Materials and Methods: Sixty freshly extracted maxillary incisors teeth collected in saline. Access cavity prepared and canals were made free of bacterial and pulp. The teeth were mounted on the bacteria collecting apparatus. Root canals were contaminated with the Fusobacterium Nucleatum (ATCC25586) and dried at 37°C for 24 h. In Group 1 (Control group): No instrumentation was done and biomechanical preparation done in all other groups with Group 2: Hand K-files, Group 3: Protaper gold, Group 4: K3XF, Group 5: Edge taper platinum, and Group 6: Hyflex CM rotary file systems. Then, the extrude was collected, and it is incubated in Mueller-Hinton agar for 24 h and the number of colony forming units were counted and statistical comparison was done using Kruskal-Wallis test and Mann-Whitney U test.

Results: Hand K-files extruded more bacteria when compared to other four rotary systems, K3XF file system extruded least number of bacteria.

METHOD: Twenty pieces of fourth-generation, biomechanical testing grade, left third metacarpal composite bones were used. Resin was used to create the holding block at both ends of the bone. An oscillating saw with 0.8 mm thick saw blade was used to osteotomize the metacarpal sawbones to create a midshaft transverse metacarpal fracture model. Ten pieces were fixed with a 2.0 mm titanium locking plate via unicortical screw purchase and 10 were fixed with a 2.0 mm, four holes, titanium dynamic compression plate, bicortical purchase of screws. They were subjected to cyclic load to failure testing three-point bending and torsion.

RESULTS: There were no significant difference in stiffness and cyclic three-point bending to failure between the unicortical locking plate group and the bicortical compression plate group. The bicortical compression plate group is stiffer and has a higher cyclic bending load to failure as compared to the unicortical locking plate group.