Gates Glidden burs (Maillefer Instruments, buy DMH1 Ballaigues, Switzerland) were used to flare the coronal two thirds of the canal. All canals were dried with paper points and then obturated using cold lateral condensation (except for the positive controls) of gutta-percha points and AH plus (Dentsply DeTrey, Konstanz, Germany). All 40 roots were sectioned 3 mm from the apex. Forty teeth were assigned randomly into 1 of 4 experimental groups of 10 teeth each: in group
1, the teeth were resected apically (90 degrees angle) and the cavities were obturated with mineral trioxide aggregate (MTA); in group 2, after apical resection (90 degrees angle), a root-end cavity was prepared using ultrasonic diamond retrotips and the cavities were obturated with MTA; in group 3, the teeth
were resected apically (similar to 45 degrees angle) and the cavities were obturated with MTA; and in group 4, after apical resection (similar to 45 degrees angle), a root-end cavity was prepared using ultrasonic diamond retrotips and the cavities were obturated with MTA. An additional 6 teeth were used as controls (3 each, negative and positive controls). Apical leakage was measured using a computerized fluid filtration meter with a laser system.
Results. The mean apical microleakage was 2.0 +/- 0.4 x 10(-4), 1.6 +/- 0.6 x 10(-4), 1.6 +/- 0.9 x 10(-4), and 1.8 +/- 0.7 x 10(-4) mu L/cmH(2)O/min(-1) at 1.2 atm, MLN4924 datasheet in groups 1 to 4, respectively. Although the mean apical microleakage was greater in group 1, the differences among the 4 groups were not statistically significant (P > .05).
Conclusions. The results of these in vitro studies showed that when an adequate retrograde cavity depth is prepared, variation in the root-end cutting angle does not necessarily cause any difference in microleakage. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:e50-e55)”
“The first measurements of heat capacity of high-density polyethylene have been obtained Evofosfamide for melts in the high-temperature region of 180-260 degrees C. A heat-flow twin calorimeter was used. Abrupt transitions are noticed at 212 and 228 degrees C, analogous
to transitions seen earlier with rheological and surface tension measurements. Possible explanations for these phenomena are offered. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012″
“Water vapor was added to the feeding gas of a continuous atmospheric argon (Ar) microwave plasma jet to study its influence on plasma shape, plasma gas temperature, and OH radical concentrations. The plasma jet was created by a 2.45 GHz microwave plasma source operating at constant power of 104 W with H2O-Ar mixture flow rate of 1.7 standard liter per minute (slm). With an increase in the H2O/Ar ratio from 0.0 to 1.9%, the plasma jet column length decreased from 11 mm to 4 mm, and the plasma jet became unstable when the ratio was higher than 1.