Biocompatibility evaluation of some different polimerized denture base resins

In this study in vitro cytotoxicity of monomers of four different denture base resins which were polymerized by chemical, head, and microwave energy were analysed by inocculation method. Additionally, the cytotoxicity of these four different polymerized denture base resins were evaluated by means of agar overlay, millipore filter, and 3H- Thymidine incorporation cell culture test methods. Primary human gingival fibroblastic cell cultures obtained from gingival biopsy tissues under sterile conditions were prepared to use in cell inocculation, agar overlay, and millipore filter tests. The toxic effects of monomer on cell culture were observed after inocculations of different dilutions prepared from each specimen in accordance with ISO Technical Report No: 7405. For this reason six-stepped dilutions, which were started from 1/10 and ended at 1/106, were prepared in cell culture medium. Obtained specimens were sterilized by filtering from a millipore filter having a pore size of 0.45 nm before inocculation. Prepared filtrates were inocculated in 24 welled macrotablets in which previously human gingival fibroblast cells were cultured so, a tablet was used for each speciment. Six-stepped dilutions of 100^1 volume prepared from each of the four monomers were inocculated into the cell culture mediums which were placed in four units welled tablets. Evaluations were made on the 3rd, 6th, 12th, 18th, and 24th hours following inocculation procedure by means of microscopic controls. The cytotoxicity of denture base resin discs, which were polymerized by different methods in accordance with ISO Technical Report No: 7405, were studied by means of in vitro agar overlay test method. For this reason, human gingival fibroblasts (1,5 x 10s cell/ml65 per dish) in 15 ml of Dulbecco's Minimal Essential Medium (DMEM) supplemented with 10 % fetal bovine serum (FBS) were seeded into the petri dishes having a diameter of 100nm. These petri dishes were incubated four 96 hours at 37° C in 5 % CO2 ? Over the added agar medium, together with the sample dishes positive and negative control samples, two samples were placed into every petri dish. To follow the cellular toxicity, microscopic and macroscopic controls were done for four days. At the end of this period, toxic effects were determined according to the zone and cytolysis indexes. Cells of which agar layer had been removed by the corroboration of the data, were stained with giemza and then examined under an inverted tissue culture microscope. The toxicity symptoms were searched at the cellular level. None of the polymerized denture base resin disc samples, which were controlled for four days in the agar overlay test, showed toxicity symptoms. Proportionally 100 % toxic effect was found in the cells on zone belonging to the blotting paper which has absorbed the 1 M Ammonium molibdate solution used as a positive control. The in vitro cytotoxicity of denture base resin discs which were polymerized with different methods were investigated with millipore filter test method in accordance with ISO Technical Report No: 7405. For the test, human gingival fibroblasts (1,5 x 10s cell/ml per dish) in 6ml of Dulbecco's Minimal Essential Medium (DMEM) supplemented with 10 % fetal bovine serum (FBS) were seeded into the plastic petri dishes having a diameter of 60mm.These petri dishes were incubated for 24 hours at 37° C in 5 % CO2 incubator. 0,60 nm pore sized and sterilized (in autoclav) cellulose asetate membran filters are taken from the medium in which they were got wet, and they were settled on the surface of the cells which were produced in petri dishes. Using six petri dishes for every test sample, standart sized test samples were placed on to the membran filters in order. For improved incubation, this system was left in a medium containing 5 % CO2 at 37° C. The toxicity controls related to the samples were materialized with the investigation of cells under microscope after removing the membrans in test systems in the 6th, 12th, 24th, 36m,4&m, and 72nd hours following the inocculation. Moreover, toxicity controls, that were related with the membran66 filters used during test, were done. After a 72 hours lasting period, in none of the petri dishes, containing samples, cellular toxicity symptoms were found. 3H-Thymidine incorporation test was materialized in the micro system using certain modifications for ISOTechnical Report No:7405. In each well of the microtablets a volume of 100jd, 1 x 105 human gingival fibroblast cell containing diluted cell suspansion was placed. Polymerized denture base resin discs, which were prepared in appropriate volume to tablet wells, were placed (six samples) for each cell concentration. This system was incubated for 72 hours at 37° C In 5 % CO2. At the end of this period in each well used in the tablet 0,5m. courie ^Thymidine was added and then it was continued to to incubation for 18 hours. Cells that were collected in the cell harvester, were dried after having been absorbed to the fiber glass filter papers. Values related to specimens treated with 6 ml simulation cocktail (PPO. POPOP, TOLUEN) were recorded in the p-courrter as cpm. At the end of this test, observed findings were as following: 53 % cell proliferation in the chemically polymerized Takilon samples, 25 % cell proliferation in the heat-polymerized QC-20 samples, 13 % cell proliferation in the microwave polymerized QC-20 samples, 22 % cell inhibition in the microwave polymerized ACRON-MC samples, and 16 % cell inhibition in the heat-polymerized ACRON-MC samples. The least cytotoxic finding was obtained from autopolymerized acrylic Meliodent with a result of 7 % cell inhibition.