Aim:The aim of this in vitro study was to compare the efficacy of irrigation with the negative pressure and the traditional positive pressure in eradicating Enterococcus faecalis from the root canal.Materials and Methods:A total of 40 extracted mandibular premolars were sterilized and divided into four groups with 10 samples each. Then, they were prepared to apical size #35 (Group 1, 3) and 45 (Group 2, 4) and inoculated with E. faecalis for 7 days and then irrigated with 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. The positive pressure irrigation was performed in Group 1 and Group 2 while the negative pressure irrigation (NPI) using the Endovac in Group 3 and Group 4. Samples taken after the root canal irrigation procedures were cultured and the colony-forming units were counted. Data were statistically analyzed using the Fisher's exact test.Results:Results were statistically significant when comparing apical negative-pressure irrigation size 45 (Group 4) to positive-pressure irrigation size 35 (Group 1).Conclusion:The results of this in vitro study showed that the apical NPI method (Endovac) was more effective in removing E. faecalis from the root canal at the larger apical preparation size.
In this paper different low power 8x8 bit multipliers which are implemented with Tanner Tool v13.0 at 250MHz and 500MHz frequency with 65nm technology which is having a supply voltage 1.0v. There are different CMOS multiplier circuits are analyzed which are Array multiplier, Wallace tree multiplier, Row bypass Braun multiplier, Column bypass Braun multiplier, Row and Column bypass Braun multiplier and these multiplier are realized using bridge style full adder. All these multipliers are compared in terms of delay, power dissipation and power delay product. Simulation results show that the Array multiplier and Wallace tree multiplier using bridge style adder has less power delay product and is faster as compared to other CMOS multipliers.
Objectives: To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topography of tooth surface and interfacial gap formation at resin-tooth interface.
Material and Methods: The human molars were divided into seven groups: Diamond bur in airrotor (DA) & micromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microscopy (SEM).
Results: Interfacial gap was observed in all groups with no significant difference. SEM observations revealed CA, CCA & DA were coarser than CM, CCM, DM and SiC. SEM of etched tooth surfaces revealed complete removal of amorphous smear layer in CA & CM, partial removal in CCA, CCM, DA & DM and no removal in SiC.
Conclusions: Selecting an appropriate bur and its speed may not play an important role in bonding in terms of interfacial gap formation. Variable changes were observed in surface topography with different burs before and after acid etching.
Key words:Surface topography, resin-tooth interface, interfacial gap, bonding.
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