Root Displacement Research Articles

Accidental displacement of mandibular third molar root into the sublingual space and delayed removal

AbstractOral surgeons rarely experience accidental displacement of a mandibular impacted third molar into adjacent anatomical spaces as a complication. As any displaced third molar or its root is commonly removed at the time of displacement or within several weeks of the extraction, delayed removal several years after initial extraction is extremely rare. We report here accidental displacement of a mandibular third molar root into the sublingual space and a 5‐year delay in its removal. A 42‐year‐old woman presented to our department with pain and swelling in the lingual aspect of the left mandible. Computed tomography revealed a 15 × 11 × 9 mm lesion, with a similar density to that of the surrounding bone and involving the lingual cortex of the left mandible. A yellowish‐white hard tissue lesion was protruding from the lingual mucosa of the left mandibular ramus. The patient had undergone removal of a left impacted mandibular third molar at a private dental clinic 5 years earlier and we diagnosed the lesion as a remnant third molar root. The patient had not been informed by her dentist of accidental displacement of the tooth into the sublingual space after crown removal. After complete alleviation of inflammation, the patient underwent intraoral removal of the root under general anaesthesia. After elevating the lingual mucoperiosteal flap from the mandibular ramus to the premolar region, the root was easily removed using an elevator and forceps. Her postoperative course was uneventful and there were no complications such as lingual nerve injury.

In situ root identification through blade penetrometer testing – part 2: field testing

The spatial distribution, depths and diameters of roots in soil are difficult to quantify but important to know when reinforcement of a rooted slope or the stability of a plant is to be assessed. Previous work has shown that roots can be detected from the depth–resistance trace measured using a penetrometer with an adapted blade-shaped tip. Theoretical models exist to predict both forces and root displacements associated with root failure in either bending or tension. However, these studies were performed in dry sand under laboratory conditions, using acrylonitrile butadiene styrene root analogues rather than real roots. In this paper blade penetrometer field testing on two forested field sites, with Sitka spruce and pedunculate oak in sandy silt and clayey silt, respectively, is used to evaluate models under field conditions. Root breakages could be detected from blade penetrometer depth–resistance traces and using complementary acoustic measurements. Predictions of additional penetrometer resistance at root failure were more accurate than the displacement predictions. An analytical cable model, assuming roots are flexible and fail in tension, provided the best predictions for Sitka roots, whereas thick oak roots were better predicted assuming bending failure. These matched the modes of failure observed in three-point bending tests of the root material in each case. The presence of significant amounts of gravel made it sometimes difficult to distinguish between hitting a root or a stone. The root diameter could be predicted when root strength and stiffness, and soil penetrometer resistance were known and the right interpretative model was selected. Estimates based on peak force were more accurate than those based on root displacement. This measurement procedure is therefore a potentially valuable tool to quantify the spatial distribution of roots and their reinforcement potential in the field.

Influence of elastic modulus of intraradicular posts on the fracture load of roots restored with full crowns

Abstract Objective This study aimed to evaluate the fracture load and displacement of roots restored with posts of different elastic modulus. Material and method Thirty-six replicas of epoxy resin mixed with glass microfibers were made from an endodontically-treated human premolar root prepared to a length of 12 mm with a custom drill, leaving the apical 4 mm unprepared. Replicas were randomly restored with (n = 12): FP-LM (fiber post with low elastic modulus– 50 GPa), FP-HM (fiber post with high elastic modulus – 67 GPa) and MP (metallic post – 208 GPa), using self-curing adhesive and dual resin cement. Cores were built up with composite resin and metallic crowns were cemented in all the roots with self-adhesive resin cement with self-curing mode. Specimens were subjected to a fracture load test (45° inclination/0.5 mm/min) and displacement was registered at 100 N. Result One-way ANOVA showed that elastic modulus of the post did not affect the fracture load means (p = 0.203) (FP-LM: 237.4 ± 65.11 N; FP-HM: 236.7 ± 92.85 N; MP: 295.8 ± 108.7 N) but was statistically significant for the displacement (p < 0.00): Tukey’s test showed that FP-LM displacement mean (0.81 ± 0.15 mm) was significantly higher than those for FP-HM (0.46 ± 0.26 mm; p = 0.00) and MP (0.62 ± 0.07 mm; p = 0.04). Conclusion Posts with different elastic modulus exhibit similar fracture loads, but a lower displacement is achieved when fiber posts with a high elastic modulus and metallic posts are used.

In situ root identification through blade penetrometer testing – part 1: interpretative models and laboratory testing

Root architecture and reinforcement are important parameters to measure the safety of vegetated slopes and stream banks against slope instability and erosion or to assess the stability of plants against environmental loading (e.g. windthrow of trees). However, these are difficult to measure without time-consuming sampling or counting procedures. Previous studies proposed using a penetrometer with an adapted geometry, and showed that individual root breakages could be detected as sudden drops in penetrometer resistance. However, there are no existing models to derive root properties from the measured traces. Here, several interpretative models are developed and their performance at identifying and characterising buried acrylonitrile butadiene styrene root analogues of varying diameter and architecture in sand are assessed. It was found that models, assuming the analogues broke in bending rather than tension, provided good predictions for the force–displacement behaviour. The simple analytical bending model developed here was shown to perform almost as well as more sophisticated numerical models. For all models, the predictions of additional penetrometer force required to break the root analogue were more accurate than predictions for lateral root displacement required to reach failure. The root analogue diameter and to a lesser extent the soil resistance and root angle were shown to affect the penetrometer resistance strongly. Root branching, root length and the distance between the point of load application and a root boundary (root tip or parent root) had a much smaller effect. When the root failure mechanism, root strength, root stiffness and soil resistance are known, an accurate prediction of the root diameter can be made based on the root peak resistance value identified from a blade penetration test. Penetrometer testing, a test which is easy to perform in the field, coupled with an accurate interpretative model might therefore be an effective method to rapidly quantify the spatial distribution, depths and diameters of roots.

Imaging Appearance of Advanced Chronic Adhesive Arachnoiditis: A Retrospective Review.

Chronic adhesive arachnoiditis (CAA) is rare and has potentially devastating clinical consequences. The objective of this article is to review the clinical features of CAA and describe its appearance on imaging, to increase radiologists' awareness of this challenging diagnosis. Twenty-nine cases of advanced CAA seen at our institution over 18 years (1995-2013) were retrospectively reviewed. Chart review was performed, with attention given to data on clinical presentation, suspected cause, and interventions performed. All patients underwent MRI, and seven patients also underwent CT myelography. Clinical and imaging features were evaluated and categorized. The 29 patients ranged in age from 23 to 96 years and included 11 women and 18 men. Suspected underlying causative factors included trauma (n = 10), prior surgery (n = 9), nontraumatic subarachnoid hemorrhage (n = 7), infection (n = 3), myelography with iophendylate used as contrast medium (n = 1), Guillain-Barré syndrome (n = 1), ankylosing spondylitis (n = 1), and unknown causes (n = 1). Imaging characteristics include loculated CSF collections (n = 23), nerve root clumping, enhancement, and displacement (n = 15), cord swelling with increased T2 signal (n = 12), arachnoid septations (n = 11), cord atrophy (n = 6), syrinx (n = 5), and intrathecal calcifications (n = 3). Ten patients underwent surgical procedures, and most had only brief clinical improvement. CAA is a rare cause of devastating neurologic symptoms and chronic pain. The imaging features of CAA range from subtle to severe. Advanced arachnoiditis can present with spinal cord swelling and syrinx formation, which can mimic other disease processes. Inclusion of advanced CAA in the differential diagnosis can prevent unnecessary interventions.

Micro-anatomical responses in periodontal complexes of mice to calibrated orthodontic forces on the crown.

Correlating mechanical forces with quantifiable physical changes in the dentoalveolar complex. Male 6-week C57BL/6 mice (N=3), micro X-ray-computed tomography; post-analysis software to extract physical changes in periodontal ligament (PDL)-space. Silicone-elastic bands were placed between maxillary molars for 1week, with the contralateral side as internal control. Average displacements between crowns and roots, and changes in PDL-spaces were evaluated by registering X-ray tomograms of experimental and control hemi-maxillae. Histology illustrated mineral formation and resorption-related events within narrowed and widened volumes of the PDL-space. 3D maps of changes in PDL-space between molars illustrated coronal and root displacements of 640μm and 180μm, respectively, compared to 70μm in controls. Orthodontic tooth movement (OTM) specimens exhibited an average net change of -20μm in narrowed and +30μm in widened PDL-spaces. Bone and cementum were affected by the force on molars, and primary cementum was more affected than secondary cementum. This novel approach illustrates the importance of 3D-imaging and analysing 3D alveolar socket subjected to OTM otherwise omitted by 2D micrographs.A measured force on the crown elicits a response related to narrowed and widened regions in the 3D complex. OTM that exceeds PDL-space can illicit biological responses that attempt to restore physiologic PDL-space via remodelling of the periodontium. Regenerated weaker bone due to aseptic inflammation caused by orthodontics could leave patients at a higher risk of bone loss or root resorption if they later develop periodontitis, a form of septic inflammation.

Reoccurring Neck Injury in a College Football Player

HISTORY: A 20-year-old male community college football defensive end developed left shoulder paresthesia during a game. He was tackling an opponent and his head was forced into a left lateral rotation. After this, he developed immediate paresthesia in the left upper trapezius and upper deltoid. He was evaluated on the side line by medical staff and removed from the remainder of game. Symptoms resolved within the next two days, and he returned to competition. Two weeks later, he again had his head forced into a left lateral rotation during a tackle. Paresthesia immediately returned in the left upper trapezius and upper deltoid. However, this time pain was increased and had onset of a burning sensation. After sideline evaluation, he was removed from competition. Following the game, he continued to have severe burning pain. He was sent to a local emergency department and ultimately released home. Paresthesia resolved over the next five days, but he was not cleared to return to competition. PHYSICAL EXAMINATION: There was no deformity to the neck or upper extremity. No cervical or left shoulder tenderness to palpation. His range of motion in the left glenohumeral joint was full. Strength was full throughout the entire left upper extremity. Sensation to light touch was diminished in the left upper trapezius and upper deltoid, but normal throughout the remainder of the upper extremity. Deep tendon reflexes were 2+ in bilateral biceps, brachioradialis, and triceps. Spurling’s test was positive on the left. DIFFERENTIAL DIAGNOSIS: 1.Upper trunk brachial plexopathy 2.Cervical radiculopathy 3.Cervical stenosis TEST AND RESULTS: 1.Cervical spine anterior-posterior, lateral and flexion-extension radiographs: No fracture or destructive change, disc spaces preserved, no pathologic movement 2. Cervical Magnetic Resonance Imaging: Left paramedian/foraminal disc protrusion at C3-4 resulting in moderate left foraminal stenosis and displacement of left C4 nerve root. No spinal canal stenosis or ligamentous injury. FINAL WORKING DIAGNOSIS: Left C4 radiculopathy TREATMENT AND OUTCOMES: 1. Orthopaedic spine referral determined to treat with non-operative management 2. Physical therapy for cervical strengthening, flexibility, and traction 3. Currently being withheld from competition with undetermined return to play date

Measuring regional displacements of tongue parts on ultrasound during /ɹ/ articulation

The ability to differentiate movements of the front, back and root portions of the tongue is important to the development of mature speech coordination. This ability is particularly relevant for sounds with complex tongue shapes, such as the American English rhotic approximant /ɹ/ (“r”), but speakers also have a wider scope of coarticulatory opportunities if able to control tongue parts independently [Zharkova, 2012]. In addition, lack of independence in tongue part movement is associated with speech sound disorders [Gibbon, 1999; Gick et al., 2008]. For this study, relative displacements of tongue blade, dorsum, and root were analyzed using MATLAB-based image processing. Regions of interest (ROIs) were drawn for these three areas on ultrasound images during production of /ɑɹ/ by 25 adults. Displacements of each region were measured by tracking of local brightness maxima from images representing /ɑ/ and /ɹ/ production, resulting in ranges of relative blade, dorsum and root displacement associated with nor...

Biomechanical investigation of post-operative C5 palsy due to ossification of the posterior longitudinal ligament in different types of cervical spinal alignment

Post-operative C5palsies are among the most common complications seen after cervical surgery for ossification of the posterior longitudinal ligament (OPLL). Although C5 palsy is a well-known complication of cervical spine surgery, its pathogenesis is poorly understood and depends on many other factors. In this study, a finite element model of the cervical spine and spinal cord-nerve roots complex structures was developed. The changes in stress in the cord and nerve roots, posterior shift of the spinal cord, and displacement and elongation of the nerve roots after laminectomy for cervical OPLL were analyzed for three different cervical sagittal alignments (lordosis, straight, and kyphosis). The results suggest that high stress concentrated on the nerve roots after laminectomy could be the main cause of C5 palsy because ossification of ligaments increases spinal cord shifting and root displacement. The type of sagittal alignment had no influence on changes in cord stress after laminectomy, although cases of kyphosis with a high degree of occupying ratio resulted in greater increases in nerve root stress after laminectomy. Therefore, kyphosis with a high OPLL occupying ratio could be a risk factor for poor surgical outcomes or post-operative complications and should be carefully considered for surgical treatment.

Analysis of dentoalveolar structures with novel corticotomy-facilitated mandibular expansion: A 3-dimensional finite element study.

Surgically assisted mandibular arch expansion is an effective treatment modality for alleviating constriction and crowding. However, only mandibular symphyseal osteotomy is recommended for mandibular arch expansion. No relevant studies have compared the biomechanical responses of different corticotomy designs on mandibular expansion. Therefore, the aim of this study was to evaluate the effect of different corticotomy approaches and modes of loading on the expansion of adult mandibles using biomechanics. Nine finite element models including 2 novel corticotomy designs were simulated. Stress, strain, and displacement of crown, root, and bone were calculated and compared under different corticotomy approaches and loading conditions. The biomechanical response seen in the finite element models in terms of displacement on the x-axis was consistent from anterior to posterior teeth with parasymphyseal step corticotomy and tooth-borne force application. In addition, the amount of displacement predicted by parasymphyseal step corticotomy in the tooth-borne mode was greater compared with other models. These results suggest that parasymphyseal step corticotomy with tooth-borne force application is a viable treatment option for true bony expansion in an adult mandible.

Adenomatoid odontogenic tumor simulating periapical cyst: case report

ABSTRACT The adenomatoid odontogenic tumor is a benign, non-invasive tumor and has a slow growth. Its preferred location is the anterior maxillary area, most often causing root displacement, more rarely resorption and mostly affects young women. Being asymptomatic, this injury is discovered upon routine radiographic examination, in which, in most cases, a unilocular, radiolucent image is observed and it may have some degree of calcification within the lesion. This work aims to report the case of a 14-year-old patient who attended the Lauro Wanderley University Hospital (UFPB), complaining of increased volume over a period of 8 months, in the region of non-vital tooth 21. The CT scan showed well-delimited unilocular, radiolucent lesion, with buccal cortex resorption. The proposed treatment plan involved enucleation, followed by peripheral ostectomy and bone graft with alloplastic materials. Because of its benign character, encapsulated and slow growing, the treatment of choice for adenomatoid odontogenic tumor is conservative, the surgical enucleation of the injury being advocated. The excised piece was sent for histopathological analysis, where the AOT diagnosis was confirmed. After 7 months, new bone formation was observed without signs of recurrence.

Torque differences due to the material variation of the orthodontic appliance: a finite element study

BackgroundTorque of the maxillary incisors is crucial to occlusal relationship and esthetics and can be influenced by many factors. The aim of this study was to assess the relative influence of the material of the orthodontic appliance (adhesive, bracket, ligature, and wire) on tooth displacements and developed stresses/strains after torque application.MethodsA three-dimensional upper right central incisor with its periodontal ligament (PDL) and alveolus was modeled. A 0.018-in. slot discovery® (Dentaurum, Ispringen, Germany) bracket with a rectangular 0.018 x 0.025-in. wire was generated. The orthodontic appliance varied in the material of its components: adhesive (composite resin or resin-modified glass ionomer cement), bracket (titanium, steel, or ceramic), wire (beta-titanium or steel), and ligature (elastomeric or steel). A total of 24 models were generated, and a palatal root torque of 5° was applied. Afterwards, crown and apex displacement, strains in the PDL, and stresses in the bracket were calculated and analyzed.ResultsThe labial crown displacement and the palatal root displacement of the tooth were mainly influenced by the material of the wire (up to 150% variation), followed by the material of the bracket (up to 19% variation). The magnitude of strains developed in the PDL was primarily influenced by the material of the wire (up to 127% variation), followed by the material of the bracket (up to 30% variation) and the ligature (up to 13% variation). Finally, stresses developed at the bracket were mainly influenced by the material of the wire (up to 118% variation) and the bracket (up to 59% variation).ConclusionsThe material properties of the orthodontic appliance and all its components should be considered during torque application. However, these in silico results need to be validated in vivo before they can be clinically extrapolated.

Binary Decision Trees for Preoperative Periapical Cyst Screening Using Cone-beam Computed Tomography

IntroductionCone-beam computed tomographic (CBCT) analysis allows for 3-dimensional assessment of periradicular lesions and may facilitate preoperative periapical cyst screening. The purpose of this study was to develop and assess the predictive validity of a cyst screening method based on CBCT volumetric analysis alone or combined with designated radiologic criteria. MethodsThree independent examiners evaluated 118 presurgical CBCT scans from cases that underwent apicoectomies and had an accompanying gold standard histopathological diagnosis of either a cyst or granuloma. Lesion volume, density, and specific radiologic characteristics were assessed using specialized software. Logistic regression models with histopathological diagnosis as the dependent variable were constructed for cyst prediction, and receiver operating characteristic curves were used to assess the predictive validity of the models. A conditional inference binary decision tree based on a recursive partitioning algorithm was constructed to facilitate preoperative screening. ResultsInterobserver agreement was excellent for volume and density, but it varied from poor to good for the radiologic criteria. Volume and root displacement were strong predictors for cyst screening in all analyses. The binary decision tree classifier determined that if the volume of the lesion was >247 mm3, there was 80% probability of a cyst. If volume was <247 mm3 and root displacement was present, cyst probability was 60% (78% accuracy). ConclusionsThe good accuracy and high specificity of the decision tree classifier renders it a useful preoperative cyst screening tool that can aid in clinical decision making but not a substitute for definitive histopathological diagnosis after biopsy. Confirmatory studies are required to validate the present findings.

Endodontic management of a maxillary lateral incisor with an unusual root dilaceration diagnosed with cone beam computed tomography

Anterior teeth may have aberrant anatomical variations in the roots and root canals. Root dilaceration is an anomaly characterized by the displacement of the root of a tooth from its normal alignment with the crown which may be a consequence of injury during tooth development. This report aims to present a successful root canal treatment of a maxillary lateral incisor with unusual palatal root dilaceration (diagnosed with cone beam computed tomography) in which the access cavity was prepared from the labial aspect of the tooth to provide a straight line access to the root canal system which was instrumented using OneShape rotary file system and precurved K-files up to size 50 under copious irrigation of 2.5% NaOCl using a side-vented irrigation tip. The canal was then obturated using the warm vertical compaction technique.

The importance of prompt referral when tooth roots are displaced into the maxillary antrum

When an upper tooth is extracted a possible complication is the creation of an oro-antral communication with the added risk of displacement of tooth roots into the antrum. We present a case of a displaced palatal root of an upper first molar tooth which was found in a superior position in the maxillary antrum having been left in situ for 6 weeks. The root was in a high risk position for complications such as sinusitis, mucocoele formation and the more serious septic thrombosis of the cavernous sinus. This case report describes its safe endoscopic removal and highlights the importance of prompt referral and treatment for similar cases. CPD/Clinical Relevance: Displaced roots in the maxillary antrum during routine extraction can result in complications ranging from sinusitis to more severe complications if not managed appropriately.

Phenotypic plasticity of roots in mixed tree species agroforestry systems: review with examples from peninsular India

Agroforestry entails different life forms including mixtures of trees that occupy different soil strata and exhibit a certain degree of spatial complementarity in resource use. However, rigorous experimental studies characterising root interactions in tree–tree systems are notoriously few. We present here the available empirical evidence to support the hypothesis that occurrence of two or more tree species close to one another may favour diminished lateral spread and/or deeper root penetration of the woody components and closer the tree components are located greater will be the subsoil root activity. These evidences are based on either root excavation studies in coconut-based multistorey production systems, or 32P soil injection experiments involving binary mixtures of coconut+interplanted dicot multipurpose trees (Vateria indica, Ailanthus triphysa or Grevillea robusta), and bamboo (Bambusa bambos)+teak (Tectona grandis) or Malabar white pine (V. indica). The excavation study denotes a spatially segregated root distribution pattern of the component species. Furthermore, in the coconut + dicot tree system, interplanted dicot trees absorbed considerable quantities of the radio-label applied to the palm, which declined log-linearly with distance from the palms, signifying a substantial potential for “capturing” the lower leaching nutrients, at proximal distances. Likewise, lower teak/Vateria root activity in the surface horizons and higher activity in the deeper layers, when bamboo clumps were nearby and vice versa when they were farther apart, implied that proximity of species/individuals favoured competitive downward displacement of roots. Nutrient pumping and/or current transfer of nutrients between the rhizospheres of the two associated crops are also possible. In designing sustainable agroforestry systems, it is, therefore, advantageous to mix trees with divergent root growth habits.

Phase-Field Modeling of Grain-Boundary Grooving Under Electromigration

In the present work, we study the phenomenon of grain-boundary grooving under electromigration using a phase-field method. The specific focus of the work is to explore the role of grain boundaries as potential electromigration pathways. We consider the evolution of grooves under the combined influence of capillary and electromigration-mediated surface diffusion and electromigration-induced grain-boundary diffusion. Mechanisms of grooving are elucidated using flux density maps that indicate various regimes depending upon the direction of net material transport. When grain-boundary atomic mobility is lower than the surface mobility, the groove depth is found to be lower than that evolving solely under surface diffusion (no electromigration). At comparable or larger values of grain-boundary atomic mobility, grooving is initially expedited but shows groove replenishment at later stages. A detailed investigation using the phase-field method reveals the influence of an incumbent healing mechanism on grain-boundary grooving which is electrically induced. The drift characteristics such as edge and root displacement and velocity are examined in light of this assuaging effect.

Computational comparison of aortic root stresses in presence of stentless and stented aortic valve bio-prostheses

We provide a computational comparison of the performance of stentless and stented aortic prostheses, in terms of aortic root displacements and internal stresses. To this aim, we consider three real patients; for each of them, we draw the two prostheses configurations, which are characterized by different mechanical properties and we also consider the native configuration. For each of these scenarios, we solve the fluid–structure interaction problem arising between blood and aortic root, through Finite Elements. In particular, the Arbitrary Lagrangian–Eulerian formulation is used for the numerical solution of the fluid-dynamic equations and a hyperelastic material model is adopted to predict the mechanical response of the aortic wall and the two prostheses. The computational results are analyzed in terms of aortic flow, internal wall stresses and aortic wall/prosthesis displacements; a quantitative comparison of the mechanical behavior of the three scenarios is reported. The numerical results highlight a good agreement between stentless and native displacements and internal wall stresses, whereas higher/non-physiological stresses are found for the stented case.

Biomechanical Effects of Novel Osteotomy Approaches on Mandibular Expansion: A Three-Dimensional Finite Element Analysis

Surgically assisted mandibular arch expansion has proved to be an effective treatment modality in alleviating constriction and crowding issues. However, only mandibular symphyseal distraction osteogenesis has been in favor for the purpose of mandibular arch expansion. In addition, no relevant study has compared the biomechanical response of different osteotomy designs on mandibular expansion. The present study evaluated the effect of different osteotomy approaches and modes of loading on the expansion of the adult mandible using biomechanics. To address the research purpose, 9 finite element (FE) models, including 2 novel osteotomy designs, were simulated. Stress, strain, and displacement of crown, root, and bone were calculated and compared under different osteotomy approaches and loading conditions. The biomechanical response envisaged by the FE models in terms of displacement on the X axis was consistent from the anterior to posterior teeth with parasymphyseal step osteotomy and a hybrid mode of force application. In addition, the amount of displacement predicted by parasymphyseal step osteotomy with the hybrid mode was greater compared with that of the other models. The results of our study suggest parasymphyseal step osteotomy with the hybrid mode is a viable treatment option for true bony expansion in the adult mandible.

Repeated 3.0 Tesla Magnetic Resonance Imaging After Clinically Successful Lumbar Disc Surgery.

Prospective cohort study. To describe the naturally occurring magnetic resonance imaging (MRI) findings after successful microsurgical removal of lumbar disc herniation with repeated MRI examinations. The interpretation of MRI after spinal surgery may be particularly challenging and image findings do not always correlate to clinical findings. Early postoperative MRI has limited value in the evaluation of patients after surgery for lumbar disc herniation. Prospective study of 30 successfully operated patients, which underwent 3.0 T MRI within 24 h after surgery for lumbar disc herniation and repeated at 6 weeks and 3 months postoperatively. Postoperative image findings (nerve root enhancement, nerve root thickening, displacement or compression of the nerve root, and residual mass size and signal) were assessed quantitatively. Inter-rater reliability was tested. Inter-rater reliability between neuroradiologists was moderate for assessed MRI variables. In the immediate postoperative phase, compression or dislocation of the nerve root at the operated level was common. A residual mass at the operated level was seen in 80%, 47%, and 33% after 24 h, 6 weeks, and 3 months, respectively. Postoperative dislocation or compression of the nerve root from residual masses was seen in 67%, 24%, and 14% after 24 h, 6 weeks, and 3 months, respectively. A residual mass with a higher signal than muscle on T2-weighted images was seen in 80%, 30%, and 17% after 24 h, 6 weeks, and 3 months, respectively. A residual mass with compression or dislocation of the nerve root at the operated level, that disappears over 3 months, is a common MRI finding in patients successfully operated for symptomatic lumbar disc herniation. An expectant approach instead of early reoperations may perhaps be preferred in patients with residual pain and root compression due to residual masses with high T2-signal since these often seem to resolve spontaneously. 3.