Bacteria prior to root filling: comparison between Oslo and Montpellier

Methods: Over a period of 11 weeks, 56 samples were collected from root canals of patients treated by French and Norwegian students. These samples were analyzed by anaerobic culture and DNA-DNA hybridization.

Results: More positive cases were found in Montpellier (17/28) than in Oslo (7/28) but without statistical differences (p=0.15). There were significantly more positive cases for necrotic pulp and retreatment in Montpellier than in Oslo (p=0.005). With vital pulps, no difference was found. Students in the last academic year had significantly more positive cases than less experienced students (p=0.03 and OR=4.76). With the Checkerboard technique, no significant difference between the schools was found.

Conclusions: The relatively high frequency of positive cultures prior to root filling points to a need for reinforcement of aseptic measures in both schools. The systematic use of calcium hydroxide and possibly greater emphasis on asepsis in Oslo may explain the observed differences between the schools.