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Biomedical subjects

E Dorigo

Publications and source records attributed to E Dorigo.

At least 19 recordsLinked to original sources
PubMed2006

Surface roughness of three resin restorative materials after finishing and polishing.

AIM: The surface roughness of 3 different resin restorative materials polymerized with a halogen and a plasma arc curing light, following finishing and polishing was evaluated in vitro. METHODS: Using a metal mold, 10 block specimens were prepared from each material. A Mylar strip was placed on both sides of the mold. Five specimens from each material were cured with the halogen lamp, while the other 5 were polymerized with the plasma arc lamp. In both groups the surface exposed to curing light was finished and polished with the Enhance system (Dentsply). The opposite surface was not treated and served as a control. Both surfaces of each specimen were analyzed with a laser profilometer: the roughness average (R(a)) was evaluated. The Vickers microhardness of the polished surfaces was also calculated. All data were statistically analyzed with the Mann-Whitney test. A regression test was carried out to evaluate the possible correlation between roughness and microhardness. RESULTS: The smoothest surfaces were obtained when composites were cured against a Mylar strip. Roughness was significantly increased in both groups in the treated surfaces. A significant correlation between roughness and microhardness could not be demonstrated. CONCLUSIONS: This study demonstrated that the surface polymerized against a Mylar strip was the smoothest surface produced, while the roughness of the Mylar-formed surface was significantly increased by finishing and polishing. Surface roughness following polishing is material-dependent.

Composite Resins↗
PubMed2003

[Evaluation of colour differences in fiber post all-ceramic prosthetic restoration by spectrophotometry].

AIM: The aim of this study was to evaluate the influence of fiber post on all-ceramic prosthetic restorations, using the spectrophotometer Miniscan XE. Data were recorded according to the CIEL*a*b* system and the color difference (DE) was calculated. METHODS: Carbon fiber Composipost (RTD) and quartz fiber Lightpost (RTD) posts were used. Square specimens (12x12 mm) were prepared using 9 #1 posts, covered with Z100 (3M) composite layers of different thickness (2, 3 and 4 mm) and color A3; 12x12 mm ceramic specimens (Finesse All Ceramic - 3M) of 2 and 3 mm thickness and color A3, were prepared using both opaque dentin and not. RESULTS: With 2 and 3 mm thick ceramic layers, there was no color difference between carbon fiber specimens and quartz fiber specimens. Using the opaque dentin did not determine difference between groups. CONCLUSION: In this study, according to results, a 3 mm thick ceramic layer always produced a DE<1, independently from the endodontic post. However, 2 mm thick ceramic layers were able to cover every kind of endodontic posts, even if with a DE=+/-1.6, and therefore are clinically acceptable.

Carbon↗
PubMed2000

Concomitant amplification and expression of PAX7-FKHR and MYCN in a human rhabdomyosarcoma cell line carrying a cryptic t(1;13)(p36;q14).

Alveolar rhabdomyosarcoma (ARMS) is associated with the specific chromosomal translocation (2;13)(q35;q14) or its rarer variant t(1;13)(p36;q14), which produces the fusion gene PAX7-FKHR. Here we describe the human cell line RC2, derived from an ARMS, which harbors a cryptic t(1;13)(p36;q14) and concomitantly shows amplification of the PAX7-FKHR fusion gene and of the MYCN oncogene. The t(1;13) and MYCN oncogene were studied by standard cytogenetic analysis and molecular techniques. The reverse transcriptase polymerase chain reaction demonstrated the expression of PAX7-FKHR mRNA in RC2 cells, although karyotype analysis failed to demonstrate a t(1;13)(p36;q14) chromosomal translocation or a derivative 13 chromosome. Double minute chromosomes were detected in all the metaphases studied. Fluorescence in situ hybridization analysis revealed multiple copies of the PAX7-FKHR fusion gene localized exclusively on a subset of double minutes, whereas multiple copies of MYCN were identified on other double minute chromosomes. Southern-blot analysis demonstrated that RC2 cells contain approximately 20 copies of the MYCN oncogene. So far no continuous RMS cell line carrying the t(1;13)(p36;q14) has been described, and PAX7-FKHR and MYCN amplifications have always been reported to occur separately in rhabdomyosarcoma (RMS). The availability of an ARMS cell line that harbors the t(1;13)(p36;q14) constitutes a useful tool for further understanding the role of the PAX7-FKHR fusion gene in RMS oncogenesis and may improve knowledge of the possible relation between PAX7-FKHR and MYCN amplification.

Chromosomes, Human, Pair 1↗
PubMed2000

Cell proliferation rates and fibronectin arrangement as parameters for biocompatibility evaluation of dental metal alloys in vitro.

A short-term (72-96 hours) biocompatibility evaluation in vitro of four single phase dental metal alloys was conducted by determining cell proliferation rates correlated to the organization of the extracellular matrix protein fibronectin in human fibroblast cultures. Immunocytochemical methods were performed to detect both cell proliferation rates by 5-bromodeoxyuridine (BrdU) incorporation, and fibronectin arrangement, i.e., diffuse in the extracellular matrix, organized in fibrils or in focal adhesions. We showed that cell proliferation rates were related to fibronectin expression. In particular, a higher percentage of cells in the S-phase were related to a predominance of fibronectin organized both in fibrils and in focal adhesions. The alloy with the highest Au content seemed the most biocompatible among those tested, since it behaved in a very similar manner to the controls. On the contrary, fibroblasts exposed to the alloy with the highest percentage of Ag had the most different behavior as compared to the controls. We can assume that a correlation exists between fibronectin organization and the percentage of BrdU-positive cells and that these parameters are varying with the different metal composition of the alloys. The observation of fibronectin arrangement together with cell proliferation rates could be considered a useful tool to determine the biocompatibility of these biomaterials.

Biocompatible Materials↗
PubMed1997

The influence of dental metal alloys on cell proliferation and fibronectin arrangement in human fibroblast cultures.

The biocompatibility of six single-phase dental metal alloys was studied by determining cell proliferation rates correlated to the arrangement of fibronectin (FN) in fibroblast cultures. Immunocytochemical methods were used to detect cell proliferation by 5-bromodeoxyuridine (BrdU) incorporation, and FN organization [i.e. diffuse in the extracellular matrix and organized in fibrils or in focal adhesions (FA)] in human fibroblast cultures. Cell proliferation rates were related to FN arrangement and in particular a higher percentage of cells in the S-phase was related to a predominance of FA. The greatest difference in behaviour compared to that of the controls was detected after 120 and 168 hr: at these times, as well as at previous ones, the alloy with the highest Au content seemed the most biocompatible among those tested, as it behaved in a very similar way to the controls. In contrast, fibroblasts exposed to the other five alloys showed different behaviours from the controls. It is assumed that a correlation exists between FN organization and the percentage of BrdU-positive cells, and that these features vary in the presence of different alloys. The observation of FN arrangement together with cell proliferation rates could be another useful tool in determining the biocompatibility of dental metal alloys.

Antimetabolites↗
PubMed1994

Evaluation of sister-chromatid exchanges in mouse spermatogonia: a comparison between the classical fluorescence plus Giemsa staining and an immunocytochemical approach.

Sister-chromatid exchanges (SCE) were analyzed in mouse spermatogonia using two different protocols for bromodeoxyuridine (BrdU) exposure and detection. With the classical approach, based on subcutaneous implantation of agar-coated BrdU tablets and fluorescence plus Giemsa (FPG) staining a satisfactory differentiation of spermatogonial metaphases was obtained with 50 or 25 mg BrdU per mouse (two or one tablets respectively). Alternatively, the immunodetection of BrdU was carried out after exposure to a very low BrdU concentration (three injections i.p., 3 mg/kg b.w. each, at 5-h intervals), and after exposure to one BrdU tablet; SCE frequencies evaluated in this way were lower than those found after classical FPG staining, even when the mice were exposed to the same BrdU concentration (one tablet, 25 mg BrdU). We concluded that the two methodologies may have different sensitivities with respect to SCE detection. In addition, when the effect of a treatment with mitomycin C was tested (1 mg/kg b.w., at time intervals ranging from 24 h to 5 days), no sister-chromatid differentiation was obtained with the multiple injection protocol, or with one BrdU tablet. By contrast, with two BrdU tablets and FPG, well differentiated metaphases were found at any time interval tested after MMC treatment, and the peak frequency of SCE (3.4 times the baseline) was observed at 55 h after treatment, as expected on the basis of cell cycle duration in spermatogonia. In summary, even though the use of medium-low concentrations of BrdU was successful in untreated animals, these protocols appeared inadequate to detect SCE induction by MMC. It is possible that, in the presence of cell cycle delay induced by the treatment, interferences with the rate of BrdU uptake produce an unsatisfactory differentiation of sister chromatids.

Animals↗
PubMed1993

Persistence of chromosomal lesions induced in mouse bone marrow cells by mitomycin C, as evaluated by SCE analysis.

The frequency of sister-chromatid exchanges (SCE) was evaluated in mouse bone marrow cells at different time intervals (from 19 h to 10 days) after treatment i.p. with mitomycin C (MMC; 1 and 2 mg/kg body weight). Significantly higher frequencies of SCE were found during the first week after treatment, at both doses tested. This result confirms that chromosomal lesions induced by MMC in the mouse may persist in bone marrow cells, in agreement with previous evidence based on chromosomal aberration analysis in the same cell population. In addition, the observation of a unimodal distribution of SCE/cell frequencies at each time tested indicates that the bone marrow cell population on the whole is affected by increased SCE frequency, i.e., that persistent chromosomal lesions may be transmitted along with cell proliferation.

Animals↗
PubMed1993

The micronucleus assay in mouse peripheral blood reticulocytes demonstrates the transmission of chromosomal instability induced by mitomycin C and benzo[a]pyrene.

The frequency of micronuclei (MN) in mouse peripheral blood reticulocytes supravitally stained with acridine orange was assessed at different time intervals after treatment in vivo with two dose levels of mitomycin C (MMC) and benzo[a]pyrene. Increased frequencies were observed for many days after treatment, indicating that MN may be produced as a consequence of chromosomal instability transmitted by proliferating erythroblasts. These results confirm previous evidence of the persistent cytogenetic effects of MMC and suggest that clastogenic agents acting by different primary lesions may have a similar ability to induce this effect.

Animals↗
PubMedDate not supplied

Acetabular reinforcement rings and bone allografts in the reconstructive treatment of periprosthetic bone loss.

Medium-term results in the treatment of acetabular bone loss using bulk and/or morselized bone allografts supported by acetabular reinforcement rings are reported. A total of 164 hips in 157 patients were treated by means of this reconstruction technique. The devices employed were Müller ARRR in 24 cases and Burch-Schneider APC in 140. Mean follow-up was 67 months (minimum 12, maximum 123). A total of 4 patients developed deep infection that was treated by resection-arthroplasty. Aseptic loosening of acetabular implant following extensive resorption of bone graft was observed in 5 cases: 3 of the cases underwent acetabular revision. Clinical results were evaluated based on the Harris Hip Score: mean values of 35 and 78 were assessed preoperatively and at follow-up, respectively. X-ray signs of incorporation of bone graft were observed in all cases that progressed successfully.

Acetabulum↗
PubMedDate not supplied

Reaction exothermia of 2 relining resins for temporary crowns.

AIM: The aim of the study was to evaluate the reaction exothermia of 2 relining resins for temporary crowns. The resins used were Duralay, a methacrylate-based resin, and Protemp II, a bisacrylic resin. METHODS: The coronal parts of an adult molar and of an impacted one were used. Abutments were obtained from the crowns, while the radicular part was sectioned in order to insert a thermocouple into the pulpal chamber. During the experiment the tooth with the polymerising resin was put into an oral cavity simulator to keep a constant temperature. The thermal increase during polymerisation of the 2 resins was recorded for 6 minutes at 5 seconds intervals and with 1 and 2.5 mm dentin thickness (n = 10). Data were statistically analysed by variance analysis with Scheffe test. RESULTS: The intrapulpal thermal increase was significantly higher in relation to the type of resin (Duralay p < 0.0001), thickness (1 mm p < 0.0001) and type of dentin (young dentin p < 00001). CONCLUSIONS: In order to protect the pulp, during the direct relining of a temporary crown, it is recommendable to choose the best combination among resin, type of dentin and its residual thickness, besides adequate cooling techniques.

Composite Resins↗