Fachin et al . ( 2009 ) evaluated whether smear layer removal has any influence on the filling of the root canal system, by examining the obturation of lateral canals, secondary canals and apical deltas.
32.
In conclusion, smear layer removal under the conditions tested in this study did not affect the obturation of root canal ramifications when lateral condensation of gutta-percha was the technique used for root canal filling.
33.
This created a seal ( " obturation " ), which prevented the hot propellant gases ( expanding behind the lead projectile ) from leaking past them and prematurely igniting the remaining propellant charges in the barrel.
34.
When Britain returned to breech-loaders in 1880 it used the Elswick cup and the French De Bange obturation systems, both of which used the power of the gun's firing to achieve obturation rather than manual labour.
35.
When Britain returned to breech-loaders in 1880 it used the Elswick cup and the French De Bange obturation systems, both of which used the power of the gun's firing to achieve obturation rather than manual labour.
36.
In formal British ordnance terminology the term QF came to mean that the propellant charge is loaded in a metal, usually brass, case which provides obturation i . e . seals the breech to prevent escape of the expanding propellant gas.
37.
However, British-designed quickfiring ( " QF " in British terminology, which became synonymous with charges in metal cartridge cases ) continued to use screw breech blocks, but with their function merely to lock the cartridge in place rather than provide obturation.
38.
Forty single-rooted extracted human teeth were randomly divided into two groups one of which had the smear layer removed by 5 ml of 5 % NaOCl followed by 2.5 ml of 17 % EDTA . Obturation was performed using AH Plus sealer and Thermafil.
39.
The system was in effect a vertical sliding block such as later used by Krupp in both horizontal and vertical form, with the crucial difference that Armstrong failed to make the progression to loading the powder charge in a metal cartridge, with the result that complete obturation was impossible.
40.
There have been exceptions, however; some German naval guns during WWII used fabric powder bags with just thin brass base section, to provide obturation to the breech without adding too much weight, similar to a modern plastic shotshell with a " low-brass " base for sealing and extraction.
