24 Twenty-four male Sprague Dawley rats weighing 250--300 gr were used in the study. For preliminary study, 1 one rat was used on each experimental day . During the study period, the animals were kept in cages in groups of five and taken to daily care under standard care conditions without restriction ofno feed and water supply restrictions.
ProRoot White MTA, Medcem Pure Portland Cement, and Medcem MTA mixed according to the manufacturer's' instructions were filled placed into sterile p olyethylene tubules (internal diameter: 1.3 mm internal diameter, x external diameter: 1.6 mm external diameter, x length: 5.0 mm length) sterilized with ethylene oxide gas, as specified by ISO , with using a sterile Llentulo. Twenty-one empty polyethylene tubes remained empty to bewere used as in the control group.
Surgical Procedures The rats were anesthetized in an ether jar, followed byand then received intraperitoneal administration of 70- mg/kg ketamine and 10- mg/kg xylazine intraperitoneally. The operation area (backs) of the anesthetizedeach rats were was shaved with a certain razor blade, and the surgical area was disinfected with Betadine skin disinfectant ,. After shaving, the operation area wasand covered with sterile drapes to be exposed. In orderTo induce local hemostasis, operations of 0.5 cc, 0.006- mg/ml 4% articaine containing epinephrine (Ultracaine D-S-Aventis Forte, Istanbul, Turkey) by infiltrating local anesthesia was performedadministered.
Incision lines were determined marked on the dorsal, anterior, and posterior extremities of the experimental animals, two in the anterior and two in the posterior region and two in the posterior region. When determining the incision lines, cCare was taken to keep a distance of at least 2 cm distance between the placed materials to prevent them from being affected . Skin iIncisions of approximately 1 cm length long was performedwere made with the a sterile scalpel in the designated areas. The cCanals were entered through the incision site with a sterile periosteal elevator, and ducts were opened under the skin by blunt dissection approximately 2 cm deep. Subsequently, polyethylene tubules filled with the experimental material according toof the each groups and sterile empty polyethylene tubules for the control groups were placed in the prepared subcutaneous canals. The incision sites were then closed primarily using 3/0 silk sutures. Antibacterial spray was applied on the sutures.
Histological Procedures After surgery, on the 7th, 30th and 60th days, 7seven animals from each group, (21 animals) were euthanized intraperitoneally with high doses of thiopentalsodium (Pental, İ.E. Ulagay Med. San. , Istanbul, Turkey) administered intraperitoneally under ether anesthesia on Days 7, 30, and 60. Then, tThe test tubules placed were then removed together with the surrounding tissues and placed in bottles containing 10% neutral formalin. Paraffin blocks were prepared from test samples fixed in bottles containing 10% formalin for 2 two days. From the tissues embedded in the paraffin blocks, 4- μm serial sections parallel to the long axis of the tube were taken cut with a microtome (Leica SM 2000R, Leica Instruments, Wetzlar, Germany) and stained with hematoxylin and eosin (H\&E).
All histological evaluations were performed The tissue samples were histologically examined under an optical microscope (Nikon Eclipse E 600, Nikon Corp., Tokyo, Japan) at 40×x, 100×x, 200×x, and 400×x magnifications. All the slides were examined and rated by a pathologists blinded to all procedures.
