RESUMO
The antimicrobial effectiveness of three different forms of calcium hydroxide in root canals of extracted human teeth was compared. Canals were enlarged and inoculated with S. aureus, Str. faecalis. E. coli and Ps. aeruginosa in pure forms as well as in different combinations. After treatment with the tested forms of calcium hydroxide [powder, paste and points] and sealing, the roots were incubated at 37 C. At intervals, 0 hour, 24 hour, 48 hour, 72 hour and 7 days, a set of root canals was analyzed for the viability of bacterial strains. All tested forms of calcium hydroxide exhibited similar antibacterial activity against all bacteria and bacterial mixtures included in the study. Str. faecalis was the most sensitive one [after 24 hour] followed by E. coli [after 48 hour], while S. aureus and Ps. aeruginosa as well as the mixtures used were inactivated after 72 hour exposure. A similar comparative study was done on thirty patients having single rooted teeth with necrotic pulps and indicated for root canal treatment. Intracanal culture samples were taken before canal preparation for bacterial count. Patients were divided into three groups, each group received an interappointment dressing of one form of calcium hydroxide. Cultures were repeated at 3, 7 and 10 days and the antibacterial effect of different forms was expressed as percentage reduction of the viable bacterial count compared to the baseline cultures