Siemens Avanto, Erlangen, Germany) using T2-weighted turbo spin-echo fat-saturation sequence. The displacement of the medullar cone relative to the vertebral endplate of the adjacent vertebra during the passive SLR was quantified and compared with the position of the conus in the neutral (anatomic) position. Each movement was performed twice for evaluation of reproducibility. The measurements were repeated by 2 observers. Four practitioners performed the maneuvers in a random sequence to avoid series effects.Compared with the neutral (anatomic) position, the medullar cone displaced caudally in the spinal canal by 2.31 ± 1.2 mm with right (P ≤ 0.001) and 2.35 ± 1.2 mm with left SLR (P ≤ 0.001). Spearman correlations proved higher than 0.99 for intra and interobserver reliability, as well as results reproducibility testing for each maneuver.The data show that the spinal cord in the thoracolumbar region slides distally in response to the clinically applied SLR test. The high correlation values in this study show that these movements are consistent and reproducible. Because of the neural continuum, the authors speculate that this movement might be directly proportional to the sliding of the L5 and S1 neural roots. This study offers baseline measurements on which further studies in diagnosis of lumbar disc protrusion and radiculopathy may be developed.

Atrophic changes in the trigeminal nerves of patients with trigeminal neuralgia due to neurovascular compression and their association with the severity of compression and clinical outcomes.

The aim of this study was to prospectively evaluate atrophic changes in trigeminal nerves (TGNs) using measurements of volume (V) and cross-sectional area (CSA) from high-resolution 3-T MR images obtained in patients with unilateral trigeminal neuralgia (TN), and to correlate these data with patient and neurovascular compression (NVC) characteristics and with clinical outcomes. Anatomical TGN parameters (V and CSA) were obtained in 50 patients (30 women and 20 men; mean age 56.42 years, range 22-79 years) with classic TN before treatment with microvascular decompression (MVD). Parameters were compared between the symptomatic (ipsilateralTN) and asymptomatic (contralateralTN) sides of the face. Twenty normal control subjects were also included. Two independent observers blinded to the side of pain separately analyzed the images. Measurements of V (from the pons to the entrance of the nerve into Meckel's cave) and CSA (at 5 mm from the entry of the TGN into the pons) for each TGN were performed using imaging software and axial and coronal projections, respectively. These data were correlated with patient characteristics (age, duration of symptoms before MVD, side of pain, sex, and area of pain distribution), NVC characteristics (type of vessel involved in NVC, location of compression along the nerve, site of compression around the circumference of the root, and degree of compression), and clinical outcomes at the 2-year follow-up after surgery. Comparisons were made using Bonferroni's test. Interobserver variability was assessed using the Pearson correlation coefficient. The mean V of the TGN on the ipsilateralTN (60.35 ± 21.74 mm(3)) was significantly smaller (p < 0.05) than those for the contralateralTN and controls (78.62 ± 24.62 mm(3) and 89.09 ± 14.72 mm(3), respectively). The mean CSA of the TGN on the ipsilateralTN (4.17 ± 1.74 mm(2)) was significantly smaller than those for the contralateralTN and controls (5.41 ± 1.89 mm(2) and 5.64 ± 0.85 mm(2), respectively). The ipsilateralTN with NVC Grade III (marked indentation) had a significantly smaller mean V than the ipsilateralTN with NVC Grade I (mere contact), although it was not significantly smaller than that of the ipsilateralTN with NVC Grade II (displacement or distortion of root). The ipsilateralTN with NVC Grade III had a significantly smaller mean CSA than the ipsilateralTN with NVC Grades I and II (p < 0.05). The TGN on the ipsilateralTN in cured patients had a smaller mean CSA than that on the ipsilateralTN of patients with partial pain relief or treatment failure (p < 0.05). The same finding was almost found in relation to measurements of V, but the p value was slightly higher at 0.05. Results showed that TGN atrophy in patients with TN can be demonstrated by high-resolution imaging. These data suggest that atrophic changes in TGNs, which significantly correlated with the severity of compression and clinical outcomes, may help to predict long-term prognosis after vascular decompression.

Wear behaviour of monolithic zirconia crowns – clinical results

Purpose: (1) To compare the strains and the stresses values within the periodontal ligament (PDL) following the application of three types of loading regimes: pure intrusion (PI), buccal tipping (BT), and intrusion combined with buccal tipping (IT). (2) To verify the correlation between these results and the available clinical findings regarding root resorption (RR) occurrence. Methods and materials: A tridimensional finite element (FE) model was constructed with axisymmetric geometry to simulate the tooth root. The model includes root, cementum, PDL, cortical and trabecular bone. All materials were considered linear elastic, except the PDL that was modeled as a nonlinear hypo-elastic material. Based on the literature that evaluates the influence of force magnitude on the RR occurrence, the loading magnitude was defined: PI simulated by applying 25-g or 225-g of axial loading; BT by applying the same force magnitudes 90◦ to the long axis; IT combining PI and BT. The displacement of the root within the PDL was calculated as percentage of the original thickness of the PDL to verify the amount of PDL deformation. Strains and stresses at the nodes at the PDL–cementum interface at cervical, middle and apical thirds were also assessed. Results: For the PI movement, the root displaced vertically within the PDL uniformly (9% of the PDL total thickness for 25-g and 36% for 225-g). For the PI and BT, the maximum root displacement occurred at the cervical buccal third (8% and 13% for 25-g, and 33% and 57% for 225-g; respectively). Higher forces generated higher values of strains and stresses within the PDL. For the PI movement, the apical and middle thirds showed higher values of strains than the cervical third. For the BT, the apical and cervical thirds showed higher values of strains than the middle third. For the IT, the cervical and middle thirds at the buccal side showed the highest values of strain. The maximum stresses were seen at the cervical third for the PI, and at the cervical and buccal lingual sides for the BT and IT (tensile sides). Conclusion: As expected, higher orthodontic forces generated higher values of strains and stresseswithin the PDL. From clinical findings, it is possible to verify that the RR occurred mostly in areas under compression. Therefore, our results support that RR might be related with changes of the blood supply associated with the constriction of the PDL at the compression sides.

Odontogenic Myxomas with an Unusual Presentation in the Anterior Mandible: A Case Report

Odontogenic myxoma (OM) is a rare and locally invasive benign neoplasm derived from the odontogenic ectomesenchyme, found exclusively in the jaws. As a myxoma, this tumour consists mainly of spindle-shaped cells and scattered collagen fibers distributed through a loose, mucoid material. The lesion is found in age groups ranging from 10–50 years but commonly diagnosed in young adults (25–35 years). The lesion often grows without symptoms and presents as a painless swelling. It has variable radiographic presentation but often causing root displacement and resorption. In this article we present a rare case report of swelling in anterior mandible in a 31-year-old-male, diagnosed histopathologically as odontogenic myxoma.

Orthodontic loading influence on root resorption susceptibility: Finite element analysis

Purpose: (1) To compare the strains and the stresses values within the periodontal ligament (PDL) following the application of three types of loading regimes: pure intrusion (PI), buccal tipping (BT), and intrusion combined with buccal tipping (IT). (2) To verify the correlation between these results and the available clinical findings regarding root resorption (RR) occurrence. Methods and materials: A tridimensional finite element (FE) model was constructed with axisymmetric geometry to simulate the tooth root. The model includes root, cementum, PDL, cortical and trabecular bone. All materials were considered linear elastic, except the PDL that was modeled as a nonlinear hypo-elastic material. Based on the literature that evaluates the influence of force magnitude on the RR occurrence, the loading magnitude was defined: PI simulated by applying 25-g or 225-g of axial loading; BT by applying the same force magnitudes 90◦ to the long axis; IT combining PI and BT. The displacement of the root within the PDL was calculated as percentage of the original thickness of the PDL to verify the amount of PDL deformation. Strains and stresses at the nodes at the PDL–cementum interface at cervical, middle and apical thirds were also assessed. Results: For the PI movement, the root displaced vertically within the PDL uniformly (9% of the PDL total thickness for 25-g and 36% for 225-g). For the PI and BT, the maximum root displacement occurred at the cervical buccal third (8% and 13% for 25-g, and 33% and 57% for 225-g; respectively). Higher forces generated higher values of strains and stresses within the PDL. For the PI movement, the apical and middle thirds showed higher values of strains than the cervical third. For the BT, the apical and cervical thirds showed higher values of strains than the middle third. For the IT, the cervical and middle thirds at the buccal side showed the highest values of strain. The maximum stresses were seen at the cervical third for the PI, and at the cervical and buccal lingual sides for the BT and IT (tensile sides). Conclusion: As expected, higher orthodontic forces generated higher values of strains and stresseswithin the PDL. From clinical findings, it is possible to verify that the RR occurred mostly in areas under compression. Therefore, our results support that RR might be related with changes of the blood supply associated with the constriction of the PDL at the compression sides.

Analysis of Different Positions of Fiber-Reinforced Composite Retainers versus Multistrand Wire Retainers Using the Finite Element Method.

Background. The aim of this study was to evaluate root displacement of the lower incisors fixed with FRC in different positions versus FSW retainers using the finite element method. Materials and Methods. 3D finite element models were designed for a mandibular anterior segment: Model 1: flexible spiral wire bonded to the lingual teeth surfaces, Model 2: FRC bonded to the upper third of lingual teeth surfaces, and Model 3: FRC bonded to the middle third. FE analysis was performed for three models and then tooth displacements were evaluated. Results. In contrast to lateral incisors and canines, the FSW retainer caused the central teeth to move more than the teeth bonded with FRC in both loadings. Comparison between Models 2 and 3 (in vertical loading) showed that FRC retainers that bonded at the upper third of lingual teeth surfaces made central and canine teeth move less than FRC retainers bonded at the middle third; however, for lateral teeth it was the opposite. Conclusion. FRC retainers bonded at the upper third of lingual teeth surfaces make central and canine teeth move less than FRC retainers bonded at the middle third in vertical loading; however, for lateral teeth it was the opposite.

New, Clinically More Relevant Model for Nerve Root Injury in the Rat

Exposure to nucleus pulposus and displacement of intraspinal nervous structures with assessment of spontaneous behavioral changes in rats.To develop a controlled, experimental model for nerve root injury.There are a number of experimental models presented for studies on radiculopathies. One frequently used model is based on exposure to nucleus pulposus and displacement of the dorsal root ganglion (DRG). However, it is clinically more common that the nerve roots are displaced/compressed than the DRG. In this study, we developed a model for displacement of the nerve root by modifying the DRG model.After removing the left L3-L4 facet joint, the underlying disc was punctured, and the L4 nerve root was displaced laterally by an injection needle (n = 10). In sham experiments, the same procedure was performed without disc puncture and displacement (n = 10). In 10 rats, the left L4-L5 facet joint was removed. The underlying disc was punctured and the L4 DRG was displaced medially by an injection needle. Assessment of spontaneous behavioral changes was performed on days 1, 3, 7, 14, and 21, postsurgery.There was a clear increase in duration of the behavior "unloading of the paw" after displacement of the DRG that was most pronounced on day 1 and then gradually declined. There was a similar pattern for this behavior induced by nerve root displacement, although the duration was higher than that for the DRG displacement. No apparent trends in behavioral changes were observed for the other behaviors studied.Displacement of the nerve root induced more changes in the pain behavior than displacement of the DRG, but only for the behavior unloading of the paw. Because nerve root injury is more common than DRG injury, this model may be more clinically relevant than the DRG model.N/A.

An Alternative Approach to the Bedside Assessment of Left Ventricular Systolic Function in the Emergency Department: Displacement of the Aortic Root

Left ventricular ejection fraction (LVEF) is a crucial parameter in the management of patients with dyspnea in the emergency department (ED). The use of techniques other than echocardiography such as nuclear or magnetic resonance imaging to measure LVEF is unsuitable in the ED because of time constraints. This study aimed to compare echocardiographic aortic root (AR) excursion and LVEF measurement using the modified Simpson's method (biplane method of disks) as recommended by the American Society of Echocardiography. After 2 hours of theoretical video and hands-on training with 20 patients by an experienced echocardiographer, two emergency physicians prospectively evaluated patients with dyspnea. Two-dimensional echocardiograms of the parasternal long-axis view were obtained, and the displacement of the aortic root (DAR) was studied. M-mode DAR recordings were obtained, and distances were measured as the maximized anterior displacement of the AR from the horizontal axis at end-systole by using the leading-edge methodology. LVEF was measured by an experienced cardiologist using the modified Simpson's rule. The sensitivity, specificity, positive and negative likelihood ratios (LR+, LR-), and positive and negative predictive values (PPV, NPV) were analyzed. A new formula for the prediction of the ejection fraction (EF) with the aid of DAR was then created. The mean (±SD) age with of the 70 study patients was 69.7 (±11.91) years. In these patients, DAR was highly correlated with EF (point biserial correlation coefficient = 0.79, p < 0.001) and one-way analysis of variance (ANOVA) results were significant (F = 115.9; p < 0.001). The sensitivity was 94.4; specificity, 94.1; LR+, 16.6; LR-, 0.059; PPV, 94.4; and NPV, 94.1. The results indicate that DAR is a sensitive index of left ventricular systolic function (SF) and can be used to reliably predict EF values using the rough formula of EF = 20 + 44 (DAR).