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Biomedical subjects

L Fonzi

Publications and source records attributed to L Fonzi.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Influence of amalgam fillings on Hg levels and total antioxidant activity in plasma of healthy donors.

In order to evaluate the influence of mercury (Hg) levels on antioxidant power in human plasma, 26 healthy people were evaluated by a dentist and their plasma analyzed for Hg content by atomic absorption and total antioxidant activity (TAA) by FRAP method. Hg plasma concentration correlated with number of amalgam restorations, suggesting that Hg released from fillings is a source of Hg in non-occupational exposed people. Fish consumption, in fact, showed no influence on Hg plasma levels, perhaps because Italian subjects examined in the present group used low quantity of fish at week or kinds of fish with light contamination. TAA negatively correlated with Hg plasma revealing a pro-oxidant role of Hg released from amalgam fillings.

Adult↗
PubMedDate not supplied

Salivary mercury levels in healthy donors with and without amalgam fillings.

Dental amalgam (AMG) is the most diffused dental filling material. Since it is constituted for at least 40-45% of Hg, many questions have raised about its safe use. Hg particles from dental amalgam dissolve in saliva and, being ingested, they reach the blood stream through the intestinal mucosa. It has been demonstrated that amalgam fillings continuously release Hg vapour and that there is detectable Hg in expired and inspired air of amalgam owners. It is not yet fully accepted that AMG fillings represent the principal source of Hg for man and the aim of this study was to evaluate if the mercury level in saliva: 1) was higher within people bearing dental amalgam restorations than in people with no restorations; 2) was different between males or females; 3) increased in relation to the surface of amalgam restorations. The results showed a correlation between number of fillings and salivary Hg, between amalgam surface and salivary Hg. The Authors could finally assert that AMG fillings represented the principal source of salivary Hg in the subjects studied.

Adolescent↗
PubMedDate not supplied

Release of mercury from dental amalgam and its influence on salivary antioxidant activity.

Dental amalgam fillings are known to release significant levels of mercury (Hg) in saliva which could represent a continuous source of oxidative damage to tissues. The present investigation was aimed at verifying this hypothesis by determining a possible correlation between salivary Hg levels and salivary total antioxidant activity (TAA), used as an index of oxidative stress. Samples of saliva from 34 healthy donors were analyzed for Hg content, through vapor atomic absorption spectrometry, and for TAA, by determining the ferric reducing ability ('FRAP' method). A significant correlation between Hg and the number of amalgam restorations or total amalgam surface was evident in both the male and female subjects. A significant negative correlation between TAA and Hg levels or number of amalgam restorations or amalgam surface was evident in females, indicating that small increases in salivary Hg were sufficient to produce a decrease in salivary TAA. On the other hand, no significant correlation was found in the males. The present study provides, for the first time, evidence of a pro-oxidant role of the amalgam Hg chronically released in saliva.

Adolescent↗
PubMedDate not supplied

Morpho-structural variations of bacterial spores after treatment in steam vacuum assisted autoclave.

This study intended to verify, through microbiological techniques and TEM investigations, the killing of bacterial spores after treatment in steam autoclave, and to propose strictly morphological considerations about the target of this sterilisation process. Autoclave is the most common device for sterilising instruments in order to prevent cross infections in dental offices. The autoclave efficiency has been improved in the last years and part of this improvement is related to both a better and more correct use of the autoclave system and to the technological innovations introduced in the last generation of devices. However, associations as ADA or CDC suggest to regularly verify the process of 'autoclaving' through biological indicators (BI). The most commonly used BI are made of spores strips or suspensions of Bacillus Subtilis (pb 168) and Bacillus Stearothermophilus (ATCC 10149). They visually prove, changing colours on enzymatic base, the death of micro-organism and if the physical parameters, necessary for sterilisation, have been achieved. These two strains of endospore-forming bacteria were processed and prepared following two different techniques: Karnovsky fixed and epon embedded--phosphotungstic acid fixed for direct observation. The kind and the extent of analysed modifications are extremely various: from deep lacerations, which changed the spore structure, to little clefts which let the cytoplasm go out.

Bacillus subtilis↗
PubMedDate not supplied

Effects of Nd: YAG laser irradiation on the root canal wall dentin of human teeth: a SEM study.

The purpose of this study was to observe the morphological and histological changes on the root canal walls after Nd:YAG laser application. Twenty vital, recently extracted single-rooted human teeth were used for this study. Root canals were cleaned and shaped by a conventional step-back technique--by means of k files up to a 20 k-file type at working length--and subsequently shaped by Ni-Ti root-canal rotary instrumentation up to 30/06 and irrigated with 2.5% hypochlorite solution. Ten teeth (control group) were left unlased, while the other ten teeth were irradiated with Nd:YAG laser by means of a 320 microns fibre inserted in the root canal at 1 mm from the apex with a power of 1.5 Watt and a frequency of 15 pps for five seconds in retraction with rotating movements. The control specimen showed debris and smear layer on the root canal surface obscuring the dentin tubules. The root canal walls irradiated with Nd:YAG laser showed a clear glazed surface, some open dentinal tubules and some surface craters with cracks. Such results confirm that smear layer and debris are removable with Nd:YAG laser, however clearing all root canal walls is still difficult and, if the energy level and duration of application are inadequate, a certain degree of thermal damage and morphological changes in dentin structure are observable.

Aluminum Silicates↗
PubMedDate not supplied

[The first appearance of Meckel's cartilage in the fetus].

Meckel's cartilage plays an important role in the topographical organisation and in the differentiation of the facial structure during the embryonal and even much later during the foetal period. Our observations on serial sections carried out in two human foetuses aged 12 and 16 weeks indicate that the two dorsal (tympanic) and ventral (mandibular) branches of Meckel's cartilage are perfectly defined at 16 weeks. In the dorsal branch, the primordia of the incus and of head of the malleus are still composed on non-ossified cartilage. In the ventral branch, it is also possible to describe at 16 weeks three posterior, medial and anterior parts which are composed of cartilage. The initiating role played by the ventral part of Meckel's cartilage on the ossification of the mandible leads during the embryonal period to the formation of the mandibular primary growth center, which is therefore clearly defined in our first stage at 12 weeks. The partial fibrous evolution and the regression of the major part of the ventral branch of Meckel's cartilage only start after 16 weeks of intrauterine life.

Branchial Region↗
PubMedDate not supplied

[The persistence of ontogenic characteristics in the adult masseter muscle].

During embryonic and foetal development, the masseter is formed from two successive generations of muscle fibers in a manner which is very similar to that which has been previously described for other skeletal muscles. This phenotype is characterised by the persistence of ontogenic myosin isoforms (embryonic and foetal myosin heavy chains, embryonic light chain) and by the presence of two distinct populations of fibers: small diameter fibers which coexpress the embryonic, foetal and fast isoforms of the myosin heavy chains but never express the slow isoform; large diameter fibers which express the slow myosin heavy chain either exclusively or in variable associations with the other isoforms. These characteristics of the human masseter muscle probably correspond not only to its embryological origin and its special innervation, but also to the functional constraints to which it is submitted after birth.

Adult↗
PubMedDate not supplied

Cytoskeletal and membrane bound antigens in human oral normal and malignant keratinocytes: an intensity of staining analysis.

In this study, we tested the hypothesis that a significant difference exists in the integrated optical density (IOD) of membrane and cytoplasmic antigens in monolayer keratinocytes cultures. Oral normal and two malignant (SCC15 and SCC25) keratinocyte cultures were stained with antibodies specific for E-cadherin, beta-catenin, beta-1 integrin, cytokeratin (CK) 14, CK19, CK10/11 and involucrin. The IOD recorded (n = 12) was analyzed for significant differences using a two-way analysis of variance (significance level set at alpha = 0.05); antibodies and cell cultures were grouped according to Tukey's Group Comparison post-test. The majority of normal cell cultures exhibited E-cadherin, beta-catenin, involucrin and beta-1 integrin IOD values significantly higher than the two SCC cell lines. No definite staining pattern distinguished normal and malignant cells in relation to cytokeratins 14, 19 and 10/11. Our observations suggest that IOD measures constitute a good predictor of antigen steady state levels in monolayer cell cultures. According to these observations, SCC cell lines and normal cells appear to differ in the expression of E-cadherin, beta-catenin, beta-1 integrin and involucrin, although some variability within normal cells can also be observed.

Antibodies↗
PubMedDate not supplied

[State of the art: posture and occlusion].

The Authors of this work propose to give an evaluation about actual relationship between posture and occlusion, trying of to give some indications about posture's meaning, organizing the relation about five points: Posture's definition Posture's history Posture's models of study Occlusal support en posture Diagnostic procedures.

Biomechanical Phenomena↗
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[Enamel pearls: the ultrastructural aspects and morphogenesis hypotheses].

Five enamel pearls were examined by scanning electron microscope. Some external pearls presented a bare enamel surface, others were covered by a thin layer of cementum. The enamel pearls showed irregular dystrophic enamel surface or a thin layer without structure, rows of irregular Tome's processes pits, enamel caps and focal holes. Some enamel pearls revealed little areas of enamel surface resorption like-resorbing lacunae with, in some cases, areas of tissue repair.

Dental Enamel↗
PubMedDate not supplied

[In vivo and in vitro biocompatibility tests of endodontic cements].

The major goal endodontic therapy has been achieved by condensing filling materials into the root canal. It's not uncommon to find excess material into the periapical tissue. It therefore becomes obligatory to use fillings materials that have acceptable biocompatibility. The purpose of this investigation was to obtain a "toxicity profile" of some endodontics materials and to compare our observations to results present in literature. The gutta-percha and five endodontic filling cements were tested "in vivo" and "in vitro". The in vivo biocompatibility involved the placement of the test material in 10 mm. Teflon tubes with an outer diameter of 1.3 mm which were implanted subcutaneously into rats. The implants were left in situ for periods of 30 and 90 days. The "hemolysis test" is designed for "in vitro" evaluations. The histological examination showed different intensity and extent cellular responses. In some cases severe infiltration of inflammatory cell and areas with necrotic were seen. At conclusion, the endodontics material evaluated showed slight, moderate and severe reactions; therefore a different pattern in tissue response.

Animals↗
PubMedDate not supplied

Etiopathogenesis, prevention and therapeutic strategies of snoring pathologies.

The sleep of adults and childrens is often disturbed from obstructive respiratory desorders evidenced from snoring. Scientific literature agrees in considering that as a dangerous pathology called roncopathy. Statistics show that about 50% of adult population over 50 yrs snores (exspecially males) and some of that has a dangerous period of prolonged and frequent obstructive sleep apneas. Results of polisomnographic tests show that 4% of total population suffer of apneas extremely severe and dangerous for life. Roncopathy is often associated to a lot of troubles: pulmonary, gastroenterologic, endocrinologic, of behaviour and especially cardiovascular and neurologic and this could explain the motif of high nocturnal percentage of myocardial infarction, ictus and sudden death. In this work we evidence the anatomical and functional etiology of snoring and sleep apneas and expose the surgical and medical therapeutic options up to day available.

Adult↗
PubMedDate not supplied

Evaluation of biocompatibility of metallic dental materials in cell culture model.

Biocompatibility of metals for dental use was tested using a three-dimensional model consisting of oral keratinocytes cultured on de-epidermised sub-mucosa. The toxicity of orthodontic metallic wire and soldering material was assessed through parameters such as the morphology and growth rate of the keratinocytes, as well as by classical histology, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sharp composition of metallic wires and soldering materials was assessed by Auger Electron Spectroscopy (AES). The results of our experiment showed that the new model revealed inhibition of keratinocyte growth and stratification near soldering material, whereas mucosal cells were able to grow and layer out on dental wire. It is concluded that this experimental model, which simulates the oral environment, is useful for studying the effects of materials for dental use for its sensibility and reproducibility. Moreover it can provide morpho-functional information which cannot be achieved by traditional methods.

Cell Culture Techniques↗
PubMedDate not supplied

Cytokeratin 20-expressing M cells in tonsils take up particulate antigen. A site for the delivery of vaccines against oral pathogens?

Quantitative and qualitative control of oral bacterial flora is a major issue in oral pathology and in the prophylaxis against cavities. Recent findings suggest that it is possible to induce local immune responses delivering antigens on palatine tonsils. M cells play an important role in the start of the immune response. These cells are located in the epithelia overlaying mucosal lymphoid follicles and are responsible for the uptake of particulate antigens. The identification of reliable markers for M cell is therefore extremely important. Since it has been reported that tonsillar immunization leads to the secretion of high levels of specific salivary antibody, we undertook a study to identify a marker for tonsillar M cells in order to plan strategies of oral immunization against oral pathogens. We studied cytokeratin 20 expression in rabbit tonsils by immunofluorescence and confocal microscopy. Cytokeratin 20 immunoreactive cells were observed in all samples examined. These cells were identified as M cells as they co-expressed vimentin, a well-known marker of rabbit M cells, and they actively uptook particulate material. It is therefore possible to hypothesize the use of tonsil M cells as a possible site for antigen delivery of particle-based vaccines against oral pathogens.

Animals↗