Antibacterial Effectiveness of Calcium Hydroxide Combined with Chlorhexidine or Sodium Hypochlorite Vehicle Against Gram Positive and Gram Negative Bacteria in the Root Canal. Adding of CHX may enhance the antibacterial activity of Ca(OH)2 against klebsiella spp. as a gram negative bacteria, while adding of NaOCl enhance the bactericidal of Ca(OH)2 against both types of bacteria with interesting effect on streptococcus spp. as gram-negative bacteria. However, they were not able to produce complete eradication of bacteria. Till date, there is no literature investigate the antimicrobial...