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Updated: Oct 2, 2025
Oral Biofilm Sampling for Microbiome Analysis in Healthy Children
Published on: December 31, 2017
Improving the microbial sampling and analysis of secondary infected root canals by passive ultrasonic irrigation
Milena Kluge1, Johanna Trüschler2, Fadil Elamin3
1Department of Orthodontics and Dentofacial Orthopaedics, Dental School, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. milena.kluge@med.uni-heidelberg.de.
Objective:
The persistence of pathogenic microorganisms in root canals is the most common reason for the failure of root canal treatment and the necessity of a root filling treatment, which results in an uncertain prognosis due to technical complexity and the variety of highly adaptable microorganisms. This study evaluated the effect of passive ultrasonic irrigation (PUI) on the outcome of the microbial analysis of root canal-treated teeth with persistent or recurrent apical inflammation in vivo.
Materials And Methods:
Sample collection was performed after root filling removal (sample S1, control group) and after PUI with NaCl (sample S2) using sterile paper points. In total, 19 samples were obtained. Quantification was performed by means of serial dilution of the samples. Subcultivated pure cultures were identified using MALDI-TOF MS complemented by the Vitek-2-System or PCR, followed by sequencing of the 16S rRNA gene. The results of the samples (S1 and S2) were evaluated regarding their bacterial count and composition.
Results:
The total count of bacteria and the number of aerobic/facultative anaerobic microorganisms significantly increased in the S2-samples after application of PUI. The number of obligate anaerobic microorganisms showed an increase after PUI, although it was not significant. We detected 12 different aerobic/facultative anaerobic microorganisms before PUI, and in 21 cases after PUI. Two different obligate anaerobic microorganisms were found in S1 samples compared to nine different species in S2 samples.
Conclusions:
PUI is a powerful method for detaching bacteria in infected root canals and enables a more precise analysis of the etiology of persistent endodontic infections.
Clinical Relevance:
This study indicates that PUI exerts a positive cleansing effect and adds to the accessibility of microorganisms during the application of bactericidal rinsing solution in root canal treatments.
Insights
Passive ultrasonic irrigation (PUI) effectively dislodges bacteria from root canals, improving microbial analysis for persistent endodontic infections. This method enhances the detection of diverse microorganisms, aiding in understanding treatment failures.
Area of Science:
- Endodontology
- Microbiology
- Infectious Diseases
Background:
- Root canal treatment failure is often due to persistent microorganisms, leading to apical inflammation.
- Accurate identification of these microorganisms is crucial for understanding and managing treatment failures.
Purpose of the Study:
- To evaluate the impact of passive ultrasonic irrigation (PUI) on microbial analysis outcomes in root canal-treated teeth with persistent apical inflammation.
- To assess PUI's effectiveness in detaching bacteria for more precise etiological analysis.
Main Methods:
- Samples were collected from root canals before and after PUI with NaCl using sterile paper points.
- Bacterial quantification involved serial dilution, with identification via MALDI-TOF MS, Vitek-2-System, and 16S rRNA gene sequencing.
- Analysis focused on bacterial count and composition changes.
Main Results:
- PUI significantly increased the total bacterial count and the prevalence of aerobic/facultative anaerobic microorganisms.
- A notable increase in detected species was observed post-PUI, from 12 to 21 aerobic/facultative anaerobic types.
- The diversity of obligate anaerobic microorganisms also increased significantly after PUI.
Conclusions:
- Passive ultrasonic irrigation is a potent method for detaching bacteria from infected root canals.
- PUI enhances the accessibility of microorganisms, leading to more accurate microbial analysis and etiological understanding of persistent endodontic infections.
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