الفهرس 
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Abstract
In the sealing ability study a total of 80 freshly extracted human upper central incisors with straight roots, extracted for periodontal reasons, were selected for this study. Canals were enlarged using crown down technique and the eighty samples were divided into two equal groups according to the bonding agent used.
After cleaning and shaping of all samples, subgroup a1 and subgroup b1 were flooded with tenso-active agent for 5 min Vertical compaction technique was used for obturation using system B. Sealing ability of all groups and subgroups was evaluated using dye penetration method utilizing black India ink.
In the second part of the study twelve healthy white female Wistar-Furth rats were selected for this part of the study. The time of observation for group I was2 days, group II was 2 weeks and group III was 3 weeks. Each group was divided into four subgroups according to the material applied in the Teflon tube. In each rat four Teflon tubes were implanted into four different sites in the dorsal subcutaneous connective tissue.
Animals were anesthetized and four surgical sites were determined at sufficient distance from each other at the dorsal surface of the rat. A 3 mm long incision was made and Teflon tubes were placed. At each observation period a 5mm of the surrounding tissues were excised. Histological sections were mounted on glass slides and processed for staining using Hematoxylin and Eosin.
The effect of the dose and time interval on cell viability was evaluated. All the steps were done under complete sterile conditions using laminar flow. Preparation of mononuclear cells was done and the first step was the evaluation of effect of dose on cell viability. Tested materials were added to tubes in different doses. One DROP (20 µL) in the first tube, two drops (40 µL) in the second tube, three drops (60 µL) in the third tube, four drops(80 µL) in the fourth tube and five drops (100 µL) in the fifth tube. The optical density of dye extracts was measured using a spectrophotometer.
Percentage cell viability was calculated. Evaluation of effect of time interval on cell viability was the second step were cells were divided into 20 sterile tubes. The tubes were divided into 4 groups according to the tested material. Tested materials were added to each tube using 2 drops doze. In each group the incubation periods were 1, 2, 4, 6 and 24 hours. At the end of incubation, 200 uL of media with cells were incubated in triplicate in 96-well plate. The optical density of dye extracts was measured using the spectrophotometer.