Biomedical subjects

A Bonaccorso

Publications and source records attributed to A Bonaccorso.

At least 19 recordsLinked to original sources

PubMed2003

[Pancreatic pseudocysts. Clinical contribution].

Aim of this study was to compare, taking into consideration data from the literature, the various diagnostic examinations and therapeutic modalities nowadays available to manage patients affected by pancreatic pseudocysts. Personal experience regarding three patients with post-necrotic pancreatic pseudocysts is reported; these patients complained of epigastric pain with nausea and tenderness in the upper abdominal quadrants. Diagnosis was made by CT. In one case a progressive decrease of the pseudocyst was observed; the second patient was treated by a pseudocyst-jejunostomy; the last patient initially underwent a trans-gastric percutaneous drainage for infection of the pseudocyst and afterwards an open pseudocyst-gastrostomy. All patients were cured, even if the second patient during the postoperative course developed a pleuric effusion, which was treated by thoracentesis. Pancreatic pseudocysts in 20% of cases resolve spontaneously, as observed in one of our patients. In other cases, a surgical operation is needed, now feasible through an endoscopic, percutaneous, laparotomic or laparoscopic approach. The endoscopic and percutaneous approach are indicated only in selected cases, so that the "gold standard" treatment is still the laparotomic one, especially by a pseudocyst-jejunostomy, which also in our experience has given the best result. Very promising also, according to the latest data from the literature, seems the laparoscopic approach, by which a wide communication between the stomach and the pseudocyst is obtained.

Aged↗

PubMed2001

Wear of nickel-titanium endodontic instruments evaluated by scanning electron microscopy: effect of ion implantation.

The present work analyzes possible increases in resistance to wear of nickel-titanium endodontic instruments that have undergone a process of ionic implantation. ProFile .04 taper #25 instruments were subjected to ionic implantation with bands of nitrogen ions of 250 KeV, currents in the order of 10 microA/cm2, and doses of 2 x 10(17) ions/ cm2. The instruments were used to make preparations in acrylic endodontic training blocks. Scanning electron microscopic investigations showed that after 60 s of work inside the endodontic training blocks nonionic implanted control instruments showed small modifications in their blades, and their tips showed the first signs of wear. After 240 s the control instruments showed consistent signs of wear and frequent changes to their surfaces. After 240 s of use the ionic-implanted instruments did not present any significant changes in the micromorphology of their surfaces. The implanted instruments did not manifest the typical signs of wear and did not show the surface changes that quickly affect the working life of untreated endodontic instruments manufactured from nickel-titanium.

Dental Instruments↗

PubMed2001

Defects in GT rotary instruments after use: an SEM study.

Used rotary nickel-titanium instruments require frequent replacement. This laboratory study evaluated defects of GT Rotary instruments before and after usage. The instruments were fixed into custom-made holders and photographed in an SEM at x 260 to x 12,000 magnification at preset points. Instrument sizes 20 with 1.0, 0.8, and 0.6 taper and instrument sizes 35 with 1.2 taper were used in 12 canals. The used instruments were cleaned and then reexamined in an SEM as before. The presence of 11 types of conditions was scored from the pre- and postusage photographs. No instruments fracturing or plastic deformation was observed during the test. The presence of debris, pitting, and scraping changed significantly. Imperfections were found on used GT Rotary instruments and the presence of defects (pitting, scraping, and blunt-cutting edges) increased in all of the instruments. The behavior of GT Rotary instruments with usage seems to be different, compared with that found in other instruments.

Dental High-Speed Technique↗

PubMed2000

The effect of surface treatments of nickel-titanium files on wear and cutting efficiency.

OBJECTIVES: This study was designed to verify whether nitridation treatment of the cutting surfaces resulted in surface or subsurface changes that produced an increase in the resistance to wear in nickel titanium (NiTi) endodontic files. STUDY DESIGN: Some experimental samples were exposed to ionic implantation by using 150 keV of nitrogen ions and doses of 1 x 10(17) ions per cm(2). Other samples were exposed to thermal nitridation processes performed for 480 minutes at 500 degrees C temperature. Control samples were not exposed to any process. The chemical composition of the surface layers of each sample was determined by means of x-ray photoelectron spectroscopy. The cutting efficiency was tested on an endotraining bloc. RESULTS: The experimental instruments showed in-depth distributions of chemical composition that were different from those seen in the control group; thermal-nitridated instruments demonstrated a surface ratio of nickel to titanium of 0.5. Implanted samples had a higher N/Ti ratio (1.2); this ratio may be due to the presence of a layer of titanium nitride. Samples in the experimental groups showed an increase in cutting ability as compared with the controls. CONCLUSIONS: Thermal nitridation and nitrogen-ionic implantation treatment of nickel-titanium files produced a higher wear resistance and an increased cutting capacity.

Dental Alloys↗

PubMed1999

Effect of sterilization on the cutting efficiency of rotary nickel-titanium endodontic files.

OBJECTIVE: Nickel-titanium instruments that offer greater flexibility than instruments made of other metallic materials have been developed. This study evaluated the behavior in vitro of nickel-titanium rotary instruments under repeated sterilization cycles. STUDY DESIGN: To investigate changes in cutting ability and superficial alterations, 36 ProFile instruments, 18 with a taper of .04 and 18 with a taper of .06, were exposed to different sterilization cycles. Samples were divided into 3 groups of 12 files each. The 12 group A samples were exposed to 14 cycles of sterilization for 30 minutes; the 12 group B samples were exposed to 7 cycles of sterilization for 30 minutes; the 12 group C samples were not sterilized and served as a control group. Chemical compositions of the near surface layers of samples of each group were determined by means of Auger spectroscopy. RESULTS: The instruments that underwent the greatest number of sterilizations (group A) showed in-depth distributions of chemical composition that were different from those seen in the control group; this was the result of greater amounts of titanium oxide on the surfaces of the sterilized instruments. The files of group A showed a decrease in cutting efficiency in comparison with those of the control group. CONCLUSIONS: On the basis of this research on nickel-titanium files, we determined that repeated sterilizations under autoclave alter the superficial structure of such instruments.

Dental Instruments↗

PubMed1999

[Comparison of different finishing methods for composites and compomers. Profilometric analysis].

BACKGROUND: Reconstructions with aesthetical materials neither finished nor polished can be extremely irregular and wrinkled. For this reason they represent an ideal basis for the growing of pigmentation which come from food remainings and the nestle of bacteria on the plaque. The finishing of aesthetical materials is a fundamental step in conservative dentistry. The finishing session regarding the aesthetical restorations should be considered and planned at the moment of their insertion in the prepared hollows. The finishing should not be considered an option, but the conclusion of all the conservative treatment. Purpose of the search is to examine and assess, through a technical equipment measuring the superficial wrinkledness of the materials, the action of 4 systems of finishing and polishing on two aesthetical materials widely used in the daily practice by dental surgeons: a compomer (Compoglass, Vivadent) and a composite (Spectrum, Dentsply). METHODS: For each of these two materials some little slabs model have been prepared, choosing the universal colour in the colorimetric scale. The two types of filling materials have been compared with 4 systems of finishing and polishing: Sof-Lex Pop-on (3M), Enhance system (Dentsply), Hawe Micro Disc (Howe Neos), Heawe Gommini Polisher (Heawe Neos). The total working time did not overcome 1 minute. The little slabs have been obtained, pressing the resin between two slides used in microscopy. In the hope to guarantee in the different samples, a uniform thickness, we have used a technical device. On each covering slide we have put a weight of 0.5 kg for 5 minutes. The thickness of the little slabs obtained was 2 mm. Thus, pressed between the two slides, the aesthetical material has been photopolymerized according to the time suggested by Manufacturing Industries. The sizes concerning the wrinkledness of samples subjected to different treatments have been carried out using a pointed profilometer with high sensitivity. (Tencor-P10). This instrument used in the National Laboratory of Catania, called INFN, is able to graphitize the wrinkledness of a surface "survbeying" it with a diamond ultramicrometric point. RESULTS: All tested systems gradually produce the upper layers of the materials less suitable to resist the assault of plaque bacteria as time passed. The 3M coarse and medium grain Disks are very abrasive and for this reason the surface of the materials is ill-shaped. Those disks with fine and extra fine grain, smooth the tracks left by previous disks. As they have been always used according to their decreasing granulometry, the disks are used only for removing small composite pieces in excess and to improve micromorphology of the restauration. The "Gommini" are less abrasive than Disks. In a few minutes and often with only one step they produce a much regular and polished fillings surface. CONCLUSIONS: The "Gommini" have a preference when the last photopolymerization has left a regular layer, with a very good micromorphology. Actually, "Gommini" do not remove much material, but they continue to smooth the outline of the reconstruction. Disks are not classified as being of first quality in the finishing of composites and compomers.

Composite Resins↗

PubMed1999

[Von Recklinghausen osteitis fibrosa cystica. A clinical case].

In Recklinghausen's disease the skeleton lesions are often the first signal of the pathology. The main clinical manifestations are represented by bony lesions which appear as multicystic lesions with loss of the hard lamina and skull malformation and asymmetry. In this disease there is a relevant osteoclastic activity which prevails over the osteoblastic one associated to the fibrous substitution of the marrow, sometimes producing micro or macro cysts. The typical alteration consists of an increase along the endosteal and trabecular surfaces in the number of osteoclasts which can be found in small reabsorption gaps. This is the cause of a cortical and trabecular reduction which can appear as interrupted. Histologic lesions consist in the replacement of bone tissue with fibrous and osteoid tissue. These bony lesions are not characteristic of the disease but to be distinguished from other pathologies such as for example Paget's disease and other forms of fibrous dysplasia (Gardner's syndrome, Leontiasis ossea). A case personally observed is described: a women, 29 years old, suffering from Recklinghausen's disease with face and skull asymmetry, condyles and glenoid cavity deformation, abnormal face reduction. Observing the planigraphy on the right side of the temporomandibular articulation, flattened glenoid cavity and condyles with irregular outlines can be noticed, aplastic coronoid cuts, altered jaw. The patient was submitted to surgery for dental extraction followed by a biopsy which showed some regressive alterations on cellular level of the bony structure.

Adult↗

PubMed1999

[Non-Hodgkin lymphoma of the maxilla. Report of a case].

Lymphomas are primitive neoplasias of the lympho-reticular system and are classified into two principal categories: Hodgkin's lymphoma (HL) and Non-Hodgkin's Lymphoma (NHL) each classified into low, medium and high grades, according to their clinical and cytological characteristics. The treatment and prognosis of such neoplasias vary according to the distribution of the illness and to the moment of initial diagnosis. In NHL, treatment depends prevalently on the histological subtype. Over the last few years it has been possible to associate to defined nosographic entities a characteristic phenotype, and to formulate a phenotypical classification of chronic lymphoproliferating illnesses. The classification of the Working Formulation subdivides lymphomas into groups of increasing malignancy. In histological sections, non-Hodgkins lymphomas are relatively homogeneous, uniformly cellular and dominated by malign lymphocytes. The symptomatology of NHL can vary according to the different location. The clinical manifestation of NHL can be in the form of swelling or ulceration. In contrast with lymphonodal lymphoma, in which the spread through blood to distant lymphonodal regions or extra lymphonodal areas is rapid, the extra lymphonodal ones show a clinical course of illness comparable with those of carcinomas. The authors present the case of a 89 year-old patient with an ulcerated, non painful swelling in the upper right alveolar maxillary region, showing slow development, soft consistency and indefinite edges; this lesion did not affected the normal physiological functions of the stomatognathic apparatus, thus explaining why the patient had noticed the appearance of the process two years prior to the visit but had not reported it. The pathological case-history shows traumas at the site of the lesions due to dentures. At the moment of the visit, the ortopathomographic examination of the upper and lower dental arch shows the presence of a lesion in the right maxillary region, radiographically opaque, with ill-defined margins and signs of continuity with the homolateral maxillary sinus.

Aged↗

PubMed1998

[The role of cell adhesion molecules in the formation of periapical granulomas].

Cell adhesion molecules (CAMs) are cell surface proteins involved in the binding of cells, usually leukocytes, to each other, to endothelial cells, or to extracellular matrix. Specific signals produced in response to wounding and infection control the expression and activation of certain of these adhesion molecules. The interactions and responses then initiated by binding of these CAMs to their receptors/ligands play important roles in the mediation of the inflammatory and immune reactions that consult one line of the body's defense against these insults. Most of the CAMs characterized so far fall into three general families of proteins: the immunoglobulin (Ig) superfamily, the integrin family, or the selectine family. Recent studies have indicated that selectins (E,L,P) are implicated in cell trafficking, an important aspect of inflammation-related process. Regulation of white blood cell trafficking from the blood vascular compartment to regions of pathogenic exposure is one of the most important functions of the immune system. The distinct phases of leukocyte migration include: rolling, activation, firm adhesion, transendothelial migration and subendothelial migration. The selectins have been implicated in the first step of this cascade. An inflammatory response is first evoked in the pulpal tissue in an attempt to neutralize the injurious agent and to dispose of damaged tissue and cells. The pulpal vessels dilate and blood flow to the tooth increases. At the same time, permeability of the vessels increases allowing leakage of fluid and leukocytes into the tissue.

Cell Adhesion Molecules↗

PubMed1998

[Cell communication in the development of the oral cavity].

The cadherins are a family of a calcium-dependent cell adhesion molecules that are regulated both spatially and temporally during development. Epithelial cadherin (E-cadherin) is present in the epithelial cells in both the embryo and yolk sac during organogenesis. In many studies, the presence of E-cadherin was analyzed during normal and disturbed craniofacial development with respect to palate and tooth formation. E-cadherin was present in epithelia of both ectodermal and endodermal origin. The expression level of E-cadherin increased with age and differentiation. The expression pattern of E-cadherin implies that this molecule has a role during normal development of the epithelia of the cranio-facial complex. Morphogenesis and cell differentiation in the developing tooth are controlled by a series of reciprocal interactions between the epithelial and mesenchymal tissues. The exact molecular mechanisms operating in these interactions are unknown at present, but both structural components of the extracellular matrix (ECM) and diffusible growth factors have been suggested to be involved. In this review article we summarize our findings on the distribution patterns of three ECM molecules and two cell surface receptors during tooth morphogenesis through bud, cap, and bell stages of development. The examined molecules include fibronectina and tenascin, which all represent components of the mesenchymal ECM, the cell surface proteoglycan, syndecan, which functions as a receptor for interstitial matrix. Based on the observed changes in distribution patterns and on experimental evidence, roles are suggested for these molecules in epithelial-mesenchymal interactions during tooth development. C-Cam is a cell surface glycoprotein that is involved in cell adhesion and may play a role in histogenesis and organogenesis. It is a member of the carcinoembryonic antigen (CEA) gene family, which is a subfamily of the immunoglobulin gene superfamily. The presence of C-CAM in all proliferating craniofacial epithelia indicates that this molecule may play an important role in development.

Cell Adhesion↗

PubMed1998

[SEM (Scanning Electron Microscopy) study of the deterioration of ProFile .04 and .06].

BACKGROUND: The ProFile are endodontic instruments made by a special nickel-titanium alloy. They have to work on constant rotation at a speed of 350 revolutions per minute. The purpose of the study is to assess, through SEM research, a possible deterioration of different ProFile conicity. METHODS: Sixteen dental elements pulled out for period dental reasons have been used as samples to assess the progressive deterioration of .04 and .06 ProFile conicity. Eight molars and eight premolars with a total of 36 radicular canals were examined. The types of ProFile tested were 8: they were respectively 4 with .04 conicity and 4 with .06 conicity. Before being used, all instruments are previously studied through SEM. The tested ProFile with .04 conicity had a diameter of 15, 25, 30 and 45. Those with .06 conicity had a diameter of 20, 25, 30 and 35. Each tested ProFile was introduced inside a radicular canal and was turned for 180 seconds with a constant rotation of 200 revolutions per minute. After this first step, the alterations produced by the instrument could be observed through SEM. Afterwards, the same ProFile has worked again inside another radicular canal with the same time and the same number of turns, before being observed again through SEM. We have continued using this method up to the break of the instrument. RESULTS: The instruments with .04 conicity and smaller diameter are subject to a faster deterioration, more visible at the point. After a working time of 180 seconds all the instruments have their distinct morphological alterations: after other 180 seconds it is possible to often observer an alteration to the pitch of the instrument. The breaking times are related to the diameter and conicity of ProFile tested. CONCLUSIONS: Endodontic nickel-titanium instruments, even if they represent a progress in the field of canal preparation, undergo some alterations in their shape if they are put under inevitable mechanical stress. The damages can be: break at the top of the instrument and loss of cutting abilities at the turns level.

Bicuspid↗

PubMed1998

[Recklinghausen neurofibromatosis. Report of a case].

Neurofibromatoses are genetic disorders of the nervous system that primarily affect the development and growth of neural cell tissues. These disorders produce other abnormalities such as skin changes and bone deformities. Neurofibromatoses occur in both sexes and in all races and ethnic groups. Scientists have classified these disorders as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). Other types of neurofibromatoses may exist, but are not yet identified. Nearly 50% of the cases shows a well definited familiarity for the disease, according to an autosomal dominant transmission, while the other 50% of patients shows a negative history of familiarity, according to a new chromosomal mutation interesting the same autosomal genes of the dominant transmission. Oral localization is more rare showing an incidence ranging from 4 to 7% in most series of different authors. The most frequent involvement site in oral neurofibromatosis is the tongue, followed by the oral mucosa and floor of the mouth; palate and maxillary-mandibular bones are a rare localization of the disease. In the present, the clinical, radiological, histopathological and therapeutical aspects of a clinical case of neurofibromatosis, presenting as mandibular tumor, are examined. The clinical case reported, a 37 year old man, was essentially characterized by a positive family history for the disease, a neurofibroma of the oral mucosa.

Adult↗

PubMed1996