Efficacy of calcium hydroxide, Er:YAG laser or gaseous ozone against Enterococcus faecalis in root canals

To evaluate the efficacy of Ca(OH)2, Er:YAG laser or gaseous ozone (either alone or combined with instrumentation and various irrigants) against Enterococcus faecalis in root canals.

180 extracted, human, single-rooted teeth were divided into four groups of 45 teeth each. In Group 1 root canal enlargement up to ISO-size 60 (MAF) was performed, whereas only initial shaping (MAF ISO-size 40) was carried out in Groups 2 to 4. After sterilization all teeth were inoculated with E. faecalis and incubated for 3 days, followed by evaluation of CFU. Subsequently, root canal enlargement up to ISO-size 60 was performed in Groups 2 to 4 using NaCl solution (0.9%) in Group 2, NaOCl (1%) in Group 3 and CHX (0.2%) in Group 4. Finally, each group of 45 teeth was subdivided into three groups (n= 15 each) either applying Ca(OH)2 for 7 days, using Er:YAG laser radiation for 30 seconds or gaseous ozone for 120 seconds, followed by final evaluation of CFU.

Both in Groups 1 and 2 the median reduction of bacteria after application of Ca(OH)2 (factor 10(4) each) and ozone (in Group 1: factor 5 x 10(3); in Group 2: factor 5 x 10(4)), respectively, was significantly higher than after Er:YAG laser treatment (factor 102 each, Mann-Whitney test). The antibacterial efficacy was significantly increased by the additional use of NaOCl or CHX as irrigants in all subgroups (Groups 3 and 4) compared to corresponding subgroups of Group 1 (Mann-Whitney test).