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Biomedical subjects

P Menghini

Publications and source records attributed to P Menghini.

At least 19 recordsLinked to original sources
PubMed2002

Observations on dental prostheses and restorations subjected to high temperatures: experimental studies to aid identification processes.

In large scale disasters associated with fire the damage caused by heat can make medico-legal identification of human remains difficult. Teeth, restorations and prostheses, all of which are resistant to even quite high temperatures can be used as aids in the identification process. In this project the behaviour and morphology of teeth and dental prostheses exposed to a range of high temperatures was studied. Healthy teeth, dental restorations and prostheses were placed in a furnace and heated at a rate of 30 degrees C/min and the effects of the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined by stereomicroscopy and scanning electron microscopy (SEM). Our observations show that some prostheses and restorative materials resist higher temperatures than theoretically predictable and that even when a restoration is lost because of detachment or change of state its ante-mortem presence can be confirmed and detected by both stereomicroscopic examination and SEM of the residual cavity. We further conclude that a reasonably reliable estimation of the temperature of exposure can be made from an analysis of the teeth and restorative materials.

Composite Resins↗
PubMed1995

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition.

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

Calcinosis↗
PubMed1994

Collagen fiber arrangement in temporo-mandibular joint (TMJ) disks from human subjects with functional diseases. Scanning electron microscopy investigations.

Twelve articular disks from patients with temporo-mandibular joint (TMJ) arthropathy were studied and compared with two normal disks. Scanning electron microscopy (SEM) examination of the surfaces and of longitudinal and cross-sections of the disks allowed the observation of the arrangement of the collagen fiber component in different parts of the disk. The superficial part of the articular disks appears to be formed by rather compact fibers. The internal portion is usually formed by bundles of collagen fibers in sheets, alternating with isolated fibers arranged in a parallel or irregular way. In some samples, blood vessels were observed. Our investigations suggested that the appearance of vascularization is the first remarkable histological change that can be observed in functionally abnormal articular disks.

Collagen↗
PubMed1993

Lipoma of the corpus callosum in a neonate: sonographic evaluation.

Lipomas of the corpus callosum are benign neoplasms which are rarely diagnosed in pediatric patients. In infants they are congenital lesions consisting of collections of adipose tissue; their etiology is unclear. We describe a case of callosal lipoma discovered by sonography in a 2-day-old neonate.

Brain Neoplasms↗
PubMed1993

Darrow-Gamble disease: ultrasonographic and radiographic findings.

A case of Darrow-Gamble disease is presented with review of the radiographic and ultrasonographic appearance of this rare cause of profound chronic diarrhea beginning at birth. The disease is caused by a defect of active intestinal chloride transport which results in a large loss of the electrolytes and water. To prevent growth retardation and renal involvement an adequate replacement therapy is necessary. This uncommon anomaly was detected by ultrasound 3 weeks before delivery. Both sonography and radiography were useful diagnostic tools in the postnatal period. The clinical features of the lesion are also discussed.

Chlorides↗
PubMed1993

Observations on the enamel of odontomas.

The morphological study of odontomas provides an alternative model for observing the formation of dental tissues, since different maturing stages are present simultaneously. Investigations were performed on decalcified samples (using light microscopy and transmission electron microscopy) and on undecalcified samples of complex odontoma enamel (using transmission electron microscopy). Simultaneous presence of prismatic enamel at various maturing stages with different structural characteristics was observed. Such enamel was sometimes associated with layers of ameloblastic cells with characteristics of cells in functional activity. In other sites, the enamel did not present a prismatic structure but it appeared as unstructured material clusters with abundant organic component. It was concluded that the theory according to which an ecto-mesenchymal inductive failure occurs in odontomas is not confirmed. The defect seen at the beginning of the differentiated and anomalous tissue maturation may be related to latest events in the development of the enamel organ. In this regard, it was concluded that such events involve the efficiency of the ameloblasts and the possible alterations in the organic matrix.

Adolescent↗
PubMed1991

[Dental tissue-composite bonding. SEM study].

The Authors investigated the different operative methods effects in the transition zone between human fresh teeth calcified tissues and a composite material. Morphological observations, done by means of standard and back scattered scanning electron microscopy, demonstrated the Gluma adhesion system efficiency towards enamel and dentin if manufacturing's applying systems are carefully followed, by showing a structure with no solutions of continuity between tooth and restoration.

Composite Resins↗
PubMed1991

[An ultrastructural study of the fibrillary component of dental tissues].

The recent interest for highly sophisticated techniques of dental tissue preparation aiming to display very particular structures, moved the AA. to improve the literature suggestions. In particular they made TEM and SEM observations of transitional zones between healthy and normal pulp and dentin after decalcification and trypsin at different concentrations treatment. The images obtained draw in the attention the study facilities of a technique that really removes all the non collagenic material. The data obtained in the pericellular zones also allowed some interventions in the recent literature discussion about inter-odontoblastic fibres.

Decalcification Technique↗
PubMed1991

[Guided tissue regeneration: an ultrastructural observation by transmission electron microscopy and scanning electron microscopy].

PTFE membranes are used for guided tissue regeneration in order to treat angular bone defects or forcation involvements in surgical treatment. Ultrastructural investigations have been performed by means of electron transmission and scanning microscopy. In agreement with previous reports, fibroblast cells adhering to the reticular structure of PTFE membrane were observed; these were interposed among coagulated clusters of fibrinous material and blood cells round shaped. Elongated bacterial cells were always present in the microscope fields analysed. These observations were confirmed by means of transmission microscopy; moreover specific techniques enabled us to demonstrate that fibroblast cells were synthetizing collagen, which was present in the form of extracellular fibers mixed to fibrin clusters. Roundish and elongate bacterial cells were always observed both in the extracellular matrix and into macrophages.

Guided Tissue Regeneration, Periodontal↗
PubMed1990

Immunocytochemical detection of protein p38 in human dental pulp.

The occurrence and distribution of protein p38 (synaptophysin) were investigated by immunofluorescence. Immunoreactivity for protein p38-like antigen was detected within axons of radicular nerve trunks entering the tooth and within nerve terminals close to blood vessels. Immunoreactive structures were also observed in the para-odontoblastic region. It is proposed that protein p38, translocated within small synaptic vesicles from neuronal perikarya along the axons, may be a reliable marker for detection of nerve endings in human tooth.

Axons↗
PubMed1989

[Aprismatic external layer of deciduous and permanent teeth].

The authors verify the presence of an aprismatic layer at the surface of human deciduous and permanent, erupted and non erupted teeth, by means of the polarizing and scanning electron microscope. The results allowed the Authors to conclude that the presence of different extents of aprismatic enamel at the surface of human teeth should be regarded as a constant and normal feature, with some different frequency and organization patterns between different tooth types.

Dental Enamel↗
PubMed1989

[The effects of the CO2 laser on human dentin and cementum].

Polarizing microscopy, scanning electron microscopy and X-ray diffraction analysis have been used to study the effects of the radiations of a CO2 laser equipment on the dentine and cementum of sound human permanent teeth. The typical lesions induced in dentine and cementum differ only lightly because of the different composition of the tissues. They assume a crater-like aspect and show structural alterations, less and less severe when moving away from the beam focal center. The morphological analysis of the tissues, which loose their organic components through combustion, suggests that such lesions are the consequences of a very fast overheating followed by a fast cooling. X-ray diffraction analysis shows that the hydroxyapatite of the tissues submitted to the thermic stress does not undergo phase transformation, which means that the temperatures remain lower than 1200 degrees C.

Dental Cementum↗
PubMed1989

[Immunocytochemical study of the development of the oral cavity in the rat].

Flow cytometry and autoradiography are extensively used for the evaluation of the number of cells in S-phase in order to study the proliferative activity within tissues and organs. The recent development of a monoclonal antibody against 5-bromo-2'deoxyuridine (BrdUrd), a nonradioactive thymidine analogue that is incorporated within DNA-synthetizing cells, allows the immunochemical detection of proliferating cells. The use of this antibody allows an immunocytochemical detection of proliferating cells "in situ" on tissue sections. We have applied this new technique for the identification of proliferating cells within the tooth and other organs of rat mouth during development. We believe that this technique, for its precision and simplicity, may be a powerful tool for studying the cytokinetic and the differentiation of normal and neoplastic cells within the mouth as well as in other districts of the body.

Animals↗
PubMed1986

Alterations due to ampicillin and rifampicin in S. sanguis and S. aureus isolated from dental plaque. An electron microscopic study.

In this work we analysed the ultrastructural changes in S. aureus and S. sanguis after exposure to rifampicin and ampicillin respectively. S. aureus grown in the presence of rifampicin showed ultrastructural changes that can be summarized as follows: the peripheral cell-wall increased to three to five times the normal thickness; the cross-walls were considerably (two to ten times) thicker than normal; after 8 h of exposure a complete lysis occurred. S. sanguis grown in the presence of ampicillin showed ultrastructural changes that can be summarized as follows: aggregation and condensation of ribosomes; alterations of division with the presence of asynchronous septa; in some bacterial cells a prominent bulge was observed at one pole of the cell; after 8 h of exposure a complete lysis occurred.

Ampicillin↗