Biology and cytotoxicity of dental materials: an in vitro study.

OBJECTIVE: The purpose of the experiment was to determine the degree of biocompatibility of a sealer (RO, laboratory made product) dental material in terms of cytotoxicity and animal tests. MATERIALS AND METHODS: In the present study, the biological compatibility of eight experimental composite materials was examined by in vitro methods. The bio-composites used for the cytotoxicity test were placed into direct contact with normal human fibroblasts in a cell-culture dish. After fibroblast bioassay was performed, a duplicate sample of biomaterial was placed in each well, and then the fibroblasts were incubated for 48 hours at 37°C and 5% carbon dioxide. Local reactions after the implantation of the material regarding preclinical evaluation have been carried out within the Biobase Laboratory of the "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania. The biocompatibility was studied using the tolerance test by the subcutaneous and intramuscular implantation of the cured specimens. RESULTS: The sealant C3 scored the highest value to the cell viability. The results of the present study showed that different dental materials had different effects on cells. The resin monomer TEGDMA, present in the sealer's composition, increased the amount of intracellular reactive oxygen species. Resin-based composites are cytotoxic before polymerization and immediately thereafter, whereas already set specimens cause almost no reaction. The test of tolerance showed that the composite materials do not contain any toxic, irritant substances or destructive ones for the living cells or tissues. CONCLUSIONS: The tests with experimental composite materials revealed that they are not cytotoxic for the living cells, in all versions of the materials used. All the samples of composite materials have maintained their integrity during the experiment, allowing the testing together with the embedded cells, which proved good viability, so they are suitable for dentistry use.

Assessing the biocompatibility of a dental composite product.

OBJECTIVE: The purpose of the study was to assess the biocompatibility of a composite material considering the reaction caused at the implant site during 21 days by daily observing the subjects' behavior as well as by macroscopic examination and histological examination upon expiry of the testing period. MATERIALS AND METHODS: We performed the tolerance test by implant of the composite material Dualcim. The implant test was made on two species of lab animals, Guinea pigs and Wistar rats in two versions: subcutaneous implant and intramuscular÷perimuscular implant. RESULTS: After a 21 days period, when the implant was in direct contact with the tissue, no change of the shape and consistency, color or surface of the implant occurred. Around the implants, the biocompatibility was kept under physiological limits. CONCLUSIONS: The product, in the structure and shape presented, could be easily placed under good conditions, both at the level of the subcutaneous tissue and at inter-muscular level. In case of both species and in all subjects, the histological exam proved a favorable development of the relationship between the implant body and the placing site.

Studies on two biological phenomena in in vitro cell cultures: the reversibility of leukemic blast cells and the immunologic enhancement of tumor growth.

The nature of the leukemic process is discussed with respect to the possible in vitro transformation of the leukemic blast cells into myeloid differentiated cells. During the period 1968-1970 we noticed this process in bone marrow cultures in fluid medium. The differentiation was established on morphologic and cytochemical criteria; the proportion of mature cells or those undergoing maturation with peroxidase positive reaction increased over 50% reaching even 70-80%. Our recent observations can be discussed from several points of view but leukemic blast cell reversibility is now a phenomenon with therapeutical applications. The phenomenon of malignant cells growth enhancement has been considered as an antibody mediated immune process. In a previous paper we have demonstrated in AKR mice the possibility of achieving the growth enhancement of lymphoblastic cells in mixed cultures with normal autologous or isologous splenic cells. Other investigations have been carried out by means of mixed cultures in human leukemias and malignant lymphomas. The intensity of blast-cell proliferation was followed up by comparing the number of colonies and TH3 incorporation in simple cultures with those in mixed cultures. The observations made in the 20 culture systems followed-up over 3-5 and 8-10 days proved the "malignant cell growth enhancement" by the immune mononuclear cells (lymphocytes and macrophages).

Relationships between lymphography and the histologic nodal and splenic types in Hodgkin's disease. Considerations on clinical evolution.

Trying to establish the eventual interrelations of the initial histologic nodal type and the splenic one, the general lymphographic picture, the histologic nodal type and spleen involvement, lymphographic and histologic examinations were carried out in 151 patients with Hodgkin's disease. Lympographies were performed in 139 cases, and splenectomy (followed by splenic, hepatic and abdominal lymph node biopsies) in 32. Lymphocyte depletion was found in 72.7% of the patients with lymph node obstruction diagnosed lymphographically. Splenic involvement was more frequent in cases with pathologic lymphographic picture and histologic aspects of lymphocyte predominance or nodular sclerosis. In patients with initial nodal histologic types of nodular sclerosis or lymphocyte depletion, the splenic histopathologic types were the same, but they got more severe in cases with lymphocyte predominance or mixed cellularity. Splenic biopsy might be unconclusive after protracted cytostatic treatment or splenic X-ray therapy. In the authors' opinion, early routine splenectomy is rather more advisable than differentiated splenectomy.

Comparative cytogenetic and cytologic study in malignant lymphomas.

The possibility of a cytogenetic-cytologic correlation with implications in the diagnosis, evolutivity and prognosis of malignant lymphomas was studied. Cytogenetic investigations were carried out comparatively in the lymph node and spleen lymphoid cells from 25 patients with malignant lymphomas and in normal subjects or patients with malignant tumors. The dominant malignant cellular type was found to correspond genotypically to the abnormal clone. In lymphomas with more differentiated cells the chormosomal abnormalities were limited to a single chromosomal group, while in those with less differentiated cells there were many clonal chromozomal abnormalities. The pathogenic significance of an extra-chromosome in the C-group (observed in most of the cases) is discussed.