Zoran Rakocevic

Impact of the lower third molar presence and position on the fragility of mandibular angle and condyle: A Three-dimensional finite element study.

The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3. In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side.

The treatment of scaphoid nonunion using the Ilizarov fixator without bone graft, a study of 18 cases

ObjectivesEvaluating the safety and efficacy of the Ilizarov fine-wire compression/distraction technique in the treatment of scaphoid nonunion (SNU), without the use of bone graft.DesignA retrospective review of 18 consecutive patients in one centre.Patients and Methods18 patients; 17 males; 1 female, with a mean SNU duration of 13.9 months. Patients with carpal instability, humpback deformity, carpal collapse, avascular necrosis or marked degenerative change, were excluded. Following frame application the treatment consisted of three stages: the frame was distracted 1 mm per day until radiographs showed a 2-3 mm opening at the SNU site (mean 10 days); the SNU site was then compressed for 5 days, at a rate of 1 mm per day, with the wrist in 15 degrees of flexion and 15 degrees of radial deviation; the third stage involved immobilization with the Ilizarov fixator for 6 weeks. The technique is detailed herein.ResultsRadiographic (CT) and clinical bony union was achieved in all 18 patients after a mean of 89 days (70-130 days). Mean modified Mayo wrist scores improved from 21 to 86 at a mean follow-up of 37 months (24-72 months), with good/excellent results in 14 patients. All patients returned to their pre-injury occupations and levels of activity at a mean of 117 days. Three patients suffered superficial K-wire infections, which resolved with oral antibiotics.ConclusionsIn these selected patients this technique safely achieved bony union without the need to open the SNU site and without the use of bone graft.

Factors Affecting Postmortem Tooth Loss

Unassociated human bones are a particular problem during the exhumation of mass graves and a factor that limits anthropological and paleopathological analyses from archaeological contexts. Extensive anthropological literature has focused on the complex taphonomic factors that influences bone assemblages, but little attention has been paid to postmortem tooth loss and factors affecting this process. The following study focuses upon the influence of different factors on postmortem tooth loss. Three samples were investigated in the study: a medieval church cemetery containing 110 individual skeletal remains, and two samples from a series of mass graves made within the same time period in 1999, containing 402 bodies. The frequency of postmortem tooth loss was analyzed relative to postmortem interval for each sample, excavation methods, age distribution, and presence of bone loss associated with periodontal disease. Our results indicate that the degree of alveolar bone loss significantly affected both antemortem and postmortem tooth loss and that the frequency of postmortem tooth loss has the strongest correlation to time since death. These findings suggest that additional care should be taken when exhuming remains from older contexts.

Occlusal load distribution through the cortical and trabecular bone of the human mid-facial skeleton in natural dentition: A three-dimensional finite element study

Understanding of the occlusal load distribution through the mid-facial skeleton in natural dentition is essential because alterations in magnitude and/or direction of occlusal forces may cause remarkable changes in cortical and trabecular bone structure. Previous analyses by strain gauge technique, photoelastic and, more recently, finite element (FE) methods provided no direct evidence for occlusal load distribution through the cortical and trabecular bone compartments individually. Therefore, we developed an improved three-dimensional FE model of the human skull in order to clarify the distribution of occlusal forces through the cortical and trabecular bone during habitual masticatory activities. Particular focus was placed on the load transfer through the anterior and posterior maxilla. The results were presented in von Mises stress (VMS) and the maximum principal stress, and compared to the reported FE and strain gauge data. Our qualitative stress analysis indicates that occlusal forces distribute through the mid-facial skeleton along five vertical and two horizontal buttresses. We demonstrated that cortical bone has a priority in the transfer of occlusal load in the anterior maxilla, whereas both cortical and trabecular bone in the posterior maxilla are equally involved in performing this task. Observed site dependence of the occlusal load distribution may help clinicians in creating strategies for implantology and orthodontic treatments. Additionally, the magnitude of VMS in our model was significantly lower in comparison to previous FE models composed only of cortical bone. This finding suggests that both cortical and trabecular bone should be modeled whenever stress will be quantitatively analyzed.

Does the presence of an unerupted lower third molar influence the risk of mandibular angle and condylar fractures

It has been suggested that unerupted lower third molars (M3) increase the fragility of the mandibular angle and simultaneously decrease the risk of condylar fracture. However, it is unknown whether this applies regardless of the direction and point of impact of the traumatic force. The aim of this study was to investigate the impact of an unerupted M3 on the fragility of the angle and condyle in terms of a force acting from different directions and affecting different regions of the mandible. Computed tomography scans of a human mandible and finite element methodology were used to obtain two three-dimensional models: a model with, and the other without an unerupted M3. A force of 2000N was applied to three different regions of the models: the symphysis, ipsilateral body, and contralateral body, respectively. When the force was applied to the mandibular body, the results revealed increased angle fragility in cases with unerupted M3. When the force was applied to the symphysis, the condyle region showed higher fragility, irrespective of the presence of an unerupted M3. In summary, fragility of the angle and condyle regions depends on the presence of an unerupted M3 and on the direction and point of impact of the force.

Microstructural properties of the mid-facial bones in relation to the distribution of occlusal loading

Although the concept of the occlusal load transfer through the facial skeleton along the buttresses has been extensively studied, there has been no study to link microarchitecture of the mid-facial bones to the occlusal load distribution. The aim of this study was to analyze micro-structural properties of the mid-facial bones in relation to occlusal stress. The study was performed by combining the three-dimensional finite element analysis (3D FEA) and micro-computed tomography analysis (micro-CT). Clenching was simulated on the computer model of the adult male human skull which was also used as a source of bone specimens. After the FEA was run, stress was measured at the specific sites in cortical shell and trabecular bone of the model along and between the buttresses. From the corresponding sites on the skull, twenty-five cortical and thirteen cancellous bone specimens were harvested. The specimens were classified into high stress or low stress group based on the stress levels measured via the FEA. Micro-architecture of each specimen was assessed by micro-CT. In the high stress group, cortical bone showed a tendency toward greater thickness and density, lower porosity, and greater pore separation. Stress-related differences in microstructure between the groups were more pronounced in trabecular bone, which showed significantly greater bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) in the high stress group. Our results suggest that the mid-facial bones in the adult dentate male skull exhibit regional variations in cortical and trabecular bone micro-architecture that could be a consequence of different occlusal stress.

Patient–physician relationship in the aftermath of war

During the period of conflict that led to the dissolution of the former Yugoslavia, the Serbian healthcare system suffered greatly; as a result, relationships between physicians and their patients reached an all-time low. After cessation of the various wars, a group of medical students attempted to assess the state of the patient–physician relationship in Serbia. Their study showed a relationship characterised by very meek patients and rather arrogant physicians. Empowered by their engagement, the medical students constructed a set of standards for achieving a proper patient–physician relationship; physicians should be capable of hearing and understanding patients, with the result that the ensuing empowerment can enable patients and physicians to create a tool for changing the relationship between both parties.

An aggressive chondroblastoma of the knee treated with resection arthrodesis and limb lengthening using the Ilizarov technique.

This case report describes the management of a 15 year old male with a biologically aggressive chondroblastoma of the knee. Following CT, bone scan, angiography and an open biopsy, the diagnosis was confirmed histologically and immunohistochemically. The patient underwent a 13 cm en-bloc excision of the knee, and knee arthrodesis with simultaneous bone transport using an Ilizarov ring fixator. Following 136 days of bone transport, the patient achieved radiological and clinical bony union after a total frame time of 372 days. He then commenced 50% partial weight-bear in a protective knee brace and gradually worked up to full weight-bearing by 4 months. The patient developed superficial pin tract infections around the k-wires on 2 occasions; these settled with a cephalosporin antibiotic spray and local dressings. At 13 years follow-up there are no signs of disease recurrence or failure at the fusion site. The patient is able to fully weight bear and stand independently on the operated leg. Knee arthrodesis with simultaneous limb-lengthening is an effective treatment modality following en-bloc resection of an aggressive chondroblastoma. The case is discussed with reference to the literature.

Study toward resolving the controversy over the definition of allergic fungal rhinosinusitis

&NA; Dysbiosis of the microbiome on the airway mucosa leads to the development of chronic inflammatory and allergic disorders. The aim of this study was to consider the potential diagnostic criteria for allergic fungal rhinosinusitis (AFRS) and nonallergic fungal rhinosinusitis (FRS), and the role of fungal presence in an environment for the development of AFRS. In this study, 136 patients were divided into two groups: patients with positive specific immunoglobulin E (sIgE) and fungal finding (AFRS group), and patients with negative sIgE and positive fungal finding (FRS group). The study design included: anamnesis data, sIgE, eosinophil count and skin‐prick test, rhinology and computerized tomography (CT) observation and mycological finding. Our results showed: (i) the prevalence in Serbia is: AFRS 1.3%, FRS 2.8%; (ii) 30.4% patients with sIgE+ had more often severe and recurrent chronic rhinosinusitis (CRS) (P = .005) and the presence of polyps (P = .025); (iii) 46.4% patients with sIgE+ had positive fungi on the sinonasal mucosa and were considered as AFRS; (iv) patients with AFRS had more frequent asthma (P = .024) and chronicity of CRS >10 years (P = .000). The persistent fungal presence and prolonged duration of CRS could be a silent threat for the progression of inflammation and development of FRS. Lavage with hypertonic‐NaCl should be included in the everyday hygiene routine in an effort to decrease fungal load and antigenic exposure. The presence of allergological parameters and better response to corticosteroid therapy in AFRS patients should be considered as crucial diagnostic criteria for AFRS.

Hyperostosis frontalis interna in postmenopausal women—Possible relation to osteoporosis

ABSTRACT To improve our understanding of hyperostosis frontalis interna (HFI), we investigated whether HFI was accompanied by changes in the postcranial skeleton. Based on head CT scan analyses, 103 postmenopausal women were divided into controls without HFI and those with HFI, in whom we measured the thickness of frontal, occipital, and parietal bones. Women in the study underwent dual energy x-ray absorptiometry to analyze the bone density of the hip and vertebral region and external geometry of the proximal femora. Additionally, all of the women completed a questionnaire about symptoms and conditions that could be related to HFI. Women with HFI had a significantly higher prevalence of headaches, neurological and psychiatric disorders, and a significantly lower prevalence of having given birth. Increased bone thickness and altered bone structure in women with HFI was localized only on the skull, particularly on the frontal bone, probably due to specific properties of its underlying dura. Bone loss in the postcranial skeleton showed the same pattern in postmenopausal women with HFI as in those without HFI. Recording of HFI in medical records can be helpful in distinguishing whether reported disorders occur as a consequence of HFI or are related to other diseases, but does not appear helpful in identifying women at risk of bone loss.