A total of 30 freshly extracted single-rooted mandibular human premolars with oval root canals were obtained after the study was approved by the institutional review board of Kosin University Gospel Hospital, Busan, Korea (KUGH-022-08-033). Teeth presenting dental caries, cracks, and fractures were excluded. After cleansing of visible blood and gross debris, radiographs were taken to ensure a similar buccolingual dimension of the root canals. The teeth were stored in a sodium hypochlorite (NaOCl) solution diluted 1:10 with distilled water until the time of experimental usage.
To obtain standardized root lengths, the roots were sectioned 12 mm from the apex with a diamond bar under water cooling. The root canals were instrumented using a rotary instrument system (ProTaper Next, Sybron Endo, Orange, CA, USA) up to size F3. During instrumentation, the root canals were irrigated with 2 mL of 1% NaOCl using a 27-gauge side-vented needle. The smear layer formed in the root canal wall was removed using 1 mL of 17% ethylenediaminetetraacetic acid for 2 minutes. Finally, the root canals were irrigated with 2 mL of distilled water and dried with paper points.
The root canal specimens were randomly divided into 2 groups (n = 15), which were then treated with different filling materials. In the first group, each root canal was filled with ProRoot MTA. After the powder was mixed with the liquid, the mixture was inserted into an MTA carrier (MAP system, Dentsply-Maillefer, Ballaigues, Switzerland). Then, the material was placed in the root canal and compacted apically with plugger and paper points. In the other group, the root canal was filled with Endocem MTA Premixed. The material was injected into the canal and apically placed using paper points. The filling procedure was performed until the canal was filled up to 3 mm from the orifice. Then, the orifice was restored with a temporary filling material (Caviton, GC, Tokyo, Japan). The specimens were stored in phosphate-buffered saline (PBS; HyClone Laboratories Inc., Logan, UT, USA) for 30 days to facilitate biomineralization.
To obtain standardized root lengths, the roots were sectioned 12 mm from the apex with a diamond bar under water cooling. The root canals were instrumented using a rotary instrument system (ProTaper Next, Sybron Endo, Orange, CA, USA) up to size F3. During instrumentation, the root canals were irrigated with 2 mL of 1% NaOCl using a 27-gauge side-vented needle. The smear layer formed in the root canal wall was removed using 1 mL of 17% ethylenediaminetetraacetic acid for 2 minutes. Finally, the root canals were irrigated with 2 mL of distilled water and dried with paper points.
The root canal specimens were randomly divided into 2 groups (n = 15), which were then treated with different filling materials. In the first group, each root canal was filled with ProRoot MTA. After the powder was mixed with the liquid, the mixture was inserted into an MTA carrier (MAP system, Dentsply-Maillefer, Ballaigues, Switzerland). Then, the material was placed in the root canal and compacted apically with plugger and paper points. In the other group, the root canal was filled with Endocem MTA Premixed. The material was injected into the canal and apically placed using paper points. The filling procedure was performed until the canal was filled up to 3 mm from the orifice. Then, the orifice was restored with a temporary filling material (Caviton, GC, Tokyo, Japan). The specimens were stored in phosphate-buffered saline (PBS; HyClone Laboratories Inc., Logan, UT, USA) for 30 days to facilitate biomineralization.
