Apical Leakage of Different Gutta-Percha Techniques (Zapit, Dental Venture of America Inc., Anaheim of the micropipette inside the device, an infrared Hills, CA) was applied circumferentially between light was passed. Two light-sensitive photodiode the root and plastic tube. A computerized fluid was arranged on the opposite side of the micropi- filtration meter with a laser system used in this pette to detect any movement of an air bubble in- study have had a 25-µl micropipette (Microcaps, side micropipette. All operations were controlled Fisher Scientific, Philadelphia, PA, USA) mounted with PC-compatible software (Fluid Filtration’03, in horizontally.14 O2 from a pressure tank of 120 Konya, Turkey) (Figure 2). A 5-min pressurization kPa (1.2 atm) was applied at the apical side. The preload of the system was completed before tak- pressure was constant throughout the experi- ing readings. Measurements of fluid movement ment by means of a digital air pressure regula- were automatically made at 2 minutes during 8 tor added to pressure tank. A 25-µl micropipette minutes for each sample by using PC-compat- (Microcaps, Fisher Scientific, Pittsburg, PA) con- ible software. The software converts minute linear nected to the pressure reservoir by polyethylene movement of the bubble into nanoliter movement tubing (Microcaps, Fisher Scientific, Pittsburg, at a rate of one measurement. This information is PA). All pipettes, syringes and the plastic tubes fed into PC-compatible software. Leakage quan- at the apical side of the sample were filled with tity was expressed as µl.cmH2O.min-1 and means distilled water. Water was sucked back with the determined. microsyringe for approximately 2 mm. In this way, an air bubble created in the micropipette and the Statistical analysis air bubble was adjusted to a suitable position in All data were statistically analyzed by One-way the syringe. The computerized fluid filtration me- ANOVA followed by Duncan tests. The confidence ter was based on basically light refraction at start- level was used 95% (P<.05). ing and ending position of air bubble movement rEsuLts inside micropipette (Figure 1). Through one side Mean microleakage measurements and stan- dard errors, in µl.cmH2O-1.min-1 1.2 atm, are shown in Table 1. According to the results of this study, Microseal technique showed the most leakage followed by lateral condensation technique (P<.05) and both techniques showed more leakage than other tech- niques (Thermafil, Soft Core, Quick-fill, System Figure 1. Computerized fluid filtration meter. 100 Figure 2. PC-compatible software. European Journal of Dentistry Table 1. Mean leakage values (µl.cmH2O-1.min-1x 10-4) and standard deviation (SD) for each tested technique. Groups Thermafil Quick-Fill Soft Core System B Microseal Lateral Condensation Positive Control Negative Control Mean Value ± SD 0.26 ± 0.08 0.32 ± 0.08 0.30 ± 0.06 0.28 ± 0.07 0.50 ± 0.05 0.44 ± 0.10 52.5 ± 0.10 0.00 ± 0.00