The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study

• Published in: International endodontic journal Vol. 57; no. 6; pp. 700 - 712
• Main Authors: Macedo, Fernanda Piffer Garcia, Soares, Adriana de Jesus, Marceliano‐Alves, Marília Fagury Videira, Martinez, Elizabeth, Lopes, Ricardo, Bastos, Luan Ferreira, Nascimento, Wayne Martins, Limoeiro, Ana Grasiela, Frozoni, Marcos
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-06-2024; Wiley
• Subjects: Bacteria; Biofilms; Candida albicans; Computed tomography; Decontamination; Dental roots; Endodontics; Enterococcus faecalis; Life Sciences; Mandible; microtomography; Molars; Root canals; Scanning electron microscopy; Sodium hypochlorite; Standardization; Statistical analysis; Candida albicans; Enterococcus faecalis; endodontics; microtomography
• ISSN: 0143-2885; 1365-2591
• DOI: 10.1111/iej.14052

Aim
To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape.
Methodology
After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical–mechanical preparation and bacterial counts were determined (CFU/mL). The final micro‐CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal–Wallis, Student–Newman–Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games–Howell test were used for analysis of micro‐CT data and Spearman's test for correlations (α = 5%).
Results
All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05).
Conclusion
The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.