[Making a mernetic root seal]

Sixty permanent human teeth, all with straight, accessible root canals were analyzed in vitro in order to compare the sealing capacity of three different instrumentation and obturating techniques, namely: Obtura system, sonic and ultrasonic techniques, and modified lateral instrumentation and condensation technique. Root canals were instrumented and obturated according to guidelines of each technique. Three layers of varnish were then applied, except on a 1 mm area around the apical foramen. The pieces were immersed in 5% methylene blue, making sure that the apical foramen kept in contact with the solution. Next, they were introduced in an incubator for a 48-hour period, at a temperature of 37 degrees C. Longitudinal sections were subsequently cut and observed on the stereoscopic microscope. Penetration values of the dye in each specimen were obtained by means of a micrometric slide. These were analyzed in a computer by the Student T method, yielding a value of P greater than 0.5, meaning there is no statistical difference in the comparison of the three techniques under study.