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Clin Oral Investig. 2019 Mar 19. doi: 10.1007/s00784-019-02865-5. [Epub ahead of print]

Is it really penetration? Part 2. Locomotion of Enterococcus faecalis cells within dentinal tubules of bovine teeth.

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Clinic of Operative Dentistry, Medical Faculty Carl Gustav Carus, TU Dresden, Fetscherstr.74, 01307, Dresden, Germany.
Clinic of Operative Dentistry, Medical Faculty Carl Gustav Carus, TU Dresden, Fetscherstr.74, 01307, Dresden, Germany.
Vertriebsgesellschaft GmbH, Geistlich Biomaterials, Schneidweg 5, 76534, Baden-Baden, Germany.
Institute of Material Science, Chair for Biomaterials, TU Dresden, Technische Universität Dresden, Budapester Strasse 27, 01069, Dresden, Germany.
Institute of Lightweight Engineering and Polymer Technology (ILK), Faculty of Mechanical Engineering, Technische Universität Dresden, Holbeinstrasse 3, 01307, Dresden, Germany.



The aim of the present vitro study was to examine the question whether devitalized Enterococcus faecalis (E. faecalis) cells can migrate into dentinal tubules and if that process takes place in a time-dependent manner.


Sixty bovine root canals were incubated with devitalized and vital streptomycin-resistant E. faecalis strains after root canal enlargement (size 80, taper .02) with 3% NaOCl solution. Incubation times 7, 14, 21, 28, 35, and 42 days. Samples were processed for analysis by scanning electron microscopy (SEM) and DAPI (4',6-diamidino-2-phenylindole) staining. The penetration depth was calculated with the measurement tool of the Axio Vision program (Zeiss, Jena, Germany). Statistical analysis was performed by Kruskal-Wallis (α = 0.05) and Mann-Whitney U test (p < 0.05).


Devitalized E. faecalis strains were able to migrate into dentinal tubules. The total number and penetration depth of devitalized E. faecalis cells was lower compared to the vital suspension of E. faecalis. It was noted, that bacterial penetration was not common to all of the dentinal tubules in the vital E. faecalis control and especially in the devitalized control. The migration took place in a time-dependent migration characteristic.


Devitalized E. faecalis cells are still able to migrate into the dentinal tubules due to possible electrokinetic and osmotic processes. Thereby, increased exposure times lead to a time-dependent penetration characteristic.


Since devitalized bacteria can migrate as well into dentinal tubules, the presence of bacteria within dentinal tubules cannot be interpreted as a failure of tested preparation regimens.


Bacterial penetration; DAPI method; Dentinal tubules; Devitalized bacteria; E. faecalis cells; Root canal


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