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Biomedical subjects

R Mongiorgi

Publications and source records attributed to R Mongiorgi.

At least 55 records · Page 3Linked to original sources
PubMed1988

Mineralization and calcium fixation within a porous apatitic ceramic material after implantation in the femur of rabbits.

Cylinders (0.8 cm long, 1.0 cm of diameter and with an axial hole), constituted, after firing, of a ceramic mixture of hydroxylapatite (HA) and beta-tricalciumphosphate (beta-TCP) in a 10:1 ratio, were implanted into mid-diaphyseal defects of one femur of 20 rabbits and stabilized with intramedullary rods. The implantation sites were checked radiographically every month, and after 3 months (3 animals) and 6 months (17 animals) the rabbits were sacrificed and the implants with the surrounding tissue were embedded in methylmethacrylate, cut to thick sections and analyzed by scanning electron microscopy (SEM). Porosimetric and x-rays diffraction analyses were carried out before and after implantation of the cylinders, and the state of mineralization at the bone-implant interface was determined by EDAX microprobe analysis. Bony callus formation started at 1 month at the osteotomy sites, as judged by radiography, but after 3 months a not-mineralized zone had still been demonstrated between bone and the implants. At 6 months, 13 implants showed themselves firmly fixed in their implantations beds, while 4 implants were only incorporated at their proximal ends. In bone contact zones, an enrichment of Ca2+ was displayed by microanalytical techniques in the outer zone of the implanted samples which may be explained by an apparent additional phase transformation of HA into TCP, thanks to the change of the Ca/P ratio, that takes place in vivo.

Animals↗
PubMed1988

Densitometric analysis in in vivo evaluation of synthetic salmon calcitonin activity.

In women suffering from post-menopausal osteoporosis, we evaluated the effectiveness of two cyclic treatments with synthetic salmon calcitonin over a whole year, using an average daily dose of 16 and 32 IU, respectively. This treatment was compared with treatment with oral calcium carbonate. The results, evaluated by peripheral densitometry of the radius, showed a 3.2% loss of bone mineral content (BMC) in the women treated only with calcium carbonate, a loss of 1% in those treated with an average dose of 16 IU/day of calcitonin and an increase of 4% in the women treated with an average dose of 32 IU/day (an increase just above the statistically significant limit using the paired t-test). An average dose of 32 IU/day probably represents the minimum effective dose of calcitonin required to produce a significant increase in bone mineral mass, when used according to a sequential scheme.

Aged↗
PubMed1983

Mineral alterations in senile osteoporosis.

This research investigates the occurrence of involutional processes of mineral transformation in elderly patients with clinical, radiographic and histological signs of senile osteoporosis. The decreased ability to withstand static and dynamic stresses proved to be associated either with the quantitative reduction in trabeculae or with the altered morphology of hydroxyapatite (HA) crystals. This variation produces a non-homogeneous mineral distribution which leads to a substantial alteration of the system of the stress lines producing mechanical bone behaviour. This altered distribution in mineral density has been attributed to the dynamic loss of balance between osteoblastic and osteoclastic activity; this is believed to be a peculiarity of senile osteoporosis.

Adult↗
PubMed1980

Characterization of synthetic apatites for bioceramic implants.

Hydroxyapatite has been studied as a substance suitable for surgical substitution of bones and teeth with emphasis on its biocompatibility. The present work tries to identify the characteristics of this material either from the chemico-physical-structural point of view, or from the technological one, evaluating the best performance. By X-ray, i.r., thermal, chemical and SEM analyses, the relationship of different phenomena involved in the sintering was evaluated. Technological tests demonstrated the stability and the workability characteristics. In particular, the influence of CO2 was studied, in connection with the most suitable technique for hydroxyapatite (HAP) sintering, considering the eventual aims and requirements for industrial production.

Ceramics↗
PubMedDate not supplied

Thickness and morphology of resin-infiltrated dentin layer in young, old, and sclerotic dentin.

The purpose of the present study was to evaluate the morphology of the resin tags and the resin-infiltrated dentin layer (RIDL) of several bonding systems in superficial vs deep young, old, and sclerotic human dentin. Dentin was obtained after the removal of occlusal enamel from extracted molars. Phosphoric acid gels (35-37%) were used to etch dentin before the application of bonding systems (OptiBond FL; Prime & Bond 2.0; Scotchbond Multi-Purpose Plus and Scotchbond 1; One Step). Each bonded specimen was then sectioned into two halves. One half was polished using a standard procedure to evaluate RIDL thickness and morphology by SEM. The other half was demineralized and deproteinized to evaluate the presence and the morphology of resin tags. RIDL was thinner in superficial dentin than in deeper dentin for all the materials tested regardless of the type of dentin. Sclerotic and old dentin showed thinner RIDL, with short resin tags, and fewer lateral branches than normal dentin.

Acid Etching, Dental↗
PubMedDate not supplied

Marginal hybrid layer in Class V restorations.

The aim of this study was to evaluate the morphology of the hybrid layer (identified as marginal hybrid layer) along the cervical margins of Class V restorations using several bonding systems. Class V restorations were prepared in vitro at the CEJ in extracted third molars. Three different bonding systems were selected: Scotchbond 1 (Single Bond), Scotchbond MP, and Clearfil Liner Bond 2V. After finishing each restoration with disks, each margin was polished for one minute with polishing paste. The margins of half of the restorations were then treated with 10% phosphoric acid for five seconds, washed in deionized water, and then stored in water for 24 hours before SEM analysis. The margins of the other half of the restorations were treated with 10% phosphoric acid for five seconds, then with 1.5% NaOCl gel for two minutes to remove noninfiltrated collagen, then washed and stored in water for 24 hours. Each sample was gold coated and observed under SEM. A one-way ANOVA was performed to determine if there were any statistically significant differences in hybrid layer thicknesses. The thickness of the marginal hybrid layer measured under SEM was 1.5-2.5 microns thick in Scotchbond MP and Scotchbond 1 but varied from 0.0 to 12.0 microns in Clearfil Liner Bond 2V when observed after NaOCl postpolishing procedures. Far more porosities were seen in the marginal hybrid layer of Clearfil Liner Bond 2V. Enamel margins were free from a hybrid layer in both groups. This study demonstrated that collagen fibrils are not completely infiltrated by adhesive resin at the CEJ level along the cavorsurface margin of the restorations. The presence of noninfiltrated collagen along the external margins may reduce the sealing capability of bonding systems, leaving many open spaces and gaps, which may jeopardize the durability of the bond over time.

Acid Etching, Dental↗
PubMedDate not supplied

[The X-ray fluorescence (XRF) spectrometry of biomaterials used in dentistry. 2].

In this work we analyze the following biomaterial: biomaterials used in this study are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-Oss, Biostite, Osprovit, Merck Hydroxiapatite. The quantitative XRF analysis was performed by a Philips PW 1480 with Rh tube. This research, besides underlining the possibility of applying the XRF method to the analysis of biomaterials. This study, shows the facility and the rapidity in the preparation of samples and standards in the form of tablets to undergo the analysis: furthermore the study shows the possibility of verify the analysis on the same sample in the future, because the tablet if well conserved, does not deteriorate. We can also verify a good analytic accuracy both for the principal elements (Ca, P) and for trace elements. The analyses show a moderate variability in the Ca/P ratio in the hydroxylapatites, and a greater variability in the secondary and trace elements.

Biocompatible Materials↗
PubMedDate not supplied

[X-ray powder diffraction (XRD) in the study of biomaterials used in dentistry. 3].

This study considers X-ray power diffraction (XRD) applied to the study of mineral-based biomaterials used in odontostomatology. By means of this method the following materials were analysed: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable fine Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxyapatite. These analysis allow the identification of the crystalline phases, the study of the crystallinity and the crystal chemistry of the samples prepared as powder mixtures. This method permits the determination of the physical chemical and crystalline characteristics of these mineral based biomaterials formed by powders or transformable in powders. All of this information is indispensable for the evaluation of the functional biocompatibility of a biomaterial when its reaction in a biological environment is already known. This method has a great number of advantages against the traditional methods, marking with solid phases, it does not destroy the sample, it does not modify the physical or chemical characteristics and gives more information.

Biocompatible Materials↗
PubMedDate not supplied

[The characteristics and properties of calcium phosphates in biomaterial formulations used in dentistry. 1].

In this work we present the features and the properties of natural and synthetic apatites, which we use in an experimental study of various commercial products composed by calcium phosphate. After having considered the general concepts of biomaterials and biocompatibility, we describe non biological tests used for the characterization of these products. Biomaterials used in this study are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2 Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxiapatite. Tests used are: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and thermodifferential analysis (TG, DTG, DTA), scanner-ing electron microscopy (SEM) morphological analysis. Last but not least, we underline the particular features of these tests whose interpretation allows a more precise definition of the bioactivity of a biocompatible material.

Biocompatible Materials↗
PubMedDate not supplied

[The characterization by Fourier-transform infrared vibration spectroscopy of mineral-based biomaterials commonly used in dentistry. 4].

In this study the following biomaterials were analysed by means of Fourier transform infrared vibrational spectroscopy (FTIR); they are: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable fine Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2 Osprogel, Bio-Oss, Biostite, Osprovit, Merck Hydroxyapatite. The analysis was performed with a Jasco 5300-FTIR. At 64 readings for spectrum with a 2 cm-1 resolution. By means of this method it has been possible to perform a structural study at a molecular level of the commercial products mentioned before. The analysis showed which of the samples examined had lost the apatite OH- group during production. It also allowed the identification of some of the hydroxyapatites examined as carbonate apatites. Finally, it allowed the identification and quantification of the organic substances in the examined products.

Biocompatible Materials↗
PubMedDate not supplied

[The thermal analysis of mineral-based biomaterials used in dentistry. 5].

In this study the following commercial products were thermo-analysed (TG, DTG, DTA): reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, non reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-Oss, Biostite, Osprovit, Merck Hydroxiapatite. The apparatus utilized was a Setaram TAG 24, in a symmetrical set up, which gave the TG, DTG and DTA analysis simultaneously. The analysis of all the materials were performed in correct operative conditions. The thermo analyses gave useful information about the thermal stability of the samples. The TG analysis gave the data relative to the percentage of weight loss due to the volatile substances in the samples (H2Oass C, OH-, CO2). The DTG graph made it possible to establish the presence of carbonate apatite and/or hydroxyapatite or the absence of both the substances. Finally, DTA and DTG analyses allowed show the presence of various organic substances. These data were very useful to characterize the examined materials and confirmed the extreme importance and sensibility of this method.

Biocompatible Materials↗