Elimination of E. faecalis from primary root canals using a non-instrumentation technique and rotary systems: an ex-vivo study

Background: Biofilm removal plays a key role in the long-term success of root canal therapy. This ex-vivo study aimed to compare the antibacterial efficacy of two rotary instrumentation systems (ProTaper Ultimate and Pro AF Baby Gold) and an irrigation-based non-instrumentation endodontic treatment (NIET) in eliminating Enterococcus faecalis (E. faecalis) biofilms from extracted mandibular second primary molars. Methods: A total of 45 extracted mandibular second primary molars were used. Only teeth with at least two-thirds of the root length intact and without structural anomalies were included. Five teeth served as a negative control group, while the remaining 40 were contaminated with E. faecalis and randomly assigned to four groups (n = 10) based on the preparation technique. Group 1: irrigation-only NIET; Group 2: ProTaper Ultimate; Group 3: Pro AF Baby Gold; and a positive control group (no instrumentation or irrigation) comprised the study groups. After treatment, biofilm samples were collected, and bacterial load was quantified by colony-forming unit (CFU) counting. Data were analyzed with the Kruskal-Wallis H test with Dunn’s multiple comparisons for post hoc pairwise testing and the Mann-Whitney U test. Statistical significance level was set at 0.05. Results: The median bacterial counts were 7.99 in the control group, 6.81 in Group 1, 4.73 in Group 2, and 0.00 in Group 3. Group 1 showed no significant difference from the control group (p = 0.3985), but differed significantly from Group 2 (p = 0.0031) and Group 3 (p < 0.0001). Both rotary systems effectively reduced E. faecalis biofilms, with the highest efficacy observed in Group 3. In contrast, NIET provided limited bacterial reduction. Conclusions: While NIET may be useful in pediatric patients, its limited antibacterial efficacy highlights the need for further improvement before it can be considered a reliable clinical alternative.

Enterococcus faecalis; Primary molars; Root canal treatment; Non-instrumentation endodontic treatment

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