The influence of working length on the reduction of biofilm and planktonic bacteria in oval canals with reciprocating instrumentation

Arieth Cristina Sacomani ,Marcos Frozoni,Adriana De Jesus Soares,Fernanda Tessaro Cintra

doi:10.33448/rsd-v10i5.14765

Arieth Cristina Sacomani , Marcos Frozoni + Show 2 more

Open Access

https://doi.org/10.33448/rsd-v10i5.14765

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Abstract

To evaluate the influence of reciprocating single-file instrumentation with different working lengths (WL) on the reduction of planktonic bacteria and bacterial biofilm in Enterococcus faecalis-contaminated oval root canals. Methodology: Fifty-five human single-rooted canines were used. Fifty were inoculated with E. faecalis for 21 days for biofilm formation. To confirm the formation of biofilm adhered to the root canal wall, 5 contaminated samples from positive control group were analyzed by SEM. Samples were assigned into 3 groups (n = 15) according to working length determined, G+1 root canal preparation 1 mm beyond the apical foramen, G0 root canal preparation at the major foramen, and G-1 root canal preparation 1 mm short of the major foramen. Five roots were not inoculated to serve as a negative control. Bacteriological samples were collected prior to preparation, initial collection (S1), and after reciprocating instrumentation (S2) by disaggregating biofilm to quantify the reduction of planktonic bacteria and intracanal biofilm at different WL. Bacterial quantitation was performed using colony-forming units per milliliter (CFU / mL) count. Statistical analysis was performed at the significance level of 0.05. Results: No bacterial growth was observed in the negative control. All positive controls demonstrated bacterial growth; S1 from all teeth were positive for bacteria with no significant difference. The post-hoc analysis showed G+1 promoting a significantly higher disinfection than G-1 (p<0,05) and G-1 similar disinfection to G0 (P=962). Conclusion: Instrumentation as close as possible to major foramen or beyond it improves decontamination in oval root canals with reciprocating instrumentation.

Highlights

The success of root canal therapy in teeth presenting with necrotic pulps is based on the proper disinfection of the entire root canal system
While planktonic bacteria are removed during root canal instrumentation and irrigation, the removal of biofilm is of great challenge
In the positive control group, the bacterial counting showed no bacteria in the S2 counting

Summary

Introduction

The success of root canal therapy in teeth presenting with necrotic pulps is based on the proper disinfection of the entire root canal system. The persistence of the infection after the treatment is completed might risk the healing or lead to the appearance of apical periodontitis (RIcucci et al 2009). Bacterial infection within the root canal system involves planktonic bacteria and biofilm-organized bacteria. While planktonic bacteria are removed during root canal instrumentation and irrigation, the removal of biofilm is of great challenge. The bacteria organized in a biofilm are harbored in a polysaccharide layer, protecting them from regular irrigation. Root canal ramifications and isthmuses prevent the root canal instrumentation from reaching all of the root canal walls. It is known that the apical third is the region with more incidence of ramifications (De Deus et al 1975). Previous studies demonstrated that oval canals cannot be properly instrumented regardless of the root canal instrumentation system used (Versiani et al 2013)

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