In the second session, after two weeks a full thickness mucoperiosteal buccal flap with one releasing incision was reflected. This allowed access to the periradicular tissue in the mandibular and maxillary Tubacin 537049-40-4 canine region. The cortical bone over the root ends was removed using a #6 round bur in a high-speed handpiece, using copious saline irrigation. The root ends in both groups were resected with fissure burs approximately 3 mm from the apex at an angle approximately 45 degrees to the long axis of the root. For the teeth in the set MTA group, nothing more was done, whereas for the teeth in the fresh MTA group, root-end preparations were also made at cut roots to the depth of 3 mm. The root-end cavities prepared in the aforementioned way were filled with MTA according to the manufacturer��s recommendation.

After this stage, all mucoperiosteal flaps were replaced and sutured with 4-0 silk (Supa Co., Iran) sutures. All animals were then injected with 24 ml of 10% Dextrose serum (Daroo-pakhsh Co., Iran) subcutaneously. This was done to prevent side effects from general anesthesia during recovery, such as mortality/morbidity due to lack of appetite and glucosuria. Furthermore, 20,000 Iu/kg of penicillin (6.3.3, Sobhan Co., Iran) was intramuscularly injected to prevent infection. Intramuscular injection of vitamin B-complex (Daroo-pakhsh Co., Iran) was also done, according to the vet��s recommendation in order to increase appetite of the cats. The animals were euthanized 8 weeks after the second surgical procedure by perfusion with 10% buffered formalin.

Mandibular and maxillary block sections containing the canine teeth and surrounding tissue were obtained. One of the fresh-MTA samples was destroyed during processing due to inappropriate sectioning and was omitted from the data. These specimens were demineralized in 10% formic acid and then dehydrated in 70%, 80%, and 100% alcohol, subsequently. Once the specimens were embedded in paraffin, serial buccolingual sections of 6-��m thickness were cut through the center of the apical formation along the long axis of the teeth. Selected sections were stained with Hematoxylin & Eosin and were evaluated under a light microscope with 40x magnification (Olympus Co., Japan) by a pathologist without prior knowledge of the study. The healing was assessed by the presence or absence of newly formed bone and/or cementum adjacent to the root-end filling.

Digital photomicrographs were used to measure the cementum area on a scale of micrometers for a more accurate measurement of healing. The presence of inflammation was also considered as evidence of failure to heal. The data were analyzed with Chi-square and T-tests. RESULTS While inflammation was noted in 5 set-MTA (n=12) and in 2 fresh-MTA (n=11) samples, healing AV-951 (formation of cementum and/or bone) was found in 7 set-MTA (n=12) and in 9 fresh-MTA (n=11) samples. However, the differences proved to be statistically insignificant (P>.05).