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Biomedical subjects

G Pagavino

Publications and source records attributed to G Pagavino.

15 recordsLinked to original sources
PubMed1992

[A scanning electron microscope assessment of the changes induced by wear on subsonic endodontic instruments].

The aim of the present work was to study the wear of a special kind of subsonic instruments with usage. We have examined with scanning electron microscope new and used instruments: the first to estimate the features and degree of final touches; the second to examine how they wear after 1, 3 and 5 minutes. We tested for each period 3 instruments per size. In all we controlled 72 instruments. The results of the study show that after 5 minutes the instruments are very worn.

Materials Testing↗
PubMed1992

[Tubular sclerosis].

Tubular sclerosis is a pulp-dentin complex defensive response to several physiologic and pathologic stimuli; it leads to an increasing tubular obliteration which enormously reduces dentinal permeability. Its typical structural features are either increased peritubular dentin thickness or "caries crystals". Pathogenesis is a much debated question: some authors assert that peritubular dentin thickening is the main liable for sclerosis while others support a centrifugal theory. Another point of view considers its pathogenesis the result of many integrated mechanism.

Apatites↗
PubMed1992

[Preliminary research on the prognosis of late reimplants with prior conditioning with a fluoridated solution].

The principal factors that affect the prognosis of a posttraumatic reimplantation are the length of the extra-alveolar persistence and the manner in which the extracted tooth is preserved. Both are fundamental for the maintenance of the fiber vitality of the periodontal ligament. The necrosis of these fibers cause ankylosis. It is observed that the conditioning of the radicular surface with fluoride solutions before the reimplantation is likely to slow down the evolution of radicular resorption. To evaluate the effectiveness of such methodology six cases of traumatic extractions, characterized by a length of extra-alveolar persistency (not longer than 24 hours), and unfavorable conditions of the preserved tooth have been treated by conditioning the radicular surface with the Na-fluoride solution before the reimplantation. Another group of reimplantation cases with the same characteristics have been examined without proceeding first to the radicular conditioning. The results of the study, although preliminary, verified the positive influence of the Na fluoride upon the radicular resorption.

Follow-Up Studies↗
PubMed1990

The intercellular substance of the pulp of human, fully erupted, permanent premolar teeth.

The intercellular substance of the pulp of fully erupted, healthy, human permanent premolar teeth was studied by light microscopy. Histological and histochemical methods were applied to sections from whole, decalcified teeth and isolated, undecalcified pulps, fixed with phosphate-buffered formalin and embedded in paraplast. Fibres were mainly collagen; they formed a meshwork progressively more dense from the crown to the root apex; in the crown the fibre meshwork was denser at the periphery than in the center of the pulp. Coarse bundles of collagen fibres were found in the apical part of the pulp of about one every third teeth. Glycoproteins, recognized thanks to their P.A.S. positivity, were abundant in the basal membranes of vessels and nerve fibres and between odontoblasts, but scarce in the remaining pulp tissue. Glycosaminoglycans, recognized thanks to their alcianophilia, were more abundant in the vessel wall and in the areas with coarse bundles of collagen fibres than elsewhere in the pulp; also, they were more abundant at the periphery than in the center of the pulp. As judged by staining with alcian blue at critical electrolyte concentration, glycosaminoglycans were mostly hyaluronate, with low amounts of condroitinsulphate and dermatansulphate; some heparansulphate or keratansulphate was present only in the regions with coarse bundles of collagen fibres. The morphological and histochemical differences found among different regions of each pulp and among different pulps as well provide a basis to recognize and interpret inter-regional and inter-individual variations in the pulp response to physiological and pathological modifications affecting the hard tissues of the teeth.

Bicuspid↗
PubMed1990

[Clinical experience with a new microfilled composite].

The authors have investigated a new material for esthetic restoration for front teeth. It is a microfilled heterogene composite (Helio Progress) with spheridal prepolymer. The clinical trials were realized in cavities III, IV an V, in anomal y teeth and resin ceramic (with a pretreatment with silane). The results after 18 months have demonstrated the better characteristics of this material in relation with foreknown ones.

Composite Resins↗
PubMed1987

[Cherubism].

Explore the source record for details and available documents.

Cherubism↗
PubMedDate not supplied

[The lamina limitans. Its scanning electron microscopic aspects].

Many researches agree in maintaining that all the membraneous structure visible in the most external parts of the dental tubules must be considered not ad cytoplasmatic membranes of the odontoblastic processes but as an extracellular organic matrix which in certain conditions may appear detached from the internal wall of the tubule and simulated a superimposable aspect like that of an odontoblastic extension. The aim of this study was to examine at the SEM the state of this organic component in normal conditions and after demineralization with citric acid. Therefore the entire teeth of young people were fixed in formalin and dissected by fracturing. Some of the samples were demineralized with a citric acid solution. All the samples were dehydrated and metallized for the observation at SEM. Demineralization made the peritubular dentine disappear and expose inside every tubule a sheet-like structure which extended all along the tubules. The samples which were not demineralized did not demonstrate a similar structure because of their tight adhesion to the internal wall surface. This kind of formation which other researchers calls "lamina limitans" because of its high content of glycosaminoglycans might be a key factor in controlling the formation of peritubular dentine and tubular sclerosis and it will surely lead to further interesting research.

Decalcification Technique↗