Exploring the influence of placing bi-directional E-glass fibers as protective layer under a CAD-CAM resin composite on the fracture pattern.

OBJECTIVES: To investigate the influence of the presence and position of bidirectional E-glass fibers under a CAD-CAM resin composite on the fracture pattern evaluated both after quasi-static mechanical loading and after fatigue. METHODS: Rectangular specimens (10 mm-long, 5 mm-large and 4.2 mm-thick) were prepared and divided into four groups (n = 30/group). The control group (C-Group) consisted of a 4.2 mm-thick layer of monolithic CAD/CAM resin composite resin (Cerasmart, GC). In the 3 other groups including the placement of a fiber layer (F-Groups), the CAD/CAM resin composite layer was reduced to 3-, 2- and 1-mm thickness (F3-, F2- and F1-Groups, respectively). Two bonded layers of bidirectional E-glass FRC (Dentapreg, ADM A.S.) were bonded underneath and a light-curable resin composite base (Gaenial Posterior, GC) was then added to reach a total thickness of 4.2 mm for all samples. In each group, half of the specimens (n = 15) were submitted to quasi-static mechanical loading to failure in a universal testing machine. The other half (n = 15) was subjected to cyclic isometric stepwise loading until failure or completion of 105000 cycles (5000 cycles at 500 N, followed by five stages of 20000 cycles at 750 N, 1000 N, 1250 N, 1500 N, and 1750 N). The data were analyzed by Weibull statistics for quasi-static loading, and by the Kaplan-Meier product limit estimation procedure after fatigue. All fractured specimens were studied using light and electron microscopy techniques, and the types of fracture were determined. RESULTS: For quasi-static mechanical loading, significant differences were observed for Weibull modulus and characteristic strength between groups, with values ranging from 10.8 to 22.4 for the former and from 2336.6 to 2974.7 for the latter. Also, survival after stepwise fatigue revealed statistically significant differences between groups (p < 0.05), the lowest values of cycles before failure being observed for F1-Group - Median = 61223 (50415; 65446) - as compared to the other groups - C-Group: Median = 89005 (86189; 98195); F3-Group: Median = 85198 (77279; 87860); F2-Group: Median = 89306 (87454; 97024). Both in quasi-static loading and after fatigue, the observation of fracture modes revealed major differences. While all fractures were vertical (split) in C-Group, the majority of the specimens in F-Groups presented some degree of horizontal deflection of the crack. In all deviated fractures, fractographic analysis confirmed a toughening effect of the fiber layer. SIGNIFICANCE: The present in vitro work tends to show that the fracture pattern of CAD-CAM resin composites is favorably affected by the presence and position of an underlying bidirectional E-glass fiber layer. The placement of E-glass fibers under a CAD-CAM resin composite may therefore represent an interesting strategy to reduce the risk of catastrophic restoration failure, which could be integrated in the development of the new generation of indirect materials, possibly in 3D-printing approaches.

Micro-computed tomography evaluation of bone architecture in various forms of unilateral condylar hyperplasia.

Condylar hyperplasia is one of the causes of facial asymmetry and malocclusion, characterized by enlargement of the lower jaw due to excessive condyle growth activity. The aim of this study was to use micro-computed tomography (micro-CT) to evaluate the bone architecture of the condylar head and determine whether there are differences between patients with various forms of unilateral condylar hyperplasia (UCH): hemimandibular hyperplasia, elongation, and mixed form. The cohort consisted of 28 patients with a mean age of 21.9 years. All patients underwent surgical treatment (condylar shaving) for active pathological growth activity. The portion of the condylar head removed was imaged by micro-CT and subsequently evaluated. Micro-CT imaging and semiquantitative and quantitative evaluation of the bone structure (percentage bone volume, surface density, trabecular thickness, trabecular separation, degree of anisotropy, and porosity of the subchondral bone) did not reveal significant differences between the individual types of condylar hyperplasia (P > 0.05). There were no significant differences in bone structure between the anterior and posterior portions of the condylar head. No statistically significant differences between individual groups of UCH were found in the micro-CT evaluation of the condylar head bone architecture.

Experimental surgery as part of the development of degradable biomaterials for cardiovascular surgery

Introduction: Cardiovascular diseases are responsible for significant morbidity and mortality in the population. Artificial vascular grafts are often essential for surgical procedures in radical or palliative treatment. Many new biodegradable materials are currently under development. Preclinical testing of each new material is imperative, both in vitro and in vivo, and therefore animal experiments are still a necessary part of the testing process before any clinical use. The aim of this paper is to present the options of using various experimental animal models in the field of cardiovascular surgery including their extrapolation to clinical medicine. Methods: The authors present their general experience in the field of experimental surgery. They discuss the selection process of an optimal experimental animal model to test foreign materials for cardiovascular surgery and of an optimal region for implantation. Results: The authors present rat, rabbit and porcine models as optimal experimental animals for material hemocompatibility and degradability testing. Intraperitoneal implantation in the rat is a simple and feasible procedure, as well as aortic banding in the rabbit or pig. The carotid arteries can also be used, as well. Porcine pulmonary artery banding is slightly more difficult with potential complications. The banded vessels, explanted after a defined time period, are suitable for further mechanical testing using biomechanical analyses, for example, the inflation-extension test. Conclusion: An in vivo experiment cannot be avoided in the last phases of preclinical research of new materials. However, we try to strictly observe the 3R concept ­ Replacement, Reduction and Refinement; in line with this concept, the potential of each animal should be used as much as possible to reduce the number of animals.

Effect of diamond-like carbon doped with chromium on cell differentiation, immune activation and apoptosis.

Diamond-like carbon (DLC) is a biocompatible material that has many potential biomedical applications, including in orthopaedics. DLC layers doped with Cr at atomic percent (at.%) of 0, 0.9, 1.8, 7.3, and 7.7 at.% were evaluated with reference to their osteoinductivity with human bone marrow mesenchymal stromal cells (hMSCs), immune activation potential with RAW 264.7 macrophage-like cells, and their effect on apoptosis in Saos-2 human osteoblast-like cells and neonatal human dermal fibroblasts (NHDFs). At mRNA level, hMSCs on DLC doped with 0.9 and 7.7 at.% of Cr reached higher maximum values of both RUNX2 and alkaline phosphatase. An earlier onset of mRNA production of type I collagen and osteocalcin was also observed on these samples; they also supported the production of both type I collagen and osteocalcin. RAW 264.7 macrophages were screened using a RayBio™ Human Cytokine Array for cytokine production. 10 cytokines were at a concentration more than 2 × as high as the concentration of a positive control, but the values for the DLC samples were only moderately higher than the values on glass. NHDF cells, but not Saos-2 cells, had a higher expression of pro-apoptotic markers Bax and Bim and a lower expression of anti-apoptotic factor BCL-XL in proportion to the Cr content. Increased apoptosis was also proven by annexin V staining. These results show that a Cr-doped DLC layer with a lower Cr content can act as an osteoinductive material with relatively low immunogenicity, but that a higher Cr content can induce cell apoptosis.

The influence of purification of carp collagen used in a novel composite graft with sandwich construction of the wall on its biological properties and graft patency rates.

We compared graft outcome between two types of a novel composite three-layer carp-collagen-coated vascular graft in low-flow conditions in a sheep model. Collagen in group A underwent more cycles of purification than in group B in order to increase the ratio between collagen and residual fat. The grafts were implanted end-to-side in both carotid arteries in sheep (14 grafts in 7 sheep in group A, 18 grafts in 9 sheep in group B) and artificially stenosed on the right side. The flow in the grafts in group A decreased from 297±118 ml/min to 158±159 ml/min (p=0.041) after placement of the artificial stenosis in group A, and from 330±164ml/min to 97±29 ml/min (p=0.0052) in group B (p=0.27 between the groups). From the five surviving animals in group A, both grafts occluded in one animal 3 and 14 days after implantation. In group B, from the six surviving animals, only one graft on the left side remained patent (p=0.0017). Histology showed degradation of the intimal layer in the center with endothelization from the periphery in group A and formation of thick fibrous intimal layer in group B. We conclude that the ratio between collagen and lipid content in the novel three-layer graft plays a critical role in its patency and structural changes in vivo.

The effect of ethylene oxide sterilization on electrospun vascular grafts made from biodegradable polyesters.

The study describes the detailed examination of the effect of ethylene oxide sterilization on electrospun scaffolds constructed from biodegradable polyesters. Different fibrous layers fabricated from polycaprolactone (PCL) and a copolymer consisting of polylactide and polycaprolactone (PLCL) were investigated for the determination of their mechanical properties, degradation rates and interaction with fibroblasts. It was discovered that the sterilization procedure influenced the mechanical properties of the electrospun PLCL copolymer scaffold to the greatest extent. No effect of ethylene oxide sterilization on degradation behavior was observed. However, a delayed fibroblast proliferation rate was noticed with concern to the ethylene oxide sterilized samples compared to the ethanol sterilization of the materials.

Restoration of severely damaged endodontically treated premolars: The influence of the endo-core length on marginal integrity and fatigue resistance of lithium disilicate CAD-CAM ceramic endocrowns.

OBJECTIVES: To explore fatigue limits of ceramic endocrowns for premolars. METHODS: Forty-eight devitalized premolars were cut at the CEJ. They were restored with standardized CAD-CAM lithium disilicate reinforced ceramic restorations (IPS e.max CAD, Ivoclar-Vivadent) and divided into four Groups (n=12): overlays (Group A, no endo-core, negative control), endocrowns with an endo-core of 2mm (Group B), 4mm (GroupC) and crowns with post and core (Group D, positive control). All specimens were first submitted to thermo-mechanical cyclic loading (TCML)(1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles). Margins were analysed before and after the loading. Survived specimens were then submitted to cyclic isometric stepwise loading (5Hz, 200N to 1200N) until completion of 105000 cycles or failure. In case of fracture, fragments were analysed using SEM and failure mode was determined. Results of stepwise loading were statistically analysed by Kaplan-Meier life survival analysis and log rank test (p=0.05). RESULTS: All the specimens survived the TCML test except four specimens of Group A (early restorations' debonding). No difference in percentages of closed margins was found between endocrowns (Groups B, C) and crowns (Group D). After the stepwise test, differences in survival within the groups were not statistically significant. Most of restorations experienced non-reparable fracture. CONCLUSIONS: Endocrowns with both 2-mm and 4-mm long endo-cores displayed outcomes after fatigue equivalent to classical crowns. Results of this study discourage the use of flat overlays with only adhesive retention. CLINICAL SIGNIFICANCE: When restoring extremely destroyed devitalized premolars, adhesive strategies should be coupled to a macro-mechanical retention in the root.

[Chest drain injury of the heart]. / Poranení srdce hrudním drénem.

INTRODUCTION: Injury to the heart during chest drainage is a very rare but potentially fatal complication of the procedure. CASE REPORT: A 56-year-old, polymorbid, poorly co-operative and extremely obese patient with chronic cardiac subcompensation and pleural effusion was admitted to a district hospital. A drain was inserted into the left pleural cavity in order to evacuate the pleural effusion. Fresh oxygenated blood was flowing out from the drain. The drain was clamped immediately. Echocardiography showed drain insertion into the left ventricle. A cardiac surgeon was contacted and indicated patient transfer to a cardiac surgery department followed by an emergency surgery. During the surgery performed through a left thoracotomy, a defect in the left ventricular wall was sutured. The patient was then stabilized, transferred back to the district hospital and, after achieving cardiopulmonary compensation, discharged home. CONCLUSION: Injury to the heart in chest drainage is a very serious iatrogenic complication. If it is to be managed successfully, the site of the insertion of the drain tip needs to be correctly identified and the drain must not be extracted. A surgical department capable of adequately addressing this complication needs to be contacted promptly, as emergency surgery may be the only lifesaving possibility.Key words: chest drainage - complication - heart injury.

[Hemipelvectomy for a desmoidal tumor]. / Hemipelvektomie pro desmoidální tumor.

A case- review describing a desmoid in a young female. The tumor originated at the tendinuous attachment of the m. rectus abdominis on the pubic bone, which had had two relapses. During the third--so far the latest--procedure it required left-sided hemipelvectomy with resection of the rectum and a part of the vagina. The patient was instructed about the serious character of the disease, the requirement for the radical resection and about the requirement for a careful long-term follow-up of the patient after the procedure.

[Extragenital endometriosis as a subject of interest for the surgeon]. / Extragenitální endometrióza jako predmet zájmu chirurga.

Endometriosis is a common gynaecological disorder, affecting 10-15% of the fertile female population. Most frequently, it affects internal genitalia, the main symptoms being pelvialgia and infertility. In 5% of the cases the disorder may also affect extragenital structures and present itself as endometriomas of the appendix, the small or the large intestine, the umbilicus, the inguinal canal, the residual scars after laparotomies or the diaphragm. They may also imitate a malignancy. The diagnostic key is the cyclic character of the pain or of the bleeding to the tract and the laparoscopic confirmation of the presence of the foci. When the diagnosis is known, a simple excision, extirpation or resection suffices. In case the malignancy cannot be excluded, a more extensive procedure is indicated. The authors present two case-reviews during a twelve-year period, in both cases the sigmoid was affected. In the first case, a radical resection of the rectosigmoid due to a suspected malignancy was performed, while in the second case, a simple excision of the endometrioma where the diagnosis was known was performed. The authors stress-out advantages of the interdisciplinary approach to the treatment of the complicated cases of endometriosis, so that the disorder would be solved in one surgical procedure.

[Visceral reduction in surgical treatment of "impossibly" large abdominal hernias]. / Visceroredukce v operacním resení "nemozných" obrovských brisních kýl.

The authors present a group of 6 patients treated in 1996-2000 with giant "impossible" hernia the contents of which "lost their rights in the abdominal cavity". The patients involved were old polymorbid people (mean age 75 years), 5 suffered from acute, one from chronic obstruction of the gut. After intensive preparation the authors implemented a hernioplasty, using an excessive surgical mesh, reduced the volume of the abdominal contents by the omentum in all subjects, by the right colon in two and by a 0.5-1 m segment of the ileum in 3 patients. Only one extremely polymorbid patient died because of multiorgan failure on the 17th day after surgery. In 5 patients artificial ventilation was necessary from 2 hours to 17 days. As to complications, diarrhoea was recorded in one patient and infection of the mesh in another one. The authors conclude that the majority of "impossible" incarcerated hernias can be resolved by visceroreduction and enlargement of the volume of the abdominal cavity by inserting an excessive surgical mesh into the enlarged hernial neck. In elective operations of such hernias for the preparation forced reduction of the weight can be used and the technique of enlargement of the abdominal volume by intermittent pneumoperitoneum. In this way a giant "impossible" hernia can be treated without threatening the patient's life by cardiopulmonary failure.

Sclerosing papillary carcinoma of the thyroid with tubular features.

A case of papillary thyroid carcinoma (PTC) in a twenty-seven year old female is reported. The patient presented with complaints of a goiter and associated dysphagia. Histologically, the tumor was characterized by diffuse growth of branching tubules lined by a single layer of the tumor cells and surrounded by circularly arranged fibrous tissue of variable thickness. Focally, micropapillary projections of the epithelium budding into the lumen of tubules were visible. The cells showed features of PTC (overlapping ground glass nuclei, multiple grooves and pseudoinclusions). Nevertheless, no areas of "classical" PTC were identified. A striking feature was the presence of a severe lymphoplasmocytic infiltrate and the presence of plentiful S-100 protein positive dendritic/Langerhans cells. The tumor shares several features with diffuse sclerosing PTC, namely the age and sex of the patient, the infiltrative growth pattern and the presence of severe chronic thyroiditis that is associated with a large number of dendritic/Langerhans cells in the background. There are, however, several distinct differences - particularly the absence of massive squamous metaplasia, psammoma bodies, areas of classical PTC, and also lack of invasion of lymphatic vessels. We believe that this tumor represents an unusual example of diffuse sclerosing PTC with special tubular features.

[Primary carcinoma of the duodenum]. / Primární karcinom duodena.

The authors describe the case of a 70-year-old man with primary adenocarcinoma of the fourth segment of the duodenum. Due to the infrequency of the condition there was diagnostic and therapeutic uncertainty. After the endoscopic and bioptic diagnosis three months elapsed before an incorrectly indicated derivation operation and only after another month the tumour was resected. The exhausted patient developed postoperative pancreatitis with subsequent multiorgan failure to which he succumbed. The disease should be suspected even if the symptomatology is poor. The patient suffered only from nausea and anaemia. From the diagnostic aspect endoscopic examination is most useful for the oral segment of the duodenum and double contrast examination for the aboral one. The method of treatment is duodenopancreatectomy for the upper part and segmental resection for the distal part of the duodenum.

[Allogenic vein transplantation in vascular surgery]. / Vyuzití allogenních zilních transplantátu v cévní chirurgii.

The authors evaluate retrospectively a group of 159 applications of venous transplants for arterial reconstruction in 54 patients and for preparation of a haemodialyzation approach in the remaining 105 patients. As allograft they used the stem of the saphena magna from patients with varices kept in saline with addition of an antibiotic at a temperature of 4 degrees C. Twelve-month patency rate was in vascular reconstructions 84%, in secondary arteriovenous fistulae 45.8%. Based on data in the literature and their own experience the authors draw attention of vascular surgeons to this cheap and available material and recommend its wider use as a second choice replacement.

[Reoperation of gastric banding in obesity]. / Re-operace po gastrických bandázích pro obezitu.

From September 1988 till June 1997 the authors performed gastric banding for morbid obesity in 644 patients. In 14 (2.2%) reoperation was necessary: on account of stenosis of the stoma with excessive weight loss in 10, inadequate weight loss in four patients. Correction was performed by prolonging the circumference of the cuff in five and by re-banding of the stomach and creation of a stoma with a 12 mm diameter and a "small stomach" with a volume of 15 ml in nine patients. No death nor complications were recorded. The results with complete recovery of the condition were excellent in the group with excessive weight loss, more modest in the group with a small weight loss. The authors emphasize the necessity of comprehensive care of obese patients; an optimal bariatric operation must be followed by long-term follow-up of patients to achieve a change of lifestyle as regards dietary habits as well as regular physical activity.

[Gastric banding in the treatment of obesity]. / Gastrická bandáz v lécbe obezity.

Failure of conservative treatment of obesity stimulated the development of bariatric surgery. The authors performed in 1988-1995 GB in 248 obese patients with a mean overweight of 48.2 kg and with serious comorbidity. The mortality in the group was 1.6%, the morbidity 12.5%. Within 12 months after operation the overweight of the patients declined by 70%, within 24 months by 57%. In the majority of patients the comorbidity receded, the blood sugar level reached normal levels, dyspnoea and hypertension improved as well as the psychic state and social position. The attained results confirm that this treatment of morbid obesity is justified and the authors recommend its wider use. Perspectively laparoscopic gastric banding is associated with a reduced mortality and morbidity, however it is also associated with higher costs.